An Analysis of 

Preflight Weather 

Briefings

O. Veronika Prinzo

Civil Aerospace Medical Institute

Federal Aviation Administration

Oklahoma City, OK 73125

Alfred M. Hendrix

Ruby Hendrix

Hendrix & Hendrix

Roswell, NM 88201

February 2007

Final Report

DOT/FAA/AM-07/4

Office of Aerospace Medicine

Washington, DC 20591
NOTICE

This document is disseminated under the sponsorship 

of the U.S. Department of Transportation in the interest 

of information exchange. The United States Government 

assumes no liability for the contents thereof.

___________

This publication and all Office of Aerospace Medicine 

technical reports are available in full-text from the Civil 

Aerospace Medical Institute’s publications Web site: 

www.faa.gov/library/reports/medical/oamtechreports/index.cfm
i

Technical Report Documentation Page 

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. 

DOT/FAA/AM-07/4 

4. Title and Subtitle 5. Report Date 

An Analysis of Preflight Weather Briefings February 2007 

6. Performing Organization Code 

 

7. Author(s) 8. Performing Organization Report No. 

Prinzo OV,1 Hendrix AM,2 Hendrix R2 

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) 

 

11. Contract or Grant No. 

1

FAA Civil Aerospace Medical Institute 

P.O. Box 25082 

Oklahoma City, OK 73125 

2

 Hendrix & Hendrix 

15 Circle Drive 

Roswell, NM 88201 

12. Sponsoring Agency name and Address 13. Type of Report and Period Covered 

Office of Aerospace Medicine 

Federal Aviation Administration 

800 Independence Ave., S.W. 

Washington, DC 20591 14. Sponsoring Agency Code 

15. Supplemental Notes 

Work was accomplished under approved task AM-B-05-HRR-516 

16. Abstract 

Weather is often cited as a factor in general aviation (GA) accidents and mishaps. The type of weather 

information requested from, or provided by, automated flight service station (AFSS) specialists is dependent on 

weather conditions at the time the preflight briefing occurs. However, little is known about how this weather 

information is used by GA pilots. The purpose of this research was to document the types of AFSS weather 

information that GA pilots requested and received and how this information might influence flight planning and 

weather–based decisions. A content analysis was performed on 306 GA pilot telephone conversations with AFSS 

specialists who staffed the preflight position. Twenty-four hours of continuous recordings of one good, typical, 

and bad weather day at an AFSS in the New England, Northwest Mountain, and Southwest Region were 

obtained prior to the Federal Aviation Administration contracting out those services. The data show that more 

calls were made on days of bad weather than on days of good and typical weather within the vicinity serviced by 

the AFSS. Approximately 78% of the pilots requested a preflight briefing (they requested a standard weather 

briefing more often than any other), and about 15% declined a weather briefing when asked by the AFSS 

specialist. Of the pilot-requested preflight weather briefings, specialists relayed the following weather items: 

Weather synopsis, sky conditions (clouds), visibility, and weather conditions at the departure, en route, and 

destination point. When pilots declined preflight weather briefings, as they did in 15.4% of the calls (good 

weather 16.7%, typical weather 5.0%, bad weather 20.6%), AFSS still relayed weather synopsis and sky 

conditions (clouds) in addition to any other weather conditions that might prove to be significant during a flight. 

Whether by asking for additional information or receiving weather information from specialists, 31 pilots 

decided that it was best to change their flight plans (46.9% delayed, 15.6% postponed or cancelled their flights, 

and 15.6% looked for alternate routes and destination points). Surprisingly, 27% of the pilots who were told 

‘VFR Flight Not Recommended’ went ahead and filed a VFR flight plan anyway.

 

17. Key Words 18. Distribution Statement 

 

 

Weather, Preflight Weather Briefing,

Flight Service Station, General Aviation

Document is available to the public through the 

Defense Technical Information Center, Ft. Belvior, VA 

22060; and the National Technical Information 

Service, Springfield, VA 22161 

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price 

Unclassified Unclassified 24 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized 

iii

Abbreviations

As used in this report, the following abbreviations/acronyms 

have the meanings indicated 

Abbreviation Meaning

AFIS -------------Airborne flight information service

AFS---------------Flight Standards Service

AFSS ------------Automated Flight Service Station 

AIRMET -------Airmen’s meteorological information 

ATC -------------Air traffic control 

ATIS -------------Automatic terminal information service

CFR--------------Code of Federal Regulations

DAT -------------Digital audiotape

DVRS------------Digital voice reproducer system

EFAS-------------En route flight advisory service

FAA -------------Federal Aviation Administration 

FAAO -----------FAA Order 

FBO--------------Fixed-base operators

FSS --------------Flight Service Station 

GA ---------------General Aviation

GA-JSC----------General Aviation Joint Steering Committee

IFR --------------Instrument flight rules 

IMC--------------Instrument meteorological conditions

MOA ------------Military operations area 

MTR-------------Military training route

NM --------------Nautical mile 

NOAA ----------National Oceanic and Atmospheric Administration 

NOTAM -------Notice to Airmen 

NTSB------------National Transportation Safety Board

PFB --------------Preflight briefing

PIREP -----------Pilot weather report 

SIGMET -------Significant meteorological information 

SME -------------Subject matter expert

TFR--------------Temporary flight restrictions

USA--------------United States of America 

UTC ------------Coordinated universal time 

VFR -------------Visual flight rules 

WX---------------Weather

1

An Analysis of Preflight Weather Briefings

“... When it is evening, you say, `It will be fair weather; for the sky is red.’ 

And in the morning, `It will be stormy today, for the sky is red and threatening.’....”

—Matthew 16:2-3

Since its inception, the automated flight service station 

has evolved to be the single most widely used general 

aviation (GA) weather-information-provider. The Code 

of Federal Regulations (CFR) 14, Part 91.103 stipulates: 

“Each pilot in command shall, before beginning a flight, 

become familiar with all available information concerning that flight. This information must include- (a) For 

a flight under IFR or a flight not in the vicinity of an 

airport, weather reports and forecasts, ...” Unlike the 

14 CFR for Part 121 (domestic, flag, and supplemental) 

and Part 135 (commuter and on demand) operators, the 

regulations for Part 91 (general aviation) operators do 

not stipulate that GA pilots must contact a particular approved source for weather information. They can acquire 

any weather information in real-time from a multitude 

of sources that include television, radio, Internet, and 

AFSS or by simply going outside and looking at the 

sky conditions.1

In preparation for a flight, GA pilots can call their 

local AFSS to receive standard, abbreviated, and outlook 

preflight briefings. AFSS specialists provide them with 

local, en route, and destination weather information to 

aid route planning and go/no go decision-making when 

faced with possible adverse weather. Generally, the first 

contact by a GA pilot is with the Preflight position, where 

either a visual flight rules (VFR) or instrument flight rules 

(IFR) flight plan is filed and requests are made for any 

specific information. The Preflight position then would 

relay a briefing of items outlined in FAAO 7110.10R 

Flight Services § 3-2-1 through § 3-2-3 (Federal Aviation 

Administration, 2004). 

After departure, a GA pilot flying a VFR aircraft could 

use airborne flight information service (AFIS), but would 

normally contact the AFSS Inflight/Flight Watch position 

for additional weather information. The pilot of an IFR 

aircraft may also contact an AFSS Inflight specialist, use 

AFIS to receive weather information, or speak directly 

with an ATC specialist at a Terminal Radar Approach 

Control or En route Air Traffic Control facility. 

1

 For a record of the source of weather information to be available, 

pilots must contact an AFSS, use DUATs, or use a commercial 

weather service provider.

2

AFIS included any automated weather reports other than an AFSS 

or any other air traffic control facility. It included airborne systems, 

DUATS, etc.

Although the focus of this report is on the preflight 

weather briefings, the availability of weather information during actual flights is worthy of a separate study. 

In particular, accident data show that the number of 

in-flight contacts with AFSS, even by pilots ultimately 

involved in fatal weather accidents, averages 3% of the 

accident flights (Lenz 2006)3. According to Lenz it is this 

tactical information that is vital to pilots for avoiding 

weather hazard areas during IFR and VFR flights. Given 

the rapid and immediate access to, and availability of, 

weather information, it is surprising that weather still is 

listed as a causal or contributing factor in 30% to 35% 

of aviation accidents and incidents (Pearson, 2002). For 

a comprehensive review and summary of the NTSB 

accident reports involving fixed-wing general aviation 

aircraft weighing 12,500 pounds or less see the Nall Report (Aircraft Owners and Pilots Association Fight Safety 

Foundation 2005).

The Federal Aviation Administration (FAA) Flight 

Standards Service (AFS) General Aviation and Commercial Division’s mission has initiated numerous GA 

safety programs in response to recommendations made by 

the National Transportation Safety Board (NTSB, 1968, 

1974, 1976, 1989, 2005) regarding weather and pilot 

decision-making. The FAA-Industry General Aviation 

Joint Steering Committee (GA-JSC) has focused heavily 

on ways to mitigate accidents involving weather and pilot 

decision-making. FAA-sponsored research activities are attempting to identify the factors that give rise to GA pilots 

flying into instrument meteorological conditions.

For example, Driskill, Weissmuller, Quebe, Hand, Dittmar, and Hunter (1997) conducted a study to examine 

how pilots evaluate weather and terrain information in 

preparation of a flight. They had 150 pilots (age: 18-79 

yrs) (flight time: 6-26,500 hrs) read three sets of 27 different weather scenarios, sort them from least to most 

comfortable about completing the flight, and assign a 

comfort rating to each one. Each scenario within a set 

was unique with respect to precipitation (light rain, 

moderate rain, heavy snow), visibility (1 NM, 4 NM, 8 

NM), and ceiling (800 ft, 1800 ft, 4000 ft) and, when 

3

 All references to Lenz are from personal communication with him in 

June 2006. Michael Lenz was with the FAA’s Office of System Safety 

and is currently with the FAA’s General Aviation and Commercial 

Division.
2

combined, they were plausible according to evaluations 

performed by weather experts. The weather scenarios 

were representative of three cross-country flights that 

varied in terrain (water: Great Lakes, non-mountainous: 

North Texas, mountainous: New Mexico). The major 

finding was that pilots consistently used the available 

weather information to determine the safety risk associated 

with VFR flights for all weather and terrain conditions. 

However, pilots differed in their degree of comfort with 

the presented weather scenarios when faced with flying 

over different terrains. Driskill et al. suggested that pilots 

might differentially weigh weather information according 

to terrain such that higher values (e.g., high visibility) 

compensated for lower values in others (e.g., low ceiling) for non-mountainous terrains but not for flights 

that involved mountainous terrains (they might use an 

absolute value for the decision point).

More recently, Knecht, Harris, and Shappell (2005) 

performed a simulation study that also examined weatherrelated pilot decision-making. In their study, pilots were 

provided with a hypothetical situation in which they were 

to transport a piece of equipment from an uncontrolled 

airfield near Oklahoma City, OK, to an oilfield near 

Amarillo, TX. The equipment was crucial to bring oil 

production back on-line. The low-incentive pilots were 

told that they were paid on a per-hour basis and would 

be paid regardless of their fly/no fly decision. Pilots in the 

high-incentive group received a sizeable bonus for immediate takeoff that decreased incrementally with every 

30-min delay. In preparation for the VFR flight, all pilots 

received the same current weather report that included 

marginal visibility (1 sm, 3 sm, 5 sm) and cloud ceiling 

(1000 ft, 2000 ft). After receiving the weather report, they 

had to decide whether to fly, wait and try later, or cancel 

the flight. Those pilots choosing to wait received updated 

weather reports every 30 min until they either flew or 

two hours elapsed at which time the experiment ended 

(the weather never improved beyond marginal visibility). 

Like the findings reported by Driskell et al., the results 

of Knecht et al. suggested that pilots consider both the 

visibility and cloud ceiling(s) when deciding whether or 

not to fly. It may be that their value judgments became 

compromised when presented with external pressures 

such as a financial bonus (as evidenced with a tendency 

toward longer decision times when compared with pilots 

who were not offered a bonus). Since the vast majority 

of weather-related, fatal accidents occur on cross-country 

flights, these pressures are always present on actual flights 

(Lenz 2006).

Although informative, neither study included dynamic 

communication opportunities between the pilots and 

AFSS personnel (or access to other sources of weather 

information). Inasmuch as the most recent NTSB safety 

study (2005) reported that in 66% of the fatal and 58% of 

the non-fatal accidents, pilots received preflight weather 

information from an AFSS before their flights, it did 

not report on the quality of the information that these 

pilots received. Consequently, little is known about the 

information obtained from the AFSS and its influence 

on pilot decision-making during preflight preparations. 

While the types of services that AFSS provide are listed 

in the FAA publication FAAO 7110.10R Flight Services, 

data are not available as to either the frequency that these 

services are provided to pilots or the types of weather 

information pilots receive that might help mitigate GA 

fatal accidents related to weather or visibility. This is 

worthy of further study as related to accidents.

This study examined the communications that took 

place between the AFSS specialists staffing the Preflight 

position and pilots who called in on the telephone. The 

data were used to develop baseline descriptive statistics 

to describe the frequency of occurrence and content of 

preflight briefings with a special emphasis on documenting 

the types of weather information that pilots request and 

might use when planning a flight or making weather-based 

decisions. Specifically, we conducted a verbal content 

analysis on time-stamped digital audiotape (DAT) recordings that were obtained from FAA-operated AFSSs in 

the New England, Northwest Mountain, and Southwest 

Regions. In particular, preflight standard, abbreviated, and 

outlook weather briefings were examined that represented 

a good, typical, and bad weather day occurring around 

the area serviced by each of the three AFSS.

METHOD

Materials

Audiotapes. One AFSS in the New England, Northwest Mountain, and Southwest Region was contacted and 

asked to provide 24 hours of continuous DAT recordings 

that best represented a good, typical, and bad weather 

day at and around their facility. Each DAT contained 

separate voice records of all communication transmitted 

on the radio frequency assigned to a particular sector 

position on the left channel. The right channel contained 

the Coordinated Universal Time (UTC) time code. The 

NiceLoggerTM Digital Voice Reproducer System (DVRS) 

decoded, displayed, and correlated time with the voice 

stream in real time. Presented in Table 1 are the dates 

and times of those recordings.

AFSS Communication Spreadsheet. Five areas of 

information were identified and recorded: Facility Information included briefing number, the name of the 

facility, sector/position identifier, an assigned AFSS specialist identifier, DAT time sample, the onset of preflight 

briefing in UTC (hr:min:sec), proposed departure time, 
3

Table 1. AFSS sampled according to date and time (Local and UTC) 

FAA Region / Weather Date and Local Time Date and UTC (Zulu Time) 

New England 

Good 06/02/05 0000 to 06/02/05 2359 06/02/05 0400 to 06/03/05 0359 

Typical 06/17/05 0000 to 06/17/05 2359 06/17/05 0400 to 06/18/05 0359 

Bad 06/16/05 0000 to 06/16/05 2359 06/16/05 0400 to 06/17/05 0359 

Northwest Mountain 

Good 05/27/05 0500 to 05/29/05 0500L 05/27/05 1200 to 05/29/05 1200Z 

Typical 05/29/05 0500 to 05/31/05 0500L 05/29/05 1200 to 05/31/05 1200Z 

Bad 05/31/05 0500 to 06/02/05 0500L 05/31/05 1200 to 06/02/05 1200Z 

Southwest

Good 06/12/05 0000 to 06/12/05 2359L 06/12/05 0500 to 06/13/05 0459Z 

Typical 06/11/05 0000 to 06/11/05 2359L 06/11/05 0500 to 06/12/05 0459Z 

Bad 06/10/05 0000 to 06/10/05 2359L 06/10/05 0500 to 06/11/05 0459Z 

Figure 1. An example of a completed form containing 

pilot and AFSS specialist communications 
4

and weather. Aircraft Information contained the call 

sign, type of aircraft, and any weather-related avionics 

equipment aboard4. Flight Information recorded whether 

the pilot filed a flight plan, the type flight plan, whether 

it was a day or night flight, the purpose of the flight, and 

the method of communication with the AFSS. Pilot 

Requests/Reportsinvolved whether the pilot requested a 

preflight briefing, the type preflight briefing, the specific 

weather, NOTAMs, TFRs, special airspace activity, other 

weather information, and whether the preflight briefing 

altered the pilot’s intention to fly. AFSS Preflight Information provided for the encoding of type of briefing, 

specific weather, NOTAMs, TFRs, special use airspace, 

other information related to the safety of the flight, and 

whether VFR flight was not recommended. Presented 

in Appendix A is a description of the Excel spreadsheet 

that was developed to record/encode this data. It allows 

for the inclusion of communications between the pilot 

and Inflight and Flight Watch positions. 

Subject Matter Expert (SME)

The SME (a co-author of this report) was an instrument-rated pilot and former air traffic controller who 

had worked as an FAA Academy instructor for 8 years 

and had worked for 12 years in FAA supervision and 

management. This individual had previously encoded 

over 50,000 ATC messages, suggesting that he was highly 

familiar and expert in the extraction and codification of 

verbal messages.

Procedure

The SME was provided with, and trained on, one 

DVRS and received the most recent version of FAAO 

7110.10R Flight Services. It guided the development of 

the AFSS communication spreadsheet. The SME also 

was instructed on whom to contact at each AFSS facility, 

should additional information be needed (e.g., call-sign 

identifiers, routes).

4This information was provided by the pilots when talking with the 

AFSS specialist.

The SME listened to a voice sample stored on the DVRS 

and developed a form to record the types of information 

exchanged between pilots and AFSS specialist. While 

listening a second time, the SME recorded the contents 

of each transmission onto the data entry form such as 

the one displayed in Figure 1.

During a third pass, the accuracy of the encodings was 

evaluated, and if correct, left alone. In some instances 

additional information was added while, in others, values 

were corrected to reflect what was spoken. These data 

were entered onto the EXCEL spreadsheets and verified 

by the SME and data entry clerk. If, during error checking, a discrepancy was found, they went to the DVRS 

and listened yet again to the time sample that correlated 

with the message and data point in question.

The EXCEL spreadsheets were imported into SPSSx 

and combined to create a master database. The data were 

once again subjected to error checking, and only three 

data points were corrected.

RESULTS

As shown in Table 2, the recordings represented 306 

calls made on good, typical, and poor weather days occurring in the New England, Southwest, and Northwest 

Mountain Regions.5 Each cell in the table represents the 

number of calls according to the aircraft call sign (not in 

parentheses) made to the AFSS on a particular day and 

total number of calls (in parentheses). Not surprisingly, 

more unique calls were made on days with bad weather 

than on good and typical weather days, χ2(2) = 16.03, 

p ≤ .05 and the geographical location of the FAA AFSS 

did not matter, χ2(2) = 0.13.

The SME listened to the tapes and documented 

whether the pilot requested (239) or declined (47) a 

preflight briefing (PFB). He also recorded the types of 

5 To meet the assumptions of the Chi-Square test, 10 pilots made 

more than one call to an AFSS. Their calls were not included in the 

statistical analysis, thereby reducing the number of unique calls to 

286.

Table 2. Number of calls made to each AFSS according to weather 

FAA Region 

Weather New England Northwest 

Mountain

Southwest Total 

Good 28 (30) 30 (30) 25 (30) 083 (90) 

Typical 29 (30) 18 (20) 29 (30) 076 (80) 

Bad 41 (46) 45 (45) 41 (45) 127 (136) 

Total 98 (106) 93 (95) 95 (105) 286 (306) 
5

weather information requested by pilots or provided by 

the AFSS specialists.

The pilots generally fell into three basic groups. 1) 

Local fliers; training schools, students, aircraft buffs, 

and “hole borers” that stay within 30-50 miles of the 

departure point and return to that airport. This group 

made up a large part of the VFR briefings. 2) Fixed-base 

operators (FBOs) who rent aircraft and transport passengers for hire, advanced training, and short distance 

carriers (with stored or pre-filed flight plans), and pilots of 

larger aircraft. There appeared to be approximately 60% 

VFR and 40% IFR pilots. 3) Business, military (training 

and operations), corporate, and long-distance lifeguard 

pilots who probably will be looking at Internet aviation 

weather services while discussing the preflight briefing 

with the AFSS specialist.

As shown in Table 3, an examination of the type of 

flight plan filed revealed that the VFR pilots requested 

standard weather briefings more often than either abbreviated, outlook, or no briefings χ2

(3) = 68.17, p ≤

.05. On the other hand, IFR pilots seemed to request 

standard and abbreviated briefings to a greater extent than 

outlook briefings and no weather briefings more often 

than outlook briefings χ2(3) = 21.80, p ≤ .05.

The data presented in Tables 4-5 show that, regardless 

of weather conditions, of the pilot-requested preflight 

weather briefings, AFSS specialists relayed the following 

weather items: Weather synopsis, sky conditions (clouds), 

visibility, weather conditions at the departure, en route, 

and destination point. More detailed weather data were 

passed during periods of adverse weather. Although used 

to a lesser degree, these data included adverse conditions, 

altimeter, cloud tops, dew point, icing conditions, surface 

winds, winds aloft, temperature, thunderstorm activity, 

precipitation, precipitation intensity, visibility obscuration, other weather, PIREP, AIRMET/SIGMET, MOA, 

MTR, NOTAMs, and TFRs (see abbreviations). 

When pilots requested preflight briefings on a good 

weather day, AFSS specialists relayed weather synopsis, 

sky conditions, visibility, as well as the weather conditions 

at the departure point, en route weather conditions, and 

weather at the destination approximately 75%- 85% of 

the time with surface winds included 73.3%. During these 

briefings, pilots tended to request sky conditions, winds 

aloft, and NOTAMs to a greater extent than to request 

the weather at the destination point or en route. They 

were even less likely to request visibility, surface winds, 

or upper level winds. Pilots never requested precipitation 

intensity, icing conditions, altimeter, or TFRs.

On a typical weather day, as part of a requested preflight 

briefing, AFSS specialists relayed sky conditions, provided 

a weather synopsis, as well as relayed the weather conditions at the departure, en route, and destination points 

between 86.8% to more than 93% of the time. To a lesser 

extent (76.3%-51.3%), they also provided surface winds, 

visibility, adverse conditions, thunderstorm activity, and 

NOTAMs. Pilots, in turn, asked about the en route 

weather, sky conditions, and weather at the destination 

point, followed by requests for TFRs, weather conditions at the departure point, and NOTAMs. They never 

requested visibility obscuration, temperature, dew point, 

precipitation intensity, or altimeter information. 

Finally, on bad weather days, as part of a requested preflight briefing, AFSS specialists relayed the sky conditions, 

provided a weather synopsis, relayed adverse conditions, 

provided weather information at the departure, en route, 

and destination points, and surface winds during 80.6% 

- 89.9% of the briefings. At least 50% of these briefings 

also included visibility, AIRMET/SIGMET, precipitation, 

and winds aloft information. Pilots, in turn, requested 

the weather at their destination point, followed by en 

route conditions, weather at the departure point, and 

winds aloft. They never asked about ATC delays, visibility 

obscuration, the temperature, or dew point.

When pilots declined preflight weather briefings, as 

they did in 15.4% of the calls (good weather 16.7%, typical weather 5.0%, bad weather 20.6%), AFSS specialists 

still relayed weather synopsis and sky conditions (clouds), 

in addition to any other weather conditions that might 

prove to be significant during a flight. During these briefings, on good weather days some pilots asked about the 

weather at their destination points, TFRs, thunderstorm 

activity, and en route weather conditions. On typical 

weather days, conversations included weather conditions 

at the point of departure, en route, and at the destination, in addition to winds aloft, thunderstorm activity 

Table 3. Type of preflight weather briefing requested according to the type of flight plan filed 

Type of Preflight Weather Briefing Requested 

Flight Plan Standard Abbreviated Outlook None Total 

VFR 072 63 22 09 166 

IFR 039 35 08 38 120 

Total 111 98 30 47 286 
6

Table 4. Percentage of pilot-requested/reported weather information as a function of whether a preflight 

weather briefing was or was not requested by the pilot

Type of Weather Day for AFSS 

Type of Pilot- Good Typical Bad 

Requested/Reported 

Weather Information 

PFB

Requested1

PFB Not

Requested

PFB

Requested

PFB Not

Requested

PFB

Requested

PFB Not

Requested

Did pilot report having 

AFIS2 25.3% 13.3% 17.1% 00.0% 26.9% 25.0%

Did pilot request destination 

WX

18.7% 06.7% 23.7% 25.0% 27.8% 00.0%

Did pilot request TFRs 02.7% 06.7% 19.7% 00.0% 10.2% 10.7% 

Did pilot request 

thunderstorm activity 

01.3% 06.7% 01.3% 00.0% 03.7% 03.6%

Did pilot request winds aloft 24.0% 00.0% 10.5% 25.0% 14.8% 03.6%

Did pilot request en route 

WX conditions 

14.7% 00.0% 26.3% 25.0% 23.1% 00.0%

Did pilot request WX 

conditions at departure point 

13.3% 00.0% 15.8% 25.0% 21.3% 00.0%

Did pilot request other WX 00.0% 00.0% 07.9% 25.0% 12.0% 00.0%

Did pilot report 

thunderstorm activity 

08.0% 00.0% 14.5% 25.0% 09.3% 00.0%

Did pilot request NOTAMs 20.0% 00.0% 14.5% 00.0% 13.0% 07.1%

Did pilot request 

AIRMET/SIGMET 

04.0% 00.0% 03.9% 00.0% 11.1% 03.6%

Did pilot request PIREP 04.0% 00.0% 01.3% 00.0% 00.9% 03.6%

Did pilot request cloud tops 01.3% 00.0% 06.6% 00.0% 05.6% 03.6%

Did pilot request ATC 

delays or flow control 

advisories

00.0% 00.0% 02.6% 00.0% 00.0% 03.6%

Did pilot request icing 

conditions

00.0% 00.0% 01.3% 00.0% 03.7% 03.6%

Did pilot request sky 

conditions (clouds) 

25.3% 00.0% 25.0% 00.0% 12.0% 00.0%

Did pilot request visibility 12.0% 00.0% 10.5% 00.0% 02.8% 00.0%

Did pilot request surface 

winds

09.3% 00.0% 06.6% 00.0% 12.0% 00.0%

Did pilot request MOA or 

MTR

04.0% 00.0% 01.3% 00.0% 00.9% 00.0%

Did pilot request 

precipitation 

02.7% 00.0% 07.9% 00.0% 04.6% 00.0%

Did pilot request visibility 

obscuration

01.3% 00.0% 00.0% 00.0% 00.0% 00.0%

Did pilot request 

temperature 

01.3% 00.0% 00.0% 00.0% 00.0% 00.0%

Did pilot request dew point 01.3% 00.0% 00.0% 00.0% 00.0% 00.0%

Did pilot request 

precipitation intensity 

00.0% 00.0% 00.0% 00.0% 01.9% 00.0%

Did pilot request altimeter 00.0% 00.0% 00.0% 00.0% 00.9% 00.0%

1 The number of pilot preflight briefing (PFB) is: Good WX Requested = 75, Good WX Not Requested = 15; 

Typical WX Requested = 76, Typical WX Not Requested = 4; 

Bad WX Requested = 108, Bad WX Not Requested = 28. 

2

 AFIS is a data link aircraft flight information service that offers graphical and text weather data to pilots. 
7

Table 5. Percentage of AFSS-relayed/reported weather information as a function of whether a preflight 

weather briefing was or was not requested by the pilot

Type of Weather Day for AFSS 

Type of AFSS Good Typical Bad 

Relayed/Requested 

Weather Information 

PFB

Requested

PFB Not 

Request

PFB

Requested

PFB Not 

Requested

PFB

Requested

PFB Not 

Request

Did AFSS relay WX synopsis 86.7% 006.7% 92.1% 50.0% 88.0% 03.6%

Did AFSS relay sky 

conditions (clouds) 

85.3% 006.7% 93.4% 25.0% 88.9% 03.6%

Did AFSS relay visibility 81.3% 000.0% 73.7% 25.0% 71.3% 03.6%

Did AFSS relay destination 

WX

78.7% 006.7% 92.1% 00.0% 87.0% 03.6%

Did AFSS relay en route WX 

conditions

78.7% 000.0% 89.5% 25.0% 87.0% 03.6%

Did AFSS relay WX 

conditions at departure point 

74.7% 006.7% 86.8% 00.0% 83.3% 03.6%

Did AFSS relay surface 

winds

73.3% 000.0% 76.3% 25.0% 80.6% 03.6%

Did AFSS relay adverse 

conditions

69.3% 000.0% 68.4% 25.0% 88.0% 21.4% 

Did AFSS relay NOTAMs 62.7% 000.0% 51.3% 00.0% 49.1% 14.3% 

Did AFSS relay winds aloft 54.7% 000.0% 42.1% 00.0% 51.9% 03.6%

Did AFSS relay 

AIRMET/SIGMET 

41.3% 006.7% 31.6% 25.0% 61.1% 21.4% 

Did AFSS relay temperature 36.0% 000.0% 17.1% 00.0% 40.7% 00.0%

Did AFSS relay thunderstorm 

activity 

29.3% 000.0% 52.6% 50.0% 47.2% 07.1%

Did AFSS relay precipitation 26.7% 006.7% 38.2% 25.0% 54.6% 03.6%

Did AFSS relay altimeter 25.3% 000.0% 07.9% 00.0% 11.1% 00.0%

Did AFSS relay cloud tops 22.7% 000.0% 38.2% 25.0% 25.0% 03.6%

Did AFSS relay visibility 

obscuration

16.0% 000.0% 15.8% 00.0% 13.0% 00.0%

Did AFSS relay TFRs 16.0% 006.7% 47.4% 00.0% 29.6% 17.9% 

Did AFSS relay other WX 09.3% 000.0% 18.4% 25.0% 43.5% 21.4% 

Did AFSS relay PIREP 08.0% 000.0% 22.4% 00.0% 33.3% 03.6%

Did AFSS relay precipitation 

intensity 

08.0% 006.7% 10.5% 25.0% 33.3% 03.6%

Did AFSS relay dew point 05.3% 000.0% 10.5% 00.0% 20.4% 00.0%

Did AFSS relay MOA or 

MTR

05.3% 000.0% 02.6% 00.0% 03.7% 00.0%

Did AFSS relay icing 

conditions

01.3% 000.0% 01.3% 00.0% 25.9% 17.9% 

Did AFSS relay ATC delays 

or flow control advisories 

01.3% 000.0% 00.0% 00.0% 2.8% 03.6%

Did AFSS advise EFAS 

available 

08.0% 020.0% 22.4% 50.0% 15.7% 17.9%

Did AFSS advise current 

AFIS

20.0% 013.3% 15.8% 00.0% 21.3% 14.3%

Did AFSS request PIREP 54.7% 053.3% 36.8% 25.0% 39.8% 21.4%

Did AFSS state VFR flight 

not recommended 

10.7% 000.0% 06.6% 00.0% 10.2% 00.0%

Did pilot change flight plan 00.0% 000.0% 14.5% 00.0% 15.7% 00.0%

Did pilot change altitude 21.3% 000.0% 01.3% 00.0% 00.0% 00.0%
8

and other weather information. On bad weather days, 

their conversations included TFRs, NOTAMs, winds 

aloft, and to a much lesser extent, thunderstorm activity, AIRMETs/SIGMETs, cloud tops, icing conditions, 

PIREPs, and ATC delays/flow control advisories.

A final analysis was performed to determine what effect 

receiving a preflight briefing had on the pilots’ intentions 

to fly. The data presented in Table 6 show that 31 GA 

pilots changed their flight plans after talking with AFSS 

specialists. Whether by asking for additional information 

or receiving weather information from AFSS specialists, 

the pilots decided that it was best to change their flight 

plans. Some delayed (46.9%), postponed, or cancelled 

(15.6%) their flights while others looked for alternate 

routes and destination points (15.6%). This result shows 

that about 10% of the time, AFSS information positively 

affected the decision-making process, influenced pilot 

actions, and in these cases may have helped them avoid 

weather-related flight incidents.

Upon further investigation, for 22 of the filed flight 

plans, the AFSS specialist advised the pilot that a VFR 

flight was not recommended. Approximately 86% of these 

recommendations went to pilots who had filed VFR flight 

plans. Among this group of pilots, all but 27% changed 

their flight plan. For pilots who filed IFR flight plans, 

all but 9% decided to change their flight plans. Of the 

pilots who changed their IFR flight plans, there was not 

enough information to record their outcomes/determine 

their future plans.

DISCUSSION

We all know that weather is often cited as a factor in 

aviation accidents and mishaps. Given that weather is 

a prominent force, it is not surprising that the type of 

weather information requested from, or provided by, 

AFSS specialists is dependent on weather conditions at 

the time the preflight briefing occurs. We expect AFSS 

specialists to provide more weather information during 

periods of adverse weather. Likewise, we would not expect an AFSS specialist to provide thunderstorm activity 

to a GA pilot when there was no thunderstorm activity 

forecast anywhere in, or around, the vicinity of where 

the flight was to take place. 

The purpose of the voice tape analysis was to document 

the types of weather information that pilots requested 

and how they might use that information. In particular, 

preflight standard, abbreviated, and outlook weather 

briefings representing a good, typical, and bad weather 

day occurring around the area serviced by an AFSS in 

the Midwest Mountain, Southwest, and New England 

Regions were obtained and reviewed. Of primary interest 

was the weather information relayed by AFSS specialists 

to the pilot and the pilot’s comprehension and use of this 

information. Of lesser interest, but still important, was 

information concerning special use airspace (military 

training areas, MTRs; military operations areas MOAs; 

and temporary flight restrictions, TFRs).

We noted some differences among the facilities and 

AFSS specialists. In particular, the facilities differed in 

type of weather (based on their geographical location), 

special use airspace, terrain, requests for AFIS, requests 

for PIREPs, and their familiarity with the local flying 

public. The specialists differed mostly in the order in 

which they delivered weather items — although all of 

them seemed to follow closely the briefing guide presented 

in FAAO 7110.10R Flight Services. They also differed in 

their requests for PIREPs, suggestions to use EFAS (Flight 

Watch), the amount of verbiage spent to relay the briefing, 

and the amount of verbiage received from pilots. 

Some of the pilots declined a weather briefing. They 

did not specify their reasons to the AFSS specialists. We 

Table 6. Outcome of AFSS specialist preflight weather briefing on pilot flight plan decision making* 

Type of Weather 

Outcome Good Typical Bad Total 

Pilot changed the flight plan 

VFR Filed Flight Plan (2.01%) 05 (3.51%)08 (2.89%) 11 024

IFR Filed Flight Plan (0.40%) 01 (0.44%) 01 (1.31%) 05 007

Pilot did not change the flight plan 

VFR Filed Flight Plan (20.08%) 50 (18.42%) 42 (13.12%) 50 142 

IFR Filed Flight Plan (10.84%) 27 (10.96%) 25 (16.01%) 61 113 

Total 83 76 127 286 

*Normalized percentages are presented in parentheses, number of unique briefings 
9

can speculate that with the currently available technology 

(e.g., Internet aviation weather services and DUATS) 

these pilots felt they could adequately self-brief themselves on the weather. Even among the pilots who did 

not request a briefing, once they started talking with 

the AFSS specialists, they asked questions — they were 

searching for additional information that would lead to a 

safer and more satisfying flight experience. For example, 

marginal VFR conditions with sky conditions at 1500 

broken overcast, visibility 3 miles, light rain showers in 

the area, may have challenged the pilot’s skills; while 2500 

broken overcast, visibility 5+ miles, may have been within 

his or her comfort zone. (The former information may 

have led some pilots to decide not to fly, while the latter 

did not.) During typical weather conditions, pilots who 

did not request a preflight briefing still asked the AFSS 

specialist about the weather conditions at their departure 

point (25%), en route (25%), and at the destination point 

(25%). On marginal VFR days, they also asked about 

any TFRs, NOTAMs, AIRMETs/SIGMETs, and PIREPs 

as well as thunderstorm activity, winds aloft, cloud tops, 

ATC delays, and flow control advisories.

Notably, after hearing a preflight briefing many of the 

pilots made a determination as to whether to continue, 

delay or otherwise postpone, or cancel their intended 

flights. Sometimes the weather at the local AFSS was 

good but the weather conditions either en route or at the 

destination point were problematic. Delaying a departure 

could result in the pilot missing the weather. For others, a 

change in either the route or arrival airport, or changing 

from a VFR to an IFR flight plan allowed some of them to 

continue with their plans. Most important, the majority 

of the pilots who listened to the preflight briefing based 

their decisions on the best available information.

Always of concern were the few pilots who ignored 

the AFSS advice that “VFR Flight Not Recommended.6” 

The AFSS specialists issued this recommendation based 

on the observed or forecast conditions provided to them 

by the National Weather Service. In spite of having 

6

 7110.10R § 3−2−1-b-2. VFR Flight Not Recommended (VNR). 

Include this statement when VFR flight is proposed and sky conditions 

or visibilities are present or forecast, surface or aloft, that in your 

judgment would make flight under visual flight rules doubtful. 

Describe the conditions, affected locations, and times. EXAMPLE 

− ‘‘There are broken clouds along the entire route between niner 

and one one thousand feet at the present time. With the approach 

of a cold front, these clouds are forecast to become overcast and to 

lower to below seven thousand with mountains and passes becoming 

obscured. V−F−R flight is not recommended between Salt Lake City 

and Grand Junction after two two zero zero ZULU.” ‘‘V−F−R flight 

is not recommended in the Seattle area until early afternoon. The 

current weather at Seattle is indefinite ceiling three hundred sky 

obscured, visibility one, mist, and little improvement is expected 

before one eight zero zero ZULU.” NOTE − This recommendation 

is advisory in nature. The decision as to whether the flight can be 

conducted safely rests solely with the pilot.

received a preflight weather briefing, the AFSS specialists’ 

recommendation that VFR flight not recommended, and 

possibly other real-time, readily available weather sources 

and information, these pilots chose not to listen. They 

were aware of the risks yet made the deliberate decision 

to fly anyway. We do not know why.7

There have certainly been times when VFR pilots flew 

successfully into IFR conditions that raised their levels of 

confidence, allowing them to take on increasingly more 

challenging weather conditions (Goh and Wiegmann, 

2001). In fact, Goh, Wiegmann, and O’Hara (2002) 

reported that in their simulation study, pilots' previous 

flight experience affected their situational assessment 

and risk perception. In a follow-on simulation study 

Goh, Weigmann, and O’Hare (2002) found that in 

some instances experience aided in diagnosing weather 

conditions — more experienced pilots may be more likely 

to divert from flight into adverse weather. In other cases 

experience altered pilots’ perceptions as to their abilities 

— that is, it increased pilot confidence. Consequently, 

it reduced perceived risk and promoted VFR flight into 

IMC. What is missing are data to determine how often 

this actually happens and oversight to break this type of 

accident chain. 

What we do know is that most aviation fatalities 

and mishaps are preventable in light of the information 

provided by the AFSS. The accident reports indicate 

that flight in IMC conditions by VFR-only pilots, or 

instrument rated pilots not on IFR flight plans, poses 

a significant threat of loss of aircraft control, controlled 

flight into terrain and presents a hazard to other IFR 

aircraft that may be authorized to be in the vicinity 

(AOPA 2005). The conclusions drawn from the analysis 

of fatal weather accidents and events related to weather 

encounters indicates that timely dissemination of adverse 

weather information is a key factor to preventing weather 

encounters (Lenz, personal communication). 

The following recommendations are suggested to all 

general aviation pilots:

7

 Personal communication with Doug Pearson led him to provide 

the following insights that were derived from reviewing six years of 

NTSB accident data. He suggested that pilots who fly after being 

told “VFR Flight Not Recommended” by AFSS specialists may do 

so for the following reasons: 1) They were in a hurry, had urgent 

business to attend to or an appointment that they could not miss 

and pressed on despite IFR conditions. 2) They were experienced 

pilots and had flown through IFR conditions many times before 

and been able to fly successfully... thus slowly building up a level of 

confidence that allowed them to take on increasingly worse weather 

conditions. 3) They had flown many times before when the forecast 

was for IFR (weather forecasts are often slanted towards the worst 

possible conditions to ensure all aspects of the situation are covered 

from the aviation weather forecaster’s perspective) and they neither 

experienced IFR conditions nor were weather conditions as bad as 

previously forecast. So they pressed on even when IFR was forecast, 

believing that the weather would not be as bad as predicted.
10

1) When calling into an AFSS, let the specialist know if 

you are new to the area or unfamiliar with the typical weather patterns. The specialist’s familiarity with 

the local flying public and area specifics provides you 

with the added benefit of receiving information not 

available elsewhere. 

2) During the preflight weather briefing, pay particular 

attention to differences in weather conditions at the 

departure point, en route, and destination. Although 

you may know what it is like to fly in your home town, 

your experience with weather in different localities may 

prove to be beyond your skill or comfort level.

3) While receiving a preflight weather briefing, let the 

specialist know if you need additional information, 

more detailed information or need clarification of some 

part of that briefing. That information may lead to a 

safer and more satisfying flight experience. 

4) After receiving the preflight weather briefing, the most 

important decision you must make is whether or not 

to fly. If marginal visual flight conditions or adverse 

weather are factors, it may be best to delay, postpone, 

or cancel the flight or consider alternate routes and 

destination points.

5) Deciding to fly when the AFSS specialist indicates that 

“VFR flight not recommended” presents a significant 

risk. Before take-off, call the local AFSS and receive 

a weather update. Since your last preflight briefing, 

there could be significant weather changes that could 

adversely impact the safety and comfort of your flight 

along your filed route and at your destination point. 

Remember, 661 accidents in the USA occurred between 

1990-present where VFR into IMC was identified 

as a “cause or factor” by the NTSB. Of these, 80% 

resulted in a fatality.8

6) While in flight, call into Flight Watch for the current 

weather conditions. You also can receive an FSSrecorded weather broadcast. These weather services 

can provide you with accurate weather information 

to aid your decision-making, should weather become 

a threat. As pointed out by Lenz, an analysis of 586 

recent fatal weather accidents indicated that only 19 

pilots had updated their weather information through 

FSS/AFSS.

Unlike travelers from the past who relied solely on 

naturally occurring moon and sky conditions to predict 

local weather, modern day travelers have real-time weather 

information. For example, earlier travelers learned that 

a red sky at dusk indicated that the following day would 

probably be dry and fine for travel. They didn’t know that 

8

Data downloaded from the NTSB accident database. Data extraction 

and computation provided by Cristy Detwiler under the direction 

of Dr. Carla Hackworth. 

the evening sky’s redness resulted from the sun shining 

through dust particles that were being pushed ahead of a 

high pressure system bringing in dry air. They also learned 

that a red sky at dawn was a fair indication that a storm 

was approaching. It took centuries for people to learn that 

the sky’s redness at dawn resulted from an approaching 

low pressure system carrying a lot of moisture in the air. 

And that moisture could become rain, snow, sleet, or hail 

(depending upon season and geographical location). 

Like these early travelers, we can still look up at the 

sky to predict local weather conditions. Unlike early 

travelers, we also have very sophisticated and technologically advanced tools that experts use to provide us 

with current and future weather information. Luckily, a 

multitude of weather-providers are available with stateof-the-art forecasting tools to supplement GA pilots 

simple act of looking up at the sky and reading the local 

sky conditions. 

However, technological progress does not necessarily 

equate to improved safety. Although improvements in 

weather detection and forecasting capability have occurred, this information may not be available to GA 

pilots who are in flight. Likewise, if weather information 

is available, it may not be received in the cockpit in a 

timely manner for pilots to make safe decisions. In still 

other cases, the pilots may have received timely and accurate information but did not understand its implication 

regarding the safety of flight. As Lenz pointed out, simple 

misunderstandings regarding weather information have 

led to fatal accidents 

Both early travelers and GA pilots share a common 

thread — they must decide whether to go or stay home in 

light of the information available at the time. This simple 

choice is a primary human factor that can result in safe 

or unsafe acts. As much as the FAA’s primary mission is 

to promote safety and the FAA has reduced GA accidents 

by 12% over the last 5 years (AOPA 2005), the study 

into causal and contributing factors related to weather 

accidents offers an opportunity to reduce the largest cause 

of aviation fatalities — VFR flight into IMC. 

References

Aircraft Owners and Pilots Association (2005). Nall 

Report – Accident trends and factors for 2004. www.

aopa.org/asf/publications/nall.html. Accessed 9 

January, 2007.

Bible, Revised Standard. Matthew, from The holy Bible, 

Revised Standard version. Electronic Text Center, 

University of Virginia Library. etext.lib.virginia.

edu/rsv.browse.html. Accessed 9 January, 2007. 
11

Driskill, W.E., Weissmuller, J.J., Quebe, J., Hand, D.K., 

Dittmar, M.J., and Hunter, D.R. (1997). The use of 

weather information in aeronautical decision-making. 

Report no. DOT/FAA/AM-97/3. Washington, DC: 

Federal Aviation Administration.

Federal Aviation Administration (1995a). 7110.10R 

Flight Services. www.faa.gov/ATPUBS/FSS/INDEX.HTM. Accessed 9 January, 2007.

Goh, J., Wiegmann, D., and O’Hare, D. (2002). The 

effects of distance traveled and pilot experience 

on pilot’s decisions to continue visual flight rules 

flight into adverse weather. Aviation, Space, and 

Environmental Medicine, 73(3), 252-3. 

Goh, J. and Wiegmann, D. A. (2001). Visual flight rules 

flight (VFR) into adverse weather: An empirical investigation of the possible causes. The International 

Journal of Aviation Psychology, 11, 359-79. 

Knecht, W., Harris, H., and Shappell, S. (2005). The 

influence of visibility, cloud ceiling, financial incentive, and personality factors on general aviation pilots 

willingness to take off into marginal weather, Part I: 

The data and preliminary conclusions. Report no. 

DOT/FAA/AM-05/7. Washington, DC: Federal 

Aviation Administration.

National Transportation Safety Board. (1968). An analysis 

of U.S. general aviation accidents involving weather 

as a cause/related factor 1966, Notation 155. Washington, DC: Author.

National Transportation Safety Board. (1974). Special 

study of fatal, weather-involved general aviation accidents. Report no. NTSB-AAS-74-2. Washington, 

DC: Author. www.amelia.db.erau.edu/reports/ntsb/

aas/AAS74-02.pdf. Accessed 9 January, 2007.

National Transportation Safety Board. (1976). Non-fatal, 

weather-involved general aviation accidents. Report 

no. NTSB/AAS-76-3. Washington, DC: Author. 

www.amelia.db.erau.edu/reports/ntsb/aas/AAS76-

03.pdf. Accessed 9 January, 2007.

National Transportation Safety Board. (1989). General 

aviation accidents involving VFR flight into IMC. 

Report no. NTSB/SR-89-01. Washington, DC: 

Author. www.amelia.db.erau.edu/reports/ntsb/sr/

SR89-01.pdf. Accessed 9 January, 2007.

National Transportation Safety Board. (2005). Risk factors associated with weather-related general aviation 

accidents.Report no. NTSB/SS-05/01. Washington, 

DC: Author.

Pearson, D.C. (2002). VFR flight not recommended: A study 

of weather-related fatal aviation accidents. SR SSD 

2002-18. Atlanta GA: NOAA/National Weather 

Service. www.srh.noaa.gov/topics/attach/html/

ssd02-18.htm. Accessed 9 January, 2007.

A-1

APPENDIX A 

AFSS Communication Database Codebook

COLUMN

Variable Names Variable Descriptions & 

Value Labels Explanation/Examples

FACILITY INFORMATION 

A LINENUM Line Number Sequentially numbered briefings according to 

Facility and Sector ID.

B FAC_ID Facility ID Name of the facility (3-letter identifier).

C SEC_ID 

Sector/Position ID 

Preflight (number)

Example: PF15 

Identifies the sector/position of the facility 

recorded in FAC_ID. 

The Flight Service Station includes Preflight, 

Inflight, Flight Watch, NOTAM, and Flight Data 

positions. For this study, the Preflight position 

was used. This column will allow an expansion 

of the spreadsheet to include the Inflight and 

Flight Watch positions, using the current DAT 

tapes. It is possible that other positions may be 

combined with the Preflight position (one AFSS 

specialist working two or more positions). When 

this occurred, an attempt was made to identify 

only the preflight data. In some cases data 

collected from combined positions was included 

in the Preflight position. For example, Preflight 

(number) PF15.

D AFSS_SP 

AFSS Specialist 

1=First

2=Second

3=Third

This column contains an AFSS specialist 

number, beginning with “1.” 

Each specialist was identified by assignment of a 

unique sequential number (e.g., 1, 2, 3, etc.). 

Each change in specialist was determined by 

listening to changes in the specialist’s voice. 

E DAT_DATE_TIME DAT Date/Time Group Indicates the beginning date and time of the 

AFSS facility DAT file. 

F TIME_PFLT_BRF Time Preflight Briefing Indicates the beginning time of the preflight 

briefing to a pilot.

G PROPOSED_DPT_TIME Proposed Departure Time 

When the pilot did not state the proposed 

departure time, the encoder added 30 minutes to 

the beginning time of the preflight briefing and 

used it as the proposed departure time. 

H TYPE_WX_DAY 

Type Weather Day 

1=Good weather 

2=Typical weather 

3=Bad weather 

Identifies the weather type (good, typical, bad) 

for the day of the DAT recording, as determined 

by the facility. 
A-2

AFSS Communication Database Codebook (continued) COLUMN

Variable Names Variable Descriptions & 

Value Labels Explanation/Examples

AIRCRAFT INFORMATION 

I ACID Aircraft Identification 

The aircraft identification was taken from the 

flight plan filed, or the identification used in 

communicating with AFSS when no flight plan 

was filed. When no identification was available, 

the column contains an unknown (UNK, with 

each unknown being numbered sequentially, e.g. 

UNK1, UNK2, UNK3, etc.). In accordance with 

FAA aircraft identification procedures, the 

identification should include a prefix of 

November (N), company prefix (Delta (DAL)), 

military (Air Force 1234 (A1234)), manufacturer 

name or manufacturer assigned name, etc. 

J AC_TYPE Aircraft Type 

The FAA designator for the aircraft type and the 

suffix, when available. The suffix will give some 

indication of the avionics on board the aircraft. If 

aircraft type was unknown, encoding was 

Unknown (UNK). Some were spelled out. 

K AC_ADV_WX_EQUIP 

Aircraft Advanced Weather 

Equipment

1=Yes

2=No

This includes deicing, radar, and other 

electronics that would indicate weather. AFSS 

personnel are not required to request this 

information, and few pilots volunteer. 

L P_FP 

Did Pilot File Flight Plan 

1=Yes

2=No

Did pilot file a flight plan with the Preflight 

position entered in Sector/Position ID (SEC_ID).

M TYPE_FP 

Type Flight Plan 

1=VFR

2=IFR

Flight plans were identified/encoded as either 

VFR or IFR. The following items are normally 

included departure (takeoff location or position), 

route, destination (airfield or point of 

cancellation), type aircraft, altitude, estimated 

time of departure (ETD), estimated time en route 

(ETE), pilot name and address, and aircraft color, 

etc. 

N DAY_NIGHT 

Day or Night 

1=Day 

2-Night

Using the proposed departure time, each flight 

was identified/encoded as a day or night flight. 

As the sunrise and sunset times were not 

available, the hours 1300 to 0300 Zulu (Seattle),

1100-0100 Zulu (Fort Worth), 1000-0000 Zulu 

(Bridgeport) were considered daytime. 

O MISSION 

Mission/Purpose of flight 

1=Recreational 

2=Business 

3=Commercial 

4=Instructional

5=Unknown

6=Military 

7=Balloon/Blimp 

The purpose of the flight may be indicated by 

pilot report, identification of the aircraft 

(business jet, military, etc.). The encoder used 

some discretion in identifying the mission. When 

there was insufficient data, the encoding was “5” 

(Unknown). When Aircraft Type was 

“BALLOON,” Mission was encoded “7” 

(Balloon/Blimp) unless specifically stated 

otherwise, e.g., “1” (Recreational). 

P COMM_MTHD 

Communication Method 

1=Telephone

2=Radio

Preflight briefings are generally conducted via 

telephone. However, in some cases, radio might 

be used. This could include discrete frequency; 

transmit on aircraft frequency, receive on VOR. 
A-3

AFSS Communication Database Codebook (continued) COLUMN

Variable Names Variable Descriptions & 

Value Labels Explanation/Examples

PILOT REQUESTS/REPORTS 

Q P_REQ_PFLT_BRF 

Did Pilot Request Preflight 

Briefing

1=Yes

2=No

From the pilot contact with the AFSS Preflight 

briefer, the encoder determined if the 

communication used was a request for a preflight 

briefing. For example, “What’s it look like Dallas 

to Waco?” was considered a request for a 

briefing.

R P_TYPE_PFLT_BRF 

Type Preflight Briefing Pilot 

Requested

1=Standard

2=Abbreviated

3=Outlook

4=None

Standard briefing would be relayed in 

conjunction with a flight plan, VFR or IFR, and 

includes adverse conditions (Example: AIRMET/ 

SIGMET), synopsis, current conditions, en route 

forecast (summarized), destination forecast, winds 

aloft, NOTAM, PIREPs (requested and relayed), 

EFAS (Flight Watch) when appropriate, and 

MOA, MTR, TFR when requested. 

“Request a standard briefing.” 

“Can you give me the weather from Amarillo 

to Oklahoma City to Memphis?” 

“I’m departing Dallas to Waco to Hobby – 

what do you have for that?” 

Abbreviated briefing is relayed when the pilot 

requests information to supplement mass 

disseminated data, or updating previous briefing, 

or when the pilot requests specific data. 

“I only need winds aloft for Roswell.” 

Outlook briefing is relayed for a proposed 

departure beyond 6 hours. 

“What’s the weather look like in North Texas 

for tomorrow?” 

Many pilots do not use the terms “standard,” 

“abbreviated,” or “outlook” when requesting 

weather. Encoder used what appeared to be the 

intent. 

NOTE: Items U through AS may be included in a standard briefing. These data were encoded to record the information that the 

pilot requested or reported (before and after briefing). 

U P_REQ_DPT_WX 

Did Pilot Request Weather 

Conditions at Departure Point 

(Current and/or forecast 

weather). 

1=Yes

2=No

1-“Request weather at (departure point).” 

2-No request 

V P_REQ_ENRTE_WX 

Did Pilot Request En route 

Weather Conditions 

(Current and/or forecast 

weather). 

1=Yes

2=No

1-“What do we have going up to (point)?” 

2-No request 

W P_REQ_DEST_WX 

Did Pilot Request Destination 

Weather (Current and/or 

forecast weather). 

1=Yes

2=No

1-“Anything at (destination)?” 

2-No request 
A-4

AFSS Communication Database Codebook (continued) COLUMN

Variable Names Variable Descriptions & 

Value Labels Explanation/Examples

PILOT REQUESTS/REPORTS 

X P_REQ_PIREP 

Did Pilot Request PIREP 

1=Yes

2=No

1-“Are there any PIREPs?” 

2-No request 

Z P_REQ_TSTORM 

Did Pilot Request 

Thunderstorm Activity 

1=Yes

2=No

1-Are there any thunderstorms in the area?” 

2-No request 

AA P_REQ_ICING 

Did Pilot Request Icing 

Conditions

1=Yes

2=No

1-“Any icing?” “What altitude?” 

2-No request 

AB P_REQ_SURF_WND 

Did Pilot Request Surface 

Winds

1=Yes

2=No

1-“What are the winds?” 

2-No request 

AC P_REQ_WND_ALFT 

Did Pilot Request Winds 

Aloft

1=Yes

2=No

1-“What are the winds aloft at six thousand and 

nine thousand?” 

2-No request 

AD P_REQ_SKYCOND 

Did Pilot Request Sky 

Conditions (Clouds) 

1=Yes

2=No

1-“What are the clouds scattered or broken?” 

2-No request 

AE P_REQ_CLD_TP 

Did Pilot Request Cloud Tops 

1=Yes

2=No

1-“What are the tops?” 

2-No request 

AF P_REQ_PRECIP 

Did Pilot Request 

Precipitation

1=Yes

2=No

1-“Any rain?” 

2-No request 

AG P_REQ_PRECIP_INTNS 

Did Pilot Request 

Precipitation Intensity 

1=Yes

2=No

1-“Is the snow heavy or light?” 

2-No request 

AH P_REQ_VIS 

Did Pilot Request Visibility 

1=Yes

2=No

1-“What is the visibility at (point)?” 

2-No request 
A-5

AFSS Communication Database Codebook (continued) COLUMN

Variable Names Variable Descriptions & 

Value Labels Explanation/Examples

AI P_REQ_VIS_OBSCUR 

Did Pilot Request Visibility 

Obscuration

1=Yes

2=No

1-“Is that smoke from fires or just haze?” 

2-No request 

AJ P_REQ_TEMP 

Did Pilot Request 

Temperature 

1=Yes

2=No

1-“What is the temperature today?” 

2-No request 

AK P_REQ_DEWPT 

Did Pilot Request Dew Point 

1=Yes

2=No

1-“What is the dew point?” 

2-No request 

AL P_REQ_ALTM 

Did Pilot Request Altimeter 

1=Yes

2=No

1-“Say Phoenix altimeter.” 

2-No request 

AM P_REQ_OTR_WX 

Did Pilot Request Other 

Weather 

1=Yes

2=No

1-“Is there anything else that might help?” 

2-No request 

AN P_REQ_NOTAM 

Did Pilot Request NOTAMs 

1=Yes

2=No

1-“Do you have NOTAMs along my route?” 

2-No request 

AO P_REQ_TFR 

Did Pilot Request TFRs 

1=Yes

2=No

1-“Is the temporary restriction at Dallas still in 

effect?” 

2-No request 

AP P_REQ_MOA_MTR 

Did Pilot Request MOA or 

MTR

1=Yes

2=No

1-“Is the Pecos MOA open?” 

2-No request 

AQ P_REQ_AIRMET_SIGMET 

Did Pilot Request 

AIRMET/SIGMET 

1=Yes

2=No

1-“No SIGMETs today?” 

2-No request 

AR P_REQ_ATC_DEL_FC_ADV 

Did Pilot Request ATC 

Delays or Flow Control 

Advisories

1=Yes

2=No

Y P_RPT_PIREP 

Did Pilot Report PIREP 

1=Yes

2=No

1-“The tops of clouds are ten thousand two 

hundred.”

2-No report 

AS P_RPT_AFIS 

Did Pilot Report Having 

Automated Flight Information 

Service 

1=Yes

2=No
A-6

AFSS Communication Database Codebook (continued) COLUMN

Variable Names Variable Descriptions & 

Value Labels Explanation/Examples

AFSS PREFLIGHT INFORMATION 

NOTE: Items AT through BS were encoded if they were relayed or requested by the AFSS briefer during the preflight briefing, 

or as a reply to a pilot request, i.e., any information within these categories was encoded. 

S AFSS_ISSUES_PFLT_BRF 

Did AFSS Issue Preflight 

Briefing

1=Yes

2=No

T AFSS_TYPE_PFLT_BRF 

Type Preflight Briefing 

AFSS Issued 

1=Standard

2=Abbreviated

3=Outlook

4=None

The preflight briefing types were taken from FAA 

Order 7110.10R subpara 3-2-1: 

Standard briefing would be relayed in 

conjunction with a flight plan, VFR or IFR, and 

includes adverse conditions (Example: AIRMET/ 

SIGMET), synopsis, current conditions, en route 

forecast (summarized), destination forecast, 

winds aloft, NOTAM, PIREPs (requested and 

relayed), EFAS (Flight Watch) when appropriate, 

and MOA, MTR, TFR when requested. 

Abbreviated briefing is relayed when the pilot 

requests information to supplement mass 

disseminated data, or updating previous briefing, 

or when the pilot requests specific data. 

Outlook briefing is relayed for a proposed 

departure beyond 6 hours. 

AT AFSS_REL_ADVRS_COND 

Did AFSS Relay Adverse 

Conditions

1=Yes

2=No

AU AFSS_REL_WX_SYN 

Did AFSS Relay Weather 

Synopsis 

1=Yes

2=No

AV AFSS_REL_DPT_WX 

Did AFSS Relay Weather 

Conditions at Departure Point 

(Current and/or forecast 

weather). 

1=Yes

2=No

Current and/or forecast weather. 

1-“Yuma shows few clouds at fifteen hundred 

wind two eight zero at ten gusting to fifteen 

visibility ten or more altimeter two nine nine 

three.” 

2-No relay 

AW AFSS_REL_ENRTE_WX 

Did AFSS Relay En route 

Weather Conditions (Current 

and/or forecast weather). 

1=Yes

2=No

Current and/or forecast weather. 

1-“Looks like you’ll be east of any weather the 

winds at seven thousand are one three five at six 

at nine thousand one six zero at eight clear below 

twelve thousand.” 

2-No relay 

AX AFSS_REL_DEST_WX 

Did AFSS Relay Destination 

Weather (Current and/or 

forecast weather). 

1=Yes

2=No

Current and/or forecast weather. 

1-“Your ETA at Roswell about one four three 

zero it will be one five thousand broken visibility 

fifteen winds north three five zero at one one 

knots.”

2-No relay 
A-7

AFSS Communication Database Codebook (continued) COLUMN

Variable Names Variable Descriptions & 

Value Labels Explanation/Examples

AY AFSS_REL_PIREP 

Did AFSS Relay PIREP 

1=Yes

2=No

1-“PIREP tops ten thousand two hundred.” 

2-No relay 

AZ AFSS_REQ_PIREP 

Did AFSS Request PIREP 

1=Yes

2=No

1-“We could use a PIREP if you’re going over to 

Denver.”

2-No request 

BA AFSS_REL_TSTORM 

Did AFSS Relay 

Thunderstorm Activity 

1=Yes

2=No

1-“The front has passed and thunderstorm 

dissipated.” 

2-No relay 

BB AFSS_REL_ICING 

Did AFSS Relay Icing 

Conditions

1=Yes

2=No

1-“No icing.” “Light clear ice at nine thousand.” 

2-No relay 

BC AFSS_REL_SURF_WND 

Did AFSS Relay Surface 

Winds

1=Yes

2=No

1-“Two nine zero at twelve.” 

2-No relay 

BD AFSS_REL_WND_ALOFT 

Did AFSS Relay Winds Aloft 

1=Yes

2=No

1-“Nine thousand two seven zero at ten twelve 

thousand two eight zero at eighteen.” 

2-No relay 

BE AFSS_REL_SKYCOND 

Did AFSS Relay Sky 

Conditions (Clouds) 

1=Yes

2=No

1-“Twenty five hundred broken three thousand 

overcast.” 

2-No relay 

BF AFSS_REL_CLD_TP 

Did AFSS Relay Cloud Tops 

1=Yes

2=No

1-“A PIREP here by a one eighty two says tops 

are nine thousand five hundred.” 

2-No relay 

BG AFSS_REL_PRECIP 

Did AFSS Relay 

Precipitation

1=Yes

2=No

1-“No rain in vicinity.” “A drizzle over the east 

Cascades.” 

2-No relay 

BH AFSS_REL_PRECIP_INTNS 

Did AFSS Relay 

Precipitation Intensity 

1=Yes

2=No

1-“Light rain shower ten north of Puttman.” 

2-No relay 

BI AFSS_REL_VIS 

Did AFSS Relay Visibility 

1=Yes

2=No

1-“Visibility clear below eight thousand.” 

“Visibility ten.” 

2-No relay 

BJ AFSS_REL_VIS_OBSCUR 

Did AFSS Relay Visibility 

Obscuration

1=Yes

2=No

1-“Smoke from the fire east side of the 

mountain.”

2-No relay 
A-8

AFSS Communication Database Codebook (continued) COLUMN

Variable Names Variable Descriptions & 

Value Labels Explanation/Examples

BK AFSS_REL_TEMP 

Did AFSS Relay 

Temperature 

1=Yes

2=No

1-“Hot today. Surface temperature fifty two 

twelve thousand forty two.” 

2-No relay 

BL AFSS_REL_DEWPT 

Did AFSS Relay Dew Point 

1=Yes

2=No

1-“The dew point is forty two.” 

2-No relay 

BM AFSS_REL_ALTM 

Did AFSS Relay Altimeter 

1=Yes

2=No

1-“Seattle altimeter two nine nine two.” 

2-No relay 

BN AFSS_REL_OTR_WX 

Did AFSS Relay Other 

Weather 

1=Yes

2=No

1-“Look for some turbulence going over the 

mountain range.” 

2-No relay 

BO AFSS_REL_NOTAM 

Did AFSS Relay NOTAMs 

1=Yes

2=No

1-“We have a NOTAM that Seattle VOR is out of 

service today until fourteen hundred.” 

2-No relay 

BP AFSS_REL_TFR 

Did AFSS Relay TFRs 

1=Yes

2=No

1-“The flight restriction around the fire east of 

Puttman has expired.” 

2-No relay 

BQ AFSS_REL_MOA_MTR 

AFSS Relay MOA or MTR 

1=Yes

2=No

1-“The Pecos MOA is active zero eight zero zero 

to one six zero zero local daily.” 

2-No relay 

BR AFSS_REL_AIRMET_SIGMET 

Did AFSS Relay 

AIRMET/SIGMET 

1=Yes

2=No

1-“SIGMET has been issued for thunderstorms 

and low visibility in the area of Albuquerque.” 

2-No relay 

BS AFSS_REL_ATC_DEL_FC_AD

V

Did AFSS Relay ATC Delays 

or Flow Control Advisories 

1=Yes

2=No

BT AFSS_AFIS 

Did AFSS Advise Current 

Automated Flight 

Information Service 

1=Yes

2=No

BU AFSS_VFR_NOT_REC 

Did AFSS State VFR Flight 

Not Recommended 

1=Yes

2=No

This requirement is included in preflight 

briefings. However, it merits inclusion as a single 

variable to be recorded/encoded. 

1-“VFR flight Durango to Crested Butte not 

recommended.”

2-AFSS did not state VFR flight not 

recommended.
A-9

AFSS Communication Database Codebook (continued) COLUMN

Variable Names Variable Descriptions & 

Value Labels Explanation/Examples

BV P_CHG_FP 

Did Pilot Change Flight Plan 

1=Yes-before preflight 

briefing

2=Yes-after preflight briefing 

3=No

Flight plan or altitude change after receiving a 

preflight briefing (standard or abbreviated). The 

purpose of this data is for analysis of the actions 

taken by a pilot after a preflight briefing. 

BW P_CHG_ALT 

Did Pilot Change Altitude 

1=Yes-before preflight 

briefing

2=Yes-after preflight briefing 

3=No

Flight plan or altitude change after receiving a 

preflight briefing (standard or abbreviated). The 

purpose of this data is for analysis of the actions 

taken by a pilot after a preflight briefing. 

BY COMMENTS Encoder (SME) Comments Pilot weather requests and AFSS weather 

information relays that are out of the norm are 

recorded for further study. 

BZ PFLT_BRF_ANALYSIS 

Preflight Briefing for 

Detailed Analysis 

Y=Yes

Encoded “Y” if AFSS preflight briefing contains 

information that merits detailed analysis. 

CA P_CMTS_DAT Interesting Pilot Comments 

(from DAT)