+---------------------------------+------------------------------------+
| ![](media/image1.wmf            | **Advisory**                       |
| ){width="0.38472222222222224in" |                                    |
| height="0.3645833333333333in"}  | **Circular**                       |
|                                 |                                    |
| U.S. Department                 |                                    |
|                                 |                                    |
| of Transportation               |                                    |
|                                 |                                    |
| **Federal Aviation**            |                                    |
|                                 |                                    |
| **Administration**              |                                    |
+---------------------------------+------------------------------------+

+---------------------------------+-----------------+-----------------+
| **Subject:** Number range       | **Date:**       | **AC No:**      |
| CHAPTERGeneral Guidance and     | 9/15/2007       | 150/5300-16A    |
| Specifications for Aeronautical |                 |                 |
| Surveys: Establishment of       | **Initiated     | **Change:**     |
| Geodetic Control and Submission | by:** AAS-100   |                 |
| to the National Geodetic Survey |                 |                 |
+---------------------------------+-----------------+-----------------+

# Purpose of this Advisory Circular (AC).

This AC explains the specifications for establishing geodetic control on
or near an airport. It also describes how to submit the information to
the National Geodetic Survey (NGS) for approval and inclusion in the
National Spatial Reference System (NSRS) in support of aeronautical
information surveys.

# Audience. 

Engineering and surveying companies contracted by state aviation
agencies or local airport authorities to perform an aeronautical
information survey of an airport should read this AC thoroughly and
other related advisory circulars before commencing an airport project.

# Application.

The Federal Aviation Administration and the NGS Aeronautical Survey
Program recommend the guidance and specifications in this AC for
establishing on-airport geodetic control and submitting it to NGS for
approval and inclusion in the NSRS in support of aeronautical
information surveys. This AC does not constitute a regulation and in
general is not mandatory. However, use of these guidelines is mandatory
for surveys that are funded under Federal grant assistance programs. It
also provides one, but not the only, acceptable means of meeting the
requirements of Title 14 Code of Federal Regulations (CFR) part 139,
*Certification of Airports.* Mandatory terms such as "must" apply only
to those who conduct aeronautical information surveys using Airport
Improvement Program (AIP) or Passenger Facility Charge Program (PFC)
funds or those who seek to demonstrate compliance by use of the specific
method described by this AC.

# d. Cancellation. 

This AC cancels AC 150/5300-16, General Guidance and Specifications for
Aeronautical Surveys: Establishment of Geodetic Control and Submission
to the National Geodetic Survey, dated February 13, 2006.

# e. Principal Changes. 

The implementation of Wide Area Augmentation System (WAAS) Localizer
Performance with Vertical Guidance (LPV) instrument approaches make
additional airport surveying guidance necessary. To accommodate these
LPV approaches, this revision includes the following principal changes:

-   Assigns responsibility for determining which airports require
    permanent geodetic control to FAA Regional Airports Divisions in
    Paragraph 2.2.1.

-   Specifies when FAA Regional Airports Divisions can allow temporary
    airport control and how that control should be established in
    Paragraph 2.2.2.

-   Updates the current NGS Geoid model from Geoid03 to Geoid06 for
    Alaska.

-   Clarifies requirements for Secondary Airport Control Station (SACS)
    adjustment processing in Paragraph 8.9.7.

![](media/image2.png){width="2.5881944444444445in"
height="0.6041666666666666in"}

David L. Bennett

Director, Airport Safety and Standards

[1. INTRODUCTION](#_Application.) [1](#_Application.)

[2. ADMINISTRATION. 2](#__RefHeading___Toc123539216)

[2.1. SPECIFICATIONS 2](#__RefHeading___Toc123539217)

[2.2. AIRPORTS REQUIRING GEODETIC CONTROL MONUMENTATION.
2](#airports-requiring-geodetic-control-monumentation.)

[2.2.1. PERMANENT CONTROL 2](#a_Hlt6902967_221)

[2.2.2. TEMPORARY CONTROL. 3](#a_Hlt6902967_222)

[2.3. DEFINITIONS 2](#__RefHeading___Toc123539218)

[2.3.1. TERMINOLOGY 2](#__RefHeading___Toc123539219)

[2.3.2. MEASUREMENTS. 3](#__RefHeading___Toc123539220)

[2.4. GENERAL REQUIREMENTS 3](#__RefHeading___Toc123539221)

[2.5. MODIFICATIONS 3](#__RefHeading___Toc123539222)

[2.6. UNUSUAL CIRCUMSTANCES 3](#__RefHeading___Toc123539223)

[2.7. REPORTS 3](#__RefHeading___Toc123539224)

[2.7.1. WEEKLY STATUS REPORTS 3](#__RefHeading___Toc123539225)

[2.8. ORIGINAL DATA 4](#__RefHeading___Toc123539226)

[3. NATIONAL SPATIAL REFERENCE SYSTEM (NSRS)
4](#__RefHeading___Toc123539227)

[3.1. HORIZONTAL CONTROL 5](#__RefHeading___Toc123539228)

[3.2. VERTICAL REFERENCE 5](#__RefHeading___Toc123539229)

[3.3. GEOID MODEL 5](#__RefHeading___Toc123539230)

[4. REFERENCES AND GLOSSARY. 5](#references-and-glossary.)

[4.1. REFERENCES 5](#__RefHeading___Toc123539232)

[4.2. GLOSSARY 6](#__RefHeading___Toc123539233)

[5. QUALITY CONTROL 8](#quality-control.)

[5.1. QUALITY CONTROL PLAN 8](#__RefHeading___Toc123539235)

[6. DATA FORMATS 8](#__RefHeading___Toc123539236)

[6.1. ORIGINAL DATA 8](#__RefHeading___Toc123539237)

[6.2. FINAL DATA 9](#__RefHeading___Toc123539238)

[7. DATA MEDIUM AND FILE NAMING CONVENTION
9](#__RefHeading___Toc123539239)

[7.1. DATA MEDIUM 9](#__RefHeading___Toc123539240)

[7.2. FILE NAMING CONVENTION FOR GPS GROUND SURVEYS
9](#__RefHeading___Toc123539241)

[8. SURVEY WORK 9](#__RefHeading___Toc123539242)

[8.1. PURPOSE 9](#__RefHeading___Toc123539243)

[8.2. RECONNAISSANCE 9](#__RefHeading___Toc123539244)

[8.2.1. CONTROL STATIONS 9](#__RefHeading___Toc123539245)

[8.2.2. DATABASE SEARCH 10](#__RefHeading___Toc123539246)

[8.2.3. CONTACT WITH AIRPORT AUTHORITIES
10](#__RefHeading___Toc123539247)

[8.2.4. MARK RECOVER 11](#__RefHeading___Toc123539248)

[8.2.5. BENCH MARK SPIRIT LEVEL TIES 1](#A_825)3

[8.2.6. VISIBILITY 13](#__RefHeading___Toc123539249)

[8.2.7. NATIONAL SPATIAL REFERENCE SYSTEM (NSRS) TIES
13](#__RefHeading___Toc123539250)

[8.2.8. STATION LOCATION SKETCH AND VISIBILITY DIAGRAM
13](#__RefHeading___Toc123539251)

[8.2.9. PENCIL RUBBINGS 14](#__RefHeading___Toc123539252)

[8.2.10. PHOTOGRAPHS 14](#__RefHeading___Toc123539253)

[8.2.11. PROPOSED NEW STATION SITES 21](#__RefHeading___Toc123539254)

[8.2.12. GPS POSITIONS 21](#__RefHeading___Toc123539255)

[8.3. PROJECT SURVEY PLAN 22](#__RefHeading___Toc123539256)

[8.4. SELECTION GUIDELINES FOR AIRPORT GEODETIC CONTROL SURVEYS
23](#selection-guidelines-for-airport-geodetic-control-surveys)

[8.4.1. REQUIREMENTS 23](#__RefHeading___Toc123539258)

[8.4.2. MONUMENT SELECTION 23](#__RefHeading___Toc123539259)

[8.4.3. USE OF EXISTING STATIONS 24](#__RefHeading___Toc123539260)

[8.4.4. MONUMENT ACCESSIBILITY. 25](#monument-accessibility.)

[8.4.5. MONUMENT SITING CONSIDERATIONS 25](#__RefHeading___Toc123539262)

[8.4.6. PACS AND SACS PROXIMITY TO OTHER AIRPORT FEATURES
25](#__RefHeading___Toc123539263)

[8.4.7. INTERVISIBILITY CHOICES FOR PACS and SACS
26](#__RefHeading___Toc123539264)

[8.5. MONUMENT STABILITY 26](#__RefHeading___Toc123539265)

[8.6. MARK SETTING. 27](#__RefHeading___Toc123539266)

[8.6.1. STAMPING 28](#A_861)

[8.6.2. BRONZE DISKS 28](#__RefHeading___Toc123539267)

[8.6.3. STAINLESS STEEL ROD MARKS 30](#__RefHeading___Toc123539268)

[8.6.4 CONCRETE MARKS 37](#__RefHeading___Toc123539269)

[8.6.5. WITNESS POSTS 42](#__RefHeading___Toc123539270)

[8.7. GPS POSITIONING PROCEDURES. 42](#__RefHeading___Toc123539271)

[8.7.1. CORS SELECTION 42](#__RefHeading___Toc123539272)

[8.7.2. CTCORS SELECTION 43](#__RefHeading___Toc123539273)

[8.7.3. ACCURACY STANDARDS 44](#__RefHeading___Toc123539274)

[8.7.4. GPS OBSERVATION REQUIREMENTS 44](#__RefHeading___Toc123539275)

[8.7.5. GPS OCCUPATION AT ALL SURVEY STATIONS
53](#__RefHeading___Toc123539276)

[8.7.6. RECOMMENDED EQUIPMENT 55](#__RefHeading___Toc123539277)

[8.8. VECTOR PROCESSING 56](#__RefHeading___Toc123539278)

[8.8.1. REQUIREMENTS 56](#__RefHeading___Toc123539279)

[8.9. PACS ADJUSTMENT PROCESSING. 59](#__RefHeading___Toc123539280)

[8.9.1. SOFTWARE 59](#__RefHeading___Toc123539281)

[8.9.2. ADJUSTMENTS REQUIRED 60](#__RefHeading___Toc123539282)

[8.9.3. SOFTWARE RESULTS ACCURACY . 61](#__RefHeading___Toc123539283)

[8.9.4. NSRS TIE ACCURACY. 61](#nsrs-tie-accuracy.)

[8.9.5. BENCHMARK (VERTICAL) ACCURACY 61](#__RefHeading___Toc123539285)

[8.9.6. BLUE BOOK GUIDANCE 61](#__RefHeading___Toc123539286)

[8.9.7. SACS ADJUSTMENT PROCESSING 62](#__RefHeading___Toc123539287)

[8.10. NGS PROCEDURAL OUTLINE FOR ADJUSTING GPS DATA FOR AIRPORT
GEODETIC CONTROL SURVEYS 62](#ADJUST)

[8.11. DATA SUBMITTAL 66](#__RefHeading___Toc123539289)

[9. FINAL PROJECT REPORT 67](#final-project-report.)

[9.1. FINAL REPORT CONTENTS 67](#__RefHeading___Toc123539291)

[10. DELIVERABLES TO NGS 68](#__RefHeading___Toc123539292)

[10.1. LABOR, EQUIPMENT, AND OTHER ITEMS
68](#__RefHeading___Toc123539293)

[10.2. QUALITY CONTROL PLAN 68](#__RefHeading___Toc123539294)

[10.3. SURVEY PLAN 68](#__RefHeading___Toc123539295)

[10.4. PROJECT STATUS REPORTS 68](#__RefHeading___Toc123539296)

[10.5. PROJECT SKETCH (VECTOR DIAGRAM) 68](#__RefHeading___Toc123539297)

[10.6. FIELD LOGS 68](#__RefHeading___Toc123539298)

[10.7. VECTOR PROCESSING OUTPUT 69](#__RefHeading___Toc123539299)

[10.8. FINAL PROJECT REPORT 69](#__RefHeading___Toc123539300)

[10.9. ADJUSTMENT AND CHECKING PROGRAMS
69](#__RefHeading___Toc123539301)

[10.10. ORIGINAL DATA 69](#__RefHeading___Toc123539302)

[10.11. DESCRIPTIONS 69](#__RefHeading___Toc123539303)

[10.12. TRANSMITTAL LETTER 69](#__RefHeading___Toc123539304)

[APPENDIX 1. SURVEY DISK DIAGRAMS 71](#appendix-1.-survey-disk-diagrams)

[APPENDIX 2. NATIONAL SPATIAL REFERENCE SYSTEM
75](#appendix-2.-national-spatial-reference-system)

[APPENDIX 3. AIRPORT INTERVIEW CHECKLISTS
77](#appendix-3.-airport-interview-checklists)

[APPENDIX 4. WRITING STATION DESCRIPTIONS AND RECOVER NOTES WITH WINDESC
85](#writing-station-descriptions-and-recovery-notes-with-windesc)

[APPENDIX 5. STATION TABLE FORM 95](#appendix-5.-station-table-form)

[APPENDIX 6. EXAMPLE GPS OBSERVATION SCHEME
99](#appendix-6.-example-gps-observation-scheme)

[APPENDIX 7. INFORMATION, DATA, AND SOFTWARE AVAILABLE ON THE INTERNET
101](#appendix-7.-information-data-and-software-available-on-the-internet)

[APPENDIX 8. OUTLINE FOR PROCESSING AIRPORT GEODETIC CONTROL SURVEYS
WITH PAGE-nt
105](#appendix-8.-outline-for-processing-airport-geodetic-control-surveys-with-page-nt)

[APPENDIX 9. EXAMPLE COORDINATE COMPARISON SPREADSHEET
109](#appendix-9.-example-coordinate-comparison-spreadsheet)

[APPENDIX 10. PROJECT SUBMISSION CHECKLIST
113](#appendix-10.-project-submission-checklist)

**1. INTRODUCTION.**

Perform geodetic control surveys to establish a basic control network
for supplemental surveying, engineering, and mapping work on an airport.
The establishment of geodetic control by permanent survey monuments in
the airport vicinity is critical to the National Airspace System (NAS).
These monuments and their accurate connections to the National Spatial
Reference System (NSRS) assure accurate relativity between surveyed
points on an airport and between these points and other surveyed points
and facilities in the NAS, including the navigation satellites. This
geodetic control consists of a Primary Airport Control Station (PACS)
and two or more Secondary Airport Control Stations (SACS) tied to the
NSRS. These survey marks must be used for future aeronautical and
engineering projects related to runway/taxiway construction,
navigational aid siting, obstruction clearing, road building, and other
airport improvement activities. This document provides guidance and
specifications for establishing the geodetic control and submitting the
data to National Geodetic Survey (NGS) for publication. AC 150/5300-18
identifies the required data, collection methodologies, and accuracies
required for the collection of aeronautical information.

![](media/image3.jpeg){width="5.804861111111111in"
height="4.304861111111111in"}

Figure 1.1. Illustrates the connection of the airport to other portions
of a control network.

[]{#__RefHeading___Toc123539216 .anchor}**2. ADMINISTRATION.**

[]{#__RefHeading___Toc123539217 .anchor}**2.1. SPECIFICATIONS.** This AC
outlines the Federal Aviation Administration (FAA) requirements for
on-airport geodetic control and provides general guidance and
specifications for establishing this control on airports. The
requirements for reporting deviations, unusual circumstances, and other
issues described in the following paragraphs apply to these general
specifications.

## 2.2. AIRPORTS REQUIRING GEODETIC CONTROL MONUMENTATION. 

[]{#a_Hlt6902967_221 .anchor}**2.2.1. Permanent Control.** FAA Regional
Airports Divisions will determine which airports require permanent
geodetic control monumentation in the form of PACS or SACS based on the
activity (operational or proposed future construction) at the airport.
However, for all airports in the National Plan of Integrated Airport
Systems (NPIAS), we strongly recommend that at least the PACS be
established.

[]{#a_Hlt6902967_222 .anchor}**2.2.2. Temporary Control.** Where it is
not reasonable from a cost perspective to establish permanent control at
the airport, the Regional Airports Division may allow temporary airport
control to be established and tied to the NSRS through the use of the
NGS Online User Positioning System (OPUS).

Contracted surveyors should observe the following practices when using
the OPUS to establish temporary airport control:

a.  Establish two independent but intervisible marks on an airport as a
    conformity check and perform redundant observations.

b\. Observe each mark in two continuous and independent sessions of at
least 4 hours and submit these observations to the NGS OPUS site at
[[http://www.ngs.noaa.gov/OPUS/]{.underline}](http://www.ngs.noaa.gov/OPUS/).

c\. Review and follow all other NGS requirements outlined for use of the
OPUS.

d\. Include results of the OPUS sessions in the project report and final
deliverables.

[]{#__RefHeading___Toc123539218 .anchor}**2.3. DEFINITIONS.** This AC
makes use of the following conventions.

[]{#__RefHeading___Toc123539219 .anchor}**2.3.1. TERMINOLOGY.** The verb
"*must*" means that compliance is required. The verb "*should*" denotes
a recommendation. The contraction "*N/A*" means not applicable. The term
"*position*" means horizontal position specified as latitude and
longitude unless stated otherwise. The term "*elevation*" means the
distance of a point above a specified datum, measured along the
direction of gravity. The term "*vertical*" refers to the direction in
which the force of gravity acts. The term *"height"* means the distance,
measured along a perpendicular, between a point and a datum. The term
"*observation*" means the survey observations resulting in a position
and/or elevation for the survey mark in question, whether the mark is an
existing mark or a newly set mark. The term "set" means physically
constructed.

[]{#__RefHeading___Toc123539220 .anchor}**2.3.2. MEASUREMENTS.** Use the
U.S. Survey Foot (3.28083333333 feet = 1 meter) for any length
conversions or as required by state law. If using a conversion factor
other than the U.S. survey Foot, identify the conversion factor used and
the reason in the Survey Plan.

[]{#__RefHeading___Toc123539221 .anchor}**2.4. GENERAL REQUIREMENTS.**
The selected Contractor must provide all labor, equipment, supplies,
material, and transportation to produce and deliver data and related
products as required by this AC.

[]{#__RefHeading___Toc123539222 .anchor}**2.5. MODIFICATIONS.** The
Contractor must submit in writing requests for modifications to or
deviations from these specifications to the contract issuing authority,
NGS, and FAA points of contact (POCs) as soon as a need for them is
identified.

[]{#__RefHeading___Toc123539223 .anchor}**2.6. UNUSUAL CIRCUMSTANCES.**
The Contractor must notify the contract issuing authority of any unusual
circumstances occurring during the performance of the tasks identified
by this AC that affect the deliverables or their quality (see Section
5). The contract issuing authority, in turn, must notify FAA Airport
Surveying-GIS Program Manager and NGS Point of Contacts (POC).

[]{#__RefHeading___Toc123539224 .anchor}**2.7. REPORTS.** Thorough
reporting is required. The Contractor must submit a weekly project
status report, a Quality Control Plan (see Section 5), a Project Survey
Plan (see paragraph 9.3), and a Final Project Report (see Section 10) to
the contract issuing authority. The airport sponsor/proponent or
designated representative will send all required report submittals and
documents to the FAA Airport Surveying-GIS Program Manager, who will
forward it to NGS.

[]{#__RefHeading___Toc123539225 .anchor}**2.7.1. WEEKLY STATUS
REPORTS.** The Contractor must submit project status reports via email
every Monday afternoon by 2:00 P.M. Eastern Time, from the date of the
contract start until the work is complete. These reports must include
the following:

a.  Percentage complete for each major project task.

b.  Status of other work.

c.  Completion or expected completion dates for each task.

d.  Any unusual circumstances and/or deviations from the guidance in
    this AC.

This report should be brief, up to date, and include the prime
Contractor's firm name. These reports must break the work into phases to
allow for tracking the project's progress. The following example is a
suggested format; however, the percentage complete and completion date
are required fields. An "X" or other similar mark in the last column is
used to indicate a change in the task status since the last report.

Table 2.1. Sample Weekly Email Status Report.

  ----------------- ------------- ---- -------------- -------------- --------------
  Project Title:    ABC Regional                                     
                    Airport                                          
                    Obstruction                                      
                    Chart Survey                                     

  Contracted Firm   XYZ                                              
  Name:             Engineering                                      

  Project Manager's Joe Doe                                          
  Name:                                                              

  Project Manager's P.E                                              
  Position:                                                          

  Report Date:      MM/DD/YYYY                                       

  Task              Percentage         Date Completed NGS Approval   Updated from
                    Complete           or Estimated   Date           last report
                                       Completion                    
                                       Date                          

  Reconnaissance    100           \%   Dec 01, 2004   Dec 06, 2004   

  Survey Plan       100           \%   Dec 12, 2004   Dec 18, 2004   

  Mark Setting      90            \%   Feb 01, 2004                  X

  Observations      20            \%   Feb 15, 2004                  X

  Vector Processing               \%                                 

  Adjustment                      \%                                 
  Processing                                                         

  Final Project                   \%                                 
  Report                                                             

  Quality Control                 \%                                 

                                  \%                                 

  Additional                                                         
  Comments: In this                                                  
  section, provide                                                   
  any required                                                       
  additional                                                         
  comments, unusual                                                  
  circumstances                                                      
  encountered, or                                                    
  approved                                                           
  modifications or                                                   
  deviations from                                                    
  this AC. Be sure                                                   
  to include                                                         
  comments on any                                                    
  changed items                                                      
  indicated in the                                                   
  matrix.                                                            
  ----------------- ------------- ---- -------------- -------------- --------------

[]{#__RefHeading___Toc123539226 .anchor}**2.8. ORIGINAL DATA.**
Observation logs and other original records generated during this
project are legal records and must be retained for data accountability
by the Airport Authority. NGS will receive a copy of the original data
for quality assurance purposes. Original logs and records must be
submitted and must be legible, neat, clear, accurate, and completed in
indelible black ink. Original data must be saved, unmodified, in
hand-written or electronic form. In the original records (paper or
digital), nothing is to be erased or obliterated. All available spaces
on the recording forms should be completed. If a mistake is made on a
form, draw a single line through the mistake (e.g., ~~as demonstrated
here~~), and write the correction above or to the side. If space is too
limited to permit a field correction, restart with a new log sheet;
however, do not recopy the form in the office in order to make a "clean"
copy. An explanatory note should be made for all corrections to the
original recorded figures. It is essential for all hand-recorded
information to be neat and legible. All editing of electronic data must
be done on a copy of the original. Submit the original version of the
data, not a handmade copy, photocopy, or digital copy.

[]{#__RefHeading___Toc123539227 .anchor}**3. NATIONAL SPATIAL REFERENCE
SYSTEM (NSRS).**

All surveying and positioning must be tied to the NSRS. For further
information about the NSRS, refer to Appendix 2.

[]{#__RefHeading___Toc123539228 .anchor}**3.1. HORIZONTAL CONTROL.** The
only nationally recognized horizontal datum is North American Datum of
(NAD) 83 (YYYY), where YYYY is the year of the most recent observations.
Note: The year of observations is on the NGS datasheet next to the
latitude and longitude.

[]{#__RefHeading___Toc123539229 .anchor}**3.2. VERTICAL REFERENCE.** Use
North American Vertical Datum (NAVD) 88. For information on NAVD 88,
refer to the following website[:]{.underline}
<http://www.ngs.noaa.gov/PUBS_LIB/NAVD88/navd88report.htm>.

In Alaska and other areas outside the continental United States where
NAVD 88 bench marks are not available, make GPS ties to tidal bench
marks within the project area.

[]{#__RefHeading___Toc123539230 .anchor}**3.3. GEOID MODEL.** Use the
most recent NGS model, currently GEOID03 for contiguous 48 locations
found at <http://www.ngs.noaa.gov/PC_PROD/GEOID03/> and Geoid06 for
locations in Alaska. For information on these models, see
http://www.ngs.noaa.gov/PC_PROD/pc_prod.shtml.

For explanations of many of the terms in Section 4 of this AC, see
<http://www.ngs.noaa.gov/faq.shtml>.

# 4. REFERENCES AND GLOSSARY.

[]{#__RefHeading___Toc123539232 .anchor}**4.1. REFERENCES.**

a\. Input Formats and Specifications of the National Geodetic Survey
Data Base, the "Blue Book." Available online at
[http://www.ngs.noaa.gov/FGCS/BlueBook/]{.underline}.

b\. Station Location Sketch and Visibility Obstruction Diagram. For
information about the diagram, see
[http://www.ngs.noaa.gov/PROJECTS/FBN/]{.underline} (click on "Forms",
then "Visibility Obstruction Diagram").

c\. National Oceanic and Atmospheric Administration (NOAA) Manual
National Ocean Service (NOS) NGS 1, *Geodetic Bench Marks.* Available
online at
[http://www.ngs.noaa.gov/PUBS_LIB/GeodeticBMs.pdf]{.underline}.

d\. NGS National Continuously Operating Reference Station (CORS) System.
For information on CORS, see
[http://www.ngs.noaa.gov/CORS/]{.underline}.

e\. High Accuracy Reference Network (HARN). For more information on
HARN, see [http://www.ngs.noaa.gov:80/faq.shtml]{.underline}.

f\. Interim Federal Geodetic Control Subcommittee (FGCS) Specifications
and Procedures to Incorporate Electronic Digital/Bar-Code Leveling
Systems, version. 4.0, 15 Jul 94.

g\. Standards and Specifications for Geodetic Control Networks, FGCC,
1984.

h\. NOAA Manual NOS NGS 3, Geodetic Leveling, 1981.

i\. File Naming Convention. See paragraph 7.2.

j\. FAA Airport Identifiers. See
http://www.faa.gov/atpubs/lid/lidhme.htm.

[]{#__RefHeading___Toc123539233 .anchor}**4.2. GLOSSARY.** *Geodetic
Glossary,* NGS, 1986 (not available online). For a printed copy, contact
NGS at (301) 713-3242 or email <info_center@ngs.noaa.gov>.

ANA---Area Navigation Approach.

AZ MK---Azimuth Mark. A marked point established in connection with a
triangulation (or traverse) station to provide a starting azimuth for
dependent surveys. Keep in mind that some azimuth marks also were
positioned, and some have an underground disk. The azimuth mark is
usually a pre-stamped survey disk, generally 1/4 to 2 miles from the
horizontal station. The next consecutive azimuth mark number was used if
an earlier number was destroyed. See Appendix 1.

BM---Bench Mark.

CBN---Cooperative Base Network (NGS).

CTCORS---Central Temporary Continuously Operating Reference Station. A
permanently monumented control station established near the center of a
300 km (radius) survey area (as defined elsewhere in this document)
functioning as a temporary Continuously Operating Reference Station
(CORS).

CORS---Continuously Operating Reference Station. A permanent GPS
facility whose GPS receiver provides observables from the GPS
satellites, allowing stations occupied temporarily by GPS receivers to
be differentially positioned relative to it. CORS are related to the
North American Datum of 1983 (NAD 83) coordinate system at the 1 to 3
centimeter level either by being collocated at VLBI sites used to define
the system or by being differentially positioned relative to such a
collocated GPS station.

DISK---A thin metal plate about 9 cm in diameter with a stem attached to
the center of the bottom. The plate is slightly convex (in vertical) and
usually round (in horizontal) and contains the mark for which survey
information is known or to be determined. The plate usually also
contains a designation, year, and the name of the agency setting the
plate. It is usually made of bronze, brass, or aluminum and may be set
in a drill hole or embedded in concrete.

DOD---Department of Defense.

FAA---Federal Aviation Administration.

FBN---Federal Base Network (NGS).

FGCC---Federal Geodetic Control Committee (Changed to FGCS in October
1990).

FGCS---Federal Geodetic Control Subcommittee.

GPS---Global Positioning System.

HARN---High Accuracy Reference Network.

ITRF---International Terrestrial Reference Frame.

MARK---(1) A dot, the intersection of a pair of crossed lines, or any
other physical point corresponding to a point in a survey; (2) the
object, such as a disk, on which the mark (1) is placed; (3) the entire
monument, consisting of the mark (1), the object on which it occurs (2),
and the structure to which the object is fastened.

MONUMENT---A structure that marks the location of a point determined by
surveying. In the case of a disk in concrete, the monument would be the
entire structure. Mark, monument, and station can mean the same thing.

NAD 27---North American Datum of 1927.

NAD 83---North American Datum of 1983.

NAVD 88---North American Vertical Datum of 1988.

NGS---National Geodetic Survey, NOAA. Disks inscribed with this name
have been set from 1970 to the present.

NGVD 29---National Geodetic Vertical Datum of 1929.

NOAA---National Oceanic and Atmospheric Administration. No survey disks
have been set with this name.

NOS---National Ocean Survey, NOAA. Disks inscribed with this NOS name
were set from about 1970 to December 3, 1982.

NOS---National Ocean Service. Disks inscribed with this NOS name were
set from about 1983 to the present.

NSRS---National Spatial Reference System.

PACS---Primary Airport Control Station.

RM---Reference Mark. A survey mark of permanent character close to a
survey station to which it is related by an accurately measured distance
and azimuth. For a triangulation station, reference marks are
pre-stamped survey disks, usually within 30 meters (one tape length) of
the triangulation station. Standard procedure was to set two reference
marks, numbered clockwise from north, with the next consecutive
reference number used if an earlier number was destroyed. See Appendix
1.

SACS---Secondary Airport Control Station.

STATION---A physical location or site at which, from which, or to which
survey observations have been made. See Mark and Monument.

USACE---U.S. Army Corps of Engineers (Blue Book abbreviation is USE).

USCG---U.S. Coast Guard.

USC&GS---U.S. Coast and Geodetic Survey. Disks inscribed with USC&GS
were set from about 1900 to 1970. Over 10 different pre-stampings were
used (Bluebook abbreviation is CGS).

USE---U.S. Army Corps of Engineers or U.S. Engineers Department (old
acronym; present Blue Book abbreviation).

WAAS---Wide Area Augmentation System (FAA).

WGS 84---World Geodetic System 1984.

# 5. QUALITY CONTROL.

Check all data to ensure it is complete, reliable, and accurate. The
Contractor's personnel must become thoroughly familiar with this AC, the
Appendixes, the definitions of surveying terms, and the material covered
in the other references and publications, as required. See Section 4 for
References and Glossary.

[]{#__RefHeading___Toc123539235 .anchor}**5.1. QUALITY CONTROL PLAN.**
Submit a Quality Control Plan (QCP) covering all project tasks prior to
beginning survey work on this project. The QCP must describe how the
Contractor will meet the technical specifications required for the
project. The QCP must include at least the following elements: a check
of all manual computations (including check marks and initials), a check
of all manual data computer entries, a check of file formats, and a
check of all reports and data submitted. The Contractor must also
describe how data will be backed up and how the Contractor will ensure
original data is not modified. See paragraph 8.3, "Project Survey Plan",
and Section 11, "Deliverables to NGS". Comments on quality control and a
copy of the Quality Control Plan must be included in the Final Project
Report.

[]{#__RefHeading___Toc123539236 .anchor}**6. DATA FORMATS.**

[]{#__RefHeading___Toc123539237 .anchor}**6.1. ORIGINAL DATA.**
Original, raw digital data must be submitted and their formats must be
documented in the Final Project Report. Original paper records must also
be submitted; see paragraph 2.7. Observations for positioning PACS and
SACS must be submitted in Blue Book format. See paragraph 4.1a.

[]{#__RefHeading___Toc123539238 .anchor}**6.2. FINAL DATA.** Final
project data must be submitted in Blue Book format or in the appropriate
formats specified by this AC (for example, digital photographs).

[]{#__RefHeading___Toc123539239 .anchor}**7. DATA MEDIUM AND FILE NAMING
CONVENTION.**

[]{#__RefHeading___Toc123539240 .anchor}**7.1. DATA MEDIUM.** Submit the
data for review and approval on a CD-ROM or other pre-approved medium.

[]{#__RefHeading___Toc123539241 .anchor}**7.2. FILE NAMING CONVENTION
FOR GPS GROUND SURVEYS.** See the naming convention for Federal Base
Network (FBN) projects on the NGS website at
<http://www.ngs.noaa.gov/PROJECTS/FBN/>.

[]{#__RefHeading___Toc123539242 .anchor}**8. SURVEY WORK.**

[]{#__RefHeading___Toc123539243 .anchor}**8.1. PURPOSE.** The
establishment of geodetic control provides the required accuracy for
aeronautical information, engineering surveys, and mapping to support
planning, design, construction, operation, maintenance, and management
of airport facilities and establishes a tie to the NSRS. The NSRS
provides airports with a common, consistent set of geographical
coordinates (reference points) relative to other parts of the National
Airspace System. A project may include planning, reconnaissance, mark
recovery, mark setting, GPS observations, spirit leveling, data
processing, data analysis, data adjustment, data submittal in specified
formats, and preparing reports. GPS ground surveying methods must be
used for Airport Geodetic Control survey work specified in this section.

[]{#__RefHeading___Toc123539244 .anchor}**8.2. RECONNAISSANCE.**
Reconnaissance activities for each survey must include, but are not
limited to, the following:

a.  Review of station descriptions in the NGS database.

b.  Coordination with airport authorities (see checklist in Appendix 3).

c.  Mark recovery.

d.  Selection of PACS, SACS, and NSRS ties.

e.  Preparation of required descriptions, sketches, photographs, and
    other documentation.

f.  Compilation of a Project Survey Plan.

[]{#__RefHeading___Toc123539245 .anchor}**8.2.1. CONTROL STATIONS.** The
following types of control stations (survey marks) must be considered
for use in these projects (see Appendix 1 for drawings of typical NGS
disks):

**8.2.1.1. HORIZONTAL.**

a.  All control stations with a stability code of A, B, or C (see
    paragraph 8.5 for an explanation of stability codes), and

b.  All high-accuracy GPS control stations, including CORS, FBN, CBN,
    HARN, and PACS.

**8.2.1.2. VERTICAL.** Utilize all first‑order and second‑order NAVD 88
vertical control stations (bench marks) within the project area,
sufficient to provide vertical control for the project.

**8.2.1.3. NSRS TIE.** All horizontal and vertical points used as
control must be part of the NSRS.

[]{#__RefHeading___Toc123539246 .anchor}**8.2.2. DATABASE SEARCH.** NGS
and U. S. Coast and Geodetic Survey (USC&GS) (former name for NGS)
station descriptions are contained in the NGS Integrated Database
(NGSIDB) and are available via the NGS website. Perform a database
search for all control stations on and around the airport meeting the
criteria in 8.2.1 prior to performing the field reconnaissance. Use the
review to develop a priority list of HARN stations and bench marks for
use in NSRS ties. Many airports have existing monuments suitable for use
as PACS/SACS. Suitable stations are defined as a survey disk, rod, or
similar type monument meeting at least a stability code of "C" with a
known history of stability, considered suitable for GPS observations,
and recovered in good condition. Directly access the NGS database using
the NGS website at <http://www.ngs.noaa.gov/datasheet.html>.

[]{#__RefHeading___Toc123539247 .anchor}**8.2.3. CONTACT WITH AIRPORT
AUTHORITIES.** Close communication with airport management is a critical
part of the reconnaissance. Make appointments with airport management
well in advance to ensure a qualified airport representative is
available to discuss the survey and the procedures for working on the
airport. Proper clearances to work in the aircraft operations areas must
be obtained before performing any work at an airport. A security and
safety briefing may be required before field crews are allowed to work
on the airfield. Follow standard safety procedures, and equip all
vehicles with flashing yellow lights and aircraft radios. Contact with
the airport traffic control tower is mandatory during surveys at
controlled airports unless an escort is provided. Interview checklists
for these meetings are located in Appendix 3 of this AC.

Inquire about planned construction or changes in the airport layout.
Briefly summarize any future construction plans in the Project Survey
Plan. Discuss optimal locations for the practical use and survivability
of the monuments, and finalize the PACS and SACS monument site
selections with airport management. Inquire about underground utilities
and other hazards to setting monuments. Emphasize the importance of
keeping the area surrounding the monuments, especially the PACS, clear
of any future equipment installations or construction that might result
in loss of intervisibility between the monuments, loss of visibility to
GPS satellites, or a source of multi-path interference.

[]{#__RefHeading___Toc123539248 .anchor}**8.2.4. MARK RECOVERY.**

**8.2.4.1. SEARCH.** Make an extensive physical search in the field for
all suitable control stations found during the database search(s)
described in paragraph 8.2.2. Use existing marks meeting the PACS and
SACS requirements before setting a new monument. The use of existing
marks reduces the proliferation of marks on airports, reduces mark
setting costs, and makes it easier to maintain an accurate, up-to-date
survey database. For a discussion of "Existing Monumentation in the
Vertical Network", see pages 43-44, *Geodetic Bench Marks*, NGS, 1978.

Before using an existing mark, thoroughly check the description to
confirm the station\'s identity, stability, and location and to provide
input for an updated description or recovery note. Do not stamp existing
disks or logo caps.

NGS has set "A" or "B" order marks at many airports within the United
States. Use these marks if they meet PACS requirements. If there is an
existing "A" or "B" order station just off an airport, and it has
visibility onto the airport, an exception requiring the PACS be located
on the airport may be granted. If this situation is encountered, make a
recommendation, with justification, in the Project Survey Plan for the
approval of the FAA and NGS.

If there is an existing "A" or "B" order station just off an airport,
and appropriate sight lines onto the airport are not available, an
exception may be granted if an intermediate station (a third SACS) is
set providing visibility from the "A" or "B" order station through the
third SACS to the other two SACS on the airport. The third SACS may be
located off the airport. If a situation is encountered at an airport
requiring a third SACS, identify the requirement in the Project Survey
Plan.

The contractor must prepare digital updated descriptions or recovery
notes in the three-paragraph standard NGS format described in Appendix 4
for all NSRS marks searched for and all marks used in the project.

**8.2.4.2. MARK RECOVERY DEFINITION.** The "recovery" of a control
station includes a physical visit to the station to determine its
usability. Check each control station to---

Determine proper identity. Check the mark type, disk type, and stamping
against the NGS datasheet.

Ascertain its unmoved position. Measure the distances and angles to and
from the reference marks and/or the distances from the reference points
and the Witness Post.

Determine its condition, stability, and visibility.

Prepare a digital updated description or recovery note in NGS format.
Submit station descriptions and recovery notes in computer‑readable form
using WINDESC software available online at
http://www.ngs.noaa.gov/PC_PROD/PARTNERS/index.shtml. Appendix 4
provides detailed instructions on writing station descriptions and
recovery notes.

###  {#section .Paragraph}

![](media/image4.png){width="2.832638888888889in"
height="3.738888888888889in"}**8.2.4.3. USING MARKS OF OTHER
ORGANIZATIONS.** An existing mark of another organization meeting the
siting, construction, and intervisibility requirements established by
this AC may be used as a **PACS.** Normally this would be limited to a
disk set in a drill hole in bedrock or a stainless steel rod if there is
an indication the rod was driven to NGS driving requirements. Marks
previously established by other organizations may be used for a **SACS**
if they meet all siting, construction, and intervisibility requirements
and are stability A, B, or C.

**8.2.4.4. MARKS ON PRIVATE PROPERTY.** Contact property owners and
obtain permission before using or setting marks on private property.
Take care to return the landscape to the original condition, and ***Do
Not*** include the name and phone number of the property owner in the
station description unless the land is owned by a business or the owner
requests the information be included in the description.

**8.2.4.5. DESTROYED SURVEY MARKS.** A moved, damaged, or very loose
metal survey disk that's stability indicates it can no longer serve as
survey mark is to be removed, the recovery notes written describing the
mark as destroyed, and the disk sent to NGS. Do not describe a mark as
destroyed unless the disk is found and returned to NGS.

**8.2.4.6. DAMAGED SURVEY MARKS. Any existing disk selected for use as a
PACS or a SACS should be repaired if found loose or with edges exposed.
Any work done to repair a disk must be described completely in the
digital recovery note. Take extreme care not to alter the existing
horizontal or vertical position of the disk. Disk longevity can be
increased substantially by simply adding highway epoxy or equivalent
when the edges of a disk are exposed. This will prevent ice from forming
under the disk or a vandal from prying the disk from its location. For
all marks, perform mark maintenance as required, to include replacing
logo cap lids if missing. When an unusual situation arises, contact NGS
for recommendations before taking any action on the mark. If time
permits, send a photograph to NGS along with the description of the
situation. Notify NGS of any other marks needing mark maintenance.
Examples of mark maintenance problems include loose disks, exposed disk
edges, missing logo caps, missing logo cap lids, exposed edge of
concrete monuments, or imminent danger of destruction.**

**8.2.4.7. MARKS NOT FOUND.** As stated in paragraph 8.2.4.1, make an
extensive physical search for all control stations found in the database
search(s). If a mark is not found, enter the number of person-hours
spent searching for it in the digital recovery note. Do not state the
mark is destroyed simply because it was not found. If strong evidence
suggests a mark is destroyed, clearly state the evidence, so NGS can
determine if it is destroyed and replace it as required.

**8.2.4.8. MARKS RECOVERED BUT NOT USABLE.** For marks recovered but are
positively not usable due to complete tree canopy, etc., the recovery
requirements may be reduced to just a simple recovery note such as,
"RECOVERED AS DESCRIBED. THE MARK CAN NOT BE OCCUPIED BY GPS DUE TO
COMPLETE TREE CANOPY". For marginally usable marks, fulfill the normal
recovery requirements, including Visibility Diagram and photographs,
because, depending on other marks in the area, the mark might be needed.

![](media/image5.png){width="2.625in" height="3.441666666666667in"}

[]{#A_825 .anchor}**8.2.5. BENCH MARK SPIRIT LEVEL TIES.** If the
reconnaissance indicates the number and/or distribution of bench marks
with good sky visibility is inadequate, spirit level ties may be made to
transfer an elevation from a bench mark to a nearby existing or new
survey point having good sky visibility. Every effort should be made to
recover existing bench marks before using this method; however,
transferring elevations to existing horizontal control marks is
preferable to setting new marks. Temporary marks must not be used. Refer
to paragraph 8.7.4.4 for more information regarding the use of bench
mark ties.

[]{#__RefHeading___Toc123539249 .anchor}**8.2.6. VISIBILITY.** Adequate
GPS satellite visibility is required for all horizontal and vertical
stations selected. The visibility should be minimally restricted from 15
degrees above the horizon to the zenith, in all directions; see
paragraph 8.4 for details. Minor obstructions are acceptable, but must
be depicted on the Station Location Sketch and Visibility Diagram (see
paragraph 8.2.8). For new stations, select a site relatively free of
present and future anticipated obstructions. Utility poles in the GPS
field of view are tolerable, and they provide security and a reference
to help locate the mark. Set new marks at least 2 meters to the south
(if possible) from a pole. Do not use existing marks located within 2
meters of a pole. Marks should not be set or used if within 5 meters of
a chain link fence.

[]{#__RefHeading___Toc123539250 .anchor}**8.2.7. NATIONAL SPATIAL
REFERENCE SYSTEM (NSRS) TIES.** Each PACS must be tied to at least one
"A" or "B" order HARN station and two First- or Second-order NAVD 88
bench mark stations. The stations selected for these ties must be
recovered during the field reconnaissance. Details for selecting and
positioning the PACS (and Central Temporary Continuously Operating
Reference Station (CTCORS)) ties are listed in paragraph 8.7.4, "GPS
Observation Requirements". All reconnaissance deliverables required for
"suitable" stations are also required for the NSRS ties.

[]{#__RefHeading___Toc123539251 .anchor}**8.2.8. STATION LOCATION SKETCH
AND VISIBILITY DIAGRAM.** For all marks, observed and proposed, the
contractor must prepare and submit a station location and visibility
diagram. The form is available at
<http://www.ngs.noaa.gov/PROJECTS/FBN/> (click on "Forms", then
"Visibility Obstruction Diagram"). The station location sketch and
visibility diagram should show the survey marks' relation to nearby
features, such as

runway ends, taxiways, airport lights, fence lines, and buildings. Label
prominent features and draw dashed lines along the reference
measurements to indicate the reference objects listed in the description
(in NGS standardized format) for the station. The D-File is a clear,
concise, accurate and complete description of the station in the NGS
standardized format. The description (D-File) should enable one to go
with certainty to the immediate vicinity of the mark, and by the
measured distances to reference points and the description of the
character of the mark, it should inform the searcher of the exact
location of the mark and make its identification certain. It should
include only essential details of a permanent character." Complete the
visibility diagram and sketch the inscription and stamping detail of the
disk in the space provided. The form must be neatly and accurately
completed. ![](media/image6.png){width="2.8131944444444446in"
height="3.745833333333333in"}![](media/image7.png){width="3.3027777777777776in"
height="2.7597222222222224in"}

[]{#__RefHeading___Toc123539252 .anchor}**8.2.9. PENCIL RUBBINGS.**
Rubbings are not required during the recovery of a survey mark. However,
rubbings are required at the time of each observation at that station.
See Figure 8.3 and paragraph 8.7.5.3 for details.

[]{#__RefHeading___Toc123539253 .anchor}**8.2.10. PHOTOGRAPHS.**

**8.2.10.1. PURPOSE OF DIGITAL PHOTOS.** Is to define the digital
photographic standards for images of survey marks collected and for
other reconnaissance photographs. Many of these images will be stored in
the NGS database and available to the public so the subject matter
(survey equipment, personnel, background, etc.) must be in good taste
and professional in nature. Digital photographs are useful for station
(mark) reconnaissance, mark recovery, mark stability assessment, and
quality control and as an aid during data processing and data
verification. Some projects might require digital photographs during
several stages. Generally, three photographs per station are stored in
the NGS database.

8.2.10.2. Photographic Requirements.

**8.2.10.2.1. NUMBER OF PHOTOGRAPHS. At least three digital photographs
taken during daylight hours are required for each mark recovered or
described during the current project. This requirement is for marks
where a written, NGS format, digital description or recovery note is
prepared. For consistency within the NGS database, numbers are used to
describe the three photographs. Photograph type one is an extreme close
up as shown in Figure 8.4. Photograph type number two (Figure 8.5)
should be taken at eye-level with the station 5 to 6 feet in the
distance, and photograph type three should be taken horizontally with
the station approximately 10 to 30 feet in the distance (Figure 8.6).
All three photographs require a digital caption and correct file name as
specified in paragraphs 8.2.10.3 and 8.2.10.4.7.3. Include a small,
temporary sign in photographs two and three.**
![](media/image8.png){width="3.636111111111111in"
height="2.4472222222222224in"}

**8.2.10.2.2.** Take sufficient photographs to describe the stamping,
appearance, condition, and location of the mark and points of potential
interest, including visibility obstructions, roads, runways, taxiways,
or other dangers and any special setup requirements. Alter the
orientation of the photographs as necessary to include this information
in as few photographs as possible. (For example, for a tall obstruction,
rotate the camera 90 degrees so the long axis of the image is vertical,
as in the photo in Figure 8.6.) Capture the tops of nearby obstructions
if possible. If acceptable photographs exist in the NGS database,
additional photographs are not required, unless changes have occurred or
more than 1 year has passed. A photograph is acceptable if it meets the
requirements of this AC, it is of good visual quality, and no changes
have taken place at the location that a new photograph would help
clarify.

**8.2.10.3. CAPTION.** The photographer must write a caption for each
photograph. The caption should contain the following information in a
comma-separated format:

a.  Station designation (name).

b.  Station Permanent Identifier (PID) for existing stations in the NGS
    database; leave blank if this is a new station.

c.  Airport Location Identifier (LID) if on airport; leave blank if not
    on airport.

d.  Photo number with the cardinal direction (N, NE, E, SE, etc.) the
    camera is pointing; only photo type 3 has a direction.

e.  Station type (i.e. PACS, SACS, FBN, CBN); otherwise leave blank.

f.  Date photo was taken (DDMMYYYY).

SAMPLE CAPTION FOR NEW MARK

JONES, 2, 8JAN2001

SAMPLE CAPTION FOR EXISTING PACS ON AIRPORT

SMITH, AB1234, LAX, 3N, PACS, 8JAN2001

The cardinal direction should not be included in the captions for
photographs 1 and 2 since they are taken from above the above. The
caption may be digitally captured on the image at the time of exposure
or may be inserted later, offline. If possible, record at least the date
online. If caption information is added later, take careful notes at the
time of exposure to ensure the correct caption is added. The caption
must not obstruct any pertinent aspects of the station or surroundings.
To ensure the letters of the caption are visible, use software to erase
a rectangular area for the caption's lettering as depicted in Figures
8.4, 8.5, and 8.6.

8.2.10.4. DESCRIPTION OF PHOTOGRAPH TYPES.

**8.2.10.4.1. CLOSE-UP.** For survey marks, the first photograph (photo
type 1, Figure 8.4) is a close-up, oriented downward to show the survey
mark from directly above, with the disk or logo cap nearly filling the
image. Brush any dirt or debris off the mark to show the disk. If it has
a logo cap, the logo cap should be open. The intent of this photograph
is to clearly show the condition of the mark and all stamping on the
mark or logo cap so it is clearly legible. Use extra care to ensure the
stamping is clear. Consider setting the camera to its highest quality
and resolution modes; rub a yellow crayon across the stamping to
highlight the letters; set the camera to "macro" mode, if available;
take into account the minimum focusing distance of the camera (take test
photographs to determine the minimum focusing distance, and consult the
owner's manual); and, if a flash is used, hold the camera above and off
to the side so the flash does not create a bright spot in the middle of
the disk's image. Medium-quality camera setting and resolution modes may
be used for photographs other than the close-ups. If additional
photographs are required, number these close-ups as 1A, 1B, etc.

![](media/image9.png){width="3.698611111111111in"
height="5.416666666666667in"}

**8.2.10.4.2. EYE-LEVEL.** For survey marks, photo type 2 is oriented
vertically downward from eye level to show the monument from directly
above and to cover an area about 1 meter in diameter. Brush any dirt or
debris off the mark to show the disk and the setting, if it is a
concrete monument, clear off debris to the edge of the monument. If it
has a logo cap, the logo cap should be open. Include a small, temporary
sign in this photograph with the station designation (name) printed so
it is clearly visible in the photograph. The intent of this photograph
is to show the general condition of the mark and the immediate
surrounding area. If additional photographs are required, number these
photos 2A, 2B, etc.

**8.2.10.4.3. HORIZONTAL VIEW(S).** For survey marks, take at least one
additional daylight photograph oriented near horizontal, and show the
mark, with tripod and antenna (if possible), in the foreground and its
identifying surroundings, including any significant obstructions or
possible sources of multi-path in the background. Show the top of nearby
obstructions if possible. Consider rotating the camera 90 degrees to use
the long axis of the image to capture an entire obstruction. Place a
temporary sign in this photograph with the station designation (name)
and the direction the camera is pointing, both printed so they are
clearly visible in the photograph. If additional photographs are taken,
move around the mark to locations that are 90 degrees apart (preferably
cardinal directions). Name these photographs number 3XX, where the "XX"
is the cardinal direction the camera is pointing, for example, 3N or
3NE.

###  {#section-1 .Paragraph}

**8.2.10.5. RECONNAISSANCE PHOTOGRAPHS.** Some or all of the digital
images described in this section may be required on a given project;
refer to the project instructions. Each of these photographs requires a
sign, a caption, and the correct file name. The filenames for all
reconnaissance photographs must begin with "RE" to indicate
reconnaissance.

Table 8.1. Digital Photograph Requirements Matrix

  ------------- ----------------------------- ---------------------------
  Required Item Contents                      Description

  Sign in Photo Name and Direction (unless    Place a sign in this
                vertical photo)               photograph with the station
                                              designation (name) and the
                                              direction the camera is
                                              pointing, both printed so
                                              they are clearly visible in
                                              the photograph.

  Digital       Name, PID, LID, Number, Type, See paragraph 8.2.10.3.
  Caption       Date                          

  Photo File    RE-Name-PID-Number-Date.jpg   See Section 8.2.10.5.7.3
  Name                                        below.
  ------------- ----------------------------- ---------------------------

Generally these recon images will not be loaded in the NGS database but
might be required for use during planning and review. All reconnaissance
photographs will have digital captions. These captions may be captured
on the image or added later.

In this AC, "RE" stands for "reconnaissance" and "R" stands for "right"
runway. See the project instructions to determine which of the following
reconnaissance photographs are required.

**8.2.10.5.1. PROPOSED LOCATIONS FOR MARKS.** Take two photographs of
each proposed permanent mark location. These may be one (each) type two
photograph and one type three or two type three photographs (3A and 3B),
depending on which combination better shows the proposed mark location.
Include a tripod, stake, sign, or other device showing the proposed mark
location.

**8.2.10.5.2. RUNWAY END PHOTOGRAPHS.** Take at least three photographs
at the end of each runway (including thresholds and stopways) surveyed
in the current project, as follows:

![](media/image10.jpeg){width="3.5930555555555554in"
height="1.4979166666666666in"}

a\. Eye-Level (photo type 1). Photo taken from directly overhead above
the mark, showing about 1 meter in diameter (See Figure 8.7).

b\. Approach (photo type 3). Photo showing tripod over mark in
foreground and approach in background (see Figure 8.8).

![](media/image11.jpeg){width="6.40625in"
height="3.877083333333333in"}c. Across runway (photo type 3). Photo
taken from the side of the runway looking across the end of the runway,
with a tripod or arrow indicating the end point; include any features
used to identify the runway end (Figure 8.9).

![](media/image12.jpeg){width="3.6881944444444446in"
height="2.28125in"}**8.2.10.5.3. NAVIGATION AIDS (NAVAIDS).** Take
photo(s) (type 3) of all NAVAIDs surveyed. Show the survey tripod in
place surveyed, or if positioned remotely, add arrows and labels to the
photograph indicating the horizontal and/or vertical point(s) surveyed.

**8.2.10.5.4. DEPTH OF HOLE PHOTOGRAPHS.** Take at least one photograph
showing the hole dug or drilled for a concrete or rod mark. Place a
measuring device (e.g., tape measure or level rod) in the hole, clearly
showing the depth of the hole.

![](media/image13.jpeg){width="6.454861111111111in"
height="3.9451388888888888in"}

**8.2.10.5.5. PHOTOGRAMMETRIC CONTROL POINTS (Paneled and photo
identified).** Take two type 3 photographs of all photogrammetric
control points clearly showing the point. These photographs will be used
later as an aid in identifying the point on the aerial photographs. Show
the mark in the foreground and the nearest identifiable feature in the
background. The two photographs should be taken from two different
directions, ideally 90 degrees apart (such as from the East and the
South).

**8.2.10.5.6. OTHER REQUIRED PHOTOGRAPHS.** Additional photographs may
be required depending on the airport and surroundings. These additional
requirements should be outlined in the Statement of Work for the
project.

8.2.10.5.7. GENERAL INFORMATION FOR PHOTOGRAPHY.

**8.2.10.5.7.1. IMAGE and FILE SIZE.** Each image should be about 800 by
1000 pixels when submitted. The maximum file size for each image is 500
KB, typical file size should be about 50 to 100KB.

**8.2.10.5.7.2. IMAGE FORMAT.** Store the digital photographs in JPEG
format, approximately 50 percent reduction.

###  {#section-2 .Paragraph}

**8.2.10.5.7.3. PHOTOGRAPH FILE NAME.** Use the following file naming
convention: the optional "RE" (for reconnaissance), dash, the station
designator, dash, the PID, dash, the photo number (e.g., 1, 1A, 2, 3N,
3NE), dash, date, dot, jpg. For new marks, there is no PID. Use a
maximum of 30 alpha-numeric characters to the left of the dot.

Sample File Names

For new stations: SMITH-3-date.jpg

For existing stations: SMITH-AB1234-1-date.jpg

For recon photos: RE-SMITH-AB1234-3-date.jpg

For runway end point: RE-LAX_CL_END_RWY_12R-3-date.jpg

For the runway end point example, "RE" = reconnaissance, dash, LAX =
LID, dash, "CL END RWY 12R" = runway end point designator (CL =
centerline, END = end, RWY = runway, 12 = runway number, and R = right
(or C = center, or L = left), dash, "2" = photo number, and date. Use
underscores ( \_ ) to fill blanks. In this AC, "RE" stands for

"reconnaissance", and "R" stands for "right" runway (used if there is a
parallel set of runways). Also, the LID may be four characters rather
than just three.

**8.2.10.5.7.4. STORAGE MEDIUM.** Submit all digital photographs
together on their own medium (CD), not on the same medium with other
types of data. For airport work, submit all photographs for a given
airport in a subdirectory named for that airport.

**8.2.10.6.** Take photographs of all stations as outlined in this AC.
For RECOVERED STATIONS, take at least three photographs of each existing
control station. For PROPOSED SITES OF NEW STATIONS, take two
photographs (paragraph 8.2.11) and additionally take three photographs
of NEW STATIONS, AFTER SETTING. If the mark is a CONCRETE MARK HOLE,
then only a single photograph is required.

[]{#__RefHeading___Toc123539254 .anchor}**8.2.11. PROPOSED NEW STATION
SITES.** Use existing marks rather than setting new marks. If required,
the contractor must propose sites for new stations and propose the type
of mark to be set in the "Comments/recommendations" column of the
"Station Table" as defined in paragraph 8.3b. Prepare preliminary
digital descriptions and station location sketch and visibility
diagrams. Take two photographs of the proposed sites; one at eye level,
oriented vertically downward showing the ground in the area of the
proposed mark (photo type 2) and one oriented horizontally showing the
nearest satellite obstruction or identifying feature if no obstructions
(photo type 3). After the mark is set, capture photo type 1, and update
others as required. See Appendix 3 for digital photograph requirements.
Proposed sites for new PACS and SACS must be approved by NGS prior to
setting the marks. NGS may approve station selections based on
preliminary Project Survey Plans to facilitate efficient field
operations. New PACS and SACS should only be set if no existing mark can
meet the requirements. See paragraph 8.6, MARK SETTING, for mark setting
guidelines.

[]{#__RefHeading___Toc123539255 .anchor}**8.2.12. GPS POSITIONS.**
Obtain a hand-held GPS (pseudo-range) position for all marks found and
for proposed sites for new marks. Include this position in the text of
recovery notes and descriptions. Specify the position in the format *DDD
MM SS.ss*. Use the description you wrote to return to the station; this
verifies the description and provides a check on the adequacy of the
description and the GPS position.

[]{#__RefHeading___Toc123539256 .anchor}**8.3. PROJECT SURVEY PLAN.**
After reconnaissance but prior to mark setting or observations, submit a
Project Survey Plan to NGS. The data can be submitted online using the
NGS Project Proposal Form available at
http://www.ngs.noaa.gov/PROJECTS/proposals/project1.shtml or by sending
the data (one paper copy and one digital copy) to the NGS Point of
Contact (POC). NGS will review the plan as soon as possible, normally
within 5 work days, and send the contractor written comments and/or
approval. The contractor must not begin mark setting or data collection
until the plan is approved by NGS. At minimum, the plan must include the
following sections:

a.  **Airport Summary Report.** A separate paragraph for each airport to
    include---airport contact and access information; whether airport is
    controlled; whether escort is required; airport radio frequencies;
    intervisibility conditions between the PACS and SACS; comments on
    any future construction, unusual circumstances, use of witness
    posts, and any other miscellaneous information. Include any comments
    or deviations from this AC. The Airport Summary Report can be
    combined with the Station Table described below.

b.  **Station Table.** For each airport, submit a table listing station
    designation name, PID, establishing agency, order, stability,
    condition at recovery, and comments for each station. For new
    stations, include the proposed name in the "Name" column, identify
    them as "proposed" in the "Type" column, and indicate the proposed
    type of mark (rod, concrete, disk in bedrock) in the
    "Comments/Recommendations" column. For existing stations, the name
    and PID must be used exactly as listed in the NGS database and must
    be this way in all survey records. For existing stations found but
    not proposed for use, state the reason(s) in the
    "Comments/Recommendations" column. Identify the PACS, SACS, and all
    NSRS ties for the airport. Give status of marks not used and the
    reason. Appendix 5 contains both a blank and completed example
    station table.

c.  **Airport Control Plot.** Plot all "suitable" control on or near
    each airport on an airport map. Label each station with its
    designation and indicate if it is a PACS, SACS, Bench Mark, HARN
    Tie, or subsidiary control. Hand plotting on 8.5 x 11 paper is
    acceptable. See Appendix 5 for an example.

d.  **Photographs.** Submit photographs in accordance with paragraph
    8.2.10 for all suitable stations recovered during the survey, and
    for all new monuments that will be set.

e.  **Station Location Sketch and Visibility Diagrams.** Submit for all
    suitable stations recovered during the reconnaissance, and for all
    new monuments set (See paragraph 8.2.8).

f.  **Station Descriptions.** Submit Recovery Notes or Descriptions for
    existing marks. Encode the descriptions using WINDESC software.
    These descriptions should be used, reviewed and corrected by GPS
    observers when they travel to marks. See paragraph 8.2.4.2 and
    Appendix 4 for details on writing station descriptions.

g.  **GPS Observing Scheme.** If applicable, group airports together for
    observation/processing simultaneously. Include length of sessions
    and number of occupations. List CORS, HARN, Bench Mark, and any
    A-order ties for each airport. See Appendix 6 for an example.

h.  **Project Vector Diagram.** Depict the entire project area showing
    all occupied stations, except SACS (because of scale). Symbolically
    distinguish whether each station is a CORS, PACS, HARN Tie, Bench
    Mark or combination. Include 300km (or appropriate scale) dashed
    circles around CORS and CTCORS, and 50 km circles around PACS. Show
    the GPS vectors used for processing. For multiple airport projects,
    use one sheet of large size and additional smaller sheets depicting
    individual airports or airports grouped together for GPS
    observations. Provide a scale or note distances from the PACS to the
    CORS, HARN, and Bench Mark Ties.

i.  **Proposed Instrumentation List.** Tabulate the brand and model
    numbers of GPS equipment.

j.  **Data Processing Software.** Specify software name and version for
    the software used. Ensure the current version of all software is
    used.

k.  **Quality Control Plan.** See Section 5.

Note: Printouts of the NGS station datasheets are not required.

## 8.4. SELECTION GUIDELINES FOR AIRPORT GEODETIC CONTROL SURVEYS

[]{#__RefHeading___Toc123539258 .anchor}**8.4.1. REQUIREMENTS**.
Establish three permanent survey marks on, or within one km of, the
airport. One of these marks must be designated the Primary Airport
Control Station (PACS). Horizontal and vertical datum ties must be made
directly between the PACS and the National Spatial Reference System
(NSRS). The other two marks must be designated Secondary Airport Control
Stations (SACS). Horizontal and vertical connections must be made
directly between the SACS and the PACS.

[]{#__RefHeading___Toc123539259 .anchor}**8.4.2. MONUMENT SELECTION**.
Proper monument site selection for PACS and SACS is a primary goal for
these surveys and must be carefully considered. Consider the following
basic factors when using a existing site or selecting a new site.

a.  Monument stability.

b.  Intervisibility requirements.

c.  Visibility from the monuments to airport features such as runways,
    navigation aids, and airport obstructions off the end of runways

d.  Any previous high accuracy connection to the National Spatial
    Reference System (NSRS).

e.  Accessibility and survivability of the monuments.

[]{#__RefHeading___Toc123539260 .anchor}

**8.4.3. USE OF EXISTING STATIONS**. Use existing stations as the PACS
and SACS if they meet the accuracy, siting, construction, accuracy's and
other criteria identified in advisory circular.

**8.4.3.1. CONTROL STATION SELECTION PRIORITIES--PACS.**

![](media/image14.jpeg){width="3.0027777777777778in"
height="4.407638888888889in"}

An existing mark may be used as a PACS if the mark meets the stability
codes of A or B in that order of preference (see mark stability
standards in paragraph 8.5). An existing concrete mark with stability
code C (and 4+ feet deep, belled bottom) may be used for a PACS if the
monument meets the following seven (7) requirements.

a.  The disk already exists.

b.  The monument is poured in place in concrete.

c.  The monument is a triangulation station, reference mark, azimuth
    mark, or bench mark stamped "U.S. Coast and Geodetic Survey", or any
    mark stamped "National Geodetic Survey".

d.  The monument is set below the frost line.

e.  The monument is set in non-expansive soils.

f.  The monument shows no evidence of movement.

g.  The monument meets all siting, construction, and intervisibility
    requirements.

Note: An existing HARN station ("A" or "B" order station) does not
necessarily qualify to be a

PACS; it must still meet PACS stability and siting requirements.

**8.4.3.2. CONTROL STATION SELECTION PRIORITIES--SACS.** An existing
mark may be used as a SACS if the mark meets the stability codes of A,
B, or C in that order of preference. Other USC&GS, NGS, or NOS marks
should be used as SACS if they meet all siting, construction, and
intervisibility requirements.

### 8.4.4. MONUMENT ACCESSIBILITY.  {#monument-accessibility. .unnumbered}

The monuments must be accessible to survey crews, and allow for
unattended, secure setup of GPS equipment for long periods without
hindering airport operations. PACS and SACS must allow for setup of both
conventional (optical) and satellite surveying equipment. If possible,
SACS should be sited on high ground near the approach end of the primary
runways so they can be better utilized for obstruction surveys.
Monuments must be established in areas clear of future construction, and
should be slightly recessed to protect them from snow removal and mowing
equipment.

[]{#__RefHeading___Toc123539262 .anchor}**8.4.5. MONUMENT SITING
CONSIDERATIONS.** Consider the following items in the siting of all
monuments (new or old, control station or local network station) in the
project. The object of these standards is to ensure the stations are
stable and usable years after the survey is completed. Give equal weight
to each consideration item listed below.

a.  Adequate GPS satellite visibility (unrestricted at 15 degrees above
    the horizon). Minor obstructions are acceptable, but must be
    depicted on the Visibility Obstruction Diagram.

b.  Accessible by vehicle (two-wheel drive preferred).

c.  Stability, bedrock being most preferred.

d.  Permanency.

e.  Ease of recovery.

f.  Minimal multi-path.

g.  Appropriate geographic location and spacing.

h.  Location allows efficient use by surveying community.

i.  Accessible by public. Public property should be utilized where
    feasible.

j.  No known potential conflict with future development.

k.  Aerial-photo identifiable.

[]{#__RefHeading___Toc123539263 .anchor}**8.4.6. PACS AND SACS PROXIMITY
TO OTHER AIRPORT FEATURES.**

**8.4.6.1.** Establish the PACS in a secure area on airport property. A
GPS suitable site should be selected where surveying equipment may be
left unattended at the mark with a minimum probability of disturbance.

**8.4.6.2.** SACS should be established on airport property if
practical. However, if the siting requirements, such as, intervisibility
and spacing as described below, cannot be met, one SACS may be set off
the airport but no further than 1 km from the nearest airport boundary.

**8.4.6.3.** If establishing the PACS and SACS requires new
monumentation, the new monuments should be set no closer than 60 meters
from a runway edge, or 60 meters from the imaginary runway extension. If
an existing control station is used, this station should be at least 15
meters from a runway edge. In all cases, PACS and/or SACS should be at
least 400 meters apart.

**8.4.6.4.** Ensure sites selected for use as PACS AND SACS meet the
following minimum distance requirements to other airport features. In
addition to distance from other airport features, ensure the PACS and
SACS are separated by at least 400 meters from each other.

8.**4.6.4.1.** PACS and SACS should be located so that a surveying
tripod can be situated over the mark. In addition, if the mark could be
in peril from snow removal, mowing, and other operations, it should be
slightly recessed.

**8.4.6.4.2.** PACS and/or SACS must not be within 305 meters (1000 ft)
of the critical side of an---

a.  Instrument Landing System (ILS) Glideslope Antenna

b.  Instrument Landing System (ILS) Localizer

c.  Microwave Landing System Elevation Station

d.  Microwave Landing System Azimuth Station

**8.4.6.5.** PACS and SACS should be strategically located so as to
provide maximum use for subsequent surveys yet situated where the
chances of future disturbance will be minimal. An elevated site with
runway end visibility is desirable. PACS and SACS should also be located
where future station occupation will cause no interference to or from
aircraft, including from prop and jet blast.

[]{#__RefHeading___Toc123539264 .anchor}**8.4.7. INTERVISIBILITY CHOICES
FOR PACS and SACS** in order of priority are---

a.  The PACS and both SACS are all intervisible with each other.

b.  The PACS is intervisible with both SACS but the SACS are not
    intervisible with each other.

c.  The PACS is intervisible with one SACS and both SACS are
    intervisible with each other.

[]{#__RefHeading___Toc123539265 .anchor}**8.5. MONUMENT STABILITY.**
Stability codes A, B, and C are defined in the Blue Book, Volume 1,
Annex I, with examples given below. Only codes A and B are recommended,
however concrete posts may be selected with code C stability if the mark
is deemed stable from review of soil conditions and average frost depth.

a.  Stability code A = expected to hold an elevation. Examples: rock
    outcrops; rock ledges; bedrock; massive structures with deep
    foundations; large structures with foundations on bedrock; or
    sleeved deep settings (10 feet or more) with galvanized steel pipe,
    galvanized steel, stainless steel, or aluminum rods.

b.  Stability code B = probably hold an elevation. Examples: unsleeved
    deep settings; massive retaining walls; abutments and piers of large
    bridges or tunnels; unspecified rods or pipe in a sleeve less than
    10 feet; or sleeved copper-clad steel rods.

c.  Stability code C = may hold an elevation but subject to ground
    movement. Examples: Metal rods with base plates less than 10 feet
    deep; concrete posts (3 feet or more deep); large boulders;
    retaining walls for culverts or small bridges; footings or
    foundation walls of small to medium-size structures; or foundations
    such as landings, platforms, or steps.

[]{#__RefHeading___Toc123539266 .anchor}

**8.6. MARK SETTING**. After the Project Survey Plan is approved by NGS,
fieldwork may begin. Marks must be set to NGS specifications for type,
length, material, stability, stamping, driving, etc. outlined in NOAA
Manual NOS NGS1, Geodetic Bench Marks, Floyd, 1978 and this document.

The importance of setting quality monuments cannot be over emphasized.
Properly located and set monuments provide decades of valuable use for
surveying operations. Proper attention and workmanship must be given to
all the steps in the process including the basic tasks of hole digging,
rod driving, concrete mixing and pouring, and finishing the monument.
The only physical evidence remaining after a survey is completed are the
monuments; therefore, permanency and neatness of the monument and the
surrounding area are of utmost importance.

Where new marks are required, PACS and SACS must be monumented in
accordance with the following criteria: the paragraphs below, and the
Appendixes to this document. Additional requirements are found in:
*Federal Base Network Station Selection Guidelines;* and *NOAA Manual
NOS NGS1, Geodetic Bench Marks*, Floyd, 1978.

Proposed sites for new marks should be discussed with airport management
after existing marks are recovered. Inquire about underground utilities
and future construction affecting mark longevity. "MISS UTILITY"\--type
services offered through local utility companies should be contacted
before driving rod or digging, and may be required by state or local
regulation.

The preliminary station descriptions and sketches must be updated after
the mark is set, and photo type 1 (close-up, see 8.2.10.4.1 and Figure
8.5) must be captured along with updates of other photographs, as
required. For concrete marks, take a photograph after the hole is dug
and before the concrete is poured showing a level rod in the hole (to
show the depth of the hole). The file name for this photograph must
start with "RE" for reconnaissance; see 8.2.10.4.7.3.

a.  **PACS.** New PACS must meet stability code A or B requirements as
    defined in paragraph 8.5. New rod marks must meet the "Quality Code
    B" requirements found in the NGS Document *NOAA Manual NOS NGS1,
    Geodetic Bench Marks*, Floyd, 1978.

b.  **SACS.** New SACS must meet stability code A, B, or C requirements
    as defined in paragraph 8.5. Bronze disks set in rock outcrops,
    massive structures, or as concrete monuments must be used for new
    SACS.

[]{#A_861 .anchor}**8.6.1. STAMPING.** New PACS and SACS must have a
unique stamping. Marks set at an airport with an official FAA location
identifier must be stamped with that identifier, followed by a
sequential letter, followed by the year the mark was set. Disks and
"logo caps" must be stamped before they are set in place.

[]{#__RefHeading___Toc123539267 .anchor}**8.6.2. BRONZE DISKS.**

**8.6.2.1.** Standard bronze, horizontal disks must be used for rock
outcrop, massive structure, and concrete marks. A rock outcrop in which
a disk is set must be hard and a part of the main ledge and NOT a
detached fragment. A disk set in a drill hole must be well countersunk
and adequately fixed in place using highway epoxy or equivalent
material. The disks must be fastened so they will effectively resist
extraction, change of elevation, or rotation. Disks also must be well
countersunk in areas where snow plowing is possible. If the top of the
disk is not below the level of the surrounding material, a snow plow can
scrape off the brass from the top of the disk or, worse, break the disk
off the stem.

Traditionally, NGS has set disks so the lettering can be read normally
(correct side up) when the observer is south of the disk and facing
north across the disk.

#### ![](media/image15.jpeg){width="3.033333333333333in" height="3.9916666666666667in"}

**8.6.2.2 SETTING A DISK IN BEDROCK OR A STRUCTURE.** Sound bedrock is
the most desirable setting for geodetic survey control points. Besides
the ease and cost effectiveness with which a disk can be installed in
bedrock, it provides the most stable setting for use in terms of both
underground activity and disturbances inflicted by people. Always use
bedrock when a suitable outcrop exits. As a rule of thumb, the bedrock
is considered potentially good if the distance between joints and
fissures is greater than 1 meter. The National Geodetic Survey geodetic
control disks are made of brass or bronze. They are about 9 centimeters
in diameter and have a spherical surface to support the foot of a
leveling rod and a center point for plumbing survey equipment.
Information is imprinted on this surface to identify the monument and to
aid the user in obtaining data on it. This logo is recessed so it does
not interfere with the leveling rod or other survey equipment. A
deformed shank, about 7.5 centimeters long, is silver-soldered or
otherwise attached to the bottom surface of the disk to help prevent the
disk from being dislodged.

The step-by-step procedure for setting the disk in bedrock utilizing
cement is as follows:

a.  Stamp the station designation and setting year on the top surface of
    the disk using 4.75-millimeter (3/16-inch) alphanumeric steel dies.

b.  Pick a fairly level and accessible spot on the outcrop that is fully
    attached to the bulk of the rock. A simple test can be performed to
    help determine the condition and integrity of the rock by placing
    ones hand in the area that the disk will be set, then striking the
    outcrop with a moderately heavy hammer and feeling for vibration.
    Sound outcrop will force the hammer to rebound with each impact and
    vibration through the rock should be minimal at best.

c.  Drill a 2.5-centimeter diameter hole about 10 centimeters into the
    bedrock and recess the area around the top of the hole to a diameter
    slightly larger than that of the disk. When the installation is
    completed, the top of the surface of the disk should sit level and
    slightly below the surface of the surrounding rock. Chisel a drain
    channel through the low edge of the drilled recess to allow water to
    drain from around the finished mark. Safety goggles should be worn
    when drilling into bedrock or masonry.

d.  Clean the disk by wetting then rubbing all surfaces with cement to
    remove unwanted oils and rinse. Fill the depression on the underside
    of the disk with mortar using a trowel. Hold the disk loosely upside
    down by the end of the shank, then gently tap the domed surface of
    the disk from below with the handle of the trowel several times.
    This will allow the mortar to settle and trapped air to escape. This
    is very important because it will prevent the existence of highly
    undesirable voids under the disk once it is in place.

e.  Place the shank of the disk into the drilled hole and press the mark
    firmly into place. A slight rotation of the disk back and forth and
    gentle tapping with the end of the trowel handle helps settle the
    disk completely and evenly into the drilled recess in the bedrock.
    The disk is considered set when the slight back-and-forth movement
    stops and the disk sets firmly in place. Work excess mortar around
    the outer edge of the disk, making sure it is smooth and slightly
    overlapping the top outside edges of the disk for security. An
    exposed edge of the disk would provide an area that could be used to
    dislodge it. Fresh mortar on the upper surface of the disk can be
    easily cleaned off and out of any stamping.

f.  Sprinkle some dry cement on the exposed surface of the disk, then
    rub it with a clean rag or short bristled brush using circular
    strokes. This will clean the disk very nicely, removing all excess
    mortar from its surface and recessed letters. Rubbing the wet mortar
    around the edge of the disk in the same manner is done intentionally
    to finish its surface and help prevent cracking. Brush away loose
    cement and make sure the finished product has a neat appearance.

g.  While the mortar is still wet, it must be covered to prevent heavy
    rains or other foreign debris from ruining its surface and to
    conceal the disk from people who might tamper with it. A piece of
    wood, cardboard, heavy paper, or similar biodegradable item will
    suffice.

The installation is complete. Once all accumulated trash is picked up,
leave the site clean and in good order.

[]{#__RefHeading___Toc123539268 .anchor}**8.6.3. STAINLESS STEEL ROD
MARKS.** A stainless steel rod three-dimensional (3-D) drivable survey
monument is the recommended survey marker producing the stability
required for most conditions. These monuments are suitable for a PACS if
the stability meets code "B" (see paragraph 8.5 for stability
requirements) requirements. The principal component of this monument is
a 9/16-inch stainless steel rod driven into the ground, utilizing a
gasoline-powered![](media/image16.png){width="1.8in"
height="1.6444444444444444in"}

reciprocating hammer, until refusal or a reduced driving rate has been
achieved. The rod must be driven until the rod refuses to drive further,
or until a driving rate of 60 seconds per foot is achieved. The rounded
top of the rod is the survey datum point.

![](media/image17.jpeg){width="3.265972222222222in"
height="4.322916666666667in"}Record the length of rod driven for entry
into the station description. The minimum acceptable length of rod is 4
meters (see Table 3, page 27, *Geodetic Bench Marks*) unless the rod
becomes embedded in rock and cannot be extracted. New rod marks should
be allowed to settle for at least 1 day before observations. A 1-meter
long, grease-filled finned sleeve must be used with this mark. These
monuments have the upper 3 feet of the rod encased in a 1-inch grease
filled plastic extruded fin sleeve held horizontally stable by
back-filled, washed sand. Effects of up-and-down ground movement during
freeze/thaw or wet/dry conditions are alleviated by the grease-filled
sleeve promoting vertical stability. A 5- or 6-inch PVC pipe with
attached standard aluminum logo cap protects and identifies the top of
the monument. Either a 5- or a 6-inch diameter PVC pipe may be used as
long as the logo cap fits correctly. The logo cap can fit on either the
inside or the outside of the pipe.

**8.6.3.1.** If bedrock is found only a few feet beneath the surface, a
concrete mark may be set instead of a rod mark if the concrete will rest
directly on the bedrock. Drill several holes in the bedrock so the
concrete monument will be affixed to the bedrock. Utilize rebar to
anchor the monument if feasible. The area of the bedrock where the
concrete will be placed must be brushed or washed off thoroughly.
Install a standard concrete monument with brass disk (see paragraph
8.6.4).

**8.6.3.3.** Recommended Equipment for Setting Monuments. This
information and photographs in this document are intended only for the
purpose of providing the user with guidelines for planning and
implementing this style of survey monument. The distribution of this
document or the mention of a commercial company or product contained
herein does not constitute, in any way, an endorsement by the FAA, NGS,
or any agency of the U.S.
Government.![](media/image18.png){width="3.2354166666666666in"
height="2.2604166666666665in"}

**Rod Drivers and Accessories:**

1--Any driver with a minimum impact force of 25-foot pounds per blow,
such as Wacker Model BHB 25 (with tool kit) or Pionjar Model 120 (with
tool kit), for driving stainless steel rods.

1--Rod Driving Insert, holds machine on rod and acts as impact point
while driving rods.

1--Shovel Bit, for machine to help start and dig holes (not required but
might be helpful).

1--Pint Required Oil Type and Calibrated Container, for determining
gas/oil mix.

1--Gas Container and Gasoline, for driving machine and generator.

**Digging the Hole:**

1--Post Hole Digger, capable of digging a hole 4 feet deep.

1--Gas Powered Post Hole Digger with Augurs (not required but increases
productivity).

1--Digging Bar, for rocks and hard to dig holes.

**Driving the Rod:**

1--2-pound Hammer, to start rods, stamp designations, etc.

2--8-inch Quality Pipe Wrenches (i.e. Rigid), for attaching lengths of
stainless steel rods.

1--Bottle Loctite, for cementing threads into the stainless steel rods.

**Finishing the Rod:**

1--Hack Saw with extra Quality Blades, for cutting stainless steel rod.

1--4- or 5-inch Grinder (electric or battery powered), for finishing top
of rod.

1--Gas Powered Electric Generator, to power grinder and or drill.

2--Sanding Disks (medium grade), for grinder.

1--Steel File(s), for fine finishing top of rod.

1--Centering Sleeve, to help center punch mark on top of rod.

1--Center Punch, to punch plumbing point on top center of rod.

Assorted Sand Paper or Sanding Pad, for fine finish to top of rod.

**Finishing the Monument:**

1--1/4-inch Stamping Set, for lettering and numbering station
designation/date.

1--Hand Saw, for cutting 5- or 6-inch PVC pipe.

1--Bucket or Wheel Barrel, to mix cement/move unwanted dirt.

2--5-gallon Water Wontainers and Water, to mix cement and clean
equipment.

1--Hoe, to mix cement (can be replaced by Sharp Shooter Shovel).

1--Heavy Rubber Mallet, to help lower logo cap/5- or 6-inch PVC pipe
into cement.

1--Cement Finishing Trowel, to smooth top of concrete for neat
appearance.

1--Stiff Vegetable Type Brush, to clean logo cap and hinges.

**Assorted Accessories:**

1--Tool Box with regular assortment of tools, for incidental repairs:
Slotted and Phillips

Head Screwdrivers, Pliers, Needle Nose Pliers, Wire Cutters, Assorted
Wrenches,

Sockets, Allen Wrenches, Wire Brush.

1--Round Nose Shovel, to help dig hole and move unwanted dirt.

1--Tile Spade sometimes referred to as a Sharp Shooter Shovel, to help
dig hole and mix cement.

1--Roll Black Tar Paper (Felt Paper), for making a round form for top of
monument.

1--30-Meter Tape Measure, for distances in station description.

Leather or Cotton Gloves.

Assorted Rags or Paper Towels.

**Materials Required for Each Mark:**

Lengths of 9/16-inch Stainless Steel Rods, 4-foot sections.

1--4- to 5-inch piece of Stainless Steel Rod, used as impact point and
protection while driving rods.

Adequate supply of 3/8-inch Threaded Stainless Steel Studs.

1--Steel Spiral (fluted) Rod Entry Point, standard order.

1--Aluminum Logo Cap, standard order.

1--Schedule 40 PVC Pipe, 5- or 6-inch diameter, 24-inch length.

1--Plastic Extruded Fin Sleeve, 1-inch diameter, 3-feet minimum length.

2--Plastic End Cap Alignment Bushings, center drilled to 9/16-inch (for
extruded fin sleeve).

1--Pint PVC Cement, can be replaced with adequate Epoxy type.

1--Pint PVC Cleaning Solvent, when using PVC cement.

1--17-ounce tube, Non-Toxic, Food Grade Grease, with Applicator (i.e.
grease gun).

Ready Mix Concrete (amount depends on width and depth of hole).

2--Pounds Portland Cement, added to enhance integrity of ready mix
concrete if necessary.

0.5--Cubic Feet Washed Sand, fills bottom of hole and inside of PVC pipe
around grease sleeve.

**Setting Procedures:**

The time required to set an average mark using the following procedures
is 2 to 3 hours. Several steps, such as steps C, D, and F, should be
accomplished at a maintenance shop.

![](media/image19.png){width="2.8020833333333335in"
height="1.9256944444444444in"}

a.  Ensure the monument site selection is discussed with airport
    management and/or property owners, and the location meets all
    station siting requirements. Inquire about future construction that
    might affect mark longevity.

b.  Contact "MISS UTILITY"-type services offered by local utility
    companies to inquire about underground utilities before digging or
    driving rod.

c.  Stamp station designation and year of establishment into the blank
    area on the collar of the logo cap.

![](media/image20.png){width="2.727777777777778in"
height="1.9166666666666667in"}

d.  Cut a 20-inch section of 5- or 6-inch PVC pipe. Ensure the end that
    will receive the logo cap is cut true and is clean. Using primer and
    solvent cement formulated specifically for PVC, glue the stamped
    aluminum logo cap to the end of the 20-inch PVC section. If this
    step is performed on site, allow time for the glue to set by digging
    the hole and driving the rod after preparing the PVC and logo cap.

e.  Using a power auger or post hole digger, drill or dig a round hole
    in the ground 12 to 14 inches in diameter and 22 inches deep. Extend
    the center of the bottom of the hole by drilling or digging a 3- to
    6-inch diameter hole an additional 21 inches for a total depth of 43
    inches. This extended area will be back-filled with washed sand
    around grease sleeve.![](media/image21.png){width="2.73125in"
    height="1.945138888888889in"}

f.  Glue both plastic end cap alignment bushings on a 3-foot section of
    the plastic extruded fin sleeve. Let glued ends dry completely. Pump
    food grade grease into capped sleeve until 3/4 full, allowing for
    displacement by rod and completing the grease filled sleeve.

g.  Using a standard 3/8-inch threaded stud coated with Loctite™ (use
    Loctite™ on all *permanent* connections), attach two 4-foot sections
    of stainless steel rods together. At one end of the length of rod,
    attach a standard spiral (fluted) rod entry point with a 3/8-inch
    threaded stud. On the opposite end, attach a short 4- to 5-inch
    piece of rod with a 3/8-inch threaded stud. Tighten all connections
    using two pipe wrenches a 1/4 to 3/4 turn past the point of contact
    of all rod ends except the impact point, which will be continually
    removed. This tightening requires a certain "feel" and ensures that
    the rod ends are seated together with the greatest possible tension
    but not to the point of breaking a stud. Rods tightened in this
    fashion should not vibrate loose when they are driven into the
    ground.

h.  Center the 8-foot-long connected rod into the bottom of the hole and
    drive with a 2-pound hammer until the rod is secure and as plumb as
    possible. A 2x4 with a 1/2-inch hole can be centered and braced over
    the hole to help guide the rod straight into the ground. Drive the
    section of rod to about the top of the hole with a gas-powered
    reciprocating driver, such as Whacker model BHB 25, Pionjar model
    120, or another machine with an equivalent driving
    force.![](media/image22.png){width="2.7291666666666665in"
    height="1.886111111111111in"}

i.  Remove the short piece of the rod (impact point), leaving the
    threaded stud in the section of rod in the ground. Attach another
    4-foot section of rod and, using a new threaded stud, thread on the
    impact point. This "cycling" of a new stud from impact point into
    the top of rods in the ground ensures unweakened studs at all
    connections. Remember to coat threads on the permanent connections
    with Loctite™. Tighten securely utilizing pipe wrenches as described
    above in step f. Always tighten rods maintaining a clockwise
    pressure to avoid loosening rods already in the ground. Drive the
    new length of rod into the ground with the reciprocating
    driver.![](media/image23.png){width="2.720138888888889in"
    height="3.7465277777777777in"}

j.  Repeat step I until the rod refuses to drive further (anchored) or
    until a driving rate of 60 seconds per foot is achieved. In the
    event the rod will not sufficiently slow down to meet desired
    driving rate, terminate upon reaching 90 feet (22.5 rods). This will
    leave about 2 feet of rod out of the hole. If possible, let the rod
    set overnight, then drive the remaining 2 feet of rod to determine
    whether driving rate has reduced. If the rod feels secure in the
    ground, use this depth even though the minimum driving rate of 60
    seconds per foot has not been met. If the rod turns freely in
    clockwise direction, contact NGS for a decision about driving
    additional rods. Sometimes, all that is necessary to achieve a
    well-anchored rod is driving it a few more feet. In other instances,
    an additional 100 feet might be required. Indicate in the written
    station description the depth of rod and whether it was driven to
    refusal or met the slow driving rate. Also include a description of
    any unusual mark setting circumstances.

![](media/image24.png){width="2.8041666666666667in"
height="2.551388888888889in"}

k.  When refusal or prescribed driving rate is reached, cut off the rod
    with a hacksaw or comparable tool, always removing at least the
    tapped and threaded portion, leaving the top of rod about 3 inches
    below ground surface. Shape the top of the rod to a smooth,
    hemispherical surface using a portable grinding machine with a
    grinding attachment or sanding wheels, files, and sand paper to
    produce a nicely finished, rounded surface. Ragged edges or grinding
    marks are not acceptable on the top of the finished rod.
    ![](media/image25.png){width="2.8020833333333335in"
    height="2.2194444444444446in"}

l.  The datum point must then be created by center punching a dimple on
    top of the rod to provide a plumbing (centering) point. Place the
    centering sleeve over the top of the rounded rod to facilitate
    locating the exact center of the rod. Punch a substantial dimple,
    1/16-inch deep, into the top of the rod using a punch and hammer or
    spring-loaded center punch. Several blows might be needed to create
    a sufficient dimple. Remember, this is the actual survey point, so
    do not hesitate to spend a few extra minutes to produce a
    professional, finished
    product.![](media/image26.png){width="2.9451388888888888in"
    height="1.9791666666666667in"}

m.  Insert the grease-filled sleeve, produced in step E, over the rod
    with the unfilled portion at the top. The upper end of sleeve will
    fill as the rod displaces grease from the bottom. The datum point on
    the top of the rod should protrude through top of the sleeve about
    3-inches with the sleeve extending to the bottom of the hole. Clean
    the residual grease off the exposed top of the rod.

n.  Back-fill and pack with washed sand the bottom 23 or more inches of
    the hole around the outside of grease sleeve. This fills the bottom
    of the hole and helps stabilize the sleeve.
    ![](media/image27.png){width="1.7895833333333333in"
    height="2.207638888888889in"}

o.  Place the 5- or 6-inch PVC pipe and logo cap over and around the
    grease sleeve and rod in the center of the hole. The bottom of the
    PVC pipe should extend into the top of the sand in the bottom of the
    hole. Leave the top of the logo cap and PVC pipe slightly higher
    than the top of the ground surface until the concrete is in place.
    Back-fill the center of the PVC pipe with washed sand around and to
    within 1-inch from the top of the grease-filled sleeve. The rod
    should be centered in the PVC pipe.

![](media/image28.png){width="2.9854166666666666in"
height="2.1375in"}![](media/image29.png){width="3.3645833333333335in"
height="2.1in"}

p.  Mix concrete in a bucket or wheel barrel to a pasty, well-moistened
    consistency, like mashed potatoes. Add Portland cement, if
    necessary, in sufficient quantity (1 to 2 pounds) to enhance
    concrete mix or dry an over-moistened mixture to maintain adequate
    consistency. A good indication of adequate consistency is that the
    mix neither runs nor falls off the shovel but sluggishly slides off
    and flattens upon hitting the ground. Pour concrete into the hole
    around the logo cap and PVC pipe casing, filling to slightly below
    the ground surface.

q.  To avoid frost heaving of the PVC collar, a round form should be
    used to ensure the outside walls of the concrete are vertical and do
    not produce a mushroom-shaped wedge at the top of the mark. Open the
    logo cap and grasp the PVC pipe, then shake to settle concrete
    around the pipe to fill voids. Add concrete to within 1/2-inch of
    the ground surface.

r.  Trowel smooth the top of the concrete to a fairly finished surface.
    Tap alternate edges of the logo cap, using a rubber mallet or hammer
    and wooden block, lowering it and attached PVC pipe into the surface
    of the concrete. Finish the top of the concrete by troweling a
    smooth, finished surface, round in appearance, and sloped slightly
    outward to aid drainage of rain
    water.![](media/image32.png){width="3.1305555555555555in"
    height="2.4458333333333333in"}

s.  Add sand to the inside of the PVC pipe to bring its level to within
    1 inch of the top of the grease sleeve. Clean any overlapping
    concrete from the surface of the logo cap using the vegetable brush.
    The finished height of the logo cap and access cover should be
    slightly lower than the surface of the ground. The logo cap should
    be approximately in the center of the top of the concrete. The datum
    point should be about 3 inches below the cover of the logo cap and
    centered in the 5- or 6-inch PVC pipe. The top of the grease-filled
    sleeve should be about 3 inches below the datum point and the washed
    sand 1 inch below top of the sleeve. Clean any cement that might
    have gotten onto the exposed rod or datum point.
    ![](media/image33.png){width="3.1881944444444446in"
    height="2.0340277777777778in"}

t.  Clean all equipment and remove all debris, such as extra cement,
    excess dirt, and trash, leaving the area in the condition it was
    found.

[]{#__RefHeading___Toc123539269 .anchor}**8.6.4 CONCRETE MARKS.** New
concrete marks, with standard NGS bronze disks, may be used for SACS
only. Construction requirements are detailed below. New concrete marks
should be set slightly recessed with the ground and allowed to settle
for at least 1 day before observations. Disks set in concrete must be
centered in the top of the concrete surface and be flush or slightly
recessed with the surface of the concrete; the top of the disk must be
free of concrete. A round form must be used for the top of all concrete
marks and logo cap protective collars. This will help ensure a neat
finish and help protect against "mushrooming", which can result in frost
heave. Black tar paper (felt paper) or ready-made cardboard frames
(available at home supply stores) can be used to easily construct a
form. All loose concrete and other debris around the construction site
must be removed and the site left in excellent condition.

**8.6.4.1. CONCRETE CHARACTERISTICS.**

**8.6.4.1.1. GENERAL.** The concrete should be workable, strong, and
durable. Workability refers to the ease concrete can be effectively
placed, consolidated, and finished while remaining free from
segregation. Workability depends on the proportions of the ingredients
and the shape of the individual particles of aggregate. Strength refers
to the ability to withstand external forces without rupturing. For
survey monuments, high strength is not the most important property,
although strong concrete usually indicates it is durable. Durability is
the ability to withstand deterioration over a long time and is primarily
influenced by the water tightness of the cured concrete.

**8.6.4.1.2. DESTRUCTIVE FORCES.** Several forces can lead to weakening
or deterioration of concrete. The freezing of water in cured cement
exerts great pressure against the inner walls of the pores, tending to
break down the concrete. In fresh concrete, the expansion of freezing
water breaks the bonds developing between solid particles, making the
concrete weak and porous. Leaching and chemical attack are also
detrimental effects on concrete. Leaching occurs over a long period when
water slowly percolates through concrete and dissolves some of its
constituents. Chemical attack is particularly common in alkali soils.
Dense, impervious concrete is resistant to these destructive forces.

**8.6.4.1.3. INGREDIENTS.** The quality of the ingredients and their
proportions help determine how dense and impervious the cured concrete
will be. The ingredients include aggregate, cement, and water. The
aggregate should be clean (free from silt and clay, harmful chemicals,
and organic matter) and well-graded, i.e., it contains proportionate
amounts of many particle sizes. In specifying mix proportions, the
aggregate is usually divided into two parts---sand (particle size less
then 2/3 cm) and gravel (particle size greater than 2/3 cm). Both parts
should be well-graded. Porous aggregates split easily or are otherwise
weak or permeable resulting in poor concrete. Examples of poor
aggregates include shale, claystone, sandstone, and micaceous rocks.
Portland cement is designated by one of five types. Type I is for
general use where no special properties are needed. Type III is a
high-early-strength type for use when concrete will be curing during
cold weather. Type V is used where the concrete will be subject to an
alkali environment. Types II and IV are not suited for setting marks.
Contact local concrete companies to determine the best concrete type for
use in the work area. The water used in a concrete mix should be
relatively free of impurities such as acids, alkalies, salts, oil,
organic matter, and silt. These can decrease the strength and durability
of cured concrete. As a rule, do not use water that you would not drink.

**8.6.4.1.4. MIXING, PLACING, AND CURING.** Pre-mixed concrete materials
may be used. If raw materials are used, the suitable proportions (by
bulk volume) of cement to sand to gravel are 1:2:3. If the gravel is
made up of fragmented or angular particles, use a little less gravel and
proportionately more sand. Add only enough water to make the mix
workable. About half the water added to the mix is used in the chemical
reaction (hydration) that causes the paste to harden into binder. If too
little water is used, however, the mix will not compact properly, and
spaces will be left in the mass. A good indication of the right amount
of water is that the mix neither runs nor falls off the shovel but
sluggishly slides off and flattens upon hitting the ground.

**8.6.4.1.5. COLD WEATHER PRECAUTIONS.** The freezing of fresh concrete
has a damaging effect because the expansion of water as it freezes
separates the solid particles in the mix. This reduces the strength of
the bond and makes the concrete more porous and correspondingly less
durable. Three protective measures should be taken in cold weather,
either singly or in combination.

**8.6.4.1.5.1. USE WARM INGREDIENTS.** During the first 24 hours after a
mix has been placed, it develops little heat of its own to prevent
freezing. After 24 hours some heat is developed as a product of the
chemical reactions occurring in the mix. The use of warm ingredients is
especially beneficial during the first 24 hours. Note, however, that
mixing water above 165° F could cause a flash set. To keep the aggregate
and cement warm, store them indoors.

**8.6.4.1.5.2.** Use Type III (high-early-strength) cement or special
additives that speed curing. Calcium chloride is good for this in
amounts not exceeding 2 pounds per 94-pound sack of cement. The calcium
chloride should be dissolved in the mixing water instead of mixing it
with the other ingredients. Other additives include Thoroguard ™ and
Trimix ™. If a large number of concrete marks are being installed by
mass production using a "ready-mix" concrete, fast-curing additives
should not be added until the concrete is delivered on site.

**8.6.4.1.5.3.** Insulate the finished mark for a week after the
concrete is poured. One method is to cover the mark with boards resting
on supports. This construction is covered with paper or plastic, then by
a layer of straw, Styrofoam, or similar insulating materials more than
15 centimeters thick and finally by a layer of soil 15 to 30 centimeters
thick. Pile snow loosely on top if it is available.

**8.6.4.2. CONSTRUCTING CONCRETE MONUMENTS**[^1] **STEPS.**

a.  Obtain permission from the property owner before proposing new mark
    locations.

b.  Install a tall stake (lath) at each proposed site for a new mark.
    Write the proposed station name on the stake.

c.  Obtain clearance from "MISS UTILITY"-types services offered by local
    utility companies (underground utilities) before digging.

d.  Drill or dig a 12- to14-inch diameter hole in the ground 3.5 to 8 or
    more feet deep. The depth depends on frost penetration in the area.
    The minimum depth is 3.5 feet. Keep the sides of the hole as smooth
    as possible. The rounded, bottom portion of the monument must extend
    at least 1 foot below the frost line. See NOAA Manual NOS NGS 1,
    *Geodetic Bench Marks,* which contains a diagram showing average
    frost line depth.

e.  Enlarge the bottom portion of the hole using a shovel, such as a
    "sharp-shooter" (also called a "drain spade") so the hole is at
    least 2 inches larger in radius than the main shaft of the hole.
    This will make the bottom of the monument bell-shaped; see Figure
    8.15.

f.  Remove or tamp down the loose dirt at the bottom of the hole.

g.  Remove any loose dirt that might fall into the hole during concrete
    installation. A layer of loose dirt from the sides or top of the
    hole, mixed with the concrete, will create a fracture line (or
    plane), which could lead to the monument breaking, thus destroying
    the mark.

h.  Procure a round, cardboard form 12 inches in diameter to line the
    top 12 to 18 inches of the hole. Test fit the form in the top of the
    hole. This form will help avoid any shoulders or mushrooming effect
    near the top of the monument, which might allow for frost heave. The
    form will also help make a neater looking monument. A cardboard,
    biodegradable, 12-inch diameter form is commercially available.
    Allow the form to protrude from the ground 2 to 6 inches.

i.  Mix the concrete well before it is placed, otherwise the minute
    particles of cement will not be sufficiently wet and the aggregate
    will not be completely covered with paste. Prior to adding water,
    mix the ingredients well. Then, slowly add water and continue
    to mix. Do not make the mixture too wet.

j.  Dampen the hole before concrete is added so moisture will not be
    drawn from the fresh concrete into the surrounding soil. In no case
    should it be so wet as to be muddy.

k.  Place concrete in the hole. Continuously tamp the mix into a compact
    mass so it becomes less pervious and consequently more durable. Do
    not contaminate the interior of the monument with dirt.

l.  Place the form into the hole when the level of the concrete is
    approximately 1 foot below the surface. Continue to be careful not
    to allow any dirt to fall into the hole.

m.  Add concrete until the top is even with or slightly below the
    surface of the ground. This helps ensure the monument is not struck
    by lawn mowers, snow plows, etc.

n.  Smooth off the top of the monument with a trowel. Create a gentle
    slope toward the outside so rain water will drain off. Bevel the
    outside edge of the monument.

o.  Stamp the disk prior to installing it in a concrete monument or a
    drill hole. Stamp the disk on a stamping block that has a curved
    surface that matches the curvature of the underside of the disk.
    Neatly stamp the station designation (name) above the triangle,
    centered below "HORIZONTAL CONTROL MARK", and then stamp the year
    below the triangle.

p.  Set the disk into position in the top center of the monument with
    the top of the triangle below the name pointing north (so a visitor
    facing north will be able to read the disk\'s lettering). Placing a
    small amount of concrete on the underside of the disk before setting
    helps ensure that air is not trapped under the disk.

q.  Press the disk into the concrete until the disk edge touches the
    concrete. Then tap the disk with the handle end of the trowel until
    the top edge of the disk is flush with or slightly recessed into the
    concrete (to the point that vandals can not get a pry bar under the
    disk). Do not recess the disk a greater amount because this makes a
    hollow that will collect rainwater and possibly shorten the life of
    the mark due to freezing action.

r.  Clean the disk. Sprinkle some dry cement on the exposed surface of
    the disk, and then rub it with a clean rag or short bristled brush
    using circular strokes. This will clean the disk, removing all
    excess mortar from its surface and recessed letters. Rubbing the wet
    mortar around the edge of the disk in the same manner is done
    intentionally to finish its surface and help prevent cracking. Brush
    away loose cement and make sure the finished product has a neat
    appearance.

s.  ![](media/image34.jpeg){width="3.5555555555555554in"
    height="4.763888888888889in"}Cover the mark for at least 7 days.
    This prevents rain from making the mix too wet and from ruining the
    finished surface. It also prevents the surface from drying too
    rapidly, leaving too little water for complete hydration. In
    addition, it prevents debris from sticking to the surface of the wet
    concrete. A 12-inch diameter lid is available that fits on the
    12-inch cylindrical form. This lid will also keep out the dirt
    during the next step and final clean up.

t.  Replace dirt round the form and tamp into place. At the surface,
    replace dirt and sod around the form and tamp into place.

u.  Rake the area until neat, and remove excess materials. Do not leave
    any construction or other materials at the site. Leave the area as
    neat as or neater than when you arrived. Note: The protruding form
    and lid must be removed later during survey observations.

v.  Remove excess dirt and dispose of it properly. In some rural areas
    there might be a logical spot to dump the extra soil. If the mark is
    in an area consisting of groomed lawns, the dirt must be removed
    from the site.

w.  Remove excess concrete from the site. Proper planning should
    minimize excess concrete. Any excess must not be dumped onsite.

x.  Installation of NGS Witness Posts (see paragraph 8.6.5) are at the
    option of the firm. Generally do not use Witness Posts in areas of
    high population density nor on airports. They are very useful to
    future surveyors in more remote areas.

y.  Do not add magnetic materials to the monument.

[]{#__RefHeading___Toc123539270 .anchor}**8.6.5. WITNESS POSTS.**
Placement of witness posts on airport property must be pre-approved by
the airport manager. Witness posts should be used on an airport only
when they can be placed in a non-obtrusive area, such as a fence line or
no-mow/snow plow area, and should be driven as deep as practical so they
do not obstruct any restricted safety areas. Witness posts should not be
used when the property owner objects, when the post cannot be driven, or
when the mark should not be made easily visible because of a high risk
of vandalism.

## ![](media/image35.jpeg){width="3.9791666666666665in" height="3.0833333333333335in"}8.7. GPS POSITIONING PROCEDURES. 

GPS observation requirements are detailed in the paragraphs below. A GPS
equipment list and GPS observation scheme must be approved by NGS prior
to commencing the field observations. Observing windows must be
selected, and modified as necessary, to maximize satellite visibility
and minimize Positional Dilution of Precision (PDOP) for each session.
Incorporate any information from Notice Advisory to NAVSTAR Users (NANU)
messages, available from the USCG Navigation Center webpage, when
scheduling GPS observations to ensure optimal survey conditions.

[]{#__RefHeading___Toc123539272 .anchor}**8.7.1. CORS SELECTION.** The
CORS sites selected must be included in the NGS National CORS system.
Use as many National CORS sites in the project area as feasible.
Position each PACS directly to the nearest National CORS station. In
areas such as Alaska where a PACS is not within 300 km of a CORS, a
CTCORS must be established.

CORS maps, data, and information are available on the NGS National CORS
website (see Appendix 7 for access). Each CORS is designated by a three-
or four-letter name, followed by the antenna number. The correct antenna
name must be used when downloading data and the antennas coordinate
information. Each CORS site usually has two or more antennas. Check the
"data availability" feature on the NGS CORS website to determine which
CORS antenna was in use during observations and to see if there are any
gaps in the data. The CORS station coordinate file contains several
positions based on different Antenna Reference Points (ARP), in either
the International Terrestrial Reference Framework (ITRF) or NAD 83
reference system. Ensure the proper coordinates are used when processing
the data.

The survey disks (usually two) at each CORS site might have names
similar to the antenna names. Take care not to confuse the disk names
and positions with the antenna names and positions.

The weekly *CORS Newsletter* is available through the NGS CORS webpage.
The *Newsletter* provides information on the status of the CORS system.
Users may subscribe to the newsletter at this site.

[]{#__RefHeading___Toc123539273 .anchor}**8.7.2. CTCORS SELECTION.** A
Central Temporary Continuously Operating Reference Station (CTCORS) must
be used if the nearest CORS is more than 300 km from the PACS. The
CTCORS must be established by setting up a GPS receiver on a suitable
existing horizontal NSRS station and must provide the CORS function in
the positioning of the PACS. The position of the CTCORS must be verified
by using the GPS observation requirements in paragraph 8.7.3.1. Because
of the long distances involved and the additional stations being
positioned from the CTCORS, extreme care should be taken during the
observation and processing of this data. Separate tripod setups are
required at both the CTCORS and the PACS for each session. During all
CTCORS operations, ensure the CTCORS antenna remains fixed. Sandbags are
recommended to stabilize the tripod, and frequent checks should be made
of the antennas centering and height. CTCORS Station Selection Criteria
are listed below. The CTCORS station selection must be approved by NGS
prior to commencing field observations.

Table 8.2. CTCORS Station Selection Criteria.

  ------------------------ -------------------------------- ------------------- ----------------------
  [PRIORITY]{.underline}   [TYPE OF STATION]{.underline}    [STATION IS BENCH   [STATION IS AT
                                                            MARK]{.underline}   AIRPORT]{.underline}

  1                        WAAS, USCG, or USACE CORS mark   YES                 YES

  2                        WAAS, USCG, or USACE CORS mark   YES                 NO

  3                        WAAS, USCG, or USACE CORS mark   NO                  YES

  4                        WAAS, USCG, or USACE CORS mark   NO                  NO

  5                        A-ORDER HARN STATION             YES                 YES

  6                        A-ORDER HARN STATION             YES                 NO

  7                        A-ORDER HARN STATION             NO                  YES

  8                        A-ORDER HARN STATION             NO                  NO

  9                        B-ORDER HARN STATION             YES                 YES

  10                       B-ORDER HARN STATION             YES                 NO

  11                       B-ORDER HARN STATION             NO                  YES

  12                       B-ORDER HARN STATION             NO                  NO
  ------------------------ -------------------------------- ------------------- ----------------------

Acronyms:

Wide Area Augmentation System (WAAS); FAA

U. S. Coast Guard (USCG)

U.S. Army Corps of Engineers (USACE)

High Accuracy Reference Network (HARN)

[]{#__RefHeading___Toc123539274 .anchor}**8.7.3. ACCURACY STANDARDS.**
The required accuracy standards for PACS and SACS are outlined in Table
8.3.

Table 8.3. PACS and SACS Accuracy Standards.

+-----------------------------+-------------+--------------+----------+
| ###### ITEM                 | ######      | **VERTICAL** |          |
|                             |  HORIZONTAL |              |          |
+-----------------------------+-------------+--------------+----------+
|                             |             | **O          | **ELL    |
|                             |             | RTHOMETRIC** | IPSOID** |
+-----------------------------+-------------+--------------+----------+
| Primary Airport Control     | 5 cm        | 25 cm        | 15cm     |
| Station (PACS) ^1^          |             |              |          |
+-----------------------------+-------------+--------------+----------+
| Secondary Airport Control   | 3 cm        | 5 cm         | 4 cm     |
| Station (SACS) ^2^          |             |              |          |
+-----------------------------+-------------+--------------+----------+
| Wide Area Augmentation      | 5 cm        | 10 cm        | 10 cm    |
| System (WAAS) Reference     |             |              |          |
| Station ^1^                 |             |              |          |
+-----------------------------+-------------+--------------+----------+
| Wide Area Augmentation      | 1 cm        | 0.2 cm       | 2 cm     |
| System (WAAS) Reference     |             |              |          |
| Station ^3^                 |             |              |          |
+-----------------------------+-------------+--------------+----------+
| Notes:                      |             |              |          |
|                             |             |              |          |
| ^1^ Accuracies are relative |             |              |          |
| to the nearest              |             |              |          |
| NGS-sanctioned CORS.        |             |              |          |
|                             |             |              |          |
| ^2^ Accuracies are relative |             |              |          |
| to the PACS and other SACS  |             |              |          |
| at the airport.             |             |              |          |
|                             |             |              |          |
| ^3^ Accuracies are relative |             |              |          |
| to the other WAAS Reference |             |              |          |
| Station at the site.        |             |              |          |
+-----------------------------+-------------+--------------+----------+

![](media/image35.jpeg){width="4.1625in" height="3.4756944444444446in"}

[]{#__RefHeading___Toc123539275 .anchor}**8.7.4. GPS OBSERVATION
REQUIREMENTS.** GPS observation requirements are described in the
sections below for each type of mark. When 4-hour sessions are
specified, at least 4 hours of data are required in the final computer
reductions. Observation of sessions longer than the minimum is highly
recommended. Separate tripod setups are required for each session.

**8.7.4.1. CTCORS SITES.** The position of the CTCORS must be checked by
observing three or more independent, continuous, simultaneous
observation sessions of at least 4 hours with a CORS station. These
sessions should be the first sessions observed while positioning various
PACS. In addition, one 4-hour session must be used as a check at the end
of the project. If the distance between the CORS and CTCORS is greater
than 300 km, or at extreme latitudes, contact NGS for guidance on
increasing the length of observation sessions. All CTCORS must be tied
by GPS surveys to nearby GPS-suitable, North American Vertical Datum of
1988 (NAVD 88) bench mark(s). See specific requirements in the Bench
Mark Ties section in paragraph 8.7.4.4.

![](media/image36.jpeg){width="4.553472222222222in"
height="3.5229166666666667in"}**8.7.4.2. PRIMARY AIRPORT CONTROL STATION
(PACS) AND HARN TIE**[^2]**.** Each PACS must be positioned from the
CORS/CTCORS in two or more independent, continuous, observation sessions
of at least 4 hours in length. The observations to position the PACS
must be performed simultaneously with the CORS/CTCORS observations. The
start time of a PACS observing session on subsequent days should be at
least 2.5 hours different than the previous PACS session to incorporate
different satellite geometry.

All PACS must have a separate positional check by simultaneously
observing at least one session of 4 hours or more in length with an "A"
or "B" order HARN station. The HARN station should be within 100 km of
the PACS and should be at least 50 km from the CORS. Tie to as many "A"
order stations as possible during the project.

A single HARN station meeting the distance requirements to more than one
PACS can be used. Generally, no more than two PACS should be tied to a
single HARN station in one session. Use additional observation sessions
on the same HARN, or occupy an additional HARN station to satisfy the
HARN tie to other PACS in the same area.

An existing "A"or "B" order HARN station on an airport should be used as
a PACS if it meets the siting, construction, and intervisibility
requirements. The station must be checked with at least one 4-hour
session to a CORS. A tie to an additional HARN station is not required.

The vector processing results of the two PACS sessions must check within
3 cm. The final adjusted positions of the HARN ties should check within
±5 cm horizontal and ±10 cm ellipsoidal height of the published
positions.

**8.7.4.3. SECONDARY AIRPORT CONTROL STATIONS (SACS).** Each SACS must
be observed in two or more independent, continuous sessions of at least
1.5 hours. The session start times must be separated by at least 2.5
hours to ensure a significant change in satellite geometry.

a.  These observations must be simultaneous with PACS observations for
    that airport.

b.  If a SACS is also one of the bench marks or a HARN tie (see
    paragraph 8.7.4.4), the two or more 1.5-hour sessions are adequate
    for the tie, rather than the normal 4-hour requirement. This is due
    to the short distance from the PACS to the SACS.

c.  ![](media/image37.jpeg){width="4.28125in"
    height="3.310416666666667in"}The vector processing results for the
    two SACS sessions must check within ±3 cm.

**8.7.4.4. BENCH MARK TIES.**

**Ties to two separate NSRS NAVD 88 bench marks are required for each
PACS and CTCORS station. The ties must be performed by observing each
bench mark for at least one session of 4 hours or more in length
simultaneously with the PACS or CTCORS. The two bench marks do not need
to be observed during the same session. Bench mark ties must be selected
in accordance with the Bench Mark Priority Table on the following page.
Use of first-order bench marks is highly desirable. The two bench marks
should be as close as possible to, and no further than 50 km from, the
PACS or CTCORS. Bench marks should be at least 1 km apart to help ensure
they are not both affected by the same upheaval or subsidence effect. If
the PACS or CTCORS has a published bench mark elevation, that elevation
satisfies one of the bench mark tie requirements. A single bench mark
may satisfy one of the tie requirements for more than one PACS if it
meets the distance requirements for each PACS. Generally, no more than
two PACS should be tied to a single bench mark station in one session.
Occupy additional bench marks, or use additional observation sessions on
the same bench mark, to satisfy the bench mark ties for other PACS in
the same area. Bench mark ellipsoidal heights should agree within ±10 cm
and bench mark orthometric heights within ±15 cm of published
elevations. All bench mark elevations used in this survey must be
published NSRS NAVD 88 bench mark elevations, in meters.**

Table 8.4. Bench Mark Priority Table.

+---------+----------------------+------------------------------------+
| P       | DISTANCE TO CLOSEST  | SELECTION CRITERIA                 |
| RIORITY |                      |                                    |
|         | FIRST-ORDER BENCH    |                                    |
|         | MARK                 |                                    |
+---------+----------------------+------------------------------------+
| 1       | \< 25 KM             | Use first-order bench mark..       |
+---------+----------------------+------------------------------------+
| 2       | 25 -- 50 KM          | Use first-order bench mark if      |
|         |                      | closest;                           |
|         |                      |                                    |
|         |                      | Second-order bench mark may be     |
|         |                      | used if it is less than ½ the      |
|         |                      | distance to the first-order bench  |
|         |                      | mark..                             |
+---------+----------------------+------------------------------------+
| 3       | \> 50 KM             | Use a second-order bench mark if   |
|         |                      | it is less than 25 km away;        |
|         |                      | otherwise contact NGS.             |
+---------+----------------------+------------------------------------+

Differential geodetic (spirit) leveling (run in both directions) may be
performed to satisfy the bench mark ties. These level ties must be less
than 3 km. Two bench marks are required for the beginning of a line of
differential (spirit) leveling. Identify these two bench marks in the
Project Survey Plan. If the PACS is tied to two bench marks by spirit
leveling (within acceptable tolerances), then the two bench mark
requirement has been met. Leveling must meet third-order (or better)
requirements listed in *Interim FGCS Specifications and Procedures to
Incorporate Electronic Digital/Bar-Code Leveling Systems*, version 4.0,
15 JUL 94; *Standards and Specifications for Geodetic Control Networks*,
FGCC, 1984; and NOAA Manual NOS NGS 3, *Geodetic Leveling*, 1981.
Leveling data must be submitted in Blue Book format on CD-ROM containing
the final version of the following files: HGF, HGZ, and HA in direct
access format and RPT and ABS in sequential format. Third-order
specifications is an exception to NGS policy stating second-order, class
II, is the lowest order leveling accepted by NGS.

Third-order elevations determined by spirit leveling (run from various
agencies\' bench marks) already exist at airports in the Airport
Obstruction Chart (AOC) Program. For the AOC airports entered into the
NGS database, the NGVD 29 elevations are automatically converted to NAVD
88 elevations using the program VERTCON and will be printed on the
standard station data sheets, in meters, with a reference to VERTCON.
Check these AOC third-order elevations against elevations determined in
this survey and tabulate the result.

**8.7.4.5. SINGLE MARK LEVEL TIE (3RD ORDER).** An assumed elevation for
the bench mark can be used in the leveling since the principal concern
is with the **difference of elevation** between the bench mark and the
GPS station. It should be noted the published elevation of the GPS
station will only be published to the nearest centimeter. This is
because the absolute elevation of the bench mark cannot be verified
without incorporating other bench marks into the survey as a check. Many
projects do not provide the resources required for this multiple mark
check, but it is still imperative that the GPS station has the best
precision allowable.

Record rod readings to millimeters or hundredths of feet. The model,
type of instrument, and serial number of instrument and rods (e.g.,
fiberglass, aluminum, single piece, etc.) as well as rod scale units
(e.g., meters, feet, or bar code) [must]{.mark} be entered on the
"Observations of Bench Mark Ties" form (located at the end of section
8.7.4) where indicated.

**8.7.4.6. OBSERVING SEQUENCE FOR CONVENTIONAL LEVEL.**

**8.7.4.6.1.** Remove equipment from travel cases, attach level
instrument to tripod, and let equipment acclimate to local conditions.
Perform instrument check per manufacturer's instructions. Set up the
instrument about halfway between the stations, but no more than 70 m
(230 ft) away from either point or from one of the points and a turning
pin in the case of multiple setup requirements. Backsight distance to
foresight distance imbalance must be less than 5 meters. Accumulated
backsight to foresight distance imbalance must be less than 10 meters in
the case of multiple setups

**8.7.4.6.2.** Plumb the level rod on the highest point of the old mark.
In Figure 8.19, the old mark is M 123. Record the designation of the
point and its published elevation, noting the reference vertical datum
and units of measure.

**8.7.4.6.3.** Backsight Reading: Observe the intercept of the middle
reticule of the rod scale as a backsight reading. Record the rod reading
to the nearest millimeter (or hundredths of a foot) as indicated above.
Record the stadia reading to determine distance from the point to the
instrument.

**8.7.4.6.4.** Compute height of instrument, HI, which is the sum of the
backsight and the published elevation.

**8.7.4.6.5.** Plumb the rod on the highest point of the new bench mark.
Record the designation of the new mark, e.g., M 123 RESET or TP1 (for
turning point 1 in the case of multiple setups).

**8.7.4.6.6.** Foresight Reading: Observe the intercept of the middle
reticule of the rod scale as foresight reading. Record the stadia
reading to determine distance from the point to the instrument.

**8.7.4.6.7.** Compute the elevation of the new point, new bench mark,
or turning point, which is the difference of the HI minus the foresight.

**8.7.4.6.8.** Reset and re-level the instrument. Level backward from
the new point to the old, in the same manner as described in paragraphs
8. 7.4.6.2 through 8.7.4.6.7.

Note: The elevation computed for the old point as a result of the
backward leveling may differ by no more than +/-12D [mm]{.mark} (where
D is the shortest length of section in kilometers one way) from the
published elevation.

**8.7.4.6.9.** To compute the elevation difference from the old mark to
the new, subtract the mean of the two elevations for the old mark from
the elevation for the new mark.

**8.7.4.7. OBSERVING SEQUENCE FOR DIGITAL LEVEL.**

**8.7.4.7.1.** Remove equipment from travel cases, attach level
instrument to tripod, and let equipment acclimate to local conditions.
Perform instrument check and adjustment as outlined in the digital level
manual.

**8.7.4.7.2.** Set up the instrument about halfway between the stations.
Limit sight lengths to no more than 70 m (230 ft) from either point or
from one of the points and a turning pin in the case of multiple setup
requirements, e.g., distance between points is greater than 140 meters.
Backsight distance to foresight distance imbalance must be less than 5
meters. Accumulated backsight to foresight distance imbalance must be
less than 10 meters in the case of multiple setups. Level up the
instrument using the 3-foot screws while observing the bulls-eye bubble.
Turn on the instrument and select the backsight/foresight level program.
Confirm that you want to start, then enter the starting elevation for
the old mark. Set and confirm at least the following instrument
parameters:

a.  meaning three measurements

b.  display maximum decimal places

c.  record readings to onboard module

d.  observing configuration, such as rod type, and metric units.

**8.7.4.7.3.** Plumb the level rod on the highest point of the old mark,
e.g., domed top of disk M 123. Record the designation of the point and
its published elevation, noting the reference vertical datum and units
of measure.

**8.7.4.7.4.** Backsight Reading: Point using the vertical crosshair of
the level instrument on the middle of the rod over the old mark, and use
the focusing knob to bring the image of the rod into sharp focus.
Depress the measure button and record the rod reading. Note distance
from rod to instrument. It should be less than 70 meters.

**8.7.4.7.5.** Plumb the rod on the highest point of the new bench mark.
Record the designation of the new mark, e.g., M 123 RESET or TP1 (for
turning point 1 in the case of multiple setups).

**8.7.4.7.6.** Foresight Reading: Point and focus the level instrument
on the rod over the new mark. Depress the measure button and record the
rod reading. Note distance from rod to instrument. It should be less
than 70 meters. Note imbalance between backsight and foresight
distances. This difference must be less than 5 meters.

**8.7.4.7.7.** The elevation of the new bench mark or turning point is
computed as the sum of the backsight reading and the published elevation
minus the foresight reading.

**8.7.4.7.8.** Reset and re-level the instrument. Level backward from
the new point to the old, in the same manner as paragraphs 8.7.4.7.2
through 8.7.4.7.6. Use the elevation determined from the forward
leveling as the starting elevation for the backward leveling. The
elevation computed for the old point as a result of the backward
leveling may differ by no more than +/- 12D (where D is the shortest
length of section in kilometers one-way) from the published elevation.

**8.7.4.7.8.** To compute the elevation difference from the old mark to
the new, subtract the mean of the two elevations for the old mark from
the elevation for the new mark. The elevation for the new bench mark
will be this computed difference, mean of both forward and backward
leveling, plus the published elevation of the old bench mark.

**8.7.4.8. DATA SUBMISSION.** The following must be supplied by the
submitting office:

a.  Completed "Observations for Bench Mark Ties" form (see below).

b.  Digital Levels: Paper as well as digital copies of leveling
    observations.

**Observations for Bench Mark Ties**

+-----------------------------------+-----------------------------------+
| Original Mark Stamping:           | Replacement Mark Stamping:        |
|                                   |                                   |
| PID (if known): Elevation: [(ft / | Date of Leveling:                 |
| m)]{.underline}                   |                                   |
|                                   | Computed Elevation: [(ft /        |
| Datum: NGVD 29 or NAVD 88 (circle | m)]{.underline}                   |
| one)                              |                                   |
|                                   | (from below)                      |
+-----------------------------------+-----------------------------------+
| State: County: Latitude: N        |                                   |
| Longitude: W Datum:               |                                   |
+-----------------------------------+-----------------------------------+
| Leveling Equipment: Manufacturer  |                                   |
| Model Number Serial Number        |                                   |
|                                   |                                   |
| Level Instrument:                 |                                   |
|                                   |                                   |
| Rod \# 1:                         |                                   |
|                                   |                                   |
| Rod \# 2 (optional):              |                                   |
|                                   |                                   |
| Rod Scale Units:                  |                                   |
+-----------------------------------+-----------------------------------+

+--------+--------+--------+--------+--------+----------+-----------+
| Point  | Bac    | H.I.   | For    | Ele    | Length   | Remarks   |
|        | ksight |        | esight | vation | (ft/m)   |           |
|        |        |        |        |        | m))      |           |
+--------+--------+--------+--------+--------+----------+-----------+
| F      |        |        |        |        |          |           |
| orward |        |        |        |        |          |           |
| Ru     |        |        |        |        |          |           |
| nning: |        |        |        |        |          |           |
| Old to |        |        |        |        |          |           |
| New    |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
| Ba     |        |        |        |        |          |           |
| ckward |        |        |        |        |          |           |
| Ru     |        |        |        |        |          |           |
| nning: |        |        |        |        |          |           |
| New to |        |        |        |        |          |           |
| Old    |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
|        |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+
| Agency |        |        |        |        |          |           |
| /      |        |        |        |        |          |           |
| Firm:  |        |        |        |        |          |           |
| \_\_   |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| S      |        |        |        |        |          |           |
| igned: |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
|        |        |        |        |        |          |           |
| Ad     |        |        |        |        |          |           |
| dress: |        |        |        |        |          |           |
| \_     |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| Tele   |        |        |        |        |          |           |
| phone: |        |        |        |        |          |           |
| ( )    |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
|        |        |        |        |        |          |           |
| City / |        |        |        |        |          |           |
| State  |        |        |        |        |          |           |
| / Zip: |        |        |        |        |          |           |
| E      |        |        |        |        |          |           |
| -mail: |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
| \_\_\_ |        |        |        |        |          |           |
+--------+--------+--------+--------+--------+----------+-----------+

[]{#__RefHeading___Toc123539276 .anchor}**8.7.5. GPS OCCUPATION AT ALL
SURVEY STATIONS.** GPS observations must be performed using FGCS
approved dual frequency GPS receivers. Fixed height tripods must be used
whenever practical. Tripods with multiple height settings should be set
to the highest position. All tripods must be tested for stability, plumb
alignment (straightness of center pole), and height verification at the
beginning and end of the project. Examine all tripods for stability with
each use. Ensure hinges, clamps, and feet are secure and in good repair.
Also, check, and adjust if necessary, the position of the bubble in the
circular vial. Separate tripod setups are required for each occupation
of a station and for each GPS observing session. General information on
GPS equipment requirements and surveying can be found in the NGS *GPS
Survey Manual*, available on line at
[http://www.ngs.noaa.gov/PROJECTS/GPSmanual/](http://www.ngs.noaa.gov/ADVISORS/FBN/GPSmanual/).

![](media/image42.jpeg){width="3.3194444444444446in"
height="4.875in"}**8.7.5.1. ANTENNA SETUP.** GPS antenna setups must be
done independently for each session. The word "independent" means
separate tripod setups, separate height determinations, and separate
solutions. The height of instrument (HI) must be measured in both meters
and feet. Minimize the mixing of GPS receiver and antenna types used for
observations. Record the manufacturer, model number, and serial number
of the antenna on the field log. The following instructions are
extracted from the NGS *Survey Manual* for reference.

**8.7.5.2. GPS ANTENNA HEIGHT MEASURING INSTRUCTIONS.**

**Fixed height tripods are preferred over slip-leg tripods, as they
reduce the potential for antenna height measurement errors. Use fixed
height tripods whenever feasible. If a slip-leg tripod is used, a low
tripod setup is preferred to minimize eccentricities, though the antenna
should be set high enough to avoid obstructions. Eccentric setups
(antenna out of plumb from the station datum point) are to be avoided.
Note any eccentricities on the observation log. Tripod legs should be
well set and sandbagged or spiked to minimize movement. Plumbing bubbles
must be shaded for at least 3 minutes before use to minimize convective
currents in the bubble fluid. On tripods with rotating center poles, the
bubble must be rotated and checked level throughout a 180-degree arc.
Antennas should be oriented towards true north, as closely as can be
accomplished with a hand compass. Note the magnetic declination in your
local area to convert from magnetic north to true north.**

The proper recording of antenna height is critical. The Antenna Height
used at NGS is the vertical distance between the station datum point and
the Antenna Reference Point (ARP). Observers must carefully measure and
check this height, and record and describe all measurements and antenna
constants. Record all values to 0.0001 meters or .001 foot. All
measurement computations must be checked and initialed by another
person. Fixed-height tripods simplify the measurement of antenna height
(H). The calibrated tripod height (A) should be checked with a quick
measurement. Ensure that the antenna mates securely with the tripod
head, and that any gap (B) between the tripod head and ARP is measured
and included. The antenna height can then be computed from the equation:

#### Antenna Height H= (A + B) - Q

![](media/image43.jpeg){width="2.939583333333333in"
height="4.047916666666667in"}![](media/image42.jpeg){width="1.586111111111111in"
height="2.3333333333333335in"}

NOTE: Certain manufacturers antennas use a measuring hook to determine
the vertical distance between the mark and antenna. Record the measured
distance from the mark to the hook as A, and the offset from the hook to
the ARP as B. Slip-leg tripods antenna height (H) is usually measured by
slant-height (S)**,** the distance of the hypotenuse from the station
datum point to the bottom edge of the antenna ground plane (BGP).
Measure the slant height to at least 3 points around the antenna; these
measurements should all agree to within 1 millimeter. Independent
measurements of the antenna height above the mark in both metric and
Imperial units must be made before and after each session. From the
antenna specification sheet in your user\'s manual, determine the radius
(R) of the ground plane and the offset constant (C) between the BGP and
the ARP. The antenna height can then be computed from the following
Pythagorean equation:

###  {#section-4 .Paragraph}

Antenna Height H= ((√S 2 - R 2) - C) -- Q

Compare Metric and Imperial measurements using the following equations:

Meters = Feet × (0.3048) Example: 1.286 Meters = 4.219 Feet

Feet = Meters ÷ (0.3048) Example: 5.345 Feet = 1.629 Meters

###  {#section-5 .Paragraph}

Note that the 3-dimensional datum point of a standard survey disk is
located at or above the dimple in the disk\'s center, on a level with
the highest point of the disk, where the foot of a level rod would rest.
If the point of the fixed-height pole or slant-height measuring rod is
recessed significantly below this level to reach the bottom of the
dimple (1 millimeter or more), make a careful measurement of the
vertical separation (Q) and note this on the observation log.

**8.7.5.2. EPOCH INTERVAL AND ELEVATION MASK.** Collect GPS data at 15-
or 30-second epochs using a 15-degree elevation mask, then process the
data at a 15- or 30-second interval. When tying to the NSRS, a NGS CORS
station with a collection rate of 30 seconds may be used.

**8.7.5.3. STATION RUBBINGS.** A rubbing of the occupied mark must be
made at **each** occupation of a station. When not feasible to make the
required rubbing, a plan sketch of the mark or a photograph must be
substituted, accurately and legibly recording all markings. This
photograph, if used, is in addition to the photographs required in the
Project Survey Plan, and the stamping must be readable in this
photograph.

**8.7.5.4. OBSERVATION LOGS.** An observation log must be filled out for
each occupation of a station. Data recorded on the observation log must
include the following equipment
information:![](media/image44.jpeg){width="2.7618055555555556in"
height="3.588888888888889in"}

a.  Receiver manufacturer,

b.  Antenna manufacturer,

c.  Receiver model number (part number)

d.  Antenna model number (part number),

e.  The complete serial number of the receiver,

f.  The complete serial number of the antenna,

g.  Tripod model and serial number, and

h.  Tribrach model and serial number.

Carefully monitor the receiver operation and antenna setup during each
observing session. Note any unusual circumstances regarding satellite
visibility, receiver operation, equipment malfunction, DOD adjustment of
the satellite orbit, obstructions, weather events, tripod stability,
etc., on the observation log.

[]{#__RefHeading___Toc123539277 .anchor}**8.7.6. RECOMMENDED
EQUIPMENT.** Dual-frequency GPS receivers meeting the following
requirements are recommended:

a.  The receiver model is evaluated against the Federal Geodetic Control
    Subcommittee (FGCS) test network.

b.  State-of-the-art dual frequency with high quality C/A code or P code
    pseudo-ranges.

c.  Capable of measuring full wavelength L2 carrier phase.

d.  Must function acceptably in an Anti-Spoofing environment.

Any dual frequency L2-squared capable receiver may be used for SACS
observations.

Use GPS antenna models calibrated by NGS (see the NGS Antenna
Calibration webpage at
<http://www.grdl.noaa.gov/GRD/GPS/Projects/ANTCAL/>).

Antennas equipped with a ground plane or choke ring are preferred for
observations on the PACS and NSRS ties.

[]{#__RefHeading___Toc123539278 .anchor}**8.8. VECTOR PROCESSING.**

[]{#__RefHeading___Toc123539279 .anchor}**8.8.1. REQUIREMENTS**. Vector
processing must be performed using the latest version of the NGS
software package PAGE-NT or equivalent. The "equivalent" of PAGE-NT is
subjective, based on the software's ability to correct for the same
systematic errors that PAGE-NT corrects, apply the NGS required antenna
offsets, and reproduce the same results as PAGE-NT. This determination
will be made by NGS.

**8.8.1.1.** The NGS PAGE-NT software package and User's Manual are
available via anonymous FTP from NGS (see Appendix 7). Follow the vector
processing guidance below, the PAGE-NT User's Manual, and the Vector
Processing Outline outlined in Appendix 8.

**8.8.1.2.** The grouping of vectors into processing sessions for each
day of observations is determined by two factors: the required reference
station and the distances of each solve station from the reference
station. This vector distance determines the final solution type to be
run in PAGE-NT. Reference station requirements are detailed in the
sections below.

**8.8.1.3.** Use the following table for grouping vectors together into
sessions according to vector length:

Table 8.5. PAGE-NT Final Solution Type Determination.

  -------------------------------- --------------------------------------
  **Vector Distance for Processing **Final Solution Type**
  Session**                        

  Under 5km                        L1 Fixed

  5-100km                          Ion-Free Fixed
  -------------------------------- --------------------------------------

**8.8.1.4.** IGS precise orbit data and NGS National CORS data must be
used in data processing. For information on downloading CORS data and
ephemeris data from NGS via the Internet, see Appendix 7.

**8.8.1.5.** International Terrestrial Reference Frame (ITRF) station
coordinates must be used for all vector reductions. Information about
ITRF is available on the NGS website, under "Products Services". The
current ITRF epoch must be used in computations. The Antenna Height
value entered into the PAGE-NT "Station Information" Menu, "Up" field,
is the monument to the Antenna Reference Point (ARP). For example, 2.000
for a fixed-height tripod. The monument for a CORS is generally
coincident with the ARP; therefore, 0.000 is entered for a CORS station
unless an offset is listed on the CORS coordinate sheet. PAGE-NT will
automatically add a constant factor for the ARP to L1 phase center
distance when it merges the data.

**8.8.1.6.** Set the Tropospheric scale height in accordance with the
following table:

Table 8.6. Tropospheric Unknown Settings for PAGE-NT Sessions.

+-----------------------+-----------------------+-----------------------+
| **Vector Length**     | **Reference Station   | **Solve Station       |
|                       | Setting**             | Setting**             |
+-----------------------+-----------------------+-----------------------+
| Under 3km^1^          | OFF/FIXED             | OFF/FIXED             |
|                       |                       |                       |
|                       | (Not Highlighted)     | (Not Highlighted)     |
+-----------------------+-----------------------+-----------------------+
| 3-100km               | OFF/FIXED             | ON/SOLVE              |
|                       |                       |                       |
|                       | (Not Highlighted)     | (Highlighted)         |
+-----------------------+-----------------------+-----------------------+
| 100+km                | ON/SOLVE              | ON/SOLVE              |
|                       |                       |                       |
|                       | (Highlighted)         | (Highlighted)         |
+-----------------------+-----------------------+-----------------------+

^1^If a station is within 3 km of the reference station AND differs in
height with the reference station by 5 meters or more, set the
tropospheric scale height setting to SLV for that station.

**8.8.1.7.** Review the PAGE-NT generated plots and text outputs to
analyze each processing session. PAGE-NT's overall RMS-of-fit of the
post-fit double-difference residuals should not exceed 2.0 cm.
Investigate individual satellites with a relatively high RMS or where
integers could not be fixed. Also review the files for input errors,
such as improper reference station coordinates, antennae height errors,
or improper station names.

**8.8.1.8.** Compare the ITRF coordinates of all repeat baselines and
for NSRS ties occupied more than once. Investigate any station
coordinate comparisons not agreeing within 3 cm.

**8.8.1.9.** Submit all files and printouts as required in Appendix 10.

**8.8.2. CORS VECTORS.** At least one national CORS must be used for
determining a PACS position. However, for several airports observed
simultaneously, utilize data from as many national CORS in the project
area as feasible. CORS-to-CORS vectors strengthen the GPS network and
allow for easier error detection. Discuss with NGS the CORS-to-CORS
vectors to be processed. Generally, two 24-hour vectors must be
processed between the CORS stations to form an interconnecting network.
See paragraph 8.7.1 for more information on CORS data.

**8.8.2.1. CORS-TO-CTCORS VECTORS.** Three independent sessions between
the CORS and CTCORS are required at the beginning of the project and one
session, as a check, at the very end of the project. Process these three
sessions using the most recent ITRF coordinates published by NGS for the
CORS. If the new computed ITRF coordinates of the CTCORS differ from the
NGS ITRF coordinates by more than 3 cm in horizontal or 10 cm in
vertical (ellipsoidal or orthometric), call NGS immediately for further
instructions. These instructions might include processing additional
CORS to CTCORS sessions. Any discrepancy, even if resolved, must be
described in the project report. Keep in mind the PACS accuracy
requirement is relative to a CORS, not a CTCORS, so any discrepancy in
the CTCORS position must be included in the error budget for the PACS.
The last session at the CTCORS must be used to again check the position
of the CTCORS relative to the CORS.

**8.8.2.2. PACS, SACS, AND NSRS TIE VECTORS.** The sequential order of
vector processing is listed below. The selection of either L1 or
Ion-Free fixed for the final solution type is based on vector lengths.
See the Solution Type Determination Table (paragraph 8.6) for guidance
when grouping vectors together for a processing session.

Discuss the plan for processing any "shared" HARN and bench mark ties
with NGS if more than one airport is observed for the project.
Generally, each HARN or bench mark observation should be included in
only one processing session. Use the following guidance for preparing
the processing plan:

**8.8.2.2.1.** If a HARN station tie is NOT also a PACS, SACS, or bench
mark tie for an airport, and it is more than 50 km from a PACS, it may
be processed in the CORS-to-PACS session. In the case of multiple
airports using the same HARN, the PACS observed simultaneously with the
HARN to "share" the tie must be tied to it indirectly in the group
adjustment. Separate processing sessions from each PACS to the HARN are
not required.

**8.8.2.2.2.** If a HARN station tie is NOT also a PACS, SACS, or bench
mark tie for an airport, and it is within 50 km of a PACS, it should be
processed directly from the closest PACS. In the case of multiple
airports using the same HARN, a second nearby PACS observed
simultaneously to "share" the HARN tie must be tied to it indirectly in
the group adjustment. A separate processing session from the second PACS
to the HARN is not required.

**8.8.2.2.3**. Bench mark ties should be processed to their PACS. In the
case of multiple airports, the second, simultaneously observed, PACS
must be tied to the bench mark indirectly in the adjustment. Again, a
processing session from the second PACS to the bench mark is not
required.

**8.8.2.2.4.** Substitute CTCORS for CORS in the steps below if
applicable. To check the position of the PACS, the sequential order of
vector processing is as follows:

**8.8.2.2.4.1.** Process the first CORS-to-PACS vector, with CORS as
reference, using the latest ITRF coordinates. If more than one PACS was
observed simultaneously, include these PACS in the session if they
conform to the vector distance limitations for the session (see Solution
Type Determination, Table 8.5, above). Also include any appropriate HARN
and bench mark stations in the session.

**8.8.2.2.4.2.** Process the second CORS-to-PACS vector, with CORS as
reference, as above. Again, include appropriate PACS or HARN stations
observed simultaneously into this session.

**8.8.2.2.4.3.** Compare the resulting ITRF coordinates of the PACS and
NSRS ties used more than once. Use a spreadsheet to show the differences
between the sessions and the calculation of the mean (see Appendix 9 for
an example). The two PACS coordinates should compare within ±3 cm. If
they do, mean the positions and go on to step 4 (paragraph 8.8.2.2.4.4).
If not, contact NGS. The PACS might need to be reprocessed or
reobserved.

**8.8.2.2.4.4.** Process the first PACS to SACS session using the PACS
as the reference station and using the mean ITRF position calculated in
step 3 (paragraph 8.8.2.2.4.3). Process these short lines using the L1
frequency only. This step must be completed individually for each
airport (each PACS must be the reference station for its respective
SACS).

**8.8.2.2.4.5.** Process the second session SACS data as above. This
step must be completed individually for each airport (each PACS must be
the reference station for its respective SACS).

**8.8.2.2.4.6.** Compare the ITRF coordinates of the SACS. Include this
comparison on the same spreadsheet used for the PACS comparison.
Investigate any SACS coordinate comparisons that do not agree within 3
cm. This step must be completed individually for each airport (each PACS
must be the reference station for its respective SACS).

**8.8.2.2.5.** Discuss with NGS procedures for processing if a HARN
station or bench mark tie also serves as a PACS or SACS.

Note: PACS to SACS ties will form a separate B-file and G-file.

[]{#__RefHeading___Toc123539280 .anchor}

**8.9. PACS ADJUSTMENT PROCESSING**. All airports in a project area may
be adjusted together if airports located close together share tie
stations (CORS, bench mark, HARN). Airports can be adjusted
individually.

[]{#__RefHeading___Toc123539281 .anchor}**8.9.1. SOFTWARE**. The adjust
software package can be downloaded from the NGS website
([http://www.ngs.noaa.gov](http://www.ngs.noaa.gov/)) by accessing the
"PC Programs" link. Follow the processing guidelines in paragraph 8.10
and the written Adjust documentation when performing the adjustment.

[]{#__RefHeading___Toc123539282 .anchor}**8.9.2. ADJUSTMENTS REQUIRED.**
Five adjustments are required:

a.  **ADJUSTMENT ONE.** Perform a free adjustment to determine the
    strength of the GPS network. Hold the NAD 83 position and ellipsoid
    height of one CORS station fixed. For multiple airports, constrain
    the CORS used for the majority of the vector reductions or is
    located near the center of the project area.

Residuals on any vector component should not exceed ±3 cm and must not
exceed ±5 cm. Outliers remaining after a review of the vector reductions
may be rejected if sufficient redundancy exists or upon approval from
NGS headquarters.

A comparison must be made between the coordinates determined in this
adjustment and those currently published by NGS. Use a spreadsheet to
calculate the differences in the X, Y, and Z components (See example in
Appendix 9). Program INVERSE3D should be used to determine the exact
Delta Height and Ellipsoidal Distance for comparisons not falling well
within tolerance. As noted previously, differences of ±5 cm horizontally
and/or ±10 cm in ellipsoidal height with published positions should be
immediately brought to the attention of NGS for investigation. Consult
NGS for guidance on controls for this adjustment if any differences are
outside these tolerances. Submit all comparisons with the final report.

b.  **ADJUSTMENT TWO.** Perform a fully constrained horizontal
    adjustment. Constrain the NAD 83 coordinates (latitude, longitude,
    ellipsoid height) of all CORS or CTCORS stations and HARN tie
    stations used in processing.

c.  **ADJUSTMENT THREE.** Perform a minimally constrained free
    adjustment to determine the length of the relative accuracies of the
    adjustment. Run program QQRECORD to add QQ records to the A-file.
    Hold the NAD 83 position and ellipsoid height of one CORS station
    fixed. Use the output B-file from Adjustment Two as the input
    bluebook.

Use program BBACCUR to derive a listing of the accuracies. Examine the
accuracies to determine if all lines meet the requirements for the order
the stations will be published, e.g., CTCORS to PACS should be
1:1,000,000; PACS to SACS should be l:100,000. PACS must be published as
B-order; SACS and bench marks as first-order. Discuss any problems with
NGS and detail them in the report. Note: The final PACS and SACS
coordinates must meet the FAA accuracy requirements outlined in this AC.
The computed accuracies will help in the analysis of meeting those
requirements.

Use program ELLAC to derive the order/type of the ellipsoid heights.
This value must be edited into the \*86\* records of the final B-file.
The value chosen should be of the majority of the lines and must be used
for all stations.

d.  **ADJUSTMENT FOUR.** Perform a free vertical adjustment to determine
    the strength of the vertical network. Insert GEOID heights into the
    output B-file from Adjustment Two and use it as the input B-file.
    Use the latest version of NGS GEOID software to derive the GEOID
    heights. Hold the NAD 83 latitude and longitude of one CORS station
    and the NAVD 88 orthometric height of one bench mark (center of
    project area) fixed. Compare the published bench mark elevations
    with those obtained in this adjustment and notify NGS of any
    exceeding 15 cm. Consult NGS for guidance on bench mark controls to
    use if any checks exceed 15 cm.

e.  **ADJUSTMENT FIVE.** Perform a constrained vertical adjustment to
    determine the new GPS derived elevations for the project. This
    adjustment might need to be run several times to determine the
    optimal selection of bench marks to use as vertical constraints. In
    consultation with NGS, constrain the NAVD 88 elevations of bench
    marks, checking the best with their published positions based on the
    free vertical adjustment. Run the adjustment and review the results.
    Continue to add constraints until any "poor fitting" bench marks are
    determined. Allow poor fitting bench marks to float in the final
    vertical adjustment. Use the orthometric heights from this
    adjustment for the final B-file.

Submit a spreadsheet showing the height difference between the published
NAD 83 bench marks and their final adjusted elevations. Discuss any
outliers in the project report. Also document any actions taken as the
result of poor bench mark checks.

The **final B-file** submitted must contain the positions and
ellipsoidal heights derived from the final constrained adjustment
(Adjustment Two) and the orthometric elevations from the final vertical
adjustment (Adjustment Five). Program ELEVUP can be used to easily
combine the files. The B-file must satisfactorily run through the
required checking programs. No errors are allowed in the final B-file
submitted for data base entry.

[]{#__RefHeading___Toc123539283 .anchor}**8.9.3. SOFTWARE RESULTS
ACCURACY. ADJUST's "\'Mean Absolute Residual" statistics (from
Adjustment One) must not exceed ±2.0 cm in NORTH or in EAST, and must
not exceed ±5.0 cm in UP. ADJUST\'s maximum residual (from Adjustment
#1) should not exceed ±3.0 cm and must not exceed ±5.0 cm on the
horizontal components. The estimates could be twice as large for the
vertical component. Vectors may be rejected if the residual exceeds ±4.0
cm in any horizontal component but may not be rejected if it supplies
the only redundancy for a station. A written justification for rejecting
the vector should be included in the Final Report.**

### 8.9.4. NSRS TIE ACCURACY.  {#nsrs-tie-accuracy. .unnumbered}

HARN ties should check within ±5 cm horizontal and ±10 cm ellipsoidal
height compared to their published positions. Notify NGS immediately if
checks exceed these tolerances. Show the coordinate comparisons on a
spreadsheet (see Appendix 9).

[]{#__RefHeading___Toc123539285 .anchor}**8.9.5. BENCHMARK (VERTICAL)
ACCURACY**. Bench mark orthometric heights should agree within ±15 cm of
published elevations. Notify NGS immediately if checks exceed these
tolerances. Show the height comparisons on a spreadsheet (see Appendix
9).

[]{#__RefHeading___Toc123539286 .anchor}**8.9.6. BLUE BOOK GUIDANCE**.
Section 7 of the Blue Book, Annex L, is superseded by the following
guidelines for adjustment processing and submittal. Use these guidelines
along with the step-by-step guidelines established below of the Adjust
Procedure.

**8.9.6.1.** All adjustments must be run in three dimensions. Do NOT
scale the G-file for the PACS adjustments. Ensure all input files are
complete and free of format errors by utilizing the checking programs
(ignoring errors relating to missing codes at this time). \*86\* records
should be in the B-file before beginning the adjustment. Do not insert
GEOID heights until the horizontal adjustments are complete.

**8.9.6.2.** Ensure the proper code was inserted into the solution
coordinate system code (cc 52-53) of the G-file created by PAGE-NT.
Adjust will use this code to internally transform the ITRF vector
components to the NAD 83 reference system.

[]{#__RefHeading___Toc123539287 .anchor}**8.9.7. SACS ADJUSTMENT
PROCESSING.** The final B-file from the PACS adjustment must be used to
obtain the positions and heights of the PACS constrained in the SACS
adjustment. Only PACS positions must be held fixed. All procedures and
analysis of these adjustments must be the same as for the PACS except
the PACS serves as the control rather than the CORS and the G-file
should be scaled. The SACS adjustment must contain only observations
from the PACS to the SACS (observations in the SACS adjustment should
not be a duplicate of the observations in the PACS adjustment).

[]{#ADJUST .anchor}

**8.10. NGS PROCEDURAL OUTLINE FOR ADJUSTING GPS DATA FOR AIRPORT
GEODETIC CONTROL SURVEYS.** Number range CHAPTERThe following guidance
is recommended to supplement the guidance provided in section 8.9.

Apply these procedures to both the PACS and SACS portions of the
project. The only difference is, the G-file is scaled for the SACS
adjustments (run MODGEE after the first free adjustment) and the only
control is normally the PACS determined in the PACS adjustments. If
either SACS is used for the bench mark or HARN tie in the PACS
adjustments, consult NGS for guidance on procedures for the SACS
adjustments.

8.10.1. Complete PAGE-NT processing as outlined in paragraph 8.8 and
Appendix 8:

a.  Ensure all fixed coordinates used in processing were correct.

b.  Ensure up offset values for each station are equal to the monument
    to Antenna Reference Point (ARP).

c.  Ensure all PFR plots are acceptable.

d.  Ensure RMS values in COMBINED.SUM files are acceptable.

e.  Ensure all redundant vectors and multiple occupied station results
    check within 3 to 5 cm of each other and show comparisons using a
    spreadsheet (see Appendix 9).

8.10.2. Create input files:

a.  Use the combined G-file created in PAGE-NT.

b.  Ensure all vectors are included in the file.

c.  Ensure there are no duplicate or misspelled station ID's or
    mismatched serial numbers.

d.  Check B record, column 52-53, for proper coordinate system code
    (contact NGS).

e.  Make an A-file using program CRAFILE or by editing a previous
    A-file.

f.  Recommended II and MM records---

    i.  II159999999

    ii. MM3NYnewbb

g.  Make a B-file using program CR8BB, The B-file serial numbers must
    match the SERFIL, G-file, and D-file. Designations in the B-file and
    D-file must match.

h.  Tips for using CR8BB for windows---

    i.  Use tab key to move to each data entry window.

    ii. Input text using upper case letters.

    iii. Create \*86\* records.

8.10.3. Format and check B-file:

a.  Manually edit B-file into proper format by inserting GPS Survey
    Method Code \>4= into \*12\* record column 76.

b.  Run checking program COMPGB; do not continue adjustment unless all
    errors are corrected.

c.  Run B-file format checking programs: NEWCHKOBS and OBSCHK (ignore
    errors relating to missing codes at this time).

Note: Substitute CTCORS for CORS below if applicable.

8.10.4. Run a Free Adjustment (ADJUSTMENT 1):

8.10.4.1. A-File: Constrain the NAD 83 position and ellipsoid height
(EHT) of the CORS station.

8.10.4.1.1. For multiple airports, use the CORS station that is
centrally located in the project area or that was the reference station
for most of the CORS to PACS vectors.

8.10.4.1.2. Save copies of each A-file used. Name AAFILE.1, etc.

8.10.4.2. B-File: Use clean B-file from paragraph 8.10.3 as input.

a.  Name output file ADJOUT.1.

b.  Rename output B-file BBOUT.1.

c.  Analyze results, review residuals on vector components (all less
    than 3-5cm)

d.  If more than one CORS was used, check the agreement between the
    computed and published positions of other CORS stations used in the
    project.

e.  Check the agreement between the computed and published positions of
    the HARN and any other published stations used in the project.

8.10.5. Run a Constrained Adjustment (Adjustment Two):

a.  A-file---Constrain NAD83 position and EHT of all HARN and CORS
    stations used.

b.  B-file---Use BBOUT.1 again as input.

c.  Output---Name ADJOUT.2.

d.  Rename output B-file BBOUT.2; review results.

8.10.6. Run a Free Adjustment with Accuracies (Adjustment Three):

a.  A-file---Run program QQRECORD to add QQ records to AFILE.1 (output
    AFILE.3).

b.  B-file---Use BBOUT.2.

c.  Output---ADJOUT.3.

d.  Run program BBACCUR to obtain a listing of the length relative
    accuracies.

```{=html}
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(i) Output---BBACC.OUT; review results.

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e.  Run program ELLACC to obtain a listing of EHT accuracies.

```{=html}
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```
(i) Output---ELLACC.OUT; review results.

(ii) Manually edit the mode EHT order and class code into columns 54-55
     of each \*86\* record of BBOUT.2.

Perform the following two adjustments to obtain orthometric heights for
insertion into

the output B-file from Adjustment Two.

8.10.7. Run the latest version of NGS GEOID software to insert GEOID
heights into the B-file. Use BBOUT.2 as the input file and GEOID.OUT as
the output file.

8.10.8. Run a Free Vertical Adjustment (Adjustment Four):

8.10.8.1. A-File: Constrain the NAD83 horizontal position of one CORS
station and the NAVD 88 orthometric height of the best (center of
project, high quality) bench mark.

8.10.8.2. B-File: Use GEOID.OUT for input:

a.  Output---Name ADJOUT.4; rename output B-file BBOUT.45.

b.  Review orthometric heights with published NGS values (agree w/in
    15cm).

c.  Use spreadsheet or table to show the comparison results.

8.10.9. Run a Constrained Vertical Adjustment (Adjustment Five):

8.10.9.1. A-File: Same as ADJUSTMENT 4, except constrain additional
orthometric heights of bench marks that worked well in the Free Vertical
Adjustment.

8.10.9.2. B-File: Use GEOID.OUT for input with the output name ADJOUT.5;
rename output B-file BBOUT.5; review results and rerun using different
constraints in the A-file if necessary.

8.10.10. Run program ELEVUP to transfer orthometric heights from
ADJUSTMENT 5 to the final B-file:

a.  Input vertical deck---BBOUT.5.

b.  Input horizontal deck---BBOUT.2.

c.  Name the final B-file FNL.BBK.

    i.  Double check values in \*80\* and \*86\* records against ADJOUT.
        2 and ADJOUT.5.

d.  Rename G-File to FNL.GFL.

8.10.11. Run checking programs on the final B-file and correct errors.

a.  No error messages are allowed except those relating to the zero
    antenna height of the CORS; contact NGS for assistance in correcting
    errors identified by one of the programs.

b.  COMPGB

c.  NEWCHKOB

d.  OBSCHK

e.  OBSDES (matches B-file with description file)

f.  CHKDES (checks description file for format errors)

8.10.12. Write the final project report and submit the following digital
files (and paper copy if requested by NGS) in a :\\ProjectName\\Adjust\\
directory (if applicable, create an %%%%\\Adjust\\ subdirectory for each
grouping of airports adjusted together, where %%%% is a unique ID
created for the adjustment group).

8.10.12.1. ADJUST FILES.

a.  FNL.BBK

b.  FNL.GFL

c.  AFILE.\*

d.  ADJOUT.\*

e.  BBIN.\* (1st Bluebook)

f.  BBOUT.\*

g.  BBACC.OUT

h.  ELLACC.OUT

i.  GEOID.OUT

j.  SERFILE

8.10.12.2. OUTPUT FILES FROM CHECKING PROGRAMS.

a.  COMPGB.OUT

b.  NEWCHKOB.OUT

c.  OBSCHK.OUT

d.  OBSDES.OUT (Checks description files vs B-file)

e.  CHKDES.OUT (Checks description files)

8.10.12.3. Place a copy of the final B-file, G-file, and D-file in a
:\\ProjectName\\FinalFiles\\ directory.

[]{#__RefHeading___Toc123539289 .anchor}**8.11. DATA SUBMITTAL.** Final
project data must be submitted in Blue Book format. The Project Sketch,
descriptions, photographs, project adjustments, reports, etc., must be
both paper and digital, if possible. Submit all original data records,
see paragraphs 2.7, 6.1, and 8.3 and Section 10.

General guidance for data submitted to NGS can be found in Annex L of
the NGS Blue Book, and in *Policy of the National Ocean Service
Regarding the Incorporation of Geodetic Data of Other Organizations into
the National Geodetic Survey Data Base,* dated September 1994 (available
on line at <http://www.ngs.noaa.gov/INFO/incorp_data.html>).

# 9. FINAL PROJECT REPORT. 

A final project report detailing the GPS observations, vector
processing, and adjustment must be submitted to NGS and the contracting
authority. This report is in addition to the Project Survey Plan
described in paragraph 8.3. Photographs, updated sketches, descriptions,
and other information concerning mark setting performed for the project
must be submitted separately as a supplement to the Project Survey Plan.

[]{#__RefHeading___Toc123539291 .anchor}**9.1. FINAL REPORT CONTENTS.**
The Final Project Report must contain at least the following sections:

**9.1.1.** An overview discussion of the planning, field work, data
collection, data processing, adjustment, and data error analysis. This
discussion should include a summary of the results, problems
encountered, conditions affecting progress, and any unusual
circumstances. Include comments on any deviations from the Project
Survey Plan or this AC (include comments from weekly Status Reports).

**9.1.2.** A written description and analysis of the quality control
performed; tables showing check positions; and a listing and analysis of
all unusual circumstances, discrepancies, and deviations.

**9.1.3.** A listing of personnel who worked in the field and/or were
involved with the data processing for this project.

**9.1.4.** A listing of the brand, model number, and serial number of
all survey equipment (GPS receivers, antennas, levels, etc.) used in the
project. List the quantity, brand, type, and height of fixed height
tripods used. Include any instrumentation used for differential leveling
if done.

**9.1.5.** A listing of all software, including version, used during the
project for RINEX conversion, vector processing, adjustment, and
verification (all checking programs).

**9.1.6.** A final station list: use a table format to list each
station, the station type (PACS, SACS, etc.), and each observation
session for the station.

**9.1.7.** A final Project Vector Diagram: update the vector diagram
submitted with the Project Survey Plan (see paragraph 8.3). Submit only
a large size, readable plot (approximately 24 x 32 inches). Include
processing session designations on the vectors if feasible. Show
indirect ties to "shared" HARN stations and bench marks.

**9.1.8.** The vector processing scheme, tabulated by airport and
session, listing: reference station and solve stations with their
station type; observation time for the vector, solution type (L3 fixed,
etc.), and final RMS for the session. Provide any comments on problems
encountered or anomalies with the processing session. Note the
tropospheric unknown settings for each session. Provide any comments on
problems encountered or anomalies with the processing session. This
table can be incorporated into the spreadsheet described below.

**9.1.9.** A spreadsheet showing the comparison of the ITRF coordinates
(X,Y, and Z) of all repeat baselines and for NSRS ties occupied more
than once. Show the solution type, final RMS, and distance for each
vector. Show the calculation of the mean PACS coordinate. See Appendix 9
for an example spreadsheet.

**9.1.10.** A detailed description of the project adjustment. Discuss
each of the adjustments separately, including fixed control and the
source of the coordinates, ellipsoid heights, and NAVD 88 elevation
used. Explain unresolved error messages from the checking programs.
Discuss the analysis performed and the results of the adjustments.
Submit the spreadsheets or tables used to compare the adjusted
coordinates with their published coordinates (see paragraph 8.9).

**9.1.11.** A completed Project Submission Checklist; see Appendix 10.
Also available online at the FAA Airport Surveying--GIS website at
[http://airports-gis.faa.gov]{.underline}.

**9.1.12.** Recommendations for future projects.

[]{#__RefHeading___Toc123539292 .anchor}**10. DELIVERABLES TO NGS.**

[]{#__RefHeading___Toc123539293 .anchor}**10.1. LABOR, EQUIPMENT, AND
OTHER ITEMS.** The contractor must provide all labor, equipment,
supplies, materials, and transportation to produce and deliver the
products as required.

[]{#__RefHeading___Toc123539294 .anchor}**10.2. QUALITY CONTROL PLAN.**
Before any field work begins, submit to NGS and the contracting
authority (in paper and digital copies) a Quality Control Plan covering
all work (see Section 5). NGS will review this plan and respond with an
approval or comment letter (or email) as soon as possible, normally
within 5 working days.

[]{#__RefHeading___Toc123539295 .anchor}**10.3. SURVEY PLAN.** Before
any mark setting or GPS observations begin, the Contractor must submit a
Project Survey Plan (see paragraphs 8.3) to NGS and the contracting
authority. NGS will review this plan and respond with an approval or
comment letter (or email) as soon as possible, normally within 5 working
days. Field work may commence after the Contractor receives the approval
letter (or email).

[]{#__RefHeading___Toc123539296 .anchor}**10.4. PROJECT STATUS
REPORTS.** See paragraph 2.6.

[]{#__RefHeading___Toc123539297 .anchor}**10.5. PROJECT SKETCH (VECTOR
DIAGRAM).** Submit a vector diagram showing all computed vectors. Submit
only a large size, readable plot (approximately 24 x 32 inches). Include
processing session designations on the vectors if feasible. Submit a
paper version and a digital version if possible.

[]{#__RefHeading___Toc123539298 .anchor}**10.6. FIELD LOGS.** Submit the
original version of all the observation logs, pencil rubbing forms,
hand-written station descriptions/recovery notes, Station Location
Sketch and Visibility Diagrams, digital photographs, etc.

[]{#__RefHeading___Toc123539299 .anchor}**10.7. VECTOR PROCESSING
OUTPUT.** Submit paper copies of the COMBINED.SUM files for any
difficult to process or those producing questionable results processing
sessions. Submit the spreadsheets used for comparing the vector
processing results (see Appendix 9). Submit paper copies of any other
files requested by NGS for quality control.

[]{#__RefHeading___Toc123539300 .anchor}**10.8. FINAL PROJECT REPORT.**
Submit a Final Project Report covering Airport Geodetic Control Station
surveys; see Section 9.

[]{#__RefHeading___Toc123539301 .anchor}**10.9. ADJUSTMENT AND CHECKING
PROGRAMS.** Submit all ADJUST and checking programs input and output
files in accordance with paragraph 8.10 of this guidance (a paper copy
of COMPGB, NEWCHKOB, OBSCHK, OBSDES, CHKDESC, BBACCUR, ELLACC, and all
ADJUST files). Also, submit the digital data sheet or coordinate file
for stations used for fixed control during the adjustment (CORS
log/coordinate sheets, NGS data sheet for HARN and bench mark
coordinates, etc.). Submit paper copies of the coordinate sheet for all
CORS and CTCORS stations used during vector processing. Submit the
spreadsheets used and/or INVERSE3D program output files used for
comparing published coordinates with their adjusted coordinates.

[]{#__RefHeading___Toc123539302 .anchor}**10.10. ORIGINAL DATA.** Submit
all the original, raw data, RINEX data, precise ephemeris, and PAGE-NT
files in accordance with Appendix 8. Include the CORS RINEX data files
used for processing. For all RAW and RINEX data files not named by their
occupied station four character ID, submit an index of station names to
RAW and RINEX file. Submit a detailed directory tree listing, on paper,
to be used as an index for locating all processing, adjustment, and
supporting files submitted in digital format. Do not list the individual
files within the PAGE-NT vector processing directory for each session or
the files in the RAW and RINEX data directories. Just provide a summary
explanation of the files found in these type directories. Submit any
other digital files required by this AC or requested by NGS not
previously submitted.

[]{#__RefHeading___Toc123539303 .anchor}**10.11. DESCRIPTIONS.** Submit
the finalized description file from the NGS WINDESC software. Submit
both paper and digital formats. This includes the recovery notes
submitted with the Survey Plan and the final version of the descriptions
of new marks, written after the marks are set. Descriptions and recovery
notes should be written by one person and checked, in the field, by
another.

[]{#__RefHeading___Toc123539304 .anchor}**10.12. TRANSMITTAL LETTER.**
For all hardcopy data being sent via express mail, regular mail, etc.,
prepare a transmittal letter listing all items being sent. Include a
copy of the transmittal letter within the data package and send a second
copy to the receiving office via FAX or email. The receiving office will
check the data package against the letter, sign and date it, and FAX it
back to the sender. Be sure to include the prime contracting firm name
on all transmittals and communications.

<table>
<colgroup>
<col style="width: 3%" />
<col style="width: 3%" />
<col style="width: 5%" />
<col style="width: 8%" />
<col style="width: 1%" />
<col style="width: 0%" />
<col style="width: 1%" />
<col style="width: 6%" />
<col style="width: 1%" />
<col style="width: 0%" />
<col style="width: 2%" />
<col style="width: 13%" />
<col style="width: 0%" />
<col style="width: 2%" />
<col style="width: 1%" />
<col style="width: 1%" />
<col style="width: 0%" />
<col style="width: 10%" />
<col style="width: 0%" />
<col style="width: 0%" />
<col style="width: 1%" />
<col style="width: 5%" />
<col style="width: 4%" />
<col style="width: 11%" />
<col style="width: 1%" />
<col style="width: 7%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="7"><img src="media/image45.jpeg"
style="width:0.79236in;height:0.59653in" /></td>
<td colspan="19"><p>Data Transmittal Letter</p>
<p>FAA Airport Surveying – GIS Program</p></td>
</tr>
<tr class="even">
<td colspan="8">Project:</td>
<td colspan="18"></td>
</tr>
<tr class="odd">
<td colspan="8">Contracted Airport:</td>
<td colspan="18"></td>
</tr>
<tr class="even">
<td colspan="8">Contracting Firm Name:</td>
<td colspan="18"></td>
</tr>
<tr class="odd">
<td colspan="8">Contracting Firm Fax Number:</td>
<td colspan="18"></td>
</tr>
<tr class="even">
<td colspan="8" rowspan="8">Responsible Airport Official</td>
<td colspan="7">Name:</td>
<td colspan="11"></td>
</tr>
<tr class="odd">
<td colspan="7">Title:</td>
<td colspan="11"></td>
</tr>
<tr class="even">
<td colspan="7">Address:</td>
<td colspan="11"></td>
</tr>
<tr class="odd">
<td colspan="7">City, State:</td>
<td colspan="9"></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td colspan="7">Zip Code:</td>
<td colspan="11"></td>
</tr>
<tr class="odd">
<td colspan="7">Telephone Number:</td>
<td colspan="11"></td>
</tr>
<tr class="even">
<td colspan="7">Fax Number:</td>
<td colspan="11"></td>
</tr>
<tr class="odd">
<td colspan="7">Email address:</td>
<td colspan="11"></td>
</tr>
<tr class="even">
<td colspan="26"><strong>Data as listed on this letter were forwarded to
you by (check those that apply)</strong></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="3">Ordinary Mail</td>
<td colspan="2"></td>
<td colspan="3">Air Mail</td>
<td colspan="2"></td>
<td colspan="3">Registered Mail</td>
<td colspan="3"></td>
<td>Express</td>
<td colspan="3"></td>
<td colspan="2">GBL<a href="#fn1" class="footnote-ref" id="fnref1"
role="doc-noteref"><sup>1</sup></a></td>
<td colspan="3"></td>
</tr>
<tr class="even">
<td colspan="4">Date Forwarded:</td>
<td colspan="9"></td>
<td colspan="10">Number of Packages:</td>
<td colspan="3"></td>
</tr>
<tr class="odd">
<td colspan="4">Date Faxed:</td>
<td colspan="6"></td>
<td colspan="6">Time Faxed:</td>
<td colspan="3"></td>
<td colspan="4">Faxed By:</td>
<td colspan="3"></td>
</tr>
<tr class="even">
<td colspan="2"><strong>To:</strong></td>
<td><p><strong>┌</strong></p>
<p><strong>└</strong></p></td>
<td colspan="22"></td>
<td><p><strong>┐</strong></p>
<p><strong>┘</strong></p></td>
</tr>
<tr class="odd">
<td colspan="26"></td>
</tr>
<tr class="even">
<td colspan="26"></td>
</tr>
<tr class="odd">
<td colspan="26"></td>
</tr>
<tr class="even">
<td colspan="26"></td>
</tr>
<tr class="odd">
<td colspan="26"></td>
</tr>
<tr class="even">
<td colspan="26"></td>
</tr>
<tr class="odd">
<td colspan="26"></td>
</tr>
<tr class="even">
<td colspan="26"></td>
</tr>
<tr class="odd">
<td colspan="26"></td>
</tr>
<tr class="even">
<td colspan="26"></td>
</tr>
<tr class="odd">
<td colspan="26"></td>
</tr>
<tr class="even">
<td colspan="26"></td>
</tr>
<tr class="odd">
<td colspan="26"></td>
</tr>
<tr class="even">
<td colspan="5">From (Signature):</td>
<td colspan="7"></td>
<td colspan="10">Contracting Firm Title:</td>
<td colspan="4"></td>
</tr>
<tr class="odd">
<td colspan="5" rowspan="2">Return Receipt Copy to:</td>
<td colspan="15" rowspan="2"><p>┌ ┐</p>
<p>┘</p></td>
<td colspan="6"><p>Received the Above</p>
<p><em>(Name, Title, Date)</em></p></td>
</tr>
<tr class="even">
<td colspan="6"></td>
</tr>
</tbody>
</table>
<aside id="footnotes" class="footnotes footnotes-end-of-document"
role="doc-endnotes">
<hr />
<ol>
<li id="fn1"><p>Insert GBL number<a href="#fnref1" class="footnote-back"
role="doc-backlink">↩︎</a></p></li>
</ol>
</aside>

# APPENDIX 1. SURVEY DISK DIAGRAMS

![](media/image46.png){width="5.6875in" height="8.883333333333333in"}

![](media/image47.png){width="6.575694444444444in"
height="7.680555555555555in"}

![](media/image48.wmf){width="6.072222222222222in"
height="8.809027777777779in"}

# APPENDIX 2. NATIONAL SPATIAL REFERENCE SYSTEM

# 

![](media/image49.jpeg){width="6.508333333333334in"
height="8.564583333333333in"}

# APPENDIX 3. AIRPORT INTERVIEW CHECKLISTS

# 

#### **Airport Interview Checklists**

**A4.1 GENERAL.** Conduct interviews with the following
personnel/departments if they exist at the airport.

**A4.2 AIRPORT MANAGER/OPERATIONS MANAGER.** In this interview, obtain
permission to enter the airfield for the survey. This interview can also
provide valuable insight into the future plans for the airport,
including information about construction (recent and on-going),
obstruction changes, and operational considerations (scheduled runway
closures or special events, high security areas on the field, etc.). The
name(s) of the person(s) interviewed must be included on the runway
datasheet and in the final project report.

**A4.3 AIRPORT ENGINEERING.** This interview is only necessary or
helpful on larger airports. The Engineering Department can provide
specific information about the runway dimensions, construction projects,
and current on-airport control stations. They are sometimes helpful in
scheduling runway work times. It is helpful to include the name of the
point of contact in this department in the final project report in case
any questions arise after the survey is completed.

**A4.4 AIR TRAFFIC CONTROL.** If the field party is going to operate on
the airport without an escort, it is highly recommended to have a
face-to-face interview with the Chief Control Tower Operator or
designated representative before entering the airport airside the first
time. This interview is critical to operating safely on the airport,
obtaining operational factors, and ensuring a good working relationship
between the field team and the air traffic controllers.

**A4.5 FAA AIRWAYS FACILITIES.** This interview is necessary on any
airport with FAA navigational facilities. In some cases, the personnel
who maintain the facilities for the airport might be located at another
site, and portions of the interview might need to be accomplished by
telephone. The overall purpose of this interview is to determine all
pertinent changes to facilities (including navigational aids) since the
previous survey. Additionally, it may be necessary to schedule a
technician to accompany the field party to certain facilities to provide
access through a gate or monitor the system and associated alarms while
survey personnel are in the critical areas of the site. It is
recommended to include the name of a point of contact in this department
in the final project report in case questions arise after the survey is
completed.

+---+------------------+------------+-----+----+---+--------+--------+
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+---+------------------+------------+-----+----+---+--------+--------+
| [ |                  |            |     |    |   | Date   | In     |
| ] |                  |            |     |    |   | Com    | itials |
| { |                  |            |     |    |   | pleted | of     |
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| k |                  |            |     |    |   |        |        |
| s |                  |            |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
| 1 | Introduce team   |            |     |    |   |        |        |
| \ | and explain      |            |     |    |   |        |        |
| . | purpose of the   |            |     |    |   |        |        |
|   | survey.          |            |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
| 2 | Provide a copy   |            |     |    |   |        |        |
| \ | of the proposed  |            |     |    |   |        |        |
| . | survey schedule, |            |     |    |   |        |        |
|   | with work areas  |            |     |    |   |        |        |
|   | identif          |            |     |    |   |        |        |
|   | ied---preferably |            |     |    |   |        |        |
|   | on an airport    |            |     |    |   |        |        |
|   | map or diagram.  |            |     |    |   |        |        |
|   | Obtain approval  |            |     |    |   |        |        |
|   | of schedule,     |            |     |    |   |        |        |
|   | especially for   |            |     |    |   |        |        |
|   | runway time.     |            |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
|   | Request          | Item       |     | Y  | N |        |        |
|   | permission to    |            |     | es | o |        |        |
|   | work on the      |            |     |    |   |        |        |
|   | airfield, and    |            |     |    |   |        |        |
|   | note each of the |            |     |    |   |        |        |
|   | following items: |            |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
|   |                  | Escort     |     |    |   |        |        |
|   |                  | required?  |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
| 3 |                  | Radio      |     |    |   |        |        |
| \ |                  | req        |     |    |   |        |        |
| . |                  | uired?[^3] |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
|   |                  | Flashing   |     |    |   |        |        |
|   |                  | Light      |     |    |   |        |        |
|   |                  | required?  |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
|   |                  | Other      |     |    |   |        |        |
|   |                  | required   |     |    |   |        |        |
|   |                  | items[^4]  |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
| 4 | R                |            |     |    |   |        |        |
| \ | unways---discuss |            |     |    |   |        |        |
| . | any changes in   |            |     |    |   |        |        |
|   | length, width,   |            |     |    |   |        |        |
|   | or repaving      |            |     |    |   |        |        |
|   | occurring since  |            |     |    |   |        |        |
|   | the last survey. |            |     |    |   |        |        |
|   | Make note of any |            |     |    |   |        |        |
|   | items            |            |     |    |   |        |        |
|   | identified.      |            |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
| 5 | R                |            |     |    |   |        |        |
| \ | unways---discuss |            |     |    |   |        |        |
| . | any planned      |            |     |    |   |        |        |
|   | future changes   |            |     |    |   |        |        |
|   | to the           |            |     |    |   |        |        |
|   | runway(s).       |            |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
| 6 | Obtain and       |            |     |    |   |        |        |
| \ | review the       |            |     |    |   |        |        |
| . | current airport  |            |     |    |   |        |        |
|   | obstruction      |            |     |    |   |        |        |
|   | chart or airport |            |     |    |   |        |        |
|   | layout plan, and |            |     |    |   |        |        |
|   | ask for          |            |     |    |   |        |        |
|   | comments. Make   |            |     |    |   |        |        |
|   | notes directly   |            |     |    |   |        |        |
|   | on the document  |            |     |    |   |        |        |
|   | for field team   |            |     |    |   |        |        |
|   | use.             |            |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
| 7 | Ensure to cover  |            |     |    |   |        |        |
| \ | any questions    |            |     |    |   |        |        |
| . | identified in    |            |     |    |   |        |        |
|   | the contract     |            |     |    |   |        |        |
|   | supplementary    |            |     |    |   |        |        |
|   | instructions.    |            |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+
| 8 | Discuss changes  |            |     |    |   |        |        |
| \ | to planimetry,   |            |     |    |   |        |        |
| . | construction, or |            |     |    |   |        |        |
|   | facilities.      |            |     |    |   |        |        |
|   | Include planned  |            |     |    |   |        |        |
|   | changes.         |            |     |    |   |        |        |
+---+------------------+------------+-----+----+---+--------+--------+

<table>
<colgroup>
<col style="width: 5%" />
<col style="width: 26%" />
<col style="width: 17%" />
<col style="width: 1%" />
<col style="width: 9%" />
<col style="width: 7%" />
<col style="width: 5%" />
<col style="width: 0%" />
<col style="width: 12%" />
<col style="width: 0%" />
<col style="width: 13%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="4">Airport Manager/Operations Manager Interview</td>
<td colspan="7"><mark></mark></td>
</tr>
<tr class="even">
<td colspan="7"><p><mark></mark></p>
<p>Interview Tasks</p></td>
<td colspan="2">Date Completed</td>
<td colspan="2">Initials of Survey Party Chief</td>
</tr>
<tr class="odd">
<td rowspan="4">9.</td>
<td rowspan="4">Discuss obstructions relating to the airport.</td>
<td colspan="3">Discussion Item</td>
<td>Yes</td>
<td colspan="2">No</td>
<td colspan="2" rowspan="3"></td>
<td rowspan="3"></td>
</tr>
<tr class="even">
<td colspan="3">Has any obstruction clearing been conducted?<a
href="#fn1" class="footnote-ref" id="fnref1"
role="doc-noteref"><sup>1</sup></a></td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td colspan="3">Are there any plans for obstruction clearing?</td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td colspan="3">Are there any new obstructions in the airport
vicinity?</td>
<td></td>
<td colspan="2"></td>
<td colspan="2"></td>
<td></td>
</tr>
<tr class="odd">
<td rowspan="11">10.</td>
<td rowspan="11">Obtain/verify the airport manager’s contact
information.</td>
<td>First Name</td>
<td colspan="5"></td>
<td colspan="2" rowspan="11"></td>
<td rowspan="11"></td>
</tr>
<tr class="even">
<td>Last Name</td>
<td colspan="5"></td>
</tr>
<tr class="odd">
<td>Address Line 1</td>
<td colspan="5"></td>
</tr>
<tr class="even">
<td>Address Line 2</td>
<td colspan="5"></td>
</tr>
<tr class="odd">
<td>City</td>
<td colspan="5"></td>
</tr>
<tr class="even">
<td>State</td>
<td colspan="5"></td>
</tr>
<tr class="odd">
<td>Zip Code</td>
<td colspan="5"></td>
</tr>
<tr class="even">
<td>Telephone Number</td>
<td colspan="5"></td>
</tr>
<tr class="odd">
<td>Telephone Number</td>
<td colspan="5"></td>
</tr>
<tr class="even">
<td>Fax Number</td>
<td colspan="5"></td>
</tr>
<tr class="odd">
<td>Email Address</td>
<td colspan="5"></td>
</tr>
<tr class="even">
<td>11.</td>
<td colspan="7">Discuss field conditions for driving.</td>
<td colspan="2"></td>
<td></td>
</tr>
<tr class="odd">
<td rowspan="7">12.</td>
<td rowspan="7">Request keys for gates, as required, or obtain point of
contact information for field access</td>
<td>POC Name</td>
<td colspan="5"></td>
<td colspan="2" rowspan="7"></td>
<td rowspan="7"></td>
</tr>
<tr class="even">
<td>POC Telephone</td>
<td colspan="5"></td>
</tr>
<tr class="odd">
<td>POC Cell Number</td>
<td colspan="5"></td>
</tr>
<tr class="even">
<td rowspan="4">Other contact Information</td>
<td colspan="5">Contact Name</td>
</tr>
<tr class="odd">
<td colspan="5"></td>
</tr>
<tr class="even">
<td colspan="5">Contact Number</td>
</tr>
<tr class="odd">
<td colspan="5"></td>
</tr>
</tbody>
</table>
<aside id="footnotes" class="footnotes footnotes-end-of-document"
role="doc-endnotes">
<hr />
<ol>
<li id="fn1"><p>Obstruction Clearing completed by in (month) (year)
.</p>
<p>Obstruction clearing is planned for (month) (year) .<a href="#fnref1"
class="footnote-back" role="doc-backlink">↩︎</a></p></li>
</ol>
</aside>

###  {#section-8 .Paragraph}

<table>
<colgroup>
<col style="width: 5%" />
<col style="width: 22%" />
<col style="width: 16%" />
<col style="width: 6%" />
<col style="width: 9%" />
<col style="width: 7%" />
<col style="width: 5%" />
<col style="width: 0%" />
<col style="width: 12%" />
<col style="width: 0%" />
<col style="width: 13%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="4">Airport Manager/Operations Manager Interview</td>
<td colspan="7"><mark></mark></td>
</tr>
<tr class="even">
<td colspan="7"><p><mark></mark></p>
<p>Interview Tasks</p></td>
<td colspan="2">Date Completed</td>
<td colspan="2">Initials of Survey Party Chief</td>
</tr>
<tr class="odd">
<td rowspan="4">13.</td>
<td rowspan="4">Ask about known survey control on the airport.</td>
<td colspan="3">Discussion Item</td>
<td>Yes</td>
<td colspan="2">No</td>
<td colspan="2" rowspan="4"></td>
<td rowspan="4"></td>
</tr>
<tr class="even">
<td colspan="3">Installed PACS and SACS in good condition?</td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td colspan="3">Is the manager aware of the importance of the PACS and
SACS?</td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td colspan="3">Are there any other survey control points on the
airport?</td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td>14.</td>
<td colspan="7">Request introduction to Tower Chief or other airport
officials.</td>
<td colspan="2"></td>
<td></td>
</tr>
<tr class="even">
<td colspan="3">Name of Survey Party Chief</td>
<td colspan="6"></td>
<td colspan="2">Date</td>
</tr>
<tr class="odd">
<td colspan="3">Signature of Survey Party Chief</td>
<td colspan="6"></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td colspan="3">Name of Airport Manager or Designee</td>
<td colspan="6"></td>
<td colspan="2">Date</td>
</tr>
<tr class="odd">
<td colspan="3">Signature of Airport Manager or Designee</td>
<td colspan="6"></td>
<td colspan="2"></td>
</tr>
</tbody>
</table>

+---+--------------+--------------+---+--------------+--------+---+--------+
| T |              |              |   | []{.mark}    |        |   |        |
| o |              |              |   |              |        |   |        |
| w |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| r |              |              |   |              |        |   |        |
| C |              |              |   |              |        |   |        |
| h |              |              |   |              |        |   |        |
| i |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| f |              |              |   |              |        |   |        |
| / |              |              |   |              |        |   |        |
| W |              |              |   |              |        |   |        |
| a |              |              |   |              |        |   |        |
| t |              |              |   |              |        |   |        |
| c |              |              |   |              |        |   |        |
| h |              |              |   |              |        |   |        |
| S |              |              |   |              |        |   |        |
| u |              |              |   |              |        |   |        |
| p |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| r |              |              |   |              |        |   |        |
| v |              |              |   |              |        |   |        |
| i |              |              |   |              |        |   |        |
| s |              |              |   |              |        |   |        |
| o |              |              |   |              |        |   |        |
| r |              |              |   |              |        |   |        |
| I |              |              |   |              |        |   |        |
| n |              |              |   |              |        |   |        |
| t |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| r |              |              |   |              |        |   |        |
| v |              |              |   |              |        |   |        |
| i |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| w |              |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
| [ |              |              |   |              | Date   | I |        |
| ] |              |              |   |              | Com    | n |        |
| { |              |              |   |              | pleted | i |        |
| . |              |              |   |              |        | t |        |
| m |              |              |   |              |        | i |        |
| a |              |              |   |              |        | a |        |
| r |              |              |   |              |        | l |        |
| k |              |              |   |              |        | s |        |
| } |              |              |   |              |        | o |        |
|   |              |              |   |              |        | f |        |
| I |              |              |   |              |        | S |        |
| n |              |              |   |              |        | u |        |
| t |              |              |   |              |        | r |        |
| e |              |              |   |              |        | v |        |
| r |              |              |   |              |        | e |        |
| v |              |              |   |              |        | y |        |
| i |              |              |   |              |        | P |        |
| e |              |              |   |              |        | a |        |
| w |              |              |   |              |        | r |        |
| T |              |              |   |              |        | t |        |
| a |              |              |   |              |        | y |        |
| s |              |              |   |              |        | C |        |
| k |              |              |   |              |        | h |        |
| s |              |              |   |              |        | i |        |
|   |              |              |   |              |        | e |        |
|   |              |              |   |              |        | f |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
| 1 | Discuss      |              |   |              |        |   |        |
| \ | radio        |              |   |              |        |   |        |
| . | procedures,  |              |   |              |        |   |        |
|   | call sign,   |              |   |              |        |   |        |
|   | radio        |              |   |              |        |   |        |
|   | co           |              |   |              |        |   |        |
|   | mmunications |              |   |              |        |   |        |
|   | failure      |              |   |              |        |   |        |
|   | procedures.  |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
| 2 | Provide a    |              |   |              |        |   |        |
| \ | copy of the  |              |   |              |        |   |        |
| . | proposed     |              |   |              |        |   |        |
|   | survey       |              |   |              |        |   |        |
|   | schedule,    |              |   |              |        |   |        |
|   | with work    |              |   |              |        |   |        |
|   | areas        |              |   |              |        |   |        |
|   | identified-  |              |   |              |        |   |        |
|   | --preferably |              |   |              |        |   |        |
|   | on an        |              |   |              |        |   |        |
|   | airport map  |              |   |              |        |   |        |
|   | or diagram.  |              |   |              |        |   |        |
|   | Obtain       |              |   |              |        |   |        |
|   | approval of  |              |   |              |        |   |        |
|   | schedule     |              |   |              |        |   |        |
|   | especially   |              |   |              |        |   |        |
|   | for runway   |              |   |              |        |   |        |
|   | time.        |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
| 3 | Discuss      |              |   |              |        |   |        |
| \ | taxiway      |              |   |              |        |   |        |
| . | d            |              |   |              |        |   |        |
|   | esignations. |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
| 4 | Inquire      |              |   |              |        |   |        |
| \ | about        |              |   |              |        |   |        |
| . | restricted   |              |   |              |        |   |        |
|   | areas, radio |              |   |              |        |   |        |
|   | and visual   |              |   |              |        |   |        |
|   | blind spots. |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
| 5 | O            | First Name   |   |              |        |   |        |
| \ | btain/Verify |              |   |              |        |   |        |
| . | the Tower    |              |   |              |        |   |        |
|   | Chief's      |              |   |              |        |   |        |
|   | contact      |              |   |              |        |   |        |
|   | information. |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | Last Name    |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | Address Line |   |              |        |   |        |
|   |              | 1            |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | Address Line |   |              |        |   |        |
|   |              | 2            |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | City         |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | State        |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | Zip Code     |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | Telephone    |   |              |        |   |        |
|   |              | Number       |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | Telephone    |   |              |        |   |        |
|   |              | Number       |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | Fax Number   |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | Email        |   |              |        |   |        |
|   |              | Address      |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
| 6 | Request      | POC Name     |   |              |        |   |        |
| \ | information  |              |   |              |        |   |        |
| . | about FAA    |              |   |              |        |   |        |
|   | Facilities   |              |   |              |        |   |        |
|   | personnel.   |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | POC          |   |              |        |   |        |
|   |              | Telephone    |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | POC Cell     |   |              |        |   |        |
|   |              | Number       |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              | Other        | C |              |        |   |        |
|   |              | contact      | o |              |        |   |        |
|   |              | Information  | n |              |        |   |        |
|   |              |              | t |              |        |   |        |
|   |              |              | a |              |        |   |        |
|   |              |              | c |              |        |   |        |
|   |              |              | t |              |        |   |        |
|   |              |              | N |              |        |   |        |
|   |              |              | a |              |        |   |        |
|   |              |              | m |              |        |   |        |
|   |              |              | e |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              |              | C |              |        |   |        |
|   |              |              | o |              |        |   |        |
|   |              |              | n |              |        |   |        |
|   |              |              | t |              |        |   |        |
|   |              |              | a |              |        |   |        |
|   |              |              | c |              |        |   |        |
|   |              |              | t |              |        |   |        |
|   |              |              | N |              |        |   |        |
|   |              |              | u |              |        |   |        |
|   |              |              | m |              |        |   |        |
|   |              |              | b |              |        |   |        |
|   |              |              | e |              |        |   |        |
|   |              |              | r |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
|   |              |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
| N |              |              |   |              |        |   | Date   |
| a |              |              |   |              |        |   |        |
| m |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| o |              |              |   |              |        |   |        |
| f |              |              |   |              |        |   |        |
| S |              |              |   |              |        |   |        |
| u |              |              |   |              |        |   |        |
| r |              |              |   |              |        |   |        |
| v |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| y |              |              |   |              |        |   |        |
| P |              |              |   |              |        |   |        |
| a |              |              |   |              |        |   |        |
| r |              |              |   |              |        |   |        |
| t |              |              |   |              |        |   |        |
| y |              |              |   |              |        |   |        |
| C |              |              |   |              |        |   |        |
| h |              |              |   |              |        |   |        |
| i |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| f |              |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
| S |              |              |   |              |        |   |        |
| i |              |              |   |              |        |   |        |
| g |              |              |   |              |        |   |        |
| n |              |              |   |              |        |   |        |
| a |              |              |   |              |        |   |        |
| t |              |              |   |              |        |   |        |
| u |              |              |   |              |        |   |        |
| r |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| o |              |              |   |              |        |   |        |
| f |              |              |   |              |        |   |        |
| S |              |              |   |              |        |   |        |
| u |              |              |   |              |        |   |        |
| r |              |              |   |              |        |   |        |
| v |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| y |              |              |   |              |        |   |        |
| P |              |              |   |              |        |   |        |
| a |              |              |   |              |        |   |        |
| r |              |              |   |              |        |   |        |
| t |              |              |   |              |        |   |        |
| y |              |              |   |              |        |   |        |
| C |              |              |   |              |        |   |        |
| h |              |              |   |              |        |   |        |
| i |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| f |              |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
| N |              |              |   |              |        |   | Date   |
| a |              |              |   |              |        |   |        |
| m |              |              |   |              |        |   |        |
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| e |              |              |   |              |        |   |        |
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| n |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
| e |              |              |   |              |        |   |        |
+---+--------------+--------------+---+--------------+--------+---+--------+
| S |              |              |   |              |        |   |        |
| i |              |              |   |              |        |   |        |
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| e |              |              |   |              |        |   |        |
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+---+--------------+--------------+---+--------------+--------+---+--------+

+---+----------------------------+---+--------------+--------+---+--------+
| F |                            |   | []{.mark}    |        |   |        |
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| w |                            |   |              |        |   |        |
+---+----------------------------+---+--------------+--------+---+--------+
| [ |                            |   |              | Date   | I |        |
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|   |                            |   |              |        | e |        |
|   |                            |   |              |        | f |        |
+---+----------------------------+---+--------------+--------+---+--------+
| 1 | Discuss changes to NAVAID  |   |              |        |   |        |
| \ | systems.                   |   |              |        |   |        |
| . |                            |   |              |        |   |        |
+---+----------------------------+---+--------------+--------+---+--------+
| 2 | Discuss any plans for      |   |              |        |   |        |
| \ | NAVAID changes in the      |   |              |        |   |        |
| . | future.                    |   |              |        |   |        |
+---+----------------------------+---+--------------+--------+---+--------+
| 3 | Provide a copy of the      |   |              |        |   |        |
| \ | proposed survey schedule,  |   |              |        |   |        |
| . | with work areas            |   |              |        |   |        |
|   | identified---preferably on |   |              |        |   |        |
|   | an airport map or diagram. |   |              |        |   |        |
|   | Obtain approval of         |   |              |        |   |        |
|   | schedule especially for    |   |              |        |   |        |
|   | NAVAID critical areas.     |   |              |        |   |        |
+---+----------------------------+---+--------------+--------+---+--------+
| 3 | Ask about location,        |   |              |        |   |        |
| \ | accessibility and          |   |              |        |   |        |
| . | associated requirements,   |   |              |        |   |        |
|   | and directions to any      |   |              |        |   |        |
|   | outlying facilities.       |   |              |        |   |        |
+---+----------------------------+---+--------------+--------+---+--------+
| N |                            |   |              |        | D |        |
| a |                            |   |              |        | a |        |
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| i |                            |   |              |        |   |        |
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| f |                            |   |              |        |   |        |
+---+----------------------------+---+--------------+--------+---+--------+
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+---+----------------------------+---+--------------+--------+---+--------+
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+---+----------------------------+---+--------------+--------+---+--------+
| S |                            |   |              |        |   |        |
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+---+----------------------------+---+--------------+--------+---+--------+
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| : |                            |   |              |        |   |        |
+---+----------------------------+---+--------------+--------+---+--------+

# 

# 

# 

# This page intentionally left blank. 

# APPENDIX 4. WRITING STATION DESCRIPTIONS AND RECOVERY NOTES WITH WINDESC

# 

#### **WRITING STATION DESCRIPTIONS AND RECOVERY NOTES WITH WINDESC** 

Along with the positions and the survey marks themselves, descriptions
are one of the end products of surveying. All three must be of the
highest quality. The descriptions must be complete, accurate, and in
standardized format if the station is to be reliably and easily
recovered for use in the future. Descriptions must be in the standard
three-paragraph NGS format described below under "Description Format".

### **1.0. GENERAL.** {#general. .Paragraph}

1.1. DEFINITION OF DESCRIPTION VS. RECOVERY NOTE.

a.  A *description* details the location of a new survey mark or one not
    previously in the NGS database.

```{=html}
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```
a.  A *recovery note* is an update and/or refinement to a description
    already in the NGS database, written upon a return visit to a survey
    mark.

### **1.2 LEVELS OF COMPLEXITY OF RECOVERY NOTES.** {#levels-of-complexity-of-recovery-notes. .Paragraph}

a.  **No Changes.** If an existing station's digital description is
    complete, accurate, and meets Blue Book requirements, the station
    may be recovered with a brief recovery note, such as "RECOVERED AS
    DESCRIBED".

```{=html}
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```
a.  **Minor Changes.** If minor changes or additions to the description
    are required, they may be added after the above phrase, such as
    "RECOVERED AS DESCRIBED, EXCEPT A NEW WOODEN FENCE IS NOW 3 METERS
    NORTH OF THE STATION." See typical cases listed below.

###  {#section-13 .Paragraph}

b.  **Major Changes.** Where major changes have occurred, major
    inaccuracies are found, or required information is missing (in any
    portion of the description), a complete three-paragraph recovery
    note, with the same format as a new description, is required. If a
    measurement discrepancy is found, state that the new distance was
    verified, for example, by taping in both English units and metric
    units or with two separate measurements taken by two different
    people. See typical cases listed below.

c.  **Exemption.** If a recovery note has been written for the station
    within 1 year and no changes have taken place, a new recovery note
    is not required. Note: This might cause an error message in the
    description checking software, which can be ignored.

**1.3. SOFTWARE.** Descriptions and recovery notes must be properly
encoded into a D-file by using NGS WINDESC software. Please refer to the
NGS website at [http://www.ngs.noaa.gov/FGCS/BlueBook/]{.underline},
Annex P (Geodetic Control Descriptive Data), for information. Note:
WINDESC is used for both new descriptions and for recovery notes.

**1.4. CHECKING.** Descriptions must be written by one person and
checked by another. Recovery notes should also be checked. For example,
a mark setter can draft a description immediately after setting the
mark, and an observer can check the description during observations. For
existing marks, the reconnaissance person can draft the recovery note
and the observer can check it. Descriptions and recovery notes should be
written while at the station or immediately after visiting a station so
all details are fresh in the writer's mind.

1.5. TYPICAL RECOVERY NOTE CASES.

a.  A brief, one or two sentence recovery note is adequate when---

```{=html}
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```
i.  The mark is found and the description is completely accurate (e.g.,
    "RECOVERED AS DESCRIBED"),

ii. The mark is found and there are one or two minor changes (e.g.,
    "RECOVERED AS DESCRIBED EXCEPT A NEW WOODEN FENCE IS NOW 3 METERS
    NORTH OF THE STATION"),

iii. The mark is not found (e.g., "MARK NOT FOUND AFTER 3 PERSON-HOUR
     SEARCH"),

iv. The mark is not found and presumed destroyed, (e.g., "MARK NOT FOUND
    AND PRESUMED DESTROYED. CONSTRUCTION FOREMAN STATES THAT THE MARK
    WAS DESTROYED YESTERDAY"), or

v.  The mark is found destroyed (e.g., "THE MARK IS DESTROYED AND THE
    DISK HAS BEEN SENT TO NGS" or "THE MARK IS DESTROYED AND ITS
    PHOTOGRAPH HAS BEEN SENT TO NGS"). For NGS to consider a station
    destroyed, the agency must receive the disk or a photograph showing
    the destroyed mark.

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```
b.  A complete new three-paragraph description or recovery note is
    required when---

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```
i.  A new mark is set,

ii. An existing mark does not have a PID,

iii. An existing mark does not have an NSRS digital description (i.e., a
     description is not in the NGS database),

iv. An existing mark has only a brief description not meeting the
    three-paragraph requirement (many bench marks have only short,
    one-paragraph descriptions), or

v\. An existing mark's description is no longer accurate or complete.

**2.0. DESCRIPTION FORMAT.** The original USC&GS Special Publication No.
247, *Manual of Geodetic Triangulation,* states, "A description must be
clear, concise, and complete. It should enable one to go with certainty
to the immediate vicinity of the mark, and by the measured distances to
reference points and the description of the character of the mark, it
should inform the searcher of the exact location of the mark and make
its identification certain. It should include only essential details of
a permanent character" (page 116). NGS still follows these guidelines,
so a person with a minimal background in surveying and no local
geographic or historical knowledge can easily find the mark by logically
following the text of the description.

###  {#section-14 .Paragraph}

**2.1. FIRST PARAGRAPH.** The first paragraph is the **description of
locality.** This part of the description begins by referring to the
airline distance and direction (cardinal or intercardinal point of the
compass) from the **three** nearest, well-known mapped geographic
feature(s), usually the nearest cities or towns. Use three references
equally spaced around the horizon, if possible. **In writing the
description, always progress from the farthest to the nearest reference
point.** Distances in this part of the description must be in kilometers
(followed by miles) or meters (followed by feet) and recorded to one
decimal place. Detailed measurements that appear elsewhere in the
description should not be repeated in this paragraph. Points of the
compass should be fully spelled out. Do not use bearings or azimuths.
State the name, address, and phone number of public-sector property
owners (however, phone numbers of private property owners are NOT
included). State any advance notice and security access requirements for
reaching the station. Also, state any unusual transportation methods
that might be required to reach the station.

Sample first paragraph:

> STATION IS LOCATED ABOUT 12.9 KM (8.0 MILES) SOUTHWEST OF EASTON,
> ABOUT 6.4 KM (4.0 MILES) NORTHWEST OF CAMBRIDGE, AND ABOUT 3.6 KM (2.2
> MILES) EAST OF SMITHVILLE ON PROPERTY OWNED BY MR. H.P. LAYTON, AND
> KNOWN AS OLD GOVERNOR JACKSON'S ESTATE.

**2.2. SECOND PARAGRAPH.** The second paragraph contains the
**directions *to reach* the station.** This section is one of the most
useful parts of a description. It usually enables a stranger to go
directly to a station without a delay due to a detailed study of maps or
of making local inquiries. It is a route description that should start
from a definite point, such as (1) the nearest intersection of named or
numbered **main** highways (ideally Interstate and U.S. highways, or at
least those shown on commonly used road maps) and approximately where
that intersection is or (2) some definite and well-known geographical
feature (e.g., main post office or county courthouse) and its name and
general location. Odometer distances must be given to tenths of
kilometers (followed by tenths of miles). For roads with names and
numbers, give both.

> a\. The format for the first leg of the "to reach" paragraph:

i\. FROM THE MAIN POST OFFICE IN DOWNTOWN SMITHVILLE or FROM THE
INTERSECTION OF INTERSTATE XX AND STATE HIGHWAY YY, ABOUT 3 MI NORTH OF
SMITHVILLE,

ii. GO A DIRECTION (north, northeast, northerly, northeasterly, etc.),

iii\. ON A ROAD (name or number of road or highway or both if it has
both a name and number),

> iv\. FOR A DISTANCE (kilometers followed by miles in parentheses), and

v\. TO SOMETHING (intersection, fork in road, T‑road left or T-road
right, etc.).

> b\. The format for all other legs:

i.  TURN LEFT (or RIGHT) or TAKE RIGHT (or LEFT) FORK or CONTINUE
    STRAIGHT AHEAD,

    ii. GO A DIRECTION (north, northeast, northerly, northeasterly,
        etc.),

    iii. ON ROAD (name or number of road or highway or both if it has
         both a name and number),

    iv. FOR A DISTANCE (kilometers followed by miles in parentheses),
        and

    v.  TO SOMETHING (intersection, fork in road, side-road left or
        right, station on left or right, etc.).

###  {#section-15 .Paragraph}

c\. All five parts of each leg must be included in each segment.

Sample second paragraph:

> TO REACH THE STATION FROM THE INTERSECTION OF INTERSTATE 300 AND MAIN
> STREET (STATE HIGHWAY 101) IN JONESVILLE, GO EASTERLY ON HIGHWAY 101
> FOR 3.7 KM (2.3 MILES) TO AN INTERSECTION. TURN RIGHT AND GO SOUTH ON
> MILLER ROAD FOR 5.1 KM (3.2 MILES) TO A SIDE-ROAD RIGHT. CONTINUE
> SOUTH ON MILLER ROAD FOR 6.6 KM (4.1 MILES) TO AN INTERSECTION. TURN
> LEFT AND GO EASTERLY ON SMITH ROAD FOR 2.4 KM (1.5 MILES) TO STATION
> ON THE LEFT IN THE FENCE LINE.

Use the word "EAST" if the road goes due east and "EASTERLY" if the road
wanders in a general easterly direction. Use intermediate references,
such as Miller Road above, if the distance becomes longer than about 5
miles. The place of the end of vehicle travel should be mentioned. If
walking is required, note the approximate time required to travel the
necessary distance. If travel to the station is by boat, the place of
landing should be stated.

**2.3. THIRD PARAGRAPH.** The third paragraph provides **details of the
mark and reference measurements.** It is made up of six parts:

a.  The station mark type,

b.  How the mark is stamped,

c.  How the mark is set,

d.  Reference measurements,

e.  The handheld GPS position, and

f.  PACS or SACS designation, if appropriate.

These sections are not enumerated (e.g., a., b., c.) in the description
but must be in the stated order and include the stated information.

+---+---+-----------------------------+---+-------------------------------+
| * |   |                             |   | **EXAMPLE**                   |
| * |   |                             |   |                               |
| P |   |                             |   |                               |
| A |   |                             |   |                               |
| R |   |                             |   |                               |
| A |   |                             |   |                               |
| G |   |                             |   |                               |
| R |   |                             |   |                               |
| A |   |                             |   |                               |
| P |   |                             |   |                               |
| H |   |                             |   |                               |
| S |   |                             |   |                               |
| E |   |                             |   |                               |
| C |   |                             |   |                               |
| T |   |                             |   |                               |
| I |   |                             |   |                               |
| O |   |                             |   |                               |
| N |   |                             |   |                               |
| * |   |                             |   |                               |
| * |   |                             |   |                               |
+---+---+-----------------------------+---+-------------------------------+
| a | S |                             |   | THE MARK IS AN NGS HORIZONTAL |
| \ | t |                             |   | DISK, or A USC&GS             |
| . | a |                             |   | TRIANGULATION DISK, or A      |
|   | t |                             |   | STAINLESS STEEL ROD, or A     |
|   | e |                             |   | CHISELED "X", ETC.            |
|   | w |                             |   |                               |
|   | h |                             |   |                               |
|   | a |                             |   |                               |
|   | t |                             |   |                               |
|   | t |                             |   |                               |
|   | h |                             |   |                               |
|   | e |                             |   |                               |
|   | m |                             |   |                               |
|   | a |                             |   |                               |
|   | r |                             |   |                               |
|   | k |                             |   |                               |
|   | i |                             |   |                               |
|   | s |                             |   |                               |
|   | : |                             |   |                               |
+---+---+-----------------------------+---+-------------------------------+
| b | S |                             |   | STAMPED \--JONES 1952\--.     |
| \ | t |                             |   |                               |
| . | a |                             |   |                               |
|   | t |                             |   |                               |
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|   | r |                             |   |                               |
|   | k |                             |   |                               |
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|   | s |                             |   |                               |
|   | s |                             |   |                               |
|   | t |                             |   |                               |
|   | a |                             |   |                               |
|   | m |                             |   |                               |
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|   | d |                             |   |                               |
|   | ( |                             |   |                               |
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|   | d |                             |   |                               |
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|   | ) |                             |   |                               |
|   | : |                             |   |                               |
+---+---+-----------------------------+---+-------------------------------+
| c | S |                             |   | THE MARK IS SET IN A DRILL    |
| \ | t |                             |   | HOLE IN BEDROCK, or SET IN A  |
| . | a |                             |   | SQUARE CONCRETE MONUMENT, or  |
|   | t |                             |   | IS A ROD DRIVEN TO REFUSAL,   |
|   | e |                             |   | ETC. A GREASE-FILLED SLEEVE   |
|   | h |                             |   | ONE M LONG WAS INSTALLED.     |
|   | o |                             |   |                               |
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|   | : |                             |   |                               |
+---+---+-----------------------------+---+-------------------------------+
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|   | . |                             |   |                               |
+---+---+-----------------------------+---+-------------------------------+
|   | c | State if the mark projects  | M |                               |
|   | . | above the ground, is flush, | A |                               |
|   | 1 | or is recessed and the      | R |                               |
|   | . | amount (for a rod mark,     | K |                               |
|   |   | state the above-ground      | P |                               |
|   |   | measurement for both the    | R |                               |
|   |   | rod and the logo cap):      | O |                               |
|   |   |                             | J |                               |
|   |   |                             | E |                               |
|   |   |                             | C |                               |
|   |   |                             | T |                               |
|   |   |                             | S |                               |
|   |   |                             | 1 |                               |
|   |   |                             | 5 |                               |
|   |   |                             | C |                               |
|   |   |                             | M |                               |
|   |   |                             | ( |                               |
|   |   |                             | 5 |                               |
|   |   |                             | I |                               |
|   |   |                             | N |                               |
|   |   |                             | ) |                               |
|   |   |                             | , |                               |
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|   |   |                             | r |                               |
|   |   |                             | M |                               |
|   |   |                             | A |                               |
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|   | t |                             |   |                               |
|   | s |                             |   |                               |
|   | f |                             |   |                               |
|   | o |                             |   |                               |
|   | r |                             |   |                               |
|   | t |                             |   |                               |
|   | h |                             |   |                               |
|   | e |                             |   |                               |
|   | d |                             |   |                               |
|   | e |                             |   |                               |
|   | g |                             |   |                               |
|   | r |                             |   |                               |
|   | e |                             |   |                               |
|   | e |                             |   |                               |
|   | s |                             |   |                               |
|   | o |                             |   |                               |
|   | f |                             |   |                               |
|   | l |                             |   |                               |
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|   | n |                             |   |                               |
|   | g |                             |   |                               |
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|   | d |                             |   |                               |
|   | e |                             |   |                               |
|   | . |                             |   |                               |
+---+---+-----------------------------+---+-------------------------------+
| f | I |                             | T |                               |
| \ | f |                             | H |                               |
| . | t |                             | I |                               |
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|   | n |                             |   |                               |
|   | d |                             |   |                               |
|   | a |                             |   |                               |
|   | r |                             |   |                               |
|   | y |                             |   |                               |
|   | A |                             |   |                               |
|   | i |                             |   |                               |
|   | r |                             |   |                               |
|   | p |                             |   |                               |
|   | o |                             |   |                               |
|   | r |                             |   |                               |
|   | t |                             |   |                               |
|   | C |                             |   |                               |
|   | o |                             |   |                               |
|   | n |                             |   |                               |
|   | t |                             |   |                               |
|   | r |                             |   |                               |
|   | o |                             |   |                               |
|   | l |                             |   |                               |
|   | S |                             |   |                               |
|   | t |                             |   |                               |
|   | a |                             |   |                               |
|   | t |                             |   |                               |
|   | i |                             |   |                               |
|   | o |                             |   |                               |
|   | n |                             |   |                               |
|   | : |                             |   |                               |
+---+---+-----------------------------+---+-------------------------------+

Sample for a rod mark:

> THE STATION IS THE TOP-CENTER OF A 1.43 CM (9/16 IN) STAINLESS STEEL
> ROD DRIVEN TO REFUSAL DEPTH OF 18 M (. THE LOGO CAP IS STAMPED
> \--SMITH 2003\--. THE LOGO CAP IS MOUNTED ON A 13 CM (5 IN) DIAMETER
> PVC PIPE. A 1 M (3.3 FT) LONG GREASE-FILLED SLEEVE WAS INSTALLED. LOGO
> CAP IS FLUSH WITH THE GROUND AND TOP OF ROD IS 10 CM (3.9 IN) BELOW
> THE TOP OF THE LOGO CAP. THE MARK IS 32.4 M (101.74 FT) NORTHEAST OF
> NORTHEAST CORNER OF THE HOUSE, 16.62 M (54.5 FT) NORTH OF WATER PUMP
> ALONGSIDE OF HEDGE AROUND OLD FLOWER GARDEN, AND 4 M (12.96 FT) NORTH
> OF NORTHEAST CORNER OF HIGH HEDGE ENCLOSING OLD FLOWER GARDEN. THE HH1
> GPS IS: 304050.2N, 1201020.4W.

Sample for a concrete monument:

> THE STATION IS AN NGS HORIZONTAL DISK, STAMPED \--JONES 2003\-- SET IN
> A ROUND CONCRETE MONUMENT 1.2 M (4 FT) DEEP AND 0.3 M (12 IN) IN
> DIAMETER. IT IS SET FLUSH WITH THE GROUND. IT IS 32.4 M (101.74 FT)
> NORTHEAST OF NORTHEAST CORNER OF THE HOUSE, 16.62 M (54.5 FT) NORTH OF
> WATER PUMP ALONGSIDE OF HEDGE AROUND OLD FLOWER GARDEN, AND 4 M (12.96
> FT) NORTH OF NORTHEAST CORNER OF HIGH HEDGE ENCLOSING OLD FLOWER
> GARDEN. THE HH1 GPS IS: 304050.2N, 1201020.4W.

**3.0. IMPORTANT POINTS REGARDING DESCRIPTIONS.**

**3.1. NAMES.** Use the station designation (name) and PID, exactly as
listed in the NGS database, in all survey records. Do not add dates,
agency acronyms, or other information to the name, nor the stamping.
Frequently the stamping and the official station designation are not the
same. For example, stampings include the year set, but designations
generally do not.

**3.2. TERMINOLOGY.** Correct NGS survey terminology must be used in all
station descriptions and reports (see *Geodetic Glossary,* NGS, 1986).

**3.3. DISTANCES.** All measurements are assumed to be horizontal unless
labeled "slope". Distances measured from a line (e.g., the center line
of a road or a fence line) are assumed to be measured perpendicular to
that line. The origin of measurements at the junction of two roads is
assumed to be the intersection of center lines of both roads.
Measurements are assumed to be from the center of an object (i.e., power
pole) unless stated otherwise.

**3.4. REPAIR.** Any work done to repair a mark must be described
completely in the updated recovery note. A repair strengthens the mark
but must not change its position. For example, adding concrete or epoxy
around a disk where some is missing is a repair.

**3.5. REFERENCE MARK NAMES.** Reference marks are abbreviated "RM x" in
descriptions, but on "Reference Mark" disks they are stamped "NO. x".

**3.6. WCHKDESC.** Run the digital D-file through the WCHKDESC program
(field-level option), one of several programs within the WINDESC
Software Suite, to identify format and coding errors. This program is
accessed by (1) running the WINDESC program and (2) selecting the
program WCHKDESC from the main menu.

**3.7. METRIC CONVERSION.** Use 3.2808333333 feet equals one meter.

**3.8. ABBREVIATIONS.** Meter = M, kilometer = KM, centimeter = CM, mile
= MI, nautical mile = NM, feet = FT, inch = IN.

**4.0. THE WDESC PROGRAM.** The WDESC program, one of several programs
within the WINDESC Software Suite (available at
[http://www.ngs.noaa.gov/PC_PROD/DDPROC4.XX/ddproc.index.html]{.underline})**,
is used to encode descriptions and recovery notes in D-FILE format for
the loading of these descriptions into the NGS database. The NGS Blue
Book and the WDESC documentation contain information for properly
encoding descriptions. Helpful information is contained in the following
paragraphs.**

**When creating a description file, a backup file is automatically
created. Every time a few descriptions are entered, check them with
WCHKDESC and the file corrected. The backup should be renamed before
reopening the program or it will be overwritten.** Always exit from the
WDESC program from the pull-down File option Exit. Saving the
description file as a new filename every time the program is exited is
recommended; saving after each description is entered is also
recommended.

Remember to enter "Y" into the satellite usage code field in the
**Header Record** if the mark is suitable for GPS observations.

**Set the *condition code* on the *Description Header* form as
described** **in** *The Description Processing H**andbook, Chapter 1,
D-FILE Format (for Both Microsoft Windows 95/98/NT and UNIX): T**he
Format of a Descri**ption File (D-FILE)*, which is available by
downloading dformat.htm from Section 4 of the WINDESC page
([http://www.ngs.noaa.gov/PC_PROD/DDPROC4.XX/ddproc.index.html]{.underline}).

Three separate paragraphs are required in the descriptive text field
since they make the description much easier to read. Therefore, when
entering the text into the **Description Header** form using the WDESC
program, separate each paragraph by pressing the \[ENTER\] key on the
keyboard to add a blank line at the end of the first paragraph.

The FPR code is a field on the Description Header form in the WDESC
program. Set the "FPR" field in the Description Header form to "F", "P",
or "R" for Flush, Projected, or Recessed, respectively. In the
description, include the logo cap relationship to the ground surface
(projecting above, flush with, or recessed below), and include the
distance that the top of the rod is below the top of the logo cap. It is
important to include information regarding the exact placement of the
logo cap for future reference.

A list of the proper agency codes for the WINDESC Software Suite can be
found on the

NGS website in WINDESC , ANNEX C

([http://www.ngs.noaa.gov/FGCS/BlueBook/annexc/annexc.index.html]{.underline}).
The agency code to be used for marks that are set by the National
Geodetic Survey is NGS. The agency code for marks set by the USC&GS is
CGS. Contractors must use the code assigned to their company. If a
contractor does not have a code, send a request for one to NGS.

**5.0. MARK TYPES.**

**5.1. CONCRETE MARK.** For a concrete mark set in accordance with the
requirements of Appendix E
([http://www.ngs.noaa.gov/AERO/aerospecs.htm#vol1]{.underline}), use a
**setting code** of "07". This classifies the station with a default
**verti****cal stability code** of "C".

**5.2. ROD MARK GREATER THAN 4 METERS.** For an NGS 3-D stainless steel
rod mark driven to a depth of 4 meters or greater, use a
**monume****ntation code** of "F" and a **setting code** of "59". This
classifies the station with a default **vertical stability** **code** of
"A". If the standard 1-meter plastic sleeve is used, the vertical
stability code must be downgraded to "B".

**5.3. ROD MARKS LESS THAN 4 METERS ARE GENERALLY NOT ACCEPTABLE.** See
*Geodetic Bench Marks,* page 27, Table 3.

**5.4. DISK IN ROCK OUTCROP.** For a disk that is set in a solid rock
outcrop, use a **m****onumentation code** of "DH" or "DD" and a
**setting code** of "66". This classifies the station with a default
**vertical stability** **code** of "B".

Check the listing of valid **monumenta****tion** **codes** and
**setti****ng codes** in *The* *D**es**cription Processing Handbook,
Chapter 1, D-FILE Format (for Both* *Microsoft Windows 95/98/NT and
U**NIX): The Format of a Description File (D-FILE)*, which is available
in Annex P of the Blue Book
**(**[http://www.ngs.noaa.gov/FGCS/BlueBook/]{.underline}), for the
proper codes to use for other types of marks.

Refer to the complete directions available on the NGS website when using
the NGS software package WINDESC to write the required station
descriptions, and be sure to check your final product with WCHKDESC.

# APPENDIX 5. STATION TABLE FORM

**(Blank and Filled-in Versions)**

![](media/image50.jpeg){width="6.293055555555555in"
height="8.729861111111111in"}

![](media/image51.jpeg){width="5.947916666666667in"
height="8.603472222222223in"}

![](media/image52.jpeg){width="6.485416666666667in"
height="8.655555555555555in"}

# APPENDIX 6. EXAMPLE GPS OBSERVATION SCHEME

# 

#### ANA Multi-Airport GPS Observation Scheme

#### Maine ANA Survey, 1998

AIRPORT(S) Auburn-Lewiston Municipal Airport (LEW)

Augusta State Airport (AFN)

Observation Day -- Day 1 (045)

Number of Receivers used -- 6

CORS Tie: BRU1

A Order Tie -- n/a

Observers -- Contractor Inc. (2) and Subcontractor Inc. (2)

+-----------------------------------+-----------------------------------+
| LEW                               | AFN                               |
+-----------------------------------+-----------------------------------+
| PACS -- LEW A                     | PACS -- AUG AP STA C              |
|                                   |                                   |
| Session 1 -- 8:00 -- 13:30 (5.5   | Session 1 -- 8:00 -- 13:30 (5.5   |
| hours)                            | hours)                            |
|                                   |                                   |
| Session 2 -- 14:00 -- 19:00 (5.0  | Session 2 -- 14:00 -- 19:00 (5.0  |
| Hours)                            | hours)                            |
+-----------------------------------+-----------------------------------+
| SACS #1 -- LEW AP STA B           | SACS #1 -- AUG AP STA B           |
|                                   |                                   |
| Session 1 -- 8:00 -- 10:30 (2.5   | Session 1 -- 8:00 -- 10:30 (2.5   |
| hours)                            | hours)                            |
|                                   |                                   |
| Session 2 -- 14:00 -- 16:00 (2.0  | Session 2 -- 14:00 -- 16:00 (2.0  |
| hours)                            | hours)                            |
+-----------------------------------+-----------------------------------+
| SACS #2 -- ARP 1964               | SACS #2 -- AUG A                  |
|                                   |                                   |
| Session 1 -- 11:00 -- 13:30 (2.5  | Session 1 -- 11:00 -- 13:30 (2.5  |
| hours)                            | hours)                            |
|                                   |                                   |
| Session 2 -- 16:30 -- 19:00 (2.5  | Session 2 -- 16:30 -- 19:00 (2.5  |
| hours)                            | hours)                            |
+-----------------------------------+-----------------------------------+
| BM #1 -- E171 8:00 -- 13:00 (5.0  | BM #1 -- G 31 8:00 -- 13:00 (5.0  |
| hours)                            | hours)                            |
+-----------------------------------+-----------------------------------+
| BM #2 -- G 171 14:00 -- 19:00     |                                   |
| (5.0 hours)                       |                                   |
|                                   |                                   |
| HARN -- A 196 14:00 -- 19:00 (5.0 |                                   |
| hours)                            |                                   |
+-----------------------------------+-----------------------------------+

Remarks: Session duration is fixed, start and end times are approximate
depending on travel times, dates of survey, satellite status, weather
conditions, airport logistics, etc. Stations used for multiple airports
are listed on the center of the page.

Detailed station information is listed in the station table.

# 

# APPENDIX 7. INFORMATION, DATA, AND SOFTWARE AVAILABLE ON THE INTERNET

# 

# 

**Websites**

NGS Aeronautical Survey Program:

[http://www.ngs.noaa.gov/AERO/aero.html]{.underline}

**NGS:** [http://www.ngs.noaa.gov]{.underline}

NGS presents a wealth of information on its data products, software
programs,

and user services, as well as links to other helpful sites.

**CORS and IGS Ephemeris Data:**
[http://www.ngs.noaa.gov/CORS/]{.underline}

Information on the National CORS system and access to CORS and Precise
Ephemeris data downloads are available from NGS. Use the "User Friendly
CORS" utility to download customized RINEX data sets and IGS ephemeris.
The latest coordinate files and other metadata for each CORS site is
also available. The "Data Availability" feature can be used to determine
if a CORS site is missing data for a particular time period.

**USCG Navigation Center GPS Website:**
[http://www.navcen.uscg.gov/]{.underline}

This site provides information on the status of the GPS constellation
and provides NANU

message postings and notices for outages at WAAS and DGPS sites.

###  {#section-20 .Paragraph}

**GPS Antenna Calibration Site:**
[http://www.ngs.noaa.gov/ANTCAL/]{.underline}

This site provides information on which antennas have been calibrated.

Data and Software

**PAGE-NT**---PAGE-NT is a menu-driven suite of programs used to process
GPS data and

is suitable for projects requiring the highest accuracy. A User's
Manual, the software, and

sample data sets can be downloaded from the NGS anonymous ftp server:

ftp: ftp.ngs.noaa.gov

login: anonymous

password: your complete email address

Once logged on, go to the /pub/pnt6 directory and download all the files
using binary

transfer mode. The input1 and results1 directories contain the sample
data sets. Follow the setup instructions in the PAGE-NT User's Manual.

**ADJUST**---The ADJUST and ADJUST UTILITIES software package can be
downloaded from

NGS (http://www.ngs.noaa.gov) by accessing the "PC Software" link. Check

the site for the latest version of each program. The software performs a
least squares

adjustment on horizontal, vertical angle, and/or GPS observations. The
program comprises six

data checking programs in addition to the adjustment software. This
software package has

numerous options, such as choice of ellipsoid, and includes sample input
data. Also available---

is the source code.

**ADJUST Utilities**---Suite of programs that are used in conjunction
with PC program ADJUST. This group of programs includes the following:

> **BBACCUR** provides a formatted listing of the external and internal
> accuracies that have been computed by program ADJUST and sorted in
> numerical ascending order of external accuracy. Output from program
> ADJUST, run with accuracies, is used as input.
>
> **CLUSTER** is used to identify geodetic stations that are common to
> two data sets with respect to name or a given position tolerance.
>
> **ELEVUP** creates a B-file that combines the B-file output from the
> constrained horizontal adjustment with the B-file output from the
> constrained vertical adjustment. This new B-file contains \*80\*
> records with adjusted positions from the horizontal and \*86\* records
> with the ellipsoidal heights from the horizontal adjustment and the
> orthometric heights and GEOID heights from the vertical adjustment.
>
> **ELLACC** computes ellipsoidal height order and class for a project.
> Output from program ADJUST, run with accuracies, is used as input.
>
> **MAKE86** adds \*86\* records to the B-file. If the existing \*80\*
> records contain orthometric heights, these are added to the new \*86\*
> records.
>
> **MODGEE** scales the standard errors assigned to the observations in
> the G-file. Input is a G-file and the scaling factor.
>
> **QQRECORD** adds qq records to the A-file (used by program ADJUST) to
> compute accuracies for all observed lines. Either the G-file (for GPS
> projects) or the B-file (for classical terrestrial projects) can be
> used as input.

**Data Sheet Utilities**---

> **DSDATA** is the Digital Data Sheet extraction program. Extracts
> individual or groups of data from a DSDATA file. Includes options to
> extract by Station Identifier, Station Name, Area, and more.

**Other Software Programs**---Below is a select listing of other
software that is currently accessible online. For the full and most
recent list of NGS programs, visit the NGS PC Software webpage. Online
interactive versions of some of these programs are available from the
NGS PC Software website at
[http://www.ngs.noaa.gov/PC_PROD/pc_prod.shtml]{.underline}.

> **COMPGB** tests the consistency and compatibility of the Blue Book
> B-file (GPS project and station occupation data) and G-file (GPS
> vector data transfer file).

**CR8BB** reformats GPS project information to fit the requirements of
the National Geodetic Survey database. The file created, which is called
the B-file, contains project information, station information, and
survey measurements. The CR8BB software functions independently of the
type of GPS receivers used in a project.

> **CR8SER** extracts data from a GPS Blue Book G-file to create a
> station serial number file (serfil) for GPS observations.
>
> **WINDESC** organizes control point descriptions in accordance with
> NGS's description file (D-file) format.
>
> **DSWIN** is Windows-based software for data sheet viewing and
> extraction. It displays a list of county names as found on your CD.
> Click on a county and a list of stations appears. Click on a station
> from the list and a data sheet appears. You may save the data sheet to
> a file or print it. The search feature allows for filtering the
> station list by Point Radius, Min/Max Box, Station Name, or PID. You
> can also filter by type of control, such as first-order bench marks
> only.
>
> **GEOID03** Computes GEOID height values for the conterminous United
> States, Alaska, Puerto Rico, Virgin Islands, and Hawaii. Suitable for
> conversion of NAD 83 GPS ellipsoidal heights into NAVD 88 orthometric
> heights.
>
> **HTDP** is a horizontal time-dependent positioning software program
> that allows users to predict horizontal displacements and/or
> velocities at locations throughout the United States. This software
> also enables users to update geodetic coordinates and/or observations
> from one date to another.
>
> **INVERSE3D** is the three dimensional version of program INVERSE, and
> is the tool for computing not just the geodetic azimuth and
> ellipsoidal distance, but also the mark-to-mark distance, the
> ellipsoid height difference, the dx, dy, dz (differential X, Y, Z used
> to express GPS vectors), and the dn, de, du (differential north, east,
> up using the FROM station as the origin of the neu coordinate system).
> The program requires geodetic coordinates as input, expressed as
> either (1) latitude and longitude in degrees, minutes, and seconds or
> decimal degrees along with the ellipsoid heights for both stations, or
> (2) rectangular coordinates (X, Y, Z in the Conventional Terrestrial
> Reference System) for each station. The program works exclusively on
> the GRS80 ellipsoid, and the units are meters. Both types of
> coordinates may be used in the same computation. The program reads
> input geodetic positions as positive north and positive west.
>
> **LOOP** determines the loop misclosures of GPS base lines using the
> delta x, delta y, delta z vector components computed from a group of
> observing sessions.

# APPENDIX 8. OUTLINE FOR PROCESSING AIRPORT GEODETIC CONTROL SURVEYS WITH PAGE-NT

# 

# 

#### **Outline for Processing Airport Geodetic Control Surveys**

#### **with PAGE-NT**

1\. Place raw data files (zip format acceptable) in the following
directory:

:\\ProjectName\\RawData\\DOY\\

Project Name is two-letter state ID, plus ANA

DOY = Day of Year of Observation Files

2\. Place RINEX data files, TEQC summary file, and precise orbit files
(.SP3 format) in the

following directory:

:\\ProjectName\\RinexData\\DOY\\

3\. Ensure the latest sitecors.bin, siteigs.bin, and ant_info.\* files
are in the :\\pnt\*\\ directory.

###  {#section-23 .Paragraph}

4\. Create a SERFIL, and place into the following directory:
:\\ProjectName\\serfil\\. Create a GFILE directory
(:\\ProjectName\\gfile\\).

5\. Establish a session processing outline based on the procedures in
paragraph 8.6, of this AC. Create a directory for each processing
session (:\\ProjectName\\DOY\\DOYS\\).

S = Processing session letter

6\. Process each session following the procedures in the PAGE-NT
documentation.

-   Use the latest ITRF coordinates for the Antenna Reference Point
    (ARP) \[or monument if applicable\] of each CORS station.

-   Ensure the proper antenna height (monument to ARP) and model number
    is input in the station information menus.

-   OMIT the PACS station from the triple difference solution for the
    PACS to UNKNOWN sessions, and be sure to enter the proper (derived
    mean) coordinates for the PACS into the station information menu.

-   Use the default meteorological values.

-   Put in the proper session letter for the session (Merge RINEX Files
    screen).

-   Turn off Tropospheric Unknowns for stations if required (Baseline
    Processing Options screen: Off = Fix = Not Highlighted; On = Solve =
    Highlighted in Blue \[default\]).

7\. To run a L1 solution, first run a L3 solution. If the results are
satisfactory, rename the output file "combined.sum" to "combinedL3.sum".
Return to the Baseline Processing Options screen, and select "L1" for
the frequency of solution. Save the change before exiting the menu.
Select

check box 6 (only) under the RUN menu to run another combined solution.
Rename the output

"combined.sum" file "combinedL1.sum".

8\. Review the combined.sum, float.rms, and fixed.rms files for each
session. View plots and other files as necessary to analyze the
processing session.

9\. Create a G-file for each session by running SINEX2G under the
Utilities menu. Ensure the

gfile.inp file is correct before each run. Save the individual G-file
for each session by naming it

DOYSgf and saving it in the gfile directory or processing directory for
the session. Run SINEX2G again, appending the session G-file to the
project G-file by editing the gfile.inp file to save the file in the
:\\ProjectName\\gfile\\ directory with the name "gfile".

10\. Submit a hard copy of the processing scheme and a spreadsheet
showing the positions and X,Y,Z value differences between sessions for
each station. If requested by NGS, also submit hard copies of the
following files (for each session) with the processing report.

-   combined.sum, combinedL3.sum, combinedL1.sum

-   float.rms

-   fixed.rms

11\. Edit the "#/File Types To Delete During Clean Up" section of the
default.txt file to delete only the following files, then run "Clean Up
Output Directory" from the Run menu. Submit all of the remaining data in
the :\\ProjectName\\ directory and subdirectories on CD-ROM or other

pre-approved medium to NGS with the project report.

Files to be DELETED:

-   \*.00

-   \*.dat

-   \*.scn

-   \*.prn

-   \*.out

-   \*.pom

-   \*.new

-   eclipse

-   sum-\*.flt

-   sum-\*.fix

-   \*.sp3

-   \*.99o

-   \*.99n

12\. Place copies of the following files used during vector processing
in the :\\ProjectName\\ directory for submittal:

-   ant_info.\*

-   sitecors.bin

-   siteigs.bin

-   default.txt (template)

-   gfile.inp (template)

This page intentionally left blank.

# APPENDIX 9. EXAMPLE COORDINATE COMPARISON SPREADSHEET

#  

Tennessee ANA Survey 1999

Vector Processing Results

**Paris Henry County Airport (HZD) - Day 244** CORS - mem2

  ------------ ------------- --------------- -------------- ------------ --------- --------
               Observed ITRF                                                       
               Coordinates                                                         

  **PACS - HZD **X**         **Y**           **Z**          **SOLN**     **RMS**   **KM**
  A**                                                                              

  244A         138517.6508   -5157909.9332   3736955.8065   L3X          0.0146    172

  244B         138517.6602   -5157909.9284   3736955.8076   L3PFX        0.0170    

  difference   -0.0094       -0.0048         -0.0011                               

  MEAN         138517.6555   -5157909.9308   3736955.8071                          
  ------------ ------------- --------------- -------------- ------------ --------- --------

SACS1 - FAA HZD A

  ------------ ------------- --------------- -------------- ----------- -------- -----
  244F         138244.3948   -5158611.2409   3735995.7541   L1X         0.0057   1

  244G         138244.3946   -5158611.2392   3735995.7494   L1X         0.0073   

  difference   0.0002        -0.0017         0.0047                              
  ------------ ------------- --------------- -------------- ----------- -------- -----

SACS2 - HZD C

  ------------ ------------- --------------- -------------- ------ -------- --------
  244F         138364.7295   -5158170.6200   3736597.6080   L1X    0.0057   0.5

  244G         138364.7285   -5158170.6243   3736597.6115   L1X    0.0073   

  difference   0.0010        0.0043          -0.0035                        
  ------------ ------------- --------------- -------------- ------ -------- --------

  ------------ ------------- --------------- -------------- ------------ -------- ----
               Adjusted vs.                                                       
               Published NAD                                                      
               83                                                                 

  **HARN-GPS   **X**         **Y**           **Z**                                
  15**                                                                            

  244C obs.    145521.9648   -5141684.5452   3758877.3789   L3X          0.0113   28
  (NAD83)                                                                         

  published.   145521.9690   -5141684.5610   3758877.3980                         
  (NAD83)                                                                         

  difference   -0.0042       0.0158          -0.0191                              
  ------------ ------------- --------------- -------------- ------------ -------- ----

  ------------ ------------- ---------- ---------- ------------ -------- ----
  **BM1 - F    **NAD 83 EHT  **NAVD 88                                   
  181**        (m)**         (m)**                                       

  244D obs.    144.223       172.572               L3X          0.0116   22

  published    N/A           172.628                                     

  difference                 -0.0560                                     
  ------------ ------------- ---------- ---------- ------------ -------- ----

  ------------ --------------- ---------- ---------- ------------ -------- ----
  **BM2 - Y    **NAD 83 EHT    **NAVD 88                                   
  161**        (m)**           (m)**                                       

  244E obs.    94.516          122.698               L3X          0.0129   39

  published    N/A             122.739                                     

  difference                   -0.0410                                     
  ------------ --------------- ---------- ---------- ------------ -------- ----

Comments: 12 minute gap in CORS data from 1318-1330

GPS 15 also observed in session 242A -see sheet2 for vector comparison

Page 2

ITRF Coordinate Comparison for Multiple Occupied Stations

HARN and Bench Marks

ITRF vector comparison for GPS 15-

  ------------ ------------- --------------- -------------- ----------- --------- --------
               Observed ITRF                                                      
               Coordinates                                                        

  **HARN-GPS   **X**         **Y**           **Z**          **SOLN**    **RMS**   **KM**
  15**                                                                            

  244C         145521.3912   -5141683.0467   3758877.2319   L3X         0.0113    28

  242A         145521.3883   -5141683.0334   3758877.2145   L3PFX       0.0152    191

  Difference   0.0029        -0.0133         0.0174                               
  ------------ ------------- --------------- -------------- ----------- --------- --------

ITRF vector comparison for GPS 32-

  ------------ ------------- --------------- -------------- ----------- --------- --------
               Observed ITRF                                                      
               Coordinates                                                        

  **HARN-GPS   **X**         **Y**           **Z**          **SOLN**    **RMS**   **KM**
  32**                                                                            

  254C         90432.9992    -5169962.2991   3721755.0682   L1X         0.0099    13

  265C         90432.9988    -5169962.3238   3721755.0829   L3X         0.0099    50

  266C         90433.0042    -5169962.3131   3721755.0756   L1X         0.0085    17

  Max          0.0054        -0.0247         0.0147                               
  Difference                                                                      
  ------------ ------------- --------------- -------------- ----------- --------- --------

ITRF vector comparison for \...-

This page intentionally left blank.

# APPENDIX 10. PROJECT SUBMISSION CHECKLIST

# 

# 

<table style="width:100%;">
<colgroup>
<col style="width: 4%" />
<col style="width: 13%" />
<col style="width: 7%" />
<col style="width: 3%" />
<col style="width: 16%" />
<col style="width: 13%" />
<col style="width: 1%" />
<col style="width: 5%" />
<col style="width: 6%" />
<col style="width: 1%" />
<col style="width: 5%" />
<col style="width: 9%" />
<col style="width: 11%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="3"><img src="media/image45.jpeg"
style="width:1.50139in;height:1.12986in" /></td>
<td colspan="10"><p>Project Submission Checklist</p>
<p>GPS Projects</p>
<p>FAA Airport Surveying – GIS Program</p></td>
</tr>
<tr class="even">
<td colspan="3">Project Title:</td>
<td colspan="10"></td>
</tr>
<tr class="odd">
<td colspan="3">Accession Number:</td>
<td colspan="10"></td>
</tr>
<tr class="even">
<td colspan="3">Submitting Agency:</td>
<td colspan="10"></td>
</tr>
<tr class="odd">
<td colspan="3">Observing Agency:</td>
<td colspan="10"></td>
</tr>
<tr class="even">
<td colspan="3">Receiver Type:</td>
<td colspan="10"></td>
</tr>
<tr class="odd">
<td colspan="13"><strong>PACKAGE CONTENTS</strong></td>
</tr>
<tr class="even">
<td colspan="13">Project Report and Attachments</td>
</tr>
<tr class="odd">
<td></td>
<td colspan="6">Item</td>
<td></td>
<td colspan="5">Received by NGS</td>
</tr>
<tr class="even">
<td></td>
<td colspan="7"></td>
<td colspan="2">Yes</td>
<td>No</td>
<td>Date</td>
<td>Initials</td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">Project Report</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">Approved Reconnaissance and Project Sketch</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">Final Station List</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">Station Visibility Diagrams</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">Observation Logs</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">Equipment Failure Logs<a href="#fn1"
class="footnote-ref" id="fnref1"
role="doc-noteref"><sup>1</sup></a></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">Loop Misclosures<a href="#fn2" class="footnote-ref"
id="fnref2" role="doc-noteref"><sup>2</sup></a></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">Free Adjustment with Analysis</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">Free Adjustment with Accuracies</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">Constrained Horizontal Adjustment</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">Constrained Vertical Adjustment (NAVD88 Heights)</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">Meteorological Instrument Comparison Logs<a href="#fn3"
class="footnote-ref" id="fnref3"
role="doc-noteref"><sup>3</sup></a></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">Photographs of views from Stations<a href="#fn4"
class="footnote-ref" id="fnref4"
role="doc-noteref"><sup>4</sup></a></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">Photographs or rubbings of Station Marks</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">COMPGB Output (Validation Program – B/G file)</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">OBSDES Output (Validation program – D file)</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">OBSCHK Output (Validation program – D file)</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">CHKDESC Output (Validation program – D file)</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">ELLACC Output</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">BBACCUR Output</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7"></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7"></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7"></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7"></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7"></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td colspan="13"><strong>Digitized Data Files</strong></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="2">Data on diskette</td>
<td></td>
<td colspan="4">Data on other media (specify):</td>
<td colspan="5"></td>
</tr>
<tr class="even">
<td></td>
<td colspan="6">Item</td>
<td></td>
<td colspan="5">Received by NGS</td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7"></td>
<td colspan="2">Yes</td>
<td>No</td>
<td>Date</td>
<td>Initials</td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">Raw Phase Data (R-files)</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">Base Line Vectors (G-file)</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">Project and Station Occupation Data (Final B-file)</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">Descriptions or Recovery Notes (D-file)</td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7">Terrestrial Horizontal Observation (T-file)<a
href="#fn5" class="footnote-ref" id="fnref5"
role="doc-noteref"><sup>5</sup></a></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7">Differential Leveling Observations (L-file)<a
href="#fn6" class="footnote-ref" id="fnref6"
role="doc-noteref"><sup>6</sup></a></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7"></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7"></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="7"></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="7"></td>
<td colspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td colspan="13"><strong>Submitting Agency Identification</strong></td>
</tr>
<tr class="odd">
<td colspan="2" rowspan="2">Complied by</td>
<td colspan="4">Name</td>
<td colspan="5">Section</td>
<td colspan="2">Date</td>
</tr>
<tr class="even">
<td colspan="4"></td>
<td colspan="5"></td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td colspan="2" rowspan="2">Checked by</td>
<td colspan="4">Name</td>
<td colspan="5">Section</td>
<td colspan="2">Date</td>
</tr>
<tr class="even">
<td colspan="4"></td>
<td colspan="5"></td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td colspan="2" rowspan="2">Approved by</td>
<td colspan="4">Name</td>
<td colspan="5">Section</td>
<td colspan="2">Date</td>
</tr>
<tr class="even">
<td colspan="4"></td>
<td colspan="5"></td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td colspan="13"><strong>National Geodetic Survey
Identification</strong></td>
</tr>
<tr class="even">
<td colspan="2" rowspan="2">Received by</td>
<td colspan="3">Name</td>
<td colspan="4">Section</td>
<td colspan="4">Date</td>
</tr>
<tr class="odd">
<td colspan="3"></td>
<td colspan="4"></td>
<td colspan="4"></td>
</tr>
<tr class="even">
<td colspan="2" rowspan="2">Reviewed by</td>
<td colspan="3">Name</td>
<td colspan="4">Section</td>
<td colspan="4">Date</td>
</tr>
<tr class="odd">
<td colspan="3"></td>
<td colspan="4"></td>
<td colspan="4"></td>
</tr>
<tr class="even">
<td colspan="2" rowspan="2">Reviewed by</td>
<td colspan="3">Name</td>
<td colspan="4">Section</td>
<td colspan="4">Date</td>
</tr>
<tr class="odd">
<td colspan="3"></td>
<td colspan="4"></td>
<td colspan="4"></td>
</tr>
</tbody>
</table>
<aside id="footnotes" class="footnotes footnotes-end-of-document"
role="doc-endnotes">
<hr />
<ol>
<li id="fn1"><p>Required only for NGS contracted projects.<a
href="#fnref1" class="footnote-back" role="doc-backlink">↩︎</a></p></li>
<li id="fn2"><p>Submission optional.<a href="#fnref2"
class="footnote-back" role="doc-backlink">↩︎</a></p></li>
<li id="fn3"><p>If specified or requested.<a href="#fnref3"
class="footnote-back" role="doc-backlink">↩︎</a></p></li>
<li id="fn4"><p>If specified or requested.<a href="#fnref4"
class="footnote-back" role="doc-backlink">↩︎</a></p></li>
<li id="fn5"><p>If applicable.<a href="#fnref5" class="footnote-back"
role="doc-backlink">↩︎</a></p></li>
<li id="fn6"><p>If applicable.<a href="#fnref6" class="footnote-back"
role="doc-backlink">↩︎</a></p></li>
</ol>
</aside>

[]{#_Application. .anchor}Please provide additional comments on a
separate sheet attached to this document.

[^1]: Portions of this paragraph apply to concrete collars around rod
    marks as well as to concrete monuments.

[^2]: If a CTCORS is required for connections, substitute CTCORS for
    CORS.

[^3]: ^1^ Required Radio Frequency is MHz and preferred call sign is .

[^4]: List other required Items from line 3 above.