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DOT/FAA/AR-07/37

DOT-VNTSC-FAA-07-07

Air Traffic Organization Operations Planning

Human Factors Research\
and Engineering Group

Washington, DC 20591

**Pilot Identification of Symbols and an Exploration of Symbol Design
Issues for Electronic Displays of Aeronautical Charting Information\
\
**

**Divya C. Chandra**

**Michelle Yeh**

U.S. Department of Transportation

Research and Innovative Technology Administration

John A. Volpe National Transportation\
Systems Center

Cambridge, MA 02142

**June 2007**

This document is available to the public through the National Technical
Information Service, Springfield, Virginia, 22161.

+-----------------------------------------------------------------------+
| > Notice                                                              |
|                                                                       |
| This document is disseminated under the sponsorship of the Department |
| of Transportation in the interest of information exchange. The United |
| States Government assumes no liability for its contents or use        |
| thereof.                                                              |
+-----------------------------------------------------------------------+
|                                                                       |
+-----------------------------------------------------------------------+
| > Notice                                                              |
|                                                                       |
| The United States Government does not endorse products or             |
| manufacturers. Trade or manufacturers' names appear herein solely     |
| because they are considered essential to the objective of this        |
| report.                                                               |
+-----------------------------------------------------------------------+

+-------------------+-----+----------+------------+---+-----------------+
| **REPORT          |     |          |            | * |                 |
| DOCUMENTATION     |     |          |            | F |                 |
| PAGE**            |     |          |            | o |                 |
|                   |     |          |            | r |                 |
|                   |     |          |            | m |                 |
|                   |     |          |            | A |                 |
|                   |     |          |            | p |                 |
|                   |     |          |            | p |                 |
|                   |     |          |            | r |                 |
|                   |     |          |            | o |                 |
|                   |     |          |            | v |                 |
|                   |     |          |            | e |                 |
|                   |     |          |            | d |                 |
|                   |     |          |            | * |                 |
|                   |     |          |            |   |                 |
|                   |     |          |            | * |                 |
|                   |     |          |            | O |                 |
|                   |     |          |            | M |                 |
|                   |     |          |            | B |                 |
|                   |     |          |            | N |                 |
|                   |     |          |            | o |                 |
|                   |     |          |            | . |                 |
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|                   |     |          |            | 1 |                 |
|                   |     |          |            | 8 |                 |
|                   |     |          |            | 8 |                 |
|                   |     |          |            | * |                 |
+-------------------+-----+----------+------------+---+-----------------+
| Public reporting  |     |          |            |   |                 |
| burden for this   |     |          |            |   |                 |
| collection of     |     |          |            |   |                 |
| information is    |     |          |            |   |                 |
| estimated to      |     |          |            |   |                 |
| average 1 hour    |     |          |            |   |                 |
| per response,     |     |          |            |   |                 |
| including the     |     |          |            |   |                 |
| time for          |     |          |            |   |                 |
| reviewing         |     |          |            |   |                 |
| instructions,     |     |          |            |   |                 |
| searching         |     |          |            |   |                 |
| existing data     |     |          |            |   |                 |
| sources,          |     |          |            |   |                 |
| gathering and     |     |          |            |   |                 |
| maintaining the   |     |          |            |   |                 |
| data needed, and  |     |          |            |   |                 |
| completing and    |     |          |            |   |                 |
| reviewing the     |     |          |            |   |                 |
| collection of     |     |          |            |   |                 |
| information. Send |     |          |            |   |                 |
| comments          |     |          |            |   |                 |
| regarding this    |     |          |            |   |                 |
| burden estimate   |     |          |            |   |                 |
| or any other      |     |          |            |   |                 |
| aspect of this    |     |          |            |   |                 |
| collection of     |     |          |            |   |                 |
| information,      |     |          |            |   |                 |
| including         |     |          |            |   |                 |
| suggestions for   |     |          |            |   |                 |
| reducing this     |     |          |            |   |                 |
| burden, to        |     |          |            |   |                 |
| Washington        |     |          |            |   |                 |
| Headquarters      |     |          |            |   |                 |
| Services,         |     |          |            |   |                 |
| Directorate for   |     |          |            |   |                 |
| Information       |     |          |            |   |                 |
| Operations and    |     |          |            |   |                 |
| Reports, 1215     |     |          |            |   |                 |
| Jefferson Davis   |     |          |            |   |                 |
| Highway, Suite    |     |          |            |   |                 |
| 1204, Arlington,  |     |          |            |   |                 |
| VA 22202-4302,    |     |          |            |   |                 |
| and to the Office |     |          |            |   |                 |
| of Management and |     |          |            |   |                 |
| Budget, Paperwork |     |          |            |   |                 |
| Reduction Project |     |          |            |   |                 |
| (0704-0188),      |     |          |            |   |                 |
| Washington, DC    |     |          |            |   |                 |
| 20503.            |     |          |            |   |                 |
+-------------------+-----+----------+------------+---+-----------------+
| 1\. AGENCY USE    |     | 2\.      |            | 3 |                 |
| ONLY (Leave       |     | REPORT   |            | \ |                 |
| blank)            |     | DATE     |            | . |                 |
|                   |     |          |            | R |                 |
|                   |     | June     |            | E |                 |
|                   |     | 2007     |            | P |                 |
|                   |     |          |            | O |                 |
|                   |     |          |            | R |                 |
|                   |     |          |            | T |                 |
|                   |     |          |            | T |                 |
|                   |     |          |            | Y |                 |
|                   |     |          |            | P |                 |
|                   |     |          |            | E |                 |
|                   |     |          |            | A |                 |
|                   |     |          |            | N |                 |
|                   |     |          |            | D |                 |
|                   |     |          |            | D |                 |
|                   |     |          |            | A |                 |
|                   |     |          |            | T |                 |
|                   |     |          |            | E |                 |
|                   |     |          |            | S |                 |
|                   |     |          |            | C |                 |
|                   |     |          |            | O |                 |
|                   |     |          |            | V |                 |
|                   |     |          |            | E |                 |
|                   |     |          |            | R |                 |
|                   |     |          |            | E |                 |
|                   |     |          |            | D |                 |
+-------------------+-----+----------+------------+---+-----------------+
| 4\. TITLE AND     |     |          |            |   | 5\. FUNDING     |
| SUBTITLE          |     |          |            |   | NUMBERS         |
|                   |     |          |            |   |                 |
| Pilot             |     |          |            |   | FA6Y/DD305      |
| Identification of |     |          |            |   |                 |
| Symbols and an    |     |          |            |   |                 |
| Exploration of    |     |          |            |   |                 |
| Symbol Design     |     |          |            |   |                 |
| Issues for        |     |          |            |   |                 |
| Electronic        |     |          |            |   |                 |
| Displays of       |     |          |            |   |                 |
| Aeronautical      |     |          |            |   |                 |
| Charting          |     |          |            |   |                 |
| Information       |     |          |            |   |                 |
+-------------------+-----+----------+------------+---+-----------------+
| 6\. AUTHOR(S)     |     |          |            |   |                 |
|                   |     |          |            |   |                 |
| Divya C. Chandra  |     |          |            |   |                 |
| and Michelle Yeh  |     |          |            |   |                 |
+-------------------+-----+----------+------------+---+-----------------+
| 7\. PERFORMING    |     |          |            |   | 8\. PERFORMING  |
| ORGANIZATION      |     |          |            |   | ORGANIZATION    |
| NAME(S) AND       |     |          |            |   | REPORT NUMBER   |
| ADDRESS(ES)       |     |          |            |   |                 |
|                   |     |          |            |   | DOT-            |
| U.S. Department   |     |          |            |   | VNTSC-FAA-07-07 |
| of Transportation |     |          |            |   |                 |
|                   |     |          |            |   |                 |
| John A. Volpe     |     |          |            |   |                 |
| National          |     |          |            |   |                 |
| Transportation    |     |          |            |   |                 |
| Systems Center    |     |          |            |   |                 |
|                   |     |          |            |   |                 |
| Research and      |     |          |            |   |                 |
| Innovative        |     |          |            |   |                 |
| Technology        |     |          |            |   |                 |
| Administration    |     |          |            |   |                 |
|                   |     |          |            |   |                 |
| Cambridge, MA     |     |          |            |   |                 |
| 02142-1093        |     |          |            |   |                 |
+-------------------+-----+----------+------------+---+-----------------+
| 9\.               |     |          |            |   | 10\.            |
| SPON              |     |          |            |   | SPONSO          |
| SORING/MONITORING |     |          |            |   | RING/MONITORING |
| AGENCY NAME(S)    |     |          |            |   | AGENCY REPORT   |
| AND ADDRESS(ES)   |     |          |            |   | NUMBER          |
|                   |     |          |            |   |                 |
| U.S. Department   |     |          |            |   | D               |
| of Transportation |     |          |            |   | OT/FAA/AR-07/37 |
| Federal Aviation  |     |          |            |   |                 |
| Administration    |     |          |            |   |                 |
|                   |     |          |            |   |                 |
| Air Traffic       |     |          |            |   |                 |
| Organization      |     |          |            |   |                 |
| Operations        |     |          |            |   |                 |
| Planning          |     |          |            |   |                 |
|                   |     |          |            |   |                 |
| Human Factors     |     |          |            |   |                 |
| Research and      |     |          |            |   |                 |
| Engineering Group |     |          |            |   |                 |
|                   |     |          |            |   |                 |
| 800 Independence  |     |          |            |   |                 |
| Avenue, SW        |     |          |            |   |                 |
|                   |     |          |            |   |                 |
| Washington, D.C.  |     |          |            |   |                 |
| 20591             |     |          |            |   |                 |
|                   |     |          |            |   |                 |
| Program Manager:  |     |          |            |   |                 |
| Dr. Tom McCloy    |     |          |            |   |                 |
+-------------------+-----+----------+------------+---+-----------------+
| 11\.              |     |          |            |   |                 |
| SUPPLEMENTARY     |     |          |            |   |                 |
| NOTES             |     |          |            |   |                 |
+-------------------+-----+----------+------------+---+-----------------+
| 12a.              |     |          |            |   | 12b.            |
| DISTRIBU          |     |          |            |   | DISTRIBUTION    |
| TION/AVAILABILITY |     |          |            |   | CODE            |
| STATEMENT         |     |          |            |   |                 |
|                   |     |          |            |   |                 |
| This document is  |     |          |            |   |                 |
| available to the  |     |          |            |   |                 |
| public through    |     |          |            |   |                 |
| the National      |     |          |            |   |                 |
| Technical         |     |          |            |   |                 |
| Information       |     |          |            |   |                 |
| Service,          |     |          |            |   |                 |
| Springfield, VA   |     |          |            |   |                 |
| 22161             |     |          |            |   |                 |
+-------------------+-----+----------+------------+---+-----------------+
| 13\. ABSTRACT     |     |          |            |   |                 |
| (Maximum 200      |     |          |            |   |                 |
| words)            |     |          |            |   |                 |
|                   |     |          |            |   |                 |
| This report       |     |          |            |   |                 |
| describes a study |     |          |            |   |                 |
| designed to       |     |          |            |   |                 |
| address four      |     |          |            |   |                 |
| research          |     |          |            |   |                 |
| questions about   |     |          |            |   |                 |
| symbology for     |     |          |            |   |                 |
| electronic        |     |          |            |   |                 |
| displays of       |     |          |            |   |                 |
| charting          |     |          |            |   |                 |
| information. The  |     |          |            |   |                 |
| main research     |     |          |            |   |                 |
| question was      |     |          |            |   |                 |
| whether pilots    |     |          |            |   |                 |
| could identify a  |     |          |            |   |                 |
| set of test       |     |          |            |   |                 |
| symbols. Three    |     |          |            |   |                 |
| other research    |     |          |            |   |                 |
| questions were    |     |          |            |   |                 |
| addressed         |     |          |            |   |                 |
| regarding: (1)    |     |          |            |   |                 |
| labels for        |     |          |            |   |                 |
| navigation aid    |     |          |            |   |                 |
| symbols, (2)      |     |          |            |   |                 |
| grouping          |     |          |            |   |                 |
| navigation aids   |     |          |            |   |                 |
| into families,    |     |          |            |   |                 |
| and (3) line      |     |          |            |   |                 |
| style conventions |     |          |            |   |                 |
| on paper charts   |     |          |            |   |                 |
| and electronic    |     |          |            |   |                 |
| moving map        |     |          |            |   |                 |
| displays. The     |     |          |            |   |                 |
| tested symbols    |     |          |            |   |                 |
| are being         |     |          |            |   |                 |
| considered for    |     |          |            |   |                 |
| inclusion in an   |     |          |            |   |                 |
| updated industry  |     |          |            |   |                 |
| recommendations   |     |          |            |   |                 |
| document,         |     |          |            |   |                 |
| specifically, the |     |          |            |   |                 |
| SAE International |     |          |            |   |                 |
| Aerospace         |     |          |            |   |                 |
| Recommended       |     |          |            |   |                 |
| Practices (ARP)   |     |          |            |   |                 |
| document on       |     |          |            |   |                 |
| Electronic        |     |          |            |   |                 |
| Aeronautical      |     |          |            |   |                 |
| Symbols (ARP      |     |          |            |   |                 |
| 5289). The        |     |          |            |   |                 |
| Federal Aviation  |     |          |            |   |                 |
| Administration or |     |          |            |   |                 |
| the International |     |          |            |   |                 |
| Civil Aviation    |     |          |            |   |                 |
| Organization may  |     |          |            |   |                 |
| choose to adopt   |     |          |            |   |                 |
| this industry     |     |          |            |   |                 |
| document by       |     |          |            |   |                 |
| reference, at a   |     |          |            |   |                 |
| later date. Note  |     |          |            |   |                 |
| that this         |     |          |            |   |                 |
| research applies  |     |          |            |   |                 |
| to any electronic |     |          |            |   |                 |
| display that      |     |          |            |   |                 |
| shows the         |     |          |            |   |                 |
| symbology (i.e.,  |     |          |            |   |                 |
| symbols and       |     |          |            |   |                 |
| lines) tested in  |     |          |            |   |                 |
| this study,       |     |          |            |   |                 |
| regardless of the |     |          |            |   |                 |
| intended function |     |          |            |   |                 |
| of the display.   |     |          |            |   |                 |
+-------------------+-----+----------+------------+---+-----------------+
| 14\. SUBJECT TERM |     |          |            |   | 15\. NUMBER OF  |
|                   |     |          |            |   | PAGES           |
| Electronic        |     |          |            |   |                 |
| displays,         |     |          |            |   | 75              |
| aeronautical      |     |          |            |   |                 |
| charts,           |     |          |            |   |                 |
| symbology, moving |     |          |            |   |                 |
| map displays,     |     |          |            |   |                 |
| charting          |     |          |            |   |                 |
| information,      |     |          |            |   |                 |
| symbols           |     |          |            |   |                 |
+-------------------+-----+----------+------------+---+-----------------+
|                   |     |          |            |   | 16\. PRICE CODE |
+-------------------+-----+----------+------------+---+-----------------+
| 17\. SECURITY     | 1   |          | 19\.       |   | 20\. LIMITATION |
| CLASSIFICATION\   | 8\. |          | SECURITY   |   | OF ABSTRACT     |
| OF REPORT         | SE  |          | CLASS      |   |                 |
|                   | CUR |          | IFICATION\ |   |                 |
| Unclassified      | ITY |          | OF         |   |                 |
|                   | CLA |          | ABSTRACT   |   |                 |
|                   | SSI |          |            |   |                 |
|                   | FIC |          | Un         |   |                 |
|                   | ATI |          | classified |   |                 |
|                   | ON\ |          |            |   |                 |
|                   | OF  |          |            |   |                 |
|                   | T   |          |            |   |                 |
|                   | HIS |          |            |   |                 |
|                   | P   |          |            |   |                 |
|                   | AGE |          |            |   |                 |
|                   |     |          |            |   |                 |
|                   | Unc |          |            |   |                 |
|                   | las |          |            |   |                 |
|                   | sif |          |            |   |                 |
|                   | ied |          |            |   |                 |
+-------------------+-----+----------+------------+---+-----------------+

**This page left blank intentionally.**

**PREFACE**

This report was prepared by the Human Factors Division of the Office of
Aviation Programs at the Volpe National Transportation Systems Center.
It was completed with funding from the FAA Human Factors Research and
Engineering Group (AJP-61) in support of the Aircraft Certification
Service Avionics Branch (AIR-130). We would like to thank our FAA
program manager, Tom McCloy, as well as our technical sponsor Colleen
Donovan. We would also like to thank all the members of the SAE
International G-10 Aeronautical Charting Committee, who invested their
expertise and time to make this study so valuable. Particular thanks go
to the many pilots who donated their time and input for the study. In
addition, we would like to thank Catherine Guthy, Andrea Sparko, and Hao
Tran for assistance with the data processing, and Raquel Rodriguez, for
assistance with distributing the surveys.

The views expressed herein are those of the authors and do not
necessarily reflect the views of the Volpe National Transportation
Systems Center, the Research and Innovative Technology Administration,
or the United States Department of Transportation.

Feedback on this document may be sent to Divya Chandra
(Divya.Chandra@volpe.dot.gov) or Michelle Yeh
(Michelle.Yeh@volpe.dot.gov). Further information on this research
effort can be found at <http://www.volpe.dot.gov/hf>.

**METRIC/ENGLISH CONVERSION FACTORS**

<table style="width:100%;">
<colgroup>
<col style="width: 23%" />
<col style="width: 1%" />
<col style="width: 0%" />
<col style="width: 23%" />
<col style="width: 0%" />
<col style="width: 23%" />
<col style="width: 0%" />
<col style="width: 1%" />
<col style="width: 0%" />
<col style="width: 0%" />
<col style="width: 24%" />
</colgroup>
<thead>
<tr class="header">
<th colspan="5"><strong>ENGLISH TO METRIC</strong></th>
<th colspan="6"><strong>METRIC TO ENGLISH</strong></th>
</tr>
<tr class="odd">
<th colspan="5"><strong>LENGTH (APPROXIMATE)</strong></th>
<th colspan="6"><strong>LENGTH (APPROXIMATE)</strong></th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td>1 inch (in)</td>
<td><strong>=</strong></td>
<td colspan="2"><strong>2.5 centimeters (cm)</strong></td>
<td colspan="2"><strong>1 millimeter (mm)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>0.04 inch (in)</strong></td>
</tr>
<tr class="even">
<td><strong>1 foot (ft)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>30 centimeters (cm)</strong></td>
<td colspan="2"><strong>1 centimeter (cm)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>0.4 inch (in)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 yard (yd)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>0.9 meter (m)</strong></td>
<td colspan="2"><strong>1 meter (m)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>3.3 feet (ft)</strong></td>
</tr>
<tr class="even">
<td><strong>1 mile (mi)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>1.6 kilometers (km)</strong></td>
<td colspan="2"><strong>1 meter (m)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>1.1 yards (yd)</strong></td>
</tr>
<tr class="odd">
<td></td>
<td></td>
<td colspan="2"></td>
<td colspan="2"><strong>1 kilometer (km)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>0.6 mile (mi)</strong></td>
</tr>
<tr class="even">
<td colspan="5"><strong>AREA (APPROXIMATE)</strong></td>
<td colspan="6"><strong>AREA (APPROXIMATE)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 square inch (sq in, in<sup>2</sup>)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>6.5 square centimeters
(cm<sup>2</sup>)</strong></td>
<td colspan="2"><strong>1 square centimeter
(cm<sup>2</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>0.16 square inch (sq in,
in<sup>2</sup>)</strong></td>
</tr>
<tr class="even">
<td><strong>1 square foot (sq ft, ft<sup>2</sup>)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>0.09 square meter (m<sup>2</sup>)</strong></td>
<td colspan="2"><strong>1 square meter (m<sup>2</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>1.2 square yards (sq yd,
yd<sup>2</sup>)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 square yard (sq yd, yd<sup>2</sup>)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>0.8 square meter (m<sup>2</sup>)</strong></td>
<td colspan="2"><strong>1 square kilometer
(km<sup>2</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>0.4 square mile (sq mi,
mi<sup>2</sup>)</strong></td>
</tr>
<tr class="even">
<td><strong>1 square mile (sq mi, mi<sup>2</sup>)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>2.6 square kilometers
(km<sup>2</sup>)</strong></td>
<td colspan="2"><strong>10,000 square meters
(m<sup>2</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td colspan="2"><strong>1 hectare (ha) = 2.5 acres</strong></td>
</tr>
<tr class="odd">
<td><strong>1 acre = 0.4 hectare (he)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>4,000 square meters
(m<sup>2</sup>)</strong></td>
<td colspan="2"></td>
<td colspan="3"></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td colspan="5"><strong>MASS - WEIGHT (APPROXIMATE)</strong></td>
<td colspan="6"><strong>MASS - WEIGHT (APPROXIMATE)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 ounce (oz)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>28 grams (gm)</strong></td>
<td colspan="2"><strong>1 gram (gm)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="3"><strong>0.036 ounce (oz)</strong></td>
</tr>
<tr class="even">
<td><strong>1 pound (lb)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>0.45 kilogram (kg)</strong></td>
<td colspan="2"><strong>1 kilogram (kg)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="3"><strong>2.2 pounds (lb)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 short ton = 2,000 pounds (lb)</strong></td>
<td><strong>=</strong></td>
<td colspan="2"><strong>0.9 tonne (t)</strong></td>
<td colspan="2"><strong>1 tonne (t)</strong></td>
<td colspan="2"><p><strong>=</strong></p>
<p><strong>=</strong></p></td>
<td colspan="3"><p><strong>1,000 kilograms (kg)</strong></p>
<p><strong>1.1 short tons</strong></p></td>
</tr>
<tr class="even">
<td colspan="5"><strong>VOLUME (APPROXIMATE)</strong></td>
<td colspan="6"><strong>VOLUME (APPROXIMATE)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 teaspoon (tsp)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>5 milliliters (ml)</strong></td>
<td colspan="2"><strong>1 milliliter (ml)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>0.03 fluid ounce (fl oz)</strong></td>
</tr>
<tr class="even">
<td><strong>1 tablespoon (tbsp)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>15 milliliters (ml)</strong></td>
<td colspan="2"><strong>1 liter (l)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>2.1 pints (pt)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 fluid ounce (fl oz)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>30 milliliters (ml)</strong></td>
<td colspan="2"><strong>1 liter (l)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>1.06 quarts (qt)</strong></td>
</tr>
<tr class="even">
<td><strong>1 cup (c)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>0.24 liter (l)</strong></td>
<td colspan="2"><strong>1 liter (l)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>0.26 gallon (gal)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 pint (pt)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>0.47 liter (l)</strong></td>
<td colspan="2"></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="even">
<td><strong>1 quart (qt)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>0.96 liter (l)</strong></td>
<td colspan="2"></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="odd">
<td><strong>1 gallon (gal)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>3.8 liters (l)</strong></td>
<td colspan="2"></td>
<td colspan="3"></td>
<td></td>
</tr>
<tr class="even">
<td><strong>1 cubic foot (cu ft, ft<sup>3</sup>)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>0.03 cubic meter (m<sup>3</sup>)</strong></td>
<td colspan="2"><strong>1 cubic meter (m<sup>3</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>36 cubic feet (cu ft, ft<sup>3</sup>)</strong></td>
</tr>
<tr class="odd">
<td><strong>1 cubic yard (cu yd, yd<sup>3</sup>)</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>0.76 cubic meter (m<sup>3</sup>)</strong></td>
<td colspan="2"><strong>1 cubic meter (m<sup>3</sup>)</strong></td>
<td colspan="3"><strong>=</strong></td>
<td><strong>1.3 cubic yards (cu yd, yd<sup>3</sup>)</strong></td>
</tr>
<tr class="even">
<td colspan="5"><strong>TEMPERATURE (EXACT)</strong></td>
<td colspan="6"><strong>TEMPERATURE (EXACT)</strong></td>
</tr>
<tr class="odd">
<td><strong>[(x-32)(5/9)] °F</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>y °C</strong></td>
<td colspan="2"><strong>[(9/5) y + 32] °C</strong></td>
<td colspan="2"><strong>=</strong></td>
<td colspan="2"><strong>x °F</strong></td>
</tr>
</tbody>
</table>

![](media/image3.wmf)

![](media/image4.wmf)

For more exact and or other conversion factors, see NIST Miscellaneous
Publication 286, Units of Weights and Measures. Price \$2.50 SD Catalog
No. C13 10286 **Updated 6/17/98**

Table of Contents

[List of Figures viii](#__RefHeading___Toc183840937)

[List of Tables ix](#__RefHeading___Toc183840938)

[Executive Summary xi](#__RefHeading___Toc183840939)

[Acronyms xiii](#__RefHeading___Toc183840940)

[1 Introduction 1](#introduction)

[1.1 Existing Guidance 2](#existing-guidance)

[1.2 Goals for Industry Recommendations Document
2](#goals-for-industry-recommendations-document)

[1.3 Symbol Stereotypes for Navigation Aids
3](#symbol-stereotypes-for-navigation-aids)

[2 Method 4](#method)

[2.1 Participants 4](#participants)

[2.2 Procedure 4](#procedure)

[3 Identification of Symbols 5](#identification-of-symbols)

[3.1 Symbols Tested 5](#symbols-tested)

[3.2 Task 8](#task)

[3.3 Analysis Process 9](#analysis-process)

[3.4 Results 10](#results)

[3.5 Summary of Results for Symbol Identification Task
16](#summary-of-results-for-symbol-identification-task)

[4 Labels for Navigation Aid Symbols
19](#labels-for-navigation-aid-symbols)

[4.1 Task 19](#task-1)

[4.2 Results 20](#results-1)

[4.3 Statistical Analyses 21](#statistical-analyses)

[4.4 Summary and Discussion 22](#summary-and-discussion)

[5 Grouping Navigation Aids into Families
23](#grouping-navigation-aids-into-families)

[5.1 Task 23](#task-2)

[5.2 Results and Discussion 23](#results-and-discussion)

[6 Line Style Conventions 25](#line-style-conventions)

[6.1 Task 25](#task-3)

[6.2 Results and Discussion 26](#results-and-discussion-1)

[7 Summary and Conclusions 33](#summary-and-conclusions)

[8 References 34](#references)

[Appendix A: Questionnaire A.1](#__RefHeading___Toc183840967)

[Appendix B: Response Coding Method for the General-Symbol
Identification Task B.1](#__RefHeading___Toc183840970)

[Appendix C: Cluster Analysis Results C.1](#__RefHeading___Toc183840971)

[]{#__RefHeading___Toc183840937 .anchor}List of Figures

[Figure 1. Example of general symbol identification task.
9](#__RefHeading___Toc183840985)

[Figure 2. Example of airport symbol identification task.
9](#__RefHeading___Toc183840986)

[Figure 3. Example of the navigation-aid identification task.
19](#__RefHeading___Toc183840987)

[Figure 4. Example of line-style question for a paper chart element.
26](#__RefHeading___Toc183840988)

[Figure 5. Example of line-style question for a moving map display
element. 26](#__RefHeading___Toc183840989)

[Figure 6. Responses for how a radial or bearing line that defines an
intersection is shown on paper charts. 27](#__RefHeading___Toc183840990)

[Figure 7. Responses for how a procedure path is shown on paper charts.
28](#__RefHeading___Toc183840991)

[Figure 8. Responses for how a transition path is shown on paper charts.
28](#__RefHeading___Toc183840992)

[Figure 9. Responses for how airways are shown on paper charts.
28](#__RefHeading___Toc183840993)

[Figure 10. Responses for how a missed approach path is shown on paper
charts. 29](#__RefHeading___Toc183840994)

[Figure 11. Responses for how visual flight paths are shown on paper
charts. 29](#__RefHeading___Toc183840995)

[Figure 12. Responses for how other conditional routes are shown on
paper charts. 29](#__RefHeading___Toc183840996)

[Figure 13. Responses for how airways are shown on electronic moving map
displays. 30](#__RefHeading___Toc183840997)

[Figure 14. Responses for how the active flight plan is shown on
electronic moving map displays. 30](#__RefHeading___Toc183840998)

[Figure 15. Responses for how an alternate flight plan is shown on
electronic moving map displays. 31](#__RefHeading___Toc183840999)

[Figure 16. Responses for how a missed approach path is shown on
electronic moving map displays. 31](#__RefHeading___Toc183841000)

[Figure 17. Responses for how airspace boundaries are shown on
electronic moving map displays. 31](#__RefHeading___Toc183841001)

[Figure 18. Responses for how a state or country boundary is shown on
electronic moving map displays. 32](#__RefHeading___Toc183841002)

[]{#__RefHeading___Toc183840938 .anchor}List of Tables

[Table 1. Symbols included in the study.
6](#__RefHeading___Toc183841003)

[Table 2. Original and simplified NDB shapes.
7](#__RefHeading___Toc183841004)

[Table 3. NDB-LOM symbols. 7](#__RefHeading___Toc183841005)

[Table 4. Obstructions symbols. 7](#__RefHeading___Toc183841006)

[Table 5. Localizers. 8](#__RefHeading___Toc183841007)

[Table 6. Other symbols. 8](#__RefHeading___Toc183841008)

[Table 7. Airport symbols. 8](#__RefHeading___Toc183841009)

[Table 8. Foil (i.e., fake) shapes included in the study.
8](#__RefHeading___Toc183841010)

[Table 9. Results for the NDB-LOM family symbol shapes.
10](#__RefHeading___Toc183841011)

[Table 10. Results for obstruction symbol shapes.
11](#__RefHeading___Toc183841012)

[Table 11. Reports of obstruction details.
12](#__RefHeading___Toc183841013)

[Table 12. Results for localizer symbol shapes.
13](#__RefHeading___Toc183841014)

[Table 13. Results for other symbols. 14](#__RefHeading___Toc183841015)

[Table 14. Responses for symbols representing civil, military, or
joint-use airports. 15](#__RefHeading___Toc183841016)

[Table 15. Summary of results for symbol identification task for general
symbols. 17](#__RefHeading___Toc183841017)

[Table 16. Summary of results for airport symbols.
18](#__RefHeading___Toc183841018)

[Table 17. Test conditions for navigation-aid identification task.
19](#__RefHeading___Toc183841019)

[Table 18. Mean accuracy of identification for navigation aids.
20](#__RefHeading___Toc183841020)

[Table 19. Mean confidence score for navigation aids.
21](#__RefHeading___Toc183841021)

[Table 20. Cluster analysis results. 23](#__RefHeading___Toc183841022)

[Table 21. Features used to group navigation aid symbols and their
relative frequencies. 24](#__RefHeading___Toc183841023)

[Table 22. Linear display elements for which knowledge of line style
conventions was assessed. 25](#__RefHeading___Toc183841024)

[Table 23. Excerpt of data for low single obstruction symbol.
B.2](#__RefHeading___Toc183841025)

**This** **page left blank intentionally.**

[]{#__RefHeading___Toc183840939 .anchor}Executive Summary

This report describes a study designed to address four research
questions about symbology for electronic displays of charting
information. It is important to emphasize that this research applies to
any electronic display that shows the symbology (i.e., symbols and
lines) tested in this study, regardless of the intended function of the
display.

The main research question was whether pilots could identify a set of
test symbols selected by the SAE International Aerospace Behavior and
Technology (SAE G-10) Aeronautical Charting Committee. The test symbols,
which included 16 general symbols (e.g., obstructions and markers), and
6 airport symbols (e.g., heliport and seaport), are being considered for
inclusion in an updated industry recommendations document, specifically,
the SAE International Aerospace Recommended Practices (ARP) document on
Electronic Aeronautical Symbols (ARP 5289). Most of the tested symbol
shapes were identified as intended by a majority of participants. A few
problematic symbols were noted, and factors contributing to their
misinterpretation are discussed.

The second research question was whether labels increase the accuracy of
identifying navigation aid symbols. To explore this topic, pilots'
accuracy in identifying five navigation aid symbols was tested based on
symbol shape alone, frequency information alone, or both shape and
frequency information. For four of the five tested symbols, there was no
difference in participants' accuracy of symbol identification with or
without the labeling information. The results of this test are not
definitive, and a more detailed study is necessary to understand the
full effect of labeling information on both the speed and accuracy of
symbol identification.

The third research question was about the similarities that pilots see
between navigation aids. These similarities were explored in order to
identify sets of symbols that could be represented by a single, generic,
family symbol shape. Results showed that pilots grouped navigation aid
symbols into categories primarily based on the type of information
provided by the navigation aid.

The final research question was whether pilots recognize the line style
conventions that are in use today on paper charts and electronic
moving-map displays. Pilots were found to be fairly knowledgeable about
line conventions on paper charts, where standards are well established.
Responses to the questions about line conventions on electronic moving
map displays were more varied, which could indicate either that pilots
did not know the conventions, or that the conventions are not well
established on these displays.

Results of this research are intended to be of use to the FAA, the
International Civil Aviation Organization (ICAO), and other Civil
Aviation Authorities. These organizations may choose to adopt, by
reference, the symbology recommendations developed by the SAE G-10
Aeronautical Charting Committee at a later date. The results of this
research are also intended to be of use to industry manufacturers who
develop and/or depict symbology.

This page left blank intentionally.

[]{#__RefHeading___Toc183840940 .anchor}Acronyms

ADF Automatic Direction Finder

ANOVA Analysis of Variance

ARP Aerospace Recommended Practice

ATP Air Transport Pilot

CAA Civil Aviation Authority

DME Distance Measuring Equipment

EFB Electronic Flight Bag

EMD Electronic Map Display

FAA Federal Aviation Administration

FMS Flight Management System

GPS Global Positioning System

ICAO International Civil Aviation Organization

IFR Instrument Flight Rules

ILS Instrument Landing System

IM Inner Marker

LDA Localizer-Type Directional Aid

LMM Compass Locator at the Middle Marker

LOC Localizer

LOM Compass Locator at the Outer Marker

MM Middle Marker

MSA Minimum Safe Altitude

NACO National Aeronautical Charting Office

NDB Non-directional radio beacon

OM Outer Marker

RTCA Radio Technical Commission for Aeronautics

SDF Simplified Directional Facility

SIDs Standard Instrument Departure charts

STARs Standard Instrument Arrival charts

TAA Terminal Arrival Area

TACAN Tactical Air Navigation, a military navigation facility

TSO Technical Standard Order

US United States

VFR Visual Flight Rules

VOR Very High Frequency (VHF) Omni-directional Radio Range

VORDME A joint VOR and DME facility

VORTAC A joint VOR and TACAN facility

This page left blank intentionally.

# Introduction 

This report describes a study designed to address four research
questions about electronic symbols for aeronautical charting
information. These symbols (e.g., navigation aids and
instrument-approach symbols) are shown on many different flight-deck
systems today. For example, moving map displays typically show
navigation aid symbols and other aeronautical charting information, such
as airspace boundaries. Electronic Flight Bags (EFBs) can also show
charting information on electronic aeronautical charts, which are
generally based on paper formats. (See Chandra, Yeh, Riley, & Mangold,
2003 for a discussion of electronic charts on EFBs.) Database-driven
electronic aeronautical charts that are intended to *replace* paper
charts are also in development. These sophisticated charts will provide
customizable electronic access to *all* information shown on paper
charts, including reference values that may only be used occasionally
(e.g., minimum altitudes for various situations).

The electronic symbols used on these systems sometimes vary
significantly. Although there are industry-recommended standards for
symbols on electronic displays of aeronautical charting information (see
Section 1.1 below), these standards are not always followed. In
addition, some of the symbols that are in use currently are not well
recognized by pilots (Yeh & Chandra, 2006).

The lack of consistency in chart and map symbology is not desirable from
a human factors perspective. When different symbols are used to
represent a single object or chart element, there is a risk of
confusion. This is especially true because pilots could be using
multiple sources of information at the same time (e.g., a moving map
display *and* a paper or electronic chart), and these sources may use
different symbology conventions. In addition, there is the risk of
conflict when two manufacturers use the same symbol to represent
different chart elements. Pilots could misinterpret a symbol if they
rely upon knowledge of a different manufacturer's charts or moving map
display. The variety of symbology in use also impacts the cost of pilot
training in the airlines because airline operators need to ensure that
pilots understand all of the symbology used. Even pilots who rent
aircraft are impacted because they may be exposed to different displays
and symbology with each rental.

Moving aeronautical charting symbology towards a higher level of
standardization would help alleviate the problems noted above. In
addition, standards could lower a manufacturer's development costs
because the manufacturer would not have to design and test new symbols,
and, if the standards are invoked or referenced by a regulatory
document, the manufacturer could be comfortable that the proposed
symbology would be found acceptable by their Civil Aviation Authority
(CAA).

In order to support the development of more standardized symbology for
electronic aeronautical charts and moving map displays, the SAE
International Aerospace Behavioral Engineering Technology Committee (SAE
G-10) Aeronautical Charting Committee, is updating Aerospace Recommended
Practices (ARP) 5289, *Electronic Aeronautical Symbols* (SAE, 1997).
This document contains recommendations for symbols that are primarily
shown on charts used during operations under Instrument Flight Rules
(IFR) (e.g., instrument approach plates, arrival and departure terminal
charts, and enroute charts), although some of the symbols are also found
on charts for use under Visual Flight Rules (VFR). The current ARP 5289
document also contains a table that illustrates the recommended symbol
set alongside the symbol sets in use by several major manufacturers of
paper charts and moving map displays. Line styles are also recommended
in the document (e.g., for the missed approach track and airspace
boundaries), and there are some general suggestions on using lines of
different weights (heavy, medium, and light).

With funding and support from the Federal Aviation Administration (FAA),
the John A. Volpe National Transportation Systems Center (Volpe Center)
is working with the SAE G-10 Aeronautical Charting Committee in their
efforts to update ARP 5289 (SAE, 1997). The Volpe Center's primary task
is to determine whether pilots can correctly identify the committee's
preliminary symbol proposals. In addition, other research issues related
to electronic symbols for charting information are explored.

Note this research effort is independent of the type of electronic
display on which the symbol is shown; the results are intended to apply
regardless of the display's intended function. Therefore, the
applicability of the results may be far reaching. Results of this
research are intended to be of use to the FAA, the International Civil
Aviation Organization (ICAO), and other CAAs. These organizations may
choose to adopt, by reference, the symbology recommendations developed
by the SAE G‑10 Aeronautical Charting Committee. The results of this
research are also intended to be of use to industry manufacturers who
develop and/or depict symbology.

Research issues in the design of electronic symbology were documented in
an earlier paper (Yeh and Chandra, 2004). Two earlier studies conducted
as part of this research program were documented in Yeh and Chandra
(2005). The most recent study is reported here. The research plans are
coordinated with the FAA sponsors and the SAE G-10 Aeronautical Charting
Committee. Real-world constraints, such as display technology and pilot
knowledge are considered during experiment design and data collection.

Background for the current research study is presented below. First,
existing design guidance for electronic symbology on displays is
presented. Next, goals for the updated industry recommendations document
are reviewed. Finally, one particularly relevant Volpe Center study on
electronic navigation-aid symbols is reviewed (Yeh and Chandra, 2006).

## Existing Guidance

Design guidance for electronic symbology is provided in RTCA (2003), SAE
(1997), and ICAO (2001).

RTCA DO-257A (RTCA, 2003), which is invoked by the FAA's Technical
Standard Order (TSO) C165 (FAA, 2003), provides requirements and
recommendations for the design of electronic map displays (EMDs). This
document includes some information on what symbology to show.
Specifically, RTCA DO-257A states that:

> *The EMD shall display distinctive symbols for different fix types
> (waypoints, airports, VORs, NDBs, intersections) and the aircraft
> (ownship).*
>
> *Notes:*
>
> *1. These symbols make up the minimum required symbol set, as listed
> in Table 2-1.*
>
> *2. If the input to the EMD does not distinguish between flight plan
> fix types (e.g., VOR vs. NDB), then the waypoint symbol is acceptable.
> However, if off-route fixes (e.g., VORs) are displayed, they must use
> the distinctive symbols appropriate for the fix type.*

The other two documents mentioned above provide recommendations for what
the symbol shapes should look like, if they are shown. The SAE
International ARP 5289 (SAE, 1997) provides industry recommendations for
electronic aeronautical chart symbology. The document contains
recommendations for both symbols and lines. ICAO Annex 4 (ICAO, 2001)
provides recommended symbology primarily for paper aeronautical charts,
but it also includes recommendations for a few electronic symbols, based
on the symbology in ARP 5289.

## Goals for Industry Recommendations Document

The recommended symbols in the current ARP 5289 (SAE, 1997) were
expected to be recognizable by qualified pilots. In addition, the
symbols were thought to be simple shapes that could be drawn on the
current display technology. Unfortunately, Yeh and Chandra (2006) found
that pilots did not recognize some of the recommended symbols.
Specifically pilots did not recognize the symbols recommended in ARP
5289 for the VOR, DME, TACAN, VORTAC, and VORDME. Also, in interviews
with manufacturers of moving map displays, it became clear that some of
the proposed symbols were difficult to draw on existing displays (e.g.,
the DME, VORDME, and NDB). Another reason for the lack of
standardization may be that the display manufacturers were not aware of
ARP 5289 because it was not invoked by an FAA or ICAO document. In any
case, some of the symbols recommended in ARP 5289 are not in widespread
use among manufacturers of electronic displays.

The SAE G-10 Aeronautical Charting Committee is now updating the
recommended symbol set in ARP 5289 with the goal of recommending
recognizable shapes that can be implemented on all displays. These
proposals are being tested to ensure that they are recognizable, and
input from display manufacturers is being sought to ensure that they can
implement the symbols.

The revised ARP 5289 will provide the same type of information as in the
1997 version of the document (SAE, 1997). Specifically, recommendations
will be made for several symbols that are used on various types of paper
charts and electronic displays of charting information. Guidance will
also be provided on line styles. This document will not address
recommendations with regard to color of the symbology; all of the sample
symbols in the document will be shown in black and white. This document
also does not specifically address issues unique to three‑dimensional
displays. A table of symbols currently in use by several manufacturers
will be provided in a separate document in preparation by the Volpe
Center, an industry review of symbology.

## Symbol Stereotypes for Navigation Aids

There are eight common navigation symbols shown on both aeronautical
charts and moving map displays: DME, intersection/fix, NDB, TACAN, VOR,
VOR/DME, VORTAC, and waypoint. Because of their importance, these eight
symbols were the first research priority. A study was conducted to
determine whether pilots recognized symbols for these eight navigation
aids (see Yeh and Chandra, 2005 for full details; Yeh and Chandra, 2006
provides a summary). The Volpe Center gathered symbol shapes for these
navigation aids, which were then in use, from several chart and display
manufacturers. Shapes that were recommended for use by ICAO and SAE
International (ICAO, 2001; SAE, 1997) were also included in the study.

The symbol shapes were placed into sets according to the type of
navigation aid symbol. That is, all the DME symbol shapes were grouped,
all the intersection/fix shapes were grouped, etc. Instrument-rated
pilots, including many airline pilots, were asked to consider each group
of symbol shapes separately. For example, the pilot might start with the
set of DME symbol shapes. Within the set, he/she considered each shape
one at a time, and decided whether it represented a DME or not (yes or
no). Data from 73 pilots were obtained and aggregated. A statistical
test was computed to determine whether a given symbol shape was
considered "representative" of the set or not. In general, symbols that
received a large number of *yes* responses were considered
*representative* and symbols that received a large number of *no*
responses were considered *unrepresentative*. Symbols with a mix of yes
and no responses were neither representative nor unrepresentative. For
details of the procedure and statistical test, see Yeh and Chandra
(2005).

The results of this task identified well-recognized (stereotypical)
symbol shapes for seven of the eight symbol types studied. The only
symbol that did not have a highly recognized shape was the stand-alone
DME. This was most likely because it is unusual to see a stand-alone
DME. Most DMEs are co-located with another navigation aid, such as a
VOR, and shown as a joint VORDME facility. Yeh and Chandra (2006) also
found that some symbol shapes that are in use today were considered to
be unrepresentative, largely because of their overall shape. Variations
in color, fill, and other details generally did not impede pilots'
ability to recognize the symbol.

The SAE G-10 Aeronautical Charting Committee plans to include the
navigation-aid symbol shapes that were found to be representative by Yeh
and Chandra (2006) in the revised ARP 5289 document, with one minor
modification to the NDB symbol shape. Some of the dots in the tested NDB
shape were deleted in order to make it easier to depict on electronic
displays. The revised symbol was retested in the study reported here. In
the case of the DME symbol, where no shape was statistically determined
to be representative, the committee plans to recommend a square, which
was one of the most familiar shapes for a stand-alone DME.

# Method

Having tested eight common navigation aid symbols in detail in the
previous study (Yeh and Chandra, 2006), the next research priority was
to determine whether pilots could identify other symbols proposed by the
industry committee for commonly seen elements (e.g., obstructions,
markers, localizers, as well as airports). Three other research
questions were also addressed in this study:

1)  [Labels for navigation aid symbols]{.underline}. Do labels increase
    the accuracy of identifying navigation aids?

2)  [Grouping navigation aids into families]{.underline}. What
    similarities do pilots see between navigation aids? How would pilots
    group the symbols into "families," where a family could be
    represented by a single "generic" symbol on the electronic display?

3)  [Line style conventions on paper charts and electronic moving map
    displays]{.underline}. Do pilots recognize line style conventions
    that are in use today on paper charts and electronic moving map
    displays?

Paper-and-pencil tasks were developed to address each of the four
research questions above and incorporated into a four-part survey (see
[Appendix A](#__RefHeading___Toc183840967)). The tasks for each of these
questions are described in detail later in the report. Participants in
the study and the general procedure for the study are described below.

## Participants

Ninety-six instrument rated pilots (88 male, 6 female, and 2 who did not
submit gender information) participated in the study. Almost all of the
participants (84) held an Air Transport Pilot (ATP) rating. Their flight
experience ranged from 800 to 25,000 flight hours, with an average of
8300 flight hours. The participants had a variety of flight experience,
though the majority (62) were active airline pilots. Seventeen pilots
had military flight experience, and 37 had either private business or
corporate flight experience.[^1] Many of the pilots had a mix of flight
experience. For example, some airline pilots also had military
experience.

Seventy-six pilots indicated that they primarily used charts from
Jeppesen and 20 indicated they primarily used charts from the United
States Government National Aeronautical Charting Office (NACO).
Ninety-one pilots indicated experience with glass cockpits, 90 with
Flight Management Systems (FMS) displays, and 82 with moving map
displays.

## Procedure

Pilots were recruited through the FAA, the Air Line Pilots Association
(ALPA), the military (specifically, the Air Force Advanced Instrument
School), and a local general aviation flying club. The study was
advertised in a short verbal or written announcement (e.g., at a meeting
or in a newsletter), and interested pilots were asked to contact the
Volpe Center to have a paper questionnaire mailed to them. Participants
did not receive any compensation for their participation.

Overall, 125 questionnaires were returned. Unfortunately, 29 of these
had to be discarded, in most cases because the consent forms were not
signed, leaving 96 useable responses.[^2] The bulk of the data came from
responses to an electronic newsletter posting to ALPA members, which
explains the high number of airline pilot participants. Only a few
questionnaires were obtained from purely general aviation pilots, for
whom the study was not broadly advertised. The overall response rate was
not tracked.[^3]

# Identification of Symbols

The goal of this task was to determine whether pilots could correctly
identify the symbols proposed by the SAE G-10 Aeronautical Charting
Committee. The committee constructed the test symbol set based on
symbols in use today. The proposed symbols may not be familiar to all
pilots because they were taken from a variety of sources. The group
intends to use the results of this study to help develop a final set of
recommended symbols. For background information on the symbols and how
they are used in flight operations, see two FAA reference documents (FAA
2007a, 2007b).

## Symbols Tested

The symbols were divided into two sections in the survey. The first
section included 18 general symbols, 16 of which were real and two of
which were fake symbols, called foils. The second section included eight
airport symbols, six of which were real and two of which were foils. The
foils were not real symbols, but they were *realistic* symbols.
Responses to the foil symbols provide insights into how familiar symbol
features might influence the recognition of unfamiliar shapes.

A list of the symbols tested is given in Table 1. One shape was tested
for most of the symbol types. However, two shapes were tested for three
particular symbols, the generic localizer, MSA, and NDB. In these cases,
two shapes were tested in order to provide the SAE G-10 Aeronautical
Charting Committee with more information about how pilots interpreted
the symbols, as explained further below.

+------------------------------------------+---------------------------+
| **General Symbols**                      | **Airport Symbols**       |
+------------------------------------------+---------------------------+
| Airport Beacon                           | > Civil airport           |
|                                          | >                         |
| Back Course localizer                    | > Closed airport          |
|                                          | >                         |
| Generic Localizer Candidates, 2 shapes   | > Heliport                |
| tested                                   | >                         |
|                                          | > Joint civil-military    |
| Holding Pattern                          | > airport                 |
|                                          | >                         |
| Locator Outer Marker (LOM)               | > Military airport        |
|                                          | >                         |
| Marker (same shape for inner, middle,    | > Seaport                 |
| and outer marker)                        |                           |
|                                          |                           |
| Minimum Safe Altitude (MSA), 2 shapes    |                           |
| tested                                   |                           |
|                                          |                           |
| Multiple High Obstruction                |                           |
|                                          |                           |
| Multiple Low Obstruction                 |                           |
|                                          |                           |
| Non-directional Beacon (NDB), 2 shapes   |                           |
| tested                                   |                           |
|                                          |                           |
| Single High Obstruction                  |                           |
|                                          |                           |
| Single Low Obstruction                   |                           |
|                                          |                           |
| Terminal Arrival Area (TAA)              |                           |
+------------------------------------------+---------------------------+

[]{#__RefHeading___Toc183841003 .anchor}Table 1. Symbols included in the
study.

### Selection Criteria

As explained earlier, shapes for seven common navigation aids (the DME,
intersection/fix, TACAN, VOR, VOR/DME, VORTAC, and waypoint) were tested
earlier and agreed upon based on that study (Yeh and Chandra, 2006), so
they were excluded from the current study.

Additional criteria for symbol selection are explained below. The test
symbol shapes are shown in the next section.

-   The NDB symbol was included in this study because it was suspected
    that the original shape identified as stereotypical for an NDB in
    Yeh & Chandra (2006), shown on the left in Table 2, could not be
    depicted easily on electronic displays. Therefore, a simplified
    version of the shape, shown in Table 2, was constructed and tested
    here. The SAE G-10 Aeronautical Charting Committee was interested to
    see whether results of the earlier study, that the NDB shape with
    the circular array of dots was more easily recognized, would be
    replicated with the less dense array of dots.

-   The two candidates for generic localizer symbols (i.e., shapes that
    represent either a front or back course localizer) were based on
    variants of similar symbols in use today, which are shaped like long
    narrow arrowheads. One of the generic localizer shapes tested is
    currently used by NACO to represent a Simplified Directional
    Facility (SDF) or Localizer-Type Directional Aid (LDA) approach,
    which are both uncommon procedures. The SAE G-10 Aeronautical
    Charting Committee was not sure whether that symbol was well known.
    If not, it could potentially be reassigned to indicate a generic
    localizer symbol. The second localizer shape had a similar outline
    as the first one, but included more detail.

-   Two MSA shapes were tested in order to obtain data to discriminate
    between reasonable alternatives: the current ICAO symbol, and the
    current NACO symbol.

-   Symbols whose shapes were so generic that they were not expected to
    be identifiable in isolation were generally excluded (e.g., a plain
    circle for an airport).

-   The joint military-civil-use heliport symbols was excluded from the
    study because it occurs rarely and was expected to be unfamiliar to
    most pilots, meaning that recognition frequency would not be
    informative. There is no current symbol in use for a "military
    heliport," although one of the two airport-foil symbols incorporated
    features of both a military airport (the double ring), and a civil
    heliport (the "H" in the center of the symbol).

-   The SAE G-10 Aeronautical Charting Committee did not have proposed
    symbols for use on the profile view of instrument approach charts
    ready for testing, so they were not considered.

  ----------------------------------------- ---------------------------------------
  **Original**                              **Simplified shape**

  ![](media/image5.png){width="0.34375in"   ![](media/image6.png){width="0.375in"
  height="0.3229166666666667in"}            height="0.3645833333333333in"}
  ----------------------------------------- ---------------------------------------

[]{#__RefHeading___Toc183841004 .anchor}Table 2. Original and simplified
NDB shapes.

### Test Symbol Shapes

The general symbol shapes selected for the study can be grouped into
four categories: NDB-LOM symbols, obstructions, localizers, and other
symbols. These groups are described below, and illustrated in the
accompanying tables. The airport symbols and foil shapes are also shown
below.

> **NDB-LOM Symbols** (Table 3). Three symbol types from the NDB-LOM
> family were tested: LOM, marker, and NDB. A simplified NDB shape, NDB
> (1) was included, as discussed above. In addition, a second NDB shape,
> NDB (2) was tested. NDB (2) is a double ring that is used on some
> electronic displays.
>
> **Obstructions** (Table 4). Four shapes representing obstructions were
> tested. The four shapes distinguish between the height of the
> obstruction (high vs. low), and whether the obstruction is a single
> object or group of objects. Note that not all chart providers
> currently distinguish between low and high obstructions via the symbol
> shape.
>
> **Localizers** (Table 5). Three shapes representing localizers were
> tested, one for the back course localizer, and two candidates for a
> generic localizer symbol, as discussed above.
>
> **Other Symbols** (Table 6). Five other shapes representing a beacon,
> holding pattern, MSA, and TAA were tested. Two shapes for an MSA were
> tested. The first shape, labeled MSA (1), is recommended by ICAO, and
> the second shape, labeled MSA (2), is used in FAA (NACO) charts.
>
> **Airport Symbols** (Table 7). The six airport symbol shapes tested
> are shown in Table 7.
>
> **Foil Shapes** (Table 8). The foil shapes are shown in Table 8. As
> noted above, these shapes are not currently in use, but they do
> incorporate features of real symbols.

  ---------------------------------------- ---------------------------------------------------- --------------------------------------- ----------------------------------------------------
  LOM                                      Marker                                               NDB (1)                                 NDB (2)

  ![](media/image7.png){width="0.5625in"   ![](media/image8.png){width="0.6041666666666666in"   ![](media/image6.png){width="0.375in"   ![](media/image9.png){width="0.3854166666666667in"
  height="0.3645833333333333in"}           height="0.20833333333333334in"}                      height="0.3645833333333333in"}          height="0.3958333333333333in"}
  ---------------------------------------- ---------------------------------------------------- --------------------------------------- ----------------------------------------------------

[]{#__RefHeading___Toc183841005 .anchor}Table 3. NDB-LOM symbols.

  ----------------------------------------------------- ------------------------------------------ ----------------------------------------------------- -----------------------------------------------------
  Low, single obstruction                               Low, group obstructions                    High, single obstruction                              High, group obstructions

  ![](media/image10.png){width="0.2708333333333333in"   ![](media/image11.png){width="0.34375in"   ![](media/image12.png){width="0.3229166666666667in"   ![](media/image13.png){width="0.4479166666666667in"
  height="0.2604166666666667in"}                        height="0.25in"}                           height="0.4583333333333333in"}                        height="0.46875in"}
  ----------------------------------------------------- ------------------------------------------ ----------------------------------------------------- -----------------------------------------------------

[]{#__RefHeading___Toc183841006 .anchor}Table 4. Obstructions symbols.

  ---------------------------------------------------------------------------------------------------------------------------------------------------
  Localizer\                                            Localizer (1)                           Localizer (2)
  Back Course                                                                                   
  ----------------------------------------------------- --------------------------------------- -----------------------------------------------------
  ![](media/image14.png){width="0.2604166666666667in"   ![](media/image15.png){width="0.25in"   ![](media/image16.png){width="0.2604166666666667in"
  height="1.8333333333333333in"}                        height="1.8333333333333333in"}          height="1.8333333333333333in"}

  ---------------------------------------------------------------------------------------------------------------------------------------------------

[]{#__RefHeading___Toc183841007 .anchor}Table 5. Localizers.

  ------------------------------------------------------ ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- -----------------------------------------------------
  Beacon                                                 Holding pattern                                       MSA (1)\                                              MSA (2)\                                              TAA
                                                                                                               ICAO Version                                          NACO Version                                          

  ![](media/image17.png){width="0.17708333333333334in"   ![](media/image18.png){width="0.9569444444444445in"   ![](media/image19.png){width="1.0986111111111112in"   ![](media/image20.png){width="1.0993055555555555in"   ![](media/image21.png){width="1.0979166666666667in"
  height="0.17708333333333334in"}                        height="0.43125in"}                                   height="0.8319444444444445in"}                        height="1.2034722222222223in"}                        height="0.6006944444444444in"}
  ------------------------------------------------------ ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------------------- -----------------------------------------------------

[]{#__RefHeading___Toc183841008 .anchor}Table 6. Other symbols.

  ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------- ---------------------------------------- ----------------------------------------------------- ------------------------------------------
  Civil                                                 Closed                                                Heliport                                  Joint Civil-Military                     Military                                              Seaport

  ![](media/image22.png){width="0.3958333333333333in"   ![](media/image23.png){width="0.3333333333333333in"   ![](media/image24.png){width="0.3125in"   ![](media/image25.png){width="0.375in"   ![](media/image26.png){width="0.2916666666666667in"   ![](media/image27.png){width="0.40625in"
  height="0.3854166666666667in"}                        height="0.3229166666666667in"}                        height="0.2916666666666667in"}            height="0.3541666666666667in"}           height="0.28125in"}                                   height="0.3854166666666667in"}
  ----------------------------------------------------- ----------------------------------------------------- ----------------------------------------- ---------------------------------------- ----------------------------------------------------- ------------------------------------------

[]{#__RefHeading___Toc183841009 .anchor}Table 7. Airport symbols.

  --------------------------- ----------------------------------------------------- -----------------------------------------------------
  Foils for\                  ![](media/image28.png){width="0.4166666666666667in"   ![](media/image29.png){width="0.3333333333333333in"
  General Symbols             height="0.4166666666666667in"}                        height="0.3020833333333333in"}

  Foils for\                  ![](media/image30.png){width="0.375in"                ![](media/image31.png){width="0.3541666666666667in"
  Airport Symbols             height="0.3645833333333333in"}                        height="0.375in"}
  --------------------------- ----------------------------------------------------- -----------------------------------------------------

[]{#__RefHeading___Toc183841010 .anchor}Table 8. Foil (i.e., fake)
shapes included in the study.

## Task

The test was conducted in the form of a paper-and-pencil survey. Pilots
were shown each symbol shape without any context, and asked to identify
and write (i.e., recall) what the shape represented, and how confident
they were in their response. Specifically, the instructions read:

> For each shape below, identify it and indicate your level of
> confidence in your response. Some of the symbols are unusual, so you
> may not recognize all the symbols. Write "?" if you do not know or
> can't tell.

+---------------+------------------------------------------------------+
| !             | Symbol Type (or ?):                                  |
| [](media/imag | \_\_\_\_\_\_                                         |
| e11.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
| h="0.34375in" |                                                      |
| hei           | 1 2 3 4 5 6 7\                                       |
| ght="0.25in"} | **Low Medium High**                                  |
|               |                                                      |
|               | **Confidence Confidence Confidence**                 |
+---------------+------------------------------------------------------+

[]{#__RefHeading___Toc183840985 .anchor}Figure 1. Example of general
symbol identification task.

+---------------+------------------------------------------------------+
| !             | Airport Type (or Can't Tell):                        |
| [](media/imag | \_\_\_\_\_\_                                         |
| e27.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
| h="0.40625in" |                                                      |
| heig          | 1 2 3 4 5 6 7\                                       |
| ht="0.3854166 | **Low Medium High**                                  |
| 666666667in"} |                                                      |
|               | **Confidence Confidence Confidence**                 |
+---------------+------------------------------------------------------+

[]{#__RefHeading___Toc183840986 .anchor}Figure 2. Example of airport
symbol identification task.

The second sentence was intended to reduce the chance that pilots would
be frustrated by the inclusion of symbols that they did not recognize
(i.e., the fake shapes, called foils).

Two examples are shown below in Figure 1 and Figure 2. For the general
symbols, the expected response was a name/description for the symbol
type (e.g., *group of obstacles*). For the airport symbols, participants
were asked to identify the *type* of airport. In other words,
participants were told that the symbol represented an airport, and they
were asked to provide more details about the kind of airport that was
depicted (e.g., "seaport").

## Analysis Process

Responses for the symbol identification task varied because participants
could write in any response. In order to make sense of this variety,
response *categories* were constructed for each symbol, based on the
range of individual responses found for that symbol. For the general
symbols, each individual response was then sorted into *one* of the
response categories. For details on the process of coding the data for
the general symbols into response categories, see [Appendix
B](#__RefHeading___Toc183840970). For the airport symbols, response
categories were framed in terms of properties mentioned about the
airport, and participants' responses were sorted according to the
attributes mentioned. Some responses mentioned more than one attribute,
in which case the response was counted towards both attributes. For
example, a response such as *controlled airport with services* was
counted towards both the *Air Traffic Control* category and the
*Services* categories.

Tables showing the frequency of responses in each category were then
constructed. These tables illustrate the range of responses but, by
themselves, do not indicate whether the responses were "correct" or
"acceptable." In order to assess whether the responses were acceptable,
a judgment call was made by the subject-matter-experts in the SAE G-10
Aeronautical Charting Committee. For example, for the obstruction
symbol, the *Manmade Structure* response category was judged to be an
acceptable response, but the *Terrain* response was not, because terrain
is represented differently (e.g., by shaded contours). In some cases,
however, acceptability of a response was not clear-cut. There were some
responses that were understandable, but not technically correct. These
situations are discussed further below, as they arise.

Results of the analysis indicate which symbols were well recognized and
which were confusing. Symbols that were well recognized had a high
proportion of responses in the correct response category, and their
average confidence ratings were high relative to those for the confusing
symbols. Symbols that were confusing either had responses that were
spread out over several different response categories, or had a
substantial proportion of responses in an incorrect category. The
confusing symbols also typically had a high rate of *Can't Tell* and/or
missing responses.

## Results

The holding pattern and the two MSA shapes were recognized by all or
nearly all of the participants with high confidence. The holding pattern
and MSA (1), the ICAO version in Table 6, were both identified correctly
by 100% of the pilots. The average confidence rating for the holding
pattern was 6.67 out of 7, and 6.6 out of 7 for MSA (1). MSA (2), the
NACO version in Table 6, was identified correctly by 97% of participants
and had an average confidence rating of 6.37. Responses to the two MSA
shapes differed slightly in that more of the responses to MSA (2)
mentioned detail about its center point (26% versus 14% for MSA (1)).

Three other general shapes were well recognized: the Marker, NDB (1),
and the LOM. Detailed results for these shapes are given in Table 9. The
Marker shape was identified correctly by 90% of pilots, with an average
confidence of 6.0 out of 7. In coding responses to the Marker symbol,
distinctions between the inner marker, middle marker, and outer marker
were ignored, because the same symbol shape is planned to be recommended
for all of these elements. NDB (1), the shape with the circular array of
dots, was identified as an NDB by 83% of pilots, with an average
confidence of 6.01. This finding confirms that the simplified shape for
the NDB symbol tested here is sufficiently similar to the more detailed
shape identified as stereotypical for the NDB in Yeh and Chandra (2006).
The LOM shape was identified correctly by 70% of pilots with an average
confidence of 6.17. There were no missing responses for these three
shapes.

+---------+---------------+-----------------------------+--------------+
| **S     | **Mean        | **Response Categories**     | **Frequency\ |
| ymbol** | Confidence    |                             | (% of        |
|         | Rating (Max   |                             | Responses)** |
|         | 7)**          |                             |              |
+=========+===============+=============================+==============+
| **M     | 6.0           | A.  Marker, Marker Beacon,  | > **90%**    |
| arker** |               |     MM, OM, IM, fan marker, |              |
|         |               |     beacon alone            |              |
| !       |               |                             |              |
| [](medi |               |                             |              |
| a/image |               |                             |              |
| 8.png){ |               |                             |              |
| width=" |               |                             |              |
| 0.60416 |               |                             |              |
| 6666666 |               |                             |              |
| 6666in" |               |                             |              |
| hei     |               |                             |              |
| ght="0. |               |                             |              |
| 2083333 |               |                             |              |
| 3333333 |               |                             |              |
| 334in"} |               |                             |              |
+---------+---------------+-----------------------------+--------------+
|         |               | B.  Other                   | > 4%         |
+---------+---------------+-----------------------------+--------------+
|         |               | Both A and B                | > 3%         |
+---------+---------------+-----------------------------+--------------+
|         |               | Can't Tell                  | > 3%         |
+---------+---------------+-----------------------------+--------------+
| **NDB   | 6.01          | NDB/ADF[^4], compass        | > **83%**    |
| (1)**   |               | locator, beacon             |              |
|         |               |                             |              |
| ![      |               |                             |              |
| ](media |               |                             |              |
| /image6 |               |                             |              |
| .png){w |               |                             |              |
| idth="0 |               |                             |              |
| .375in" |               |                             |              |
| he      |               |                             |              |
| ight="0 |               |                             |              |
| .364583 |               |                             |              |
| 3333333 |               |                             |              |
| 333in"} |               |                             |              |
+---------+---------------+-----------------------------+--------------+
|         |               | Other                       | > 4%         |
+---------+---------------+-----------------------------+--------------+
|         |               | Can't Tell                  | > 13%        |
+---------+---------------+-----------------------------+--------------+
| **LOM** | 6.17          | LOM, LMM, NDB and marker,   | > **70%**    |
|         |               | compass locator with marker |              |
| ![]     |               |                             |              |
| (media/ |               |                             |              |
| image7. |               |                             |              |
| png){wi |               |                             |              |
| dth="0. |               |                             |              |
| 5625in" |               |                             |              |
| he      |               |                             |              |
| ight="0 |               |                             |              |
| .364583 |               |                             |              |
| 3333333 |               |                             |              |
| 333in"} |               |                             |              |
+---------+---------------+-----------------------------+--------------+
|         |               | Compass locator alone,      | > 13%        |
|         |               | beacon alone                |              |
+---------+---------------+-----------------------------+--------------+
|         |               | Marker alone                | > 10%        |
+---------+---------------+-----------------------------+--------------+
|         |               | NDB alone                   | > 1%         |
+---------+---------------+-----------------------------+--------------+
|         |               | Other                       | > 1%         |
+---------+---------------+-----------------------------+--------------+
|         |               | Can't Tell                  | > 5%         |
+---------+---------------+-----------------------------+--------------+

[]{#__RefHeading___Toc183841011 .anchor}Table 9. Results for the NDB-LOM
family symbol shapes.

Among the airport symbols, almost all participants correctly identified
the heliport, closed-airport, and seaport shapes. Specifically, the
heliport shape was identified by 98% of participants, with an average
confidence of 6.31 out of 7; the shape representing a closed airport was
identified by 95% of participants with an average confidence of 6.0; and
the shape representing a seaport was identified by 94% of pilots with an
average confidence of 5.93.

The remaining symbols, which received more varied responses, are
discussed in the next several sections.

### Obstruction Shapes

Responses to symbol shapes representing obstructions are shown in Table
10. The results indicate that participants were generally able to
identify these symbol shapes as either *Obstructions* or *Manmade
Structures* and they did so with a fairly high degree of confidence.

The SAE G-10 Aeronautical Charting Committee judged that either of these
response categories *(Obstruction* or *Manmade Structure)* was
acceptable. However, the committee did not intend for these symbols to
represent a natural obstacle, such as terrain, and that response
category was considered to be unacceptable. A small but significant
number of *Terrain* responses to the two "low" symbols were therefore an
indicator that those symbol shapes are potentially misleading. Neither
of the two "high" symbols yielded any *Terrain* responses. These results
are likely because of the potential inference that the low-obstruction
symbol resembles a mountain peak, whereas the high-obstruction symbol
resembles a manmade tower.

Responses to the obstruction symbol shapes were also examined to
determine the number of pilots who correctly reported *detail* about the
meaning of the symbol. Specifically, detail about the height (low versus
high) and multiplicity (single versus group) of the obstruction was
examined. Table 11 below shows that, regardless of the shape of the
symbol, correct detail about the number of obstructions (single versus
group) was reported more often than correct detail about the height of
the obstructions (74% versus 34% of the time). This implies that the
height of the obstruction was not conveyed by the symbol shape as well
as information about the number of objects.

+------------------------+----------+----------+----------+----------+
| **Response             | > **F    |          |          |          |
| Categories**           | requency |          |          |          |
|                        | > (% of  |          |          |          |
|                        | > Resp   |          |          |          |
|                        | onses)** |          |          |          |
+========================+==========+==========+==========+==========+
|                        | > **Low  | > **Low  | > **High | > **High |
|                        | >        | > Group\ | >        | > Group\ |
|                        |  Single\ | > Obstr  |  Single\ | > Obstr  |
|                        | > Obstr  | uction** | > Obstr  | uction** |
|                        | uction** | >        | uction** |          |
|                        | >        | >        |          | ![]      |
|                        | > ![]    | ![](medi | ![]      | (media/i |
|                        | (media/i | a/image1 | (media/i | mage13.p |
|                        | mage10.p | 1.png){w | mage12.p | ng){widt |
|                        | ng){widt | idth="0. | ng){widt | h="0.447 |
|                        | h="0.270 | 34375in" | h="0.322 | 91666666 |
|                        | 83333333 | >        | 91666666 | 66667in" |
|                        | 33333in" | height=" | 66667in" | hei      |
|                        | > height | 0.25in"} | height   | ght="0.4 |
|                        | ="0.2604 |          | ="0.4583 | 6875in"} |
|                        | 16666666 |          | 33333333 |          |
|                        | 6667in"} |          | 3333in"} |          |
+------------------------+----------+----------+----------+----------+
| A.  Obstruction        | > 52%    | > 46%    | > 29%    | > 33%    |
+------------------------+----------+----------+----------+----------+
| B.  Manmade Structures | > 30%    | > 29%    | > 62%    | > 56%    |
+------------------------+----------+----------+----------+----------+
| C.  Terrain            | > 8%     | > 13%    | > \--    | \--      |
+------------------------+----------+----------+----------+----------+
| Both A and B           | > 3%     | > 4%     | > 4%     | > 1%     |
+------------------------+----------+----------+----------+----------+
| Both A and C           | > 2%     | > 5%     | > \--    | \--      |
+------------------------+----------+----------+----------+----------+
| Both B and C           | > 1%     | 1%       | > 1%     | 1%       |
+------------------------+----------+----------+----------+----------+
| Other                  | > 1%     | > \--    | > \--    | > \--    |
+------------------------+----------+----------+----------+----------+
| Missing                | > 2%     | > 2%     | > 3%     | > 8%     |
+------------------------+----------+----------+----------+----------+
| **Overall Frequency    | >        | >        | >        | >        |
| of\                    |  **85%** |  **79%** |  **95%** |  **90%** |
| Acceptable Responses\  |          |          |          |          |
| (**A, B, or Both A &   |          |          |          |          |
| B)                     |          |          |          |          |
+------------------------+----------+----------+----------+----------+
| **Mean Confidence      | > 5.96   | > 6.08   | > 6.20   | > 6.19   |
| Rating (Max 7)**       |          |          |          |          |
+------------------------+----------+----------+----------+----------+

[]{#__RefHeading___Toc183841012 .anchor}Table 10. Results for
obstruction symbol shapes.

+----------------+----------+---------+---------+---------+---------+
| **Response     | *        | > **Fre |         |         |         |
| Details**      | *Overall | quency\ |         |         |         |
|                | Fre      | > (% of |         |         |         |
|                | quency** | > Re    |         |         |         |
|                |          | sponses |         |         |         |
|                |          | > with  |         |         |         |
|                |          | > the   |         |         |         |
|                |          | > de    |         |         |         |
|                |          | tail)** |         |         |         |
+================+==========+=========+=========+=========+=========+
|                |          | > **Low | > **Low | >       | >       |
|                |          | >       | >       |  **High |  **High |
|                |          | Single\ |  Group\ | >       | >       |
|                |          | >       | >       | Single\ |  Group\ |
|                |          |  Obstru |  Obstru | >       | >       |
|                |          | ction** | ction** |  Obstru |  Obstru |
|                |          | >       | >       | ction** | ction** |
|                |          | > ![    | > ![](m |         |         |
|                |          | ](media | edia/im | ![      | ![      |
|                |          | /image1 | age11.p | ](media | ](media |
|                |          | 0.png){ | ng){wid | /image1 | /image1 |
|                |          | width=" | th="0.3 | 2.png){ | 3.png){ |
|                |          | 0.27083 | 4375in" | width=" | width=" |
|                |          | 3333333 | > he    | 0.32291 | 0.44791 |
|                |          | 3333in" | ight="0 | 6666666 | 6666666 |
|                |          | > he    | .25in"} | 6667in" | 6667in" |
|                |          | ight="0 |         | he      | heigh   |
|                |          | .260416 |         | ight="0 | t="0.46 |
|                |          | 6666666 |         | .458333 | 875in"} |
|                |          | 667in"} |         | 3333333 |         |
|                |          |         |         | 333in"} |         |
+----------------+----------+---------+---------+---------+---------+
| Reports of     | 70%      | > 69%   | > 63%   | > 71%   | > 78%   |
| Number Detail\ |          |         |         |         |         |
| (single versus |          |         |         |         |         |
| group)         |          |         |         |         |         |
+----------------+----------+---------+---------+---------+---------+
| Reports of     | 34%      | > 26%   | > 22%   | > 49%   | > 38%   |
| Height Detail\ |          |         |         |         |         |
| (low versus    |          |         |         |         |         |
| high)          |          |         |         |         |         |
+----------------+----------+---------+---------+---------+---------+

[]{#__RefHeading___Toc183841013 .anchor}Table 11. Reports of obstruction
details.

### Localizer Shapes

Responses to the localizer shapes are shown in Table 12 below. A
majority of participants (65%) correctly identified the symbol shape
representing a back-course localizer as a *Localizer*. Almost half of
these correct responses (31% of the total responses) included correct
detail, that the shape represented a *back course*. The second most
common response for the back-course localizer symbol shape was *ILS*,
given by 28% of pilots. The ILS response was considered to be incorrect
by the SAE G-10 Aeronautical Charting Committee because the real ILS
shape, which indicates availability of vertical guidance, is completely
shaded or screened, not just shaded or screened on one side, as was the
symbol tested in this study. However, the ILS symbol and the localizer
symbol shapes do have a common outline. In addition, instrument approach
charts with ILS procedures show a relatively large localizer symbol on
the plan view (i.e., birds-eye view) of the chart, and they show a
relatively smaller ILS symbol in the profile view of the chart, which
depicts altitudes for the descent. Although incorrect, it is
understandable that some pilots interpreted the localizer symbol to be
an ILS symbol because of the prominence of the localizer shape on the
instrument approach chart that is labeled as an ILS procedure. Note also
that participants indicated a high confidence in their responses to the
back-course localizer symbol shape.

Responses to the Localizer (1) and Localizer (2) shapes are more varied
than responses to the back-course localizer shape. As mentioned earlier,
these two shapes are candidates for the generic localizer shape.
Localizer (1) is the shape currently used as an *SDF/LDA* shape on NACO
charts, and 24% of pilots correctly identified it as such. This is an
unexpectedly high rate of recognition for such an uncommonly used symbol
and procedure. Just 22% of pilots responded in the way that the SAE G-10
Aeronautical Charting Committee expected, calling Localizer (1) a
*Localizer*. An even larger proportion, 36% of pilots, said they could
not tell what the shape represented. Given the number of *Can't Tell*
and SDF/LDA responses, this symbol is confusing at best.

Responses to the Localizer (2) shape leaned more favorably towards the
expected *Localizer* response (42%). Fewer pilots confused this shape
with an *SDF/LDA* (10%), or with an *ILS* (10%). In addition, there was
a moderate rate of *Can't Tell* (17%); this was better than the 36% rate
for Localizer (1), but worse than the 1% rate obtained for the
back-course localizer shape.

+-----------------------+--------------+--------------+--------------+
| **Response            | **Localizer\ | **Localizer  | **Localizer  |
| Categories**          | Back         | (1)**        | (2)**        |
|                       | Course**     |              |              |
|                       |              | !            | ![]          |
|                       | ![]          | [](media/ima | (media/image |
|                       | (media/image | ge15.png){wi | 16.png){widt |
|                       | 14.png){widt | dth="0.25in" | h="0.2604166 |
|                       | h="0.2604166 | height       | 666666667in" |
|                       | 666666667in" | ="1.83333333 | height       |
|                       | height       | 33333333in"} | ="1.83333333 |
|                       | ="1.83333333 |              | 33333333in"} |
|                       | 33333333in"} |              |              |
+=======================+==============+==============+==============+
| A.  Localizer         | > 65%        | > 22%        | > 42%        |
+-----------------------+--------------+--------------+--------------+
| B.  SDF/LDA           | > \--        | > 24%        | > 10%        |
+-----------------------+--------------+--------------+--------------+
| C.  ILS               | > 28%        | > 3%         | > 10%        |
+-----------------------+--------------+--------------+--------------+
| D.  Other             | > 2%         | > 7%         | > 9%         |
+-----------------------+--------------+--------------+--------------+
| E.  Can't Tell        | > 1%         | > 36%        | > 17%        |
+-----------------------+--------------+--------------+--------------+
| Both A and B          | > \--        | > 1%         | > 4%         |
+-----------------------+--------------+--------------+--------------+
| Both A and C          | > 4%         | > 1%         | > 3%         |
+-----------------------+--------------+--------------+--------------+
| Both B and D          | > \--        | > 1%         | > \--        |
+-----------------------+--------------+--------------+--------------+
| A, B, C, and D        | > \--        | > \--        | 1%           |
+-----------------------+--------------+--------------+--------------+
| Missing               | > \--        | > 4%         | > 3%         |
+-----------------------+--------------+--------------+--------------+
| **Mean Confidence     | **6.43**     | **4.52**     | **4.91**     |
| Rating\               |              |              |              |
| (Max 7)**             |              |              |              |
+-----------------------+--------------+--------------+--------------+

[]{#__RefHeading___Toc183841014 .anchor}Table 12. Results for localizer
symbol shapes.

There is also another, more positive, way to interpret the
identification rates for the two generic localizer candidates. The rates
of identification, while low relative to other more familiar symbols,
could be seen as relatively good, considering that the symbols are new
to pilots. This point of view assumes that pilots are highly attuned to
all the details in a symbol, and the fact that they were able to
extrapolate their knowledge to these test symbols was not necessarily
expected. In other words, *despite* their novelty, the familiar outlines
of the two localizer-symbol shapes did help some pilots to infer their
meaning as expected by the industry committee.

### Confusing General Symbols

Responses for the NDB (2), TAA, and Beacon symbol shapes varied. Results
for these shapes are shown in Table 13.

The most common response for NDB (2) was *Can't Tell* (42%). The shape
was identified as either a military or generic airport by 33% of pilots.
In fact, the shape is very similar to that of a military airport (also a
double circle, but with a less space between the two circles), and
somewhat similar to the generic airport symbol (a single circle) that is
used by some display manufacturers. The instructions did not say that
airport symbols were excluded, so, without any other context, the
airport response is not unreasonable. Although some transport display
manufacturers do use this shape to represent an NDB, it was identified
as an NDB by just 8% of pilots. NDBs are rarely used in commercial
operations, so the airline pilots in this study probably had little, if
any, experience with this shape in that context. With an average rating
of 4.17, pilot confidence was low for NDB (2), confirming its
unfamiliarity.

The most common response to the TAA shape shown in Table 13 was *MSA*
(58%). The symbol shape for a TAA was described correctly by just 14% of
participants. TAAs may not be as familiar to pilots as MSAs because they
are used only on area navigation (RNAV) approaches. The MSA is visually
similar to a TAA symbol (see Table 6), but an MSA is, in fact, different
from a TAA (see FAA, 2007a and 2007b). Both the TAA and MSA provide
obstacle clearance, but in addition, a TAA provides altitude information
for the transition from the enroute structure to the terminal area with
minimal air traffic control communications.

The most common response to the star shape shown in Table 13 was *Can't
Tell* (47%). The star shape was intended to represent an airport beacon,
but was described correctly as such by only 30% of participants. A few
participants made responses that could be associated with the symbol
shape (control tower, or facility not in continuous operation). Often, a
text label is shown next to the star shape to provide context. Without
the symbol or label, the beacon symbol may have lost much of its
meaning.

+-------------+----------------+-----------------------+---+--------------+
| **Symbol**  | **Mean         | **Response            |   | **Frequency\ |
|             | Confidence     | Categories**          |   | (% of        |
|             | Rating (Max    |                       |   | Responses)** |
|             | 7)**           |                       |   |              |
+=============+================+=======================+===+==============+
| **NDB (2)** | 4.17           | NDB/ADF, compass      | > |              |
|             |                | locator, beacon       |   |              |
| ![](me      |                |                       | 8 |              |
| dia/image9. |                |                       | % |              |
| png){width= |                |                       |   |              |
| "0.38541666 |                |                       |   |              |
| 66666667in" |                |                       |   |              |
| height="    |                |                       |   |              |
| 0.395833333 |                |                       |   |              |
| 3333333in"} |                |                       |   |              |
+-------------+----------------+-----------------------+---+--------------+
|             |                | Military Airport      | > |              |
|             |                |                       |   |              |
|             |                |                       | 1 |              |
|             |                |                       | 4 |              |
|             |                |                       | % |              |
+-------------+----------------+-----------------------+---+--------------+
|             |                | Airport (generic)     | > |              |
|             |                |                       |   |              |
|             |                |                       | 1 |              |
|             |                |                       | 9 |              |
|             |                |                       | % |              |
+-------------+----------------+-----------------------+---+--------------+
|             |                | Other                 | > |              |
|             |                |                       |   |              |
|             |                |                       | 1 |              |
|             |                |                       | 5 |              |
|             |                |                       | % |              |
+-------------+----------------+-----------------------+---+--------------+
|             |                | Can't Tell            | > |              |
|             |                |                       |   |              |
|             |                |                       | 4 |              |
|             |                |                       | 2 |              |
|             |                |                       | % |              |
+-------------+----------------+-----------------------+---+--------------+
|             |                | Missing               | > |              |
|             |                |                       |   |              |
|             |                |                       | 3 |              |
|             |                |                       | % |              |
+-------------+----------------+-----------------------+---+--------------+
| **TAA**     | 5.47           | TAA/Terminal Arrival  |   | > 14%        |
|             |                | Area/Terminal Arrival |   |              |
| ![](med     |                | Altitude              |   |              |
| ia/image21. |                |                       |   |              |
| png){width= |                |                       |   |              |
| "1.09791666 |                |                       |   |              |
| 66666667in" |                |                       |   |              |
| height="    |                |                       |   |              |
| 0.600694444 |                |                       |   |              |
| 4444444in"} |                |                       |   |              |
+-------------+----------------+-----------------------+---+--------------+
|             |                | MSA                   |   | > 58%        |
+-------------+----------------+-----------------------+---+--------------+
|             |                | Other                 |   | > 14%        |
+-------------+----------------+-----------------------+---+--------------+
|             |                | Can't Tell            |   | > 10%        |
+-------------+----------------+-----------------------+---+--------------+
|             |                | Missing               |   | > 4%         |
+-------------+----------------+-----------------------+---+--------------+
| **Beacon**  | 4.98           | A.  Airport Beacon    |   | > 30%        |
|             |                |                       |   |              |
| > ![](medi  |                |                       |   |              |
| a/image17.p |                |                       |   |              |
| ng){width=" |                |                       |   |              |
| 0.177083333 |                |                       |   |              |
| 33333334in" |                |                       |   |              |
| > height="0 |                |                       |   |              |
| .1770833333 |                |                       |   |              |
| 3333334in"} |                |                       |   |              |
+-------------+----------------+-----------------------+---+--------------+
|             |                | B.  Control tower     |   | > 4%         |
+-------------+----------------+-----------------------+---+--------------+
|             |                | C.  Facility not in   |   | > 7%         |
|             |                |     continuous        |   |              |
|             |                |     operation         |   |              |
+-------------+----------------+-----------------------+---+--------------+
|             |                | D.  Other             |   | > 8%         |
+-------------+----------------+-----------------------+---+--------------+
|             |                | E.  Can't Tell        |   | > 47%        |
+-------------+----------------+-----------------------+---+--------------+
|             |                | A and B               |   | > 1%         |
+-------------+----------------+-----------------------+---+--------------+
|             |                | A, B, and C           |   | > 1%         |
+-------------+----------------+-----------------------+---+--------------+
|             |                | Missing               |   | > 1%         |
+-------------+----------------+-----------------------+---+--------------+

[]{#__RefHeading___Toc183841015 .anchor}Table 13. Results for other
symbols.

### Confusing Airport Symbols

There was variability amongst the responses to the symbol shapes for
civil, military, and joint civil-military airports. Responses for these
symbols are given in Table 14. Recall that, for airports, a single
response might have been counted towards more than one category, so the
sum of the percentages in each column can exceed 100%.

As Table 14 shows, less than half the participants identified the
distinction between the proposed shapes for military (42%), civil (30%),
and joint civil-military (23%) airports. While it may be argued that the
distinction between civil and military airports is important primarily
to military pilots, examination of the data from pilots with military
experience only showed no better identification of these symbols.
Participants' confidence in their responses to these three airport
symbols was generally neutral.

It is likely that these differences are not often pertinent to flight
operations, particularly for the majority of the participants who were
airline pilots. As a result, pilots may not have much experience
distinguishing between these civil, military, and joint-use airports.

It is interesting to note that the feature used by NACO charts to
represent services such as fuel at the airfield (i.e., squares at the
0º, 90º, 180º, and 270º points) were relatively well identified. Detail
regarding *services*, *facilities*, or *fuel* was included in the
responses of 32% of pilots for the civil airport symbol, 25% for the
joint civil-military airport symbol, and 19% for the seaport symbol.

+----------------------------+-------------+-------------+-------------+
| **Response Category**      | **Civil**   | *           | **Joint     |
|                            |             | *Military** | civil       |
|                            | ![](med     |             | -military** |
|                            | ia/image22. | ![](med     |             |
|                            | png){width= | ia/image26. | ![](m       |
|                            | "0.39583333 | png){width= | edia/image2 |
|                            | 33333333in" | "0.29166666 | 5.png){widt |
|                            | height="    | 66666667in" | h="0.375in" |
|                            | 0.385416666 | height="    | height="    |
|                            | 6666667in"} | 0.28125in"} | 0.354166666 |
|                            |             |             | 6666667in"} |
+============================+=============+=============+=============+
| Correct Airport Type       | > 30%       | > 42%       | > 23%       |
+----------------------------+-------------+-------------+-------------+
| Services                   | > 32%       | > 4%        | > 25%       |
+----------------------------+-------------+-------------+-------------+
| Runway parameter (length   | > 17%       | > 6%        | > 9%        |
| or surface)                |             |             |             |
+----------------------------+-------------+-------------+-------------+
| Air Traffic Control        | > 5%        | > 5%        | > 6%        |
+----------------------------+-------------+-------------+-------------+
| IFR/VFR                    | > 3%        | > 3%        | > 2%        |
+----------------------------+-------------+-------------+-------------+
| Other (including incorrect | > 9%        | > 11%       | > 22%       |
| airport type)              |             |             |             |
+----------------------------+-------------+-------------+-------------+
| Can't Tell                 | > 18%       | > 31%       | > 34%       |
+----------------------------+-------------+-------------+-------------+
| Missing                    | > 2%        | > 1%        | > 4%        |
+----------------------------+-------------+-------------+-------------+
| **Mean Confidence Rating\  | **5.37**    | **5.06**    | **4.78**    |
| (Max 7)**                  |             |             |             |
+----------------------------+-------------+-------------+-------------+

[]{#__RefHeading___Toc183841016 .anchor}Table 14. Responses for symbols
representing civil, military, or joint-use airports.

### Foils

The starburst-shaped foil in shown in Table 8 was not identified by 86%
of participants; 75% of pilots said *Can't Tell* and another 11%
provided no response. Those few who did provide a response indicated
that the shape represented some type of hazard area (5%), some special
kind of waypoint (5%), or some type of lighted object (3%). There is
some logic to these guesses, based on the physical shape of the object,
but clearly it is not a compelling fake symbol.

Thirty-seven percent of participants did not identify the three-pointed
star foil shape in Table 8 (32% said *Can't Tell* and 5% provided no
response), but 53% of the participants did call it a waypoint. In a
previous study (Yeh & Chandra, 2006) the stereotypical shape for a
waypoint was identified as a four-pointed star; a three-pointed star,
which was included as a foil in that study was not considered to be
representative of a waypoint based on a statistical test.

The airport foil that included components of a military airport symbol
and civil heliport symbol in Table 8 was determined to be a heliport of
some sort by 59% of participants. Of these, almost half (44%) said that
the symbol represented a military heliport. Thus, a significant number
of respondents (26% of the total sample) used the two familiar features
of the symbols to create a logical response, even though such an airport
is actually fictional; no unique symbol for military heliport is in use.
Note also that 33% of participants gave a *Can't Tell* response, and 2%
did not answer the question. While these rates may seem high, they are,
in fact, similar to the Can't Tell and missing rates for the real civil,
military, and joint civil-military airport symbols shown in Table 14.

The last foil shape, a circle with two crossing lines in it also
received some interesting responses. The most common responses focused
on the two crossing lines, which had the appearance of runways. Runway
properties such as configuration, length, or surface type were mentioned
in 43% of responses. The second most common response (20%) referred to
the user of the airfield (e.g., civil/military, private, or glider
airport). One-quarter (25%) of responses were *Can't Tell*, and 2% of
responses were missing for this foil shape.

## Summary of Results for Symbol Identification Task

The results for the general symbol shapes are summarized in Table 15
below, which shows the most well recognized symbols towards the top, and
the most confusing symbols towards the bottom. Results for the airport
symbol identification task are summarized in a similar manner in Table
16. Symbols that were recognized 70% of the time or better just show the
percent of correct responses. Peaks in the response distribution are
presented for symbols that were less well recognized. The last five
symbols in Table 15 are considered to be problematic relative to the
others in the test because their responses are more varied. These
shapes, discussed in detail above, are: the two candidates for a generic
localizer, Localizer (1) and Localizer (2), the airport beacon, the TAA,
and one of the two NDB shapes, NDB (2).

+-------------+--------------------------+--------------+-------------+
| **Name of   | **Symbol Shape**         | **Peaks in   | **Mean      |
| Symbol**    |                          | Response     | Confidence  |
|             |                          | Di           | Rating\     |
|             |                          | stribution** | (Max 7)**   |
+-------------+--------------------------+--------------+-------------+
| Holding     | ![]                      | 100% correct | 6.67        |
| Pattern     | (media/image18.png){widt |              |             |
|             | h="0.9569444444444445in" |              |             |
|             | height="0.43125in"}      |              |             |
+-------------+--------------------------+--------------+-------------+
| MSA (1)     | ![]                      | 100% correct | 6.6         |
|             | (media/image19.png){widt |              |             |
| (ICAO       | h="1.0986111111111112in" |              |             |
| version)    | height                   |              |             |
|             | ="0.8319444444444445in"} |              |             |
+-------------+--------------------------+--------------+-------------+
| MSA (2)     | ![]                      | 97% correct  | 6.37        |
|             | (media/image20.png){widt |              |             |
| (NACO       | h="1.0993055555555555in" |              |             |
| version)    | height                   |              |             |
|             | ="1.2034722222222223in"} |              |             |
+-------------+--------------------------+--------------+-------------+
| Multiple    | ![]                      | 95% correct  | 6.19        |
| High        | (media/image13.png){widt |              |             |
| Obstruction | h="0.4479166666666667in" |              |             |
|             | height="0.46875in"}      |              |             |
+-------------+--------------------------+--------------+-------------+
| Marker      | ![                       | 90% correct  | 6.00        |
|             | ](media/image8.png){widt |              |             |
|             | h="0.6041666666666666in" |              |             |
|             | height=                  |              |             |
|             | "0.20833333333333334in"} |              |             |
+-------------+--------------------------+--------------+-------------+
| Single High | ![]                      | 90% correct  | 6.20        |
| Obstruction | (media/image12.png){widt |              |             |
|             | h="0.3229166666666667in" |              |             |
|             | height                   |              |             |
|             | ="0.4583333333333333in"} |              |             |
+-------------+--------------------------+--------------+-------------+
| Single Low  | ![]                      | 85% correct  | 5.96        |
| Obstruction | (media/image10.png){widt |              |             |
|             | h="0.2708333333333333in" |              |             |
|             | height                   |              |             |
|             | ="0.2604166666666667in"} |              |             |
+-------------+--------------------------+--------------+-------------+
| NDB (1)     | ![](media/ima            | 83% correct  | 6.01        |
|             | ge6.png){width="0.375in" |              |             |
|             | height                   |              |             |
|             | ="0.3645833333333333in"} |              |             |
+-------------+--------------------------+--------------+-------------+
| Multiple    | ![](media/image1         | 79% correct  | 6.08        |
| Low         | 1.png){width="0.34375in" |              |             |
| Obstruction | height="0.25in"}         |              |             |
+-------------+--------------------------+--------------+-------------+
| LOM         | ![](media/imag           | 70% correct  | 6.17        |
|             | e7.png){width="0.5625in" |              |             |
|             | height                   |              |             |
|             | ="0.3645833333333333in"} |              |             |
+-------------+--------------------------+--------------+-------------+
| Back Course | ![]                      | 65% correct  | 6.43        |
| Localizer   | (media/image14.png){widt |              |             |
|             | h="0.2604166666666667in" | 28% ILS      |             |
|             | height                   |              |             |
|             | ="1.8333333333333333in"} |              |             |
+-------------+--------------------------+--------------+-------------+
| Localizer   | ![]                      | 42% correct  | 4.91        |
| (2)         | (media/image16.png){widt |              |             |
|             | h="0.2604166666666667in" | 10% SDF/LDA  |             |
|             | height                   |              |             |
|             | ="1.8333333333333333in"} | 10% ILS      |             |
|             |                          |              |             |
|             |                          | 17%\         |             |
|             |                          | Can't Tell   |             |
+-------------+--------------------------+--------------+-------------+
| Airport     | ![](                     | 30% correct  | 4.98        |
| Beacon      | media/image17.png){width |              |             |
|             | ="0.17708333333333334in" | 47%\         |             |
|             | height=                  | Can't Tell   |             |
|             | "0.17708333333333334in"} |              |             |
+-------------+--------------------------+--------------+-------------+
| Localizer   | ![](media/ima            | 24%\         | 4.52        |
| (1)         | ge15.png){width="0.25in" | SDF/LDA      |             |
|             | height                   |              |             |
| (NACO       | ="1.8333333333333333in"} | 22%          |             |
| symbol for  |                          | Localizer    |             |
| an SDF/LDA) |                          |              |             |
|             |                          | 36%\         |             |
|             |                          | Can't Tell   |             |
+-------------+--------------------------+--------------+-------------+
| TAA         | ![]                      | 10% correct  | 5.47        |
|             | (media/image21.png){widt |              |             |
|             | h="1.0979166666666667in" | 58% MSA      |             |
|             | height                   |              |             |
|             | ="0.6006944444444444in"} | 14%\         |             |
|             |                          | Can't Tell   |             |
+-------------+--------------------------+--------------+-------------+
| NDB (2)     | ![                       | 42%\         | 4.17        |
|             | ](media/image9.png){widt | Can't Tell   |             |
|             | h="0.3854166666666667in" |              |             |
|             | height                   | 33%\         |             |
|             | ="0.3958333333333333in"} | Military or  |             |
|             |                          | general      |             |
|             |                          | airport      |             |
+-------------+--------------------------+--------------+-------------+

[]{#__RefHeading___Toc183841017 .anchor}Table 15. Summary of results for
symbol identification task for general symbols.

+------------+----------+---------------------------+-----------------+
| **Name of  | **Symbol | **Peaks in Response       | **Mean          |
| Symbol**   | Shape**  | Distribution**            | Confidence      |
|            |          |                           | Rating\         |
|            |          |                           | (Max 7)**       |
+============+==========+===========================+=================+
| Heliport   | ![](med  | 98% correct               | 6.31            |
|            | ia/image |                           |                 |
|            | 24.png){ |                           |                 |
|            | width="0 |                           |                 |
|            | .3125in" |                           |                 |
|            | height   |                           |                 |
|            | ="0.2916 |                           |                 |
|            | 66666666 |                           |                 |
|            | 6667in"} |                           |                 |
+------------+----------+---------------------------+-----------------+
| Closed     | ![]      | 95% correct               | 6.0             |
| Airport    | (media/i |                           |                 |
|            | mage23.p |                           |                 |
|            | ng){widt |                           |                 |
|            | h="0.333 |                           |                 |
|            | 33333333 |                           |                 |
|            | 33333in" |                           |                 |
|            | height   |                           |                 |
|            | ="0.3229 |                           |                 |
|            | 16666666 |                           |                 |
|            | 6667in"} |                           |                 |
+------------+----------+---------------------------+-----------------+
| Seaport    | ![](medi | 94% correct               | 5.93            |
|            | a/image2 |                           |                 |
|            | 7.png){w |                           |                 |
|            | idth="0. |                           |                 |
|            | 40625in" |                           |                 |
|            | height   |                           |                 |
|            | ="0.3854 |                           |                 |
|            | 16666666 |                           |                 |
|            | 6667in"} |                           |                 |
+------------+----------+---------------------------+-----------------+
| Civil      | ![]      | 30% correct               | 5.37            |
|            | (media/i |                           |                 |
|            | mage22.p | 32% reference to services |                 |
|            | ng){widt |                           |                 |
|            | h="0.395 | 18% Can't Tell            |                 |
|            | 83333333 |                           |                 |
|            | 33333in" | 16% runway parameter      |                 |
|            | height   | (length or surface)       |                 |
|            | ="0.3854 |                           |                 |
|            | 16666666 |                           |                 |
|            | 6667in"} |                           |                 |
+------------+----------+---------------------------+-----------------+
| Military   | ![]      | 42% correct               | 5.06            |
|            | (media/i |                           |                 |
|            | mage26.p | 31% Can't Tell            |                 |
|            | ng){widt |                           |                 |
|            | h="0.291 |                           |                 |
|            | 66666666 |                           |                 |
|            | 66667in" |                           |                 |
|            | hei      |                           |                 |
|            | ght="0.2 |                           |                 |
|            | 8125in"} |                           |                 |
+------------+----------+---------------------------+-----------------+
| Joint      | ![](me   | 23% correct               | 4.78            |
| Civi       | dia/imag |                           |                 |
| l-Military | e25.png) | 34% Can't Tell            |                 |
|            | {width=" |                           |                 |
|            | 0.375in" | 25% reference to services |                 |
|            | height   |                           |                 |
|            | ="0.3541 | 22% other or incorrect    |                 |
|            | 66666666 | airport type              |                 |
|            | 6667in"} |                           |                 |
+------------+----------+---------------------------+-----------------+

[]{#__RefHeading___Toc183841018 .anchor}Table 16. Summary of results for
airport symbols.

# Labels for Navigation Aid Symbols

## Task

On paper charts, navigation aid symbols are often accompanied by
supporting text labels, showing information such as the name of the
facility, a shortened identifier (ID), the Morse code for the letters of
the identifier, etc. However, if all this information is shown next to
the symbol on an electronic chart, the resulting display is likely to be
cluttered. Therefore, the research question here is what help does the
text label provide in identifying the navigation aid.

In this experiment, only a small portion of the text label was studied.
Specifically, stimuli for this task (i.e., the images that were
presented) either did or did not show the frequency of the navigation
facility, which provides a clue as to the type of facility.[^5] A DME,
which provides distance information, uses UHF frequencies; these
frequencies are written as a *channel* (e.g., "Chan 31"). A VOR, which
provides bearing information, uses a VHF frequency, similar to a
broadcast commercial radio station (e.g., "103.8"). A facility that
provides both distance and bearing information, such as a VORTAC, would
show both a channel, and a VHF frequency.

Participants were asked to identify the navigation aid based on the
information shown. An example question is shown in Figure 3, which shows
a VORTAC symbol. Participants were asked to include as much detail as
possible in their answers, and in particular to try to distinguish the
symbol types (e.g., between VORs and VORDMEs). The accuracy of
identifying the navigation aid (but not the speed of identification) was
recorded, along with participants' ratings of their confidence in their
response on a scale from 1 (low confidence) to 7 (high confidence).

Five navigation aids were tested: DME, TACAN, VOR, VORDME, and VORTAC.
The test stimuli consisted of either the symbol shape alone, the
frequency alone, or the symbol shape and frequency together, as shown in
Table 17 below.

+--------------+-------------------------------------------------------+
| !            | a\) DME only c) VOR only e) VORTAC                    |
| [](media/ima |                                                       |
| ge32.png){wi | b\) TACAN only d) VORDME f) Can't Tell (?)            |
| dth="0.75in" |                                                       |
| height       | \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\   |
| ="0.26041666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\- |
| 66666667in"} | \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|              |                                                       |
|              | 1 2 3 4 5 6 7\                                        |
|              | **Low Medium High**                                   |
|              |                                                       |
|              | **Confidence Confidence Confidence**                  |
+--------------+-------------------------------------------------------+

[]{#__RefHeading___Toc183840987 .anchor}Figure 3. Example of the
navigation-aid identification task.

  ----------------------------------------------------------------------------------------------------
  **Test Condition**                            **Example**
  --------------------------------------------- ------------------------------------------------------
  Symbol Shape alone                            ![](media/image33.png){width="0.22916666666666666in"
                                                height="0.19791666666666666in"}

  Frequency alone                               ![](media/image34.png){width="0.3333333333333333in"
                                                height="0.13541666666666666in"}

  Symbol Shape + Frequency                      ![](media/image35.png){width="0.5833333333333334in"
                                                height="0.21875in"}
  ----------------------------------------------------------------------------------------------------

[]{#__RefHeading___Toc183841019 .anchor}Table 17. Test conditions for
navigation-aid identification task.

## Results

The mean accuracy for each navigation aid is presented in Table 18 for
each level of information.

  ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  **Symbol     **Symbol Alone**                                       **Frequency Alone**                                   **Symbol + Frequency**                                **Mean
  Type**                                                                                                                                                                          Accuracy**
  ------------ ------------------------------------------------------ ----------------------------------------------------- ----------------------------------------------------- --------------
  **DME**      ![](media/image36.png){width="0.3333333333333333in"    ![](media/image37.png){width="0.5in"                  ![](media/image38.png){width="0.7916666666666666in"   57%
               height="0.2604166666666667in"}                         height="0.16666666666666666in"}                       height="0.2708333333333333in"}                        

               48%                                                    80%                                                   45%                                                   

  **TACAN**    ![](media/image39.png){width="0.25in"                  ![](media/image37.png){width="0.5in"                  ![](media/image40.png){width="0.7708333333333334in"   73%
               height="0.20833333333333334in"}                        height="0.16666666666666666in"}                       height="0.2604166666666667in"}                        

               65%                                                    80%                                                   76%                                                   

  **VOR**      ![](media/image33.png){width="0.22916666666666666in"   ![](media/image34.png){width="0.3333333333333333in"   ![](media/image35.png){width="0.5833333333333334in"   80%
               height="0.19791666666666666in"}                        height="0.13541666666666666in"}                       height="0.21875in"}                                   

               81%                                                    79%                                                   83%                                                   

  **VORDME**   ![](media/image41.png){width="0.2604166666666667in"    ![](media/image34.png){width="0.3333333333333333in"   ![](media/image43.png){width="0.7916666666666666in"   71%
               height="0.22916666666666666in"}                        height="0.13541666666666666in"}                       height="0.2708333333333333in"}                        
                                                                      ![](media/image42.png){width="0.5520833333333334in"                                                         
                                                                      height="0.2604166666666667in"}                                                                              

               71%                                                    82%                                                   63%                                                   

  **VORTAC**   ![](media/image44.png){width="0.23958333333333334in"   ![](media/image34.png){width="0.3333333333333333in"   ![](media/image32.png){width="0.75in"                 85%
               height="0.20833333333333334in"}                        height="0.13541666666666666in"}                       height="0.2604166666666667in"}                        
                                                                      ![](media/image42.png){width="0.5520833333333334in"                                                         
                                                                      height="0.2604166666666667in"}                                                                              

               87%                                                    82%                                                   88%                                                   
  ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

[]{#__RefHeading___Toc183841020 .anchor}Table 18. Mean accuracy of
identification for navigation aids.

Participants' confidence in their responses was evaluated using a
*confidence* *score* to discriminate between participants who were both
confident and correct from those who were confident but incorrect. The
mean confidence score is presented in Table 19.

The confidence score was calculated by multiplying the participants'
actual confidence *rating* (+1 to +7) by +1 if the answer was correct,
and by --1 if the answer was incorrect. In other words, all correct
responses yield positive confidence scores, and all incorrect responses
yield negative confidence scores. The confidence score also
distinguishes between participants who had low confidence in an
incorrect answer and those who had high confidence in an incorrect
answer. Participants who had low confidence in their incorrect answer
yielded a *higher* confidence score than participants who had high
confidence in their incorrect answer. For example, an incorrect response
with a low confidence rating of 2 would have a confidence score of --2,
but an incorrect response with a high confidence rating of 7 would have
a lower confidence score of --7.

  ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  **Symbol     **Symbol Alone**                                       **Frequency Alone**                                   **Symbol + Frequency**                                **Mean\
  Type**                                                                                                                                                                          Confidence
                                                                                                                                                                                  Score**
  ------------ ------------------------------------------------------ ----------------------------------------------------- ----------------------------------------------------- --------------
  **DME**      ![](media/image36.png){width="0.3333333333333333in"    ![](media/image37.png){width="0.5in"                  ![](media/image38.png){width="0.7916666666666666in"   2.26
               height="0.2604166666666667in"}                         height="0.16666666666666666in"}                       height="0.2708333333333333in"}                        

               1.88                                                   4.07                                                  0.83                                                  

  **TACAN**    ![](media/image39.png){width="0.25in"                  ![](media/image37.png){width="0.5in"                  ![](media/image40.png){width="0.7708333333333334in"   3.41
               height="0.20833333333333334in"}                        height="0.16666666666666666in"}                       height="0.2604166666666667in"}                        

               2.63                                                   4.07                                                  3.52                                                  

  **VOR**      ![](media/image33.png){width="0.22916666666666666in"   ![](media/image34.png){width="0.3333333333333333in"   ![](media/image35.png){width="0.5833333333333334in"   4.25
               height="0.19791666666666666in"}                        height="0.13541666666666666in"}                       height="0.21875in"}                                   

               4.44                                                   3.77                                                  4.53                                                  

  **VORDME**   ![](media/image41.png){width="0.2604166666666667in"    ![](media/image34.png){width="0.3333333333333333in"   ![](media/image43.png){width="0.7916666666666666in"   3.10
               height="0.22916666666666666in"}                        height="0.13541666666666666in"}                       height="0.2708333333333333in"}                        
                                                                      ![](media/image42.png){width="0.5520833333333334in"                                                         
                                                                      height="0.2604166666666667in"}                                                                              

               4.20                                                   2.45                                                  2.66                                                  

  **VORTAC**   ![](media/image44.png){width="0.23958333333333334in"   ![](media/image34.png){width="0.3333333333333333in"   ![](media/image32.png){width="0.75in"                 3.96
               height="0.20833333333333334in"}                        height="0.13541666666666666in"}                       height="0.2604166666666667in"}                        
                                                                      ![](media/image42.png){width="0.5520833333333334in"                                                         
                                                                      height="0.2604166666666667in"}                                                                              

               5.50                                                   2.45                                                  5.03                                                  
  ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

[]{#__RefHeading___Toc183841021 .anchor}Table 19. Mean confidence score
for navigation aids.

## Statistical Analyses

Statistical analyses were performed on participants' accuracy and
confidence scores to compare the three levels of *information*
*provided* (symbol shape alone, frequency alone, and symbol plus
frequency). In addition, the data were analyzed with respect to pilot
experience with a particular *chart provider* because participants'
familiarity with the symbols may vary depending on the charts used.

An Analysis of Variance (ANOVA) was performed on the accuracy and
confidence scores for each navigation aid.[^6] The analysis showed no
statistical difference in accuracy as a function of the level of
information for TACANs, VORs, VORDMEs, or VORTACs (*p* \> 0.05).
However, there was a statistically significant difference in accuracy
for identifying DMEs depending on the level of information provided
\[*F*(2, 279) = 7.98, *p* \< 0.05\]. Paired comparison tests showed that
the DME was classified most accurately when frequency information was
presented alone (*p* \< 0.05). This finding may be because the DME
symbol shape by itself was not as familiar to participants, a theory
that is accordance with the results from Yeh and Chandra (2006). In that
study, some pilots commented that they never used the DME alone.

For confidence scores, there were no statistically significant
differences attributable to the level of information for DMEs, TACANs,
or VORs (*p* \> 0.05). Therefore, even though the confidence scores for
these symbols shapes may appear to vary in magnitude, from a statistical
point of view the scores are all equivalent. However, there was a
statistically significant difference in confidence score attributable to
the level of information provided for VORDMEs \[*F*(2, 251) = 3.72, *p*
\< 0.05\] and VORTACs \[*F*(2, 275) = 7.77, *p* \< 0.05\]. For both of
these navigation aids, paired comparison tests showed that participants'
confidence score was lowest when only frequency information was shown
(*p* \< 0.05). This finding is most likely because these two navigation
aids cannot be distinguished from each other by frequency information
alone. As shown in Table 19 above, the test items for the VORDME and
VORTAC with frequency information alone are identical. For these test
items, both answers were accepted, but participants' confidence in their
response suffered.

The chart provider that the pilots used generally did not affect their
responses for DMEs, TACANs, VORs, or VORTACs (*p* \> 0.05). However,
there was a statistically significant difference for VORDMEs:
participants familiar with NACO charts were more accurate than those
familiar with Jeppesen charts (85% vs. 68%, respectively) \[*F*(1, 279)
= 7.85, *p* \< 0.05\] and they were more confident as well, as shown by
a higher confidence score (4.29 vs. 2.73, respectively) \[*F*(1, 251) =
3.72, *p* \< 0.05\]. This finding is most likely a statistical anomaly
due to the relatively low number of NACO users in the current study.[^7]
To confirm this interpretation, data from this study were compared with
data from a larger sample of NACO users collected in an earlier study
(Yeh and Chandra, 2006), in which participants were asked to identify
the representative shape for each navigation aid. Although accuracy was
not measured in that study, the VORDME symbol shape presented in the
current questionnaire was considered to be representative of a VORDME by
82% of NACO users and 64% of Jeppesen users; this difference was *not*
statistically significant. Therefore, the statistical difference for the
identification of the VORDME symbol shape in this study is believed to
be an anomaly.

## Summary and Discussion

With the exception of the DME symbol, the tested navigation aid symbol
shapes could be correctly identified based on shape alone. This is
consistent with the finding from earlier Volpe Center research (Yeh and
Chandra, 2006), that pilots are not especially familiar with the symbol
for a stand-alone DME, and that the other navigation-aid symbol shapes
tested are well recognized.

The tested navigation aid symbols could also be identified correctly
based on frequency alone. The DME symbol was actually classified most
accurately when only frequency information was shown. However, for two
of the symbols, the VORDME and VORTAC, pilots' confidence in their
response was lower when they were only shown the frequency information
alone, without the symbol shape, most likely because the two are
indistinguishable from one another based on frequency information alone.

The results suggest that combining shape information with frequency
information does not significantly improve the identification accuracies
above the rates achieved with either shape alone or frequency
information alone. However, it is important to note that these results
are far from definitive. Only a small set of symbols were tested; labels
may be more meaningful for other symbols that were not tested. In
addition, the rates of accurate identification may not be sensitive
enough to detect differences in performance. Examination of response
time, i.e., how long participants took to identify the test items, may
provide more detail on the value of labels. Finally, this test only
examined the use of frequency information. Other information, such as
the name or identifier, especially if it is recognized, may be more or
less helpful.

# Grouping Navigation Aids into Families

## Task

The research question addressed here was to understand what similarities
pilots perceived among navigation aids. If similarities can be
identified, symbol families can be created such that each family could
be represented by a single "generic" symbol. Some manufacturers already
use generic symbols for groups of navigation aid symbols (e.g., a
VORDME, VORTAC, and VOR are all represented by the same shape), but the
rationale for how to create the groups is not known. The goal here was
to gather data on the relationships that pilots see between the
navigation aids, so that these can be considered when grouping the
symbols into families.

Participants were presented with the eight primary navigation symbols
(DME, fix, NDB, TACAN, VOR, VORDME, VORTAC, and waypoint). They were
asked to divide these symbols into groups of two, three, four, and five.
Participants were also asked to give a title for each group to help
explain their rationale for dividing the symbols. The groups and titles
were used to identify relationships between the navigation aids.

## Results and Discussion

Pilots' groupings of navigation aids were represented using similarity
matrices that show the number of times two navigation aids were grouped
together. (The matrices are provided and explained in [Appendix
C](#__RefHeading___Toc183840971).) The relationships between the items
were then analyzed using a cluster analysis to determine the common
groupings. The results of the cluster analysis are shown in Table 20
below for each level of classification (two, three, four, or five
groups). Dendrograms that depict the strength of the relationship among
navigation aids are provided in [Appendix
C](#__RefHeading___Toc183840971).

  ----------------------------------- -----------------------------------
  ***Two Groups***                    

  **Group 1**                         **Group 2**

  Fix, Waypoint                       DME, NDB, TACAN, VOR, VORDME,
                                      VORTAC
  ----------------------------------- -----------------------------------

  ----------------------- ----------------------- -----------------------
  ***Three Groups***                              

  **Group 1**             **Group 2**             **Group 3**

  Fix, Waypoint           DME, NDB, VOR           TACAN, VORDME, VORTAC
  ----------------------- ----------------------- -----------------------

  ---------------- --------------- --------------- -----------------------
  ***Four                                          
  Groups***                                        

  **Group 1**      **Group 2**     **Group 3**     **Group 4**

  Fix, Waypoint    NDB, VOR        DME             TACAN, VORDME, VORTAC
  ---------------- --------------- --------------- -----------------------

  ----------- ----------- ----------- ----------- -----------------------
  ***Five                                         
  Groups***                                       

  **Group 1** **Group 2** **Group 3** **Group 4** **Group 5**

  Fix,        NDB         DME         VOR         TACAN, VORDME, VORTAC
  Waypoint                                        
  ----------- ----------- ----------- ----------- -----------------------

[]{#__RefHeading___Toc183841022 .anchor}Table 20. Cluster analysis
results.

As Table 20 shows, two groups were consistent throughout the
categorization task. One group consisted of the fix and the waypoint,
and the other consisted of the TACAN, VORDME, and VORTAC. The DME, NDB,
and VOR did not have consistent groups. The NDB tended to be grouped
with the VOR, but as the number of categories participants were asked to
form increased, the NDB and VOR were separated into their own groups.

The titles that participants gave for their groups were subjectively
coded in terms of the underlying features that were used to categorize
the navigation aids. Seven features were used for this analysis, as
listed and defined in Table 21 below. The overall number of times each
feature was used by the subjects was tallied. As an example, when asked
for two groups of symbols, one subject used the titles *Point in Space*
and *Azimuth and/or Distance*. These titles were judged to be given on
the basis of what information the navigation aid provided. The titles
became more complex when there were more groups to name. For example,
one subject used the following titles for the four-group condition:
*Azimuth only, Azimuth and/or Distance, Military, Waypoint*. These
titles were based on three features: *what information* was provided,
*how much information* was provided, and who was the *intended user*.
When the participant formed two or three groups, up to two features were
coded for each title. When four or five groups were formed, up to three
features of the titles were coded.

The results of the feature tally are shown in the four right-most
columns of Table 21, which shows that the feature that participants
considered most often when grouping the navigation aids was *what
information* the navigation aid provided. This feature was used most
often regardless of the number of navigation aid groups. (To see how the
use of features varied by the number of navigation aid groups, read
across the rows of Table 21.)

  ------------------ ----------------------------------- ------------ ----------- ----------- -----------
  **Feature**        **Definition**                      **Number of                          
                                                         Navigation                           
                                                         Aid Groups**                         

                                                         **2**        **3**       **4**       **5**

  ***What            What type of information is         58           59          56          52
  Information***     provided? (e.g., distance                                                
                     information, radial/bearing                                              
                     information, or the                                                      
                     latitude/longitude of a point)                                           

  ***How much        Is only one type of information     7            28          32          30
  Information***     provided, or more than one? Are                                          
                     both radial/bearing information and                                      
                     distance provided, or just one of                                        
                     these?                                                                   

  ***Utility***      What is the utility of the          7            13          9           12
                     information provided? (e.g., How                                         
                     much precision is there?, How often                                      
                     do you use it?, Is it easy to use?                                       
                     Is it only used in particular                                            
                     conditions?)                                                             

  ***Technology***   How is the information generated    16           18          23          16
                     (by what technology, age of                                              
                     technology)?                                                             

  ***Intended        Who uses the information (e.g.,     2            6           13          18
  user***            civil/military, GA vs. transport)?                                       

  ***Unable to       The titles were based on the names  6            4           4           3
  code***            of the item (e.g., NDB, VOR-Type,                                        
                     etc). There was not enough                                               
                     information to establish what                                            
                     factor was used to separate the                                          
                     categories.                                                              

  ***Missing/Can't   Includes both *Can't Tell* (?) and  9            11          13          19
  Tell***            no entry.                                                                

                     ***Column Total***                  ***105***    ***139***   ***150***   ***150***
  ------------------ ----------------------------------- ------------ ----------- ----------- -----------

[]{#__RefHeading___Toc183841023 .anchor}Table 21. Features used to group
navigation aid symbols and their relative frequencies.

Table 21 also shows that as the number of groups increased, the total
number of features participants considered also increased. This
illustrates that as the number of groups increased, participants used
more sophisticated rules to construct the groups. For example, as the
number of groups participants were asked to form increased, more
participants used features such as how much information was provided by
the technology, the technology used, and the intended user (e.g., TACANs
are used primarily by the military). These trends are seen by reading
down the columns of Table 21.

# Line Style Conventions

## Task

The goal here was to examine whether pilots have knowledge of line style
conventions used on paper charts and electronic moving map displays.
Table 22 shows a list of the linear display elements that were assessed.
For each element, pilots were asked to choose what type of line was used
to depict that linear display element.

A sample question for a paper chart linear display element is provided
in Figure 4 below, and a sample question for an electronic moving map
display linear display element is shown in Figure 5. As shown in the
figures, examples of the line styles were provided for items relevant to
paper charts, but these were just schematic, not exact representations
of the lines used on paper charts. The SAE G-10 Aeronautical Charting
Committee agreed the sample line styles for paper charts were helpful
even though they were not specific to a particular manufacturer. No
examples were provided for moving map displays. It was expected that
there would be more variability among line styles on moving map
displays, and no representative styles for these lines were known. In
addition, the response choices for the moving map displays did not
distinguish between short, medium, and long dashed lines; only one
dashed-line choice was given. All of the questions for paper charts had
the same set of responses, and all of the moving map display questions
had the same set of responses.

+---------------------------------------+------------------------------+
| > **Paper Charts**                    | **Moving Map Displays**      |
+---------------------------------------+------------------------------+
| > Radial or bearing line that defines | > Missed approach path       |
| > an intersection                     | >                            |
| >                                     | > Airways                    |
| > Procedure path                      | >                            |
| >                                     | > Alternate (non-activated)  |
| > Missed approach path                | > flight plan                |
| >                                     | >                            |
| > Transition path                     | > State or country boundary  |
| >                                     | >                            |
| > Visual flight path                  | > Active flight plan         |
| >                                     | >                            |
| > Other conditional routes            | > Airspace boundary          |
| >                                     |                              |
| > Airways                             |                              |
+---------------------------------------+------------------------------+

[]{#__RefHeading___Toc183841024 .anchor}Table 22. Linear display
elements for which knowledge of line style conventions was assessed.

+-----------------------------------------------------------------------+
| **Airways** are represented by a:                                     |
|                                                                       |
| a.  solid, thick line ![](media/image45.png){width="1.34375in"        |
|     height="0.14583333333333334in"}                                   |
|                                                                       |
| b.  solid, medium line                                                |
|     ![](media/image46.png){width="1.3020833333333333in"               |
|     height="0.11458333333333333in"}                                   |
|                                                                       |
| c.  solid, thin line ![](media/image47.png){width="1.3125in"          |
|     height="0.11458333333333333in"}                                   |
|                                                                       |
| d.  dashed, long line                                                 |
|     ![](media/image48.png){width="1.3333333333333333in"               |
|     height="0.13541666666666666in"}                                   |
|                                                                       |
| e.  dashed, medium line ![](media/image49.png){width="1.34375in"      |
|     height="0.11458333333333333in"}                                   |
|                                                                       |
| f.  dashed, short line                                                |
|     ![](media/image50.png){width="1.3229166666666667in"               |
|     height="0.10416666666666667in"}                                   |
|                                                                       |
| g.  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_                  |
|                                                                       |
| h.  Don't know                                                        |
+-----------------------------------------------------------------------+

[]{#__RefHeading___Toc183840988 .anchor}Figure 4. Example of line-style
question for a paper chart element.

+-----------------------------------------------------------------------+
| The **missed approach path** is represented by a:                     |
|                                                                       |
| a)  solid, thick line                                                 |
|                                                                       |
| b)  solid, medium line                                                |
|                                                                       |
| c)  solid, thin line                                                  |
|                                                                       |
| d)  dashed line                                                       |
|                                                                       |
| e)  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_                  |
|                                                                       |
| f)  No specific meaning                                               |
|                                                                       |
| g)  Don't know                                                        |
+-----------------------------------------------------------------------+

[]{#__RefHeading___Toc183840989 .anchor}Figure 5. Example of line-style
question for a moving map display element.

Most of the linear display elements tested for paper charts are familiar
to pilots, but some are less familiar than others. In particular,
*visual flight paths* and *other conditional routes* are relatively
uncommon. A visual flight path might be seen on an instrument approach
into a mountainous region. The visual flight path indicates that the
runway must be in sight to proceed with the approach. Another type of
visual flight path may occur when a route is denoted in terms of visual
landmarks on the ground (e.g., "left turn at the fuel tanks"). The term
*other conditional routes* represents a variety of uncommonly used
paths. For example, a route to follow when the aircraft has lost
communication with air traffic control is a conditional route. (On NACO
charts, a lost communications path is represented as a dotted line, but
other conditional routes are not depicted.) Jeppesen may depict
conditional routes that are temporary routes set up to accommodate large
public events, or temporary routes set up to accommodate navigation aids
that are out of service.

The linear display elements tested for moving map displays were selected
without extensive formal knowledge of which were commonly depicted.
Although participants reported what moving map display they were most
familiar with, there is currently no inventory that indicates what
symbols all the different avionics vendors and map displays actually
show, and how they are depicted. (As mentioned earlier, an effort to
inventory current moving map display symbology is planned.)

## Results and Discussion

Pilots' knowledge and perception of the line conventions and stereotypes
for paper and electronic moving map displays are best depicted through
histograms, which illustrate the response trends.

### Paper charts

The histograms of participants' responses to line styles for paper chart
linear display elements are presented in Figures 6 through 12 below. The
most important feature to note in these graphs is the tightness of the
response distribution. Histograms that show strong peaks, even though
they may be across more than one response, indicate generally good
consensus. If the peak covers two responses, it is most likely because
participants could not clearly distinguish between the two responses.
For example, participants did not always distinguish between the
different thicknesses of the lines or the lengths of the dashes. For
solid lines, participants distinguished between thick and thin lines but
did not consistently distinguish between *thick* versus *medium* lines
or between *medium* versus *thin* lines. For dashed lines, participants
did not consistently distinguish between *medium* and *short* dash
lengths.

The majority of participants considered a *radial or a bearing line that
defines an intersection* (Figure 6) to be drawn with a solid, thin line
(83%) and a *procedure path* (Figure 7) to be drawn with a solid, thick
line (72%). These two responses are correct, in that they are in
agreement with current paper chart depictions; NACO and Jeppesen do in
fact use solid thin lines for a radial or bearing line that defines and
intersection, and solid thick lines for procedure paths.

For other paths, responses were more spread out. Participants' responses
showed that they considered a *transition path* to be drawn with a
solid, medium or thin, line (Figure 8). NACO uses a solid medium line to
depict a transition path, and Jeppesen uses a dashed medium line.
*Airways* (Figure 9) were considered to be drawn with a solid, medium or
thick, line. Both NACO and Jeppesen currently use a solid medium line to
depict airways.

Participants' responses indicated that they considered a *missed
approach path* (Figure 10) to be drawn with a dashed, medium or short,
line. NACO uses a dashed short line. Jeppesen uses a thick dashed line
(response *G*, or possibly *D*). The *visual flight path* (Figure 11)
was thought to be drawn with dashed lines, with an approximately equal
number of participants considering the dashes to be long, medium, or
short. NACO uses a dashed line that could be interpreted as either
medium or long for visual flight paths. Jeppesen uses a series of short
bold arrows (response *G*).

The results showed no consensus for line conventions for *conditional
routes* (Figure 12), a result that is not surprising when considering
how broad a category this description represents. In addition, NACO does
not use a single line style to represent this type of route, so pilots
who were only familiar with NACO charts could not be expected to pick a
single best answer. Jeppesen charts depict other conditional routes with
a dashed medium line (response *E*).

![](media/image51.wmf){width="6.5in" height="2.377083333333333in"}

[]{#__RefHeading___Toc183840990 .anchor}Figure 6. Responses for how a
radial or bearing line that defines an intersection is shown on paper
charts.

![](media/image52.wmf){width="6.5in" height="2.2944444444444443in"}

[]{#__RefHeading___Toc183840991 .anchor}Figure 7. Responses for how a
procedure path is shown on paper charts.

![](media/image53.wmf){width="6.5in" height="2.4972222222222222in"}

[]{#__RefHeading___Toc183840992 .anchor}Figure 8. Responses for how a
transition path is shown on paper charts.

![](media/image54.wmf){width="6.5in" height="2.377083333333333in"}

[]{#__RefHeading___Toc183840993 .anchor}Figure 9. Responses for how
airways are shown on paper charts.

![](media/image55.wmf){width="6.5in" height="2.279861111111111in"}

[]{#__RefHeading___Toc183840994 .anchor}Figure 10. Responses for how a
missed approach path is shown on paper charts.

![](media/image56.wmf){width="6.5in" height="2.4972222222222222in"}

[]{#__RefHeading___Toc183840995 .anchor}Figure 11. Responses for how
visual flight paths are shown on paper charts.

![](media/image57.wmf){width="6.5in" height="2.377083333333333in"}

[]{#__RefHeading___Toc183840996 .anchor}Figure 12. Responses for how
other conditional routes are shown on paper charts.

### Electronic Moving Map Displays

Participants' responses to line style conventions used on electronic
moving map displays are shown in Figures 13 through 18 below, which show
mixed responses to the questions. The larger variation in responses may
be because there are more manufacturers of moving map displays than
paper charts, and the symbology across these displays varies more than
the symbology on various paper charts does. Other possibilities may be
that pilots do not remember the moving map display line styles as well
as the paper lines styles, that maps may not show all of these types of
line styles, or that the electronic maps use other features, such as
color, rather than thickness and dashing of the line style to
distinguish lines. It was not possible to reconcile the responses with
specific line styles used in actual electronic moving maps displays.

Even with the larger response variability, there was general consensus
that *airways* (Figure 13) are drawn with a solid line (61%), although
participants did not distinguish between the line thicknesses. In
addition, the *active flight plan* (Figure 14) was generally thought to
be a solid line of thick to medium thickness (63% of participants).
There was no consensus for the conventions used for representing the
*alternate (non-activated) flight plan* (Figure 15), the *missed
approach path* (Figure 16), *airspace boundaries* (Figure 17), or *state
or county boundary* (Figure 18).

![](media/image58.wmf){width="6.5in" height="2.392361111111111in"}

[]{#__RefHeading___Toc183840997 .anchor}Figure 13. Responses for how
airways are shown on electronic moving map displays.

![](media/image59.wmf){width="6.5in" height="2.1222222222222222in"}

[]{#__RefHeading___Toc183840998 .anchor}Figure 14. Responses for how the
active flight plan is shown on electronic moving map displays.

![](media/image60.wmf){width="6.5in" height="2.0395833333333333in"}

[]{#__RefHeading___Toc183840999 .anchor}Figure 15. Responses for how an
alternate flight plan is shown on electronic moving map displays.

![](media/image61.wmf){width="6.5in" height="2.167361111111111in"}

[]{#__RefHeading___Toc183841000 .anchor}Figure 16. Responses for how a
missed approach path is shown on electronic moving map displays.

![](media/image62.wmf){width="6.5in" height="2.377083333333333in"}

[]{#__RefHeading___Toc183841001 .anchor}Figure 17. Responses for how
airspace boundaries are shown on electronic moving map displays.

![](media/image63.wmf){width="6.5in" height="2.1597222222222223in"}

[]{#__RefHeading___Toc183841002 .anchor}Figure 18. Responses for how a
state or country boundary is shown on electronic moving map displays.

# Summary and Conclusions

Four research questions related to development of recommendations for
electronic aeronautical chart symbology (i.e., symbols and lines) were
studied. Note that this research applies to any electronic display that
shows the symbology tested in this study, regardless of the intended
function of the display.

The main research question addressed pilot identification of several
proposed symbols. Pilots generally identified the test symbols, but a
few problematic symbols were identified. Factors contributing towards
the correct and incorrect interpretation of the confusing symbols were
explored. One such factor was the similarity of the tested symbol shape
to other symbols in use. If the test shape was similar to a well-known
symbol, the shape similarity appeared to be helpful in recognizing the
tested symbol. For example, the fact that the generic localizer shapes
were similar to the well-known front and back-course localizer shapes
potentially increased their recognition. However, if the test symbol was
similar in shape to another symbol that represented a substantively
different element, the shape similarity could have increased
misinterpretation. For example, the double-ringed NDB shape was perhaps
*too* similar to the shape for the military airport symbol.

Pilot's familiarity with a symbol, in terms of both its shape and use,
also contributed to symbol recognition. Note that familiarity of a
symbol in the aeronautical environment is affected by frequency of
exposure and use; symbols that are not often seen and used, such as the
MSA, will be harder to recognize. Symbol labels, or contextual
information, may also give the pilot valuable clues for identifying less
familiar shapes. For the airport beacon shape, for example, pilots may
have needed additional information, such as a text descriptor, for
better recognition.

The second research question in this study was whether labels increase
the accuracy of identifying navigation aids. For four of the five tested
symbols, there was no difference in participants' accuracy of symbol
identification with or without the labeling information. However, this
test was not definitive. A more detailed study is necessary to
understand the full effect of labeling information on both the speed and
accuracy of symbol identification.

The third research question explored the relationships that pilots see
between navigation aids. The goal here was to identify symbol families
that could be represented by a single generic symbol. The most common
feature used to group the navigation aids was what information was
provided (e.g., distance, radial, or point). Pilots also considered
other features, such as the amount of information, its utility, and
technology.

In the last part of the study, pilot knowledge of line style conventions
in paper charts and electronic displays was explored. Pilots were fairly
knowledgeable about paper chart conventions, although they could not
reliably distinguish between similar line widths and dash lengths.
Responses to the questions about line conventions on electronic moving
map displays were more varied, which could indicate either that pilots
did not know the conventions, or that the conventions are not well
established on these displays. A future effort is planned to document
current symbology used on electronic displays.

The SAE G-10 Aeronautical Charting Committee, and its members from the
FAA and ICAO, will consider the results of this study as they work
together to develop an updated industry recommendations document (ARP
5289). Input from the FAA sponsors and the SAE G-10 Aeronautical
Charting Committee will determine what research direction is pursued.
The overall goal of this research program is provide the FAA with data
and recommendations for the development of standards for electronic
aeronautical chart symbology. As issues arise, data will be collected to
help identify the best way to address them.

# References

Chandra, D. C., Yeh M., Riley, V. and Mangold, S.J. (2003). *Human
factors considerations in the design and evaluation of Electronic Flight
Bags (EFBs), Version 2* Cambridge, MA: USDOT Volpe National
Transportation Systems Center. (NTIS No. PB2004101967)

Federal Aviation Administration, (2003) Technical Standard Order C165.
Electronic Map Display Equipment for Graphical Depiction of Aircraft
Position.

Federal Aviation Administration (2007a). *Instrument procedures
handbook* (FAA-H-8261-1A). Washington, DC: Author.

Federal Aviation Administration (2007b). *Federal Aviation
Regulations/Aeronautical information manual* (ASA-07-FR-AM-8K).
Newcastle, WA: Aviation Supplies & Academics.

International Civil Aviation Organization (ICAO) Annex 4 (July, 2001).
Aeronautical Charts. Annex 4 to the Convention on International Civil
Aviation.

National Aeronautical Charting Office (NACO) (2004). Aeronautical Chart
User\'s Guide 6th Edition. Washington D.C.: Federal Aviation
Administration.

RTCA (2003). Minimum Operational Performance Standards for the Depiction
of Navigational Information on Electronic Maps. DO-257A. Washington,
D.C., RTCA.

Society of Automotive Engineers (SAE) (1997). *Electronic Aeronautical
Symbols*, ARP 5289. Warrendale, PA, SAE.

Yeh, M. and D. C. Chandra (2004). Issues in symbol design for electronic
displays of navigation information. *Proceedings of the 23rd Digital
Avionics Systems Conference.* Salt Lake City, UT.

Yeh, M. and D. C. Chandra (2005). *Designing and Evaluating Symbols for
Electronic Displays of Navigation Information: Symbol Stereotypes and
Symbol-Feature Rules.* (Report Nos. DOT/FAA/AR-05/48,
DOT-VNTSC-FAA-05-16) Cambridge, MA, US DOT Volpe National Transportation
Systems Center.

Yeh, M. and Chandra, D. C. (2006). Pilot stereotypes for navigation
symbols on electronic displays. In Reuzeau, F., Corker, K. & Boy, G.
(Eds.) *Proceedings of the International Conference on Human-Computer
Interaction in Aeronautics*. (pp. 66-73). Toulouse, France:
Cépaduès-Éditions.

[]{#__RefHeading___Toc183840967 .anchor}Appendix A:\
Questionnaire

*Informed Consent*

I, \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_,
understand that this study, entitled \"Flight Symbology\" is being
conducted by the Volpe National Transportation Systems Center, United
States Department of Transportation, and is being directed by Dr. Divya
Chandra. This research is funded by the Federal Aviation Administration,
Human Factors Research and Engineering Division.

**Purpose of Study.** There are many types of electronic displays that
show navigation information (e.g., VORs and Global Position System (GPS)
waypoints) to help pilots determine the aircraft's position. There are
no standards in widespread use that ensure the compatibility of the
symbols across all the various display platforms. The purpose of this
study is to understand whether certain symbol shapes are recognizable
and whether features encoded in the symbol shapes to convey additional
information about the symbol are understandable and usable. A couple of
charts are provided at the end of the questionnaire for you to use as
reference.

**Study Procedures.** This experiment addresses the design of symbols
and features used on chart and map displays. You will be shown a set of
test symbol shapes and asked to identify the symbol or identify the
feature conveyed by the symbol shape. For each question, you will be
asked to indicate your level of confidence in your answer. The study is
estimated to take less than an hour to complete.

**Discomfort and Risks.** The risks involved in your participation are
low and do not exceed those you would experience working on your home
computer for about one hour.

**Benefits to You.** Participation provides an opportunity to aid in the
development of recommendations for the design of air transport and
general aviation displays.

**Participant Responsibilities.** Please notify Dr. Divya Chandra
(617-494-3882) if you experience any discomfort during the study.

**In the Event of an Injury,** we urge that you report any immediate or
delayed injuries resulting from the study to Dr. Divya Chandra
(617-494-3882).

**Assurances and Rights of the Participant.** Your participation in this
study is completely voluntary. Your participation is strictly
confidential, and no individual names or identities will be recorded
with any data or released in any reports. Only arbitrary numbers are
used to identify pilots who provide data.

If you have any questions, please let us know. For further information
about this study, please feel free to contact:

Divya Chandra or Michelle Yeh

US DOT Volpe Center

55 Broadway

Cambridge, MA 02142

617.494.3882 / 617.494.3459

chandra@volpe.dot.gov

yeh@volpe.dot.gov

**Statement of Consent**

I have read this consent document. I understand its contents, and I
freely consent to participate in this study under the conditions
described. I may have a copy of this consent form if I request same.

Research Participant:
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_Date:
\_\_\_\_\_\_\_

**This** **page left blank intentionally.**

Background Questionnaire

+---------------------------------+------------------+-----------------+
| **Age** \_\_\_\_\_\_\_\_\_\_\_  |                  |                 |
+---------------------------------+------------------+-----------------+
| **Gender**                      | Male             | Female          |
+---------------------------------+------------------+-----------------+
| **Flight Hours** Total          | Average (per     |                 |
| \_\_\_\_\_\_\_\_\_\_\_          | month)           |                 |
|                                 | \_\_\_           |                 |
|                                 | \_\_\_\_\_\_\_\_ |                 |
|                                 |                  |                 |
|                                 | Last month       |                 |
|                                 | \_\_\_           |                 |
|                                 | \_\_\_\_\_\_\_\_ |                 |
+---------------------------------+------------------+-----------------+
| **Instrument Time** Total       | Average (per     |                 |
| \_\_\_\_\_\_\_\_\_\_\_          | month)           |                 |
|                                 | \_\_\_           |                 |
|                                 | \_\_\_\_\_\_\_\_ |                 |
|                                 |                  |                 |
|                                 | Last month       |                 |
|                                 | \_\_\_           |                 |
|                                 | \_\_\_\_\_\_\_\_ |                 |
+---------------------------------+------------------+-----------------+

**Which manufacturer provides the charts that you use most? How long?**

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Do you use charts from other manufacturers regularly? Which? How
long?**

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Ratings and Certificates**: Please check the ratings and certificates
that you have.

+-----------------------------------+-----------------------------------+
| Airline Transport \_\_\_\_\_      | Instrument \_\_\_\_\_             |
| Commercial \_\_\_\_\_             |                                   |
|                                   | Single Engine \_\_\_\_\_          |
| Rotorcraft \_\_\_\_\_             |                                   |
|                                   | Multi Engine \_\_\_\_\_           |
+-----------------------------------+-----------------------------------+

+-----------------------------------+-----------------------------------+
| Please list other ratings that    | **List the three most recent      |
| you hold:                         | aircraft you have flown**. Please |
|                                   | list them in order from most      |
| **Type Rating**                   | frequent to least frequent.       |
|                                   |                                   |
| \_\_\_\_\_\_\_\_\_\_\_\_\_\       | \_\_\_\_\_\_\_\_\_\_\_\_\_\       |
| _\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ | _\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|                                   |                                   |
| \_\_\_\_\_\_\_\_\_\_\_\_\_\       | \_\_\_\_\_\_\_\_\_\_\_\_\_\       |
| _\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ | _\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|                                   |                                   |
| \_\_\_\_\_\_\_\_\_\_\_\_\_\       | \_\_\_\_\_\_\_\_\_\_\_\_\_\       |
| _\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ | _\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|                                   |                                   |
| \_\_\_\_\_\_\_\_\_\_\_\_\_\       |                                   |
| _\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |                                   |
+-----------------------------------+-----------------------------------+

**Flight Experience**: Please check the type(s) of flying that you do:

Private IFR \_\_\_\_ VFR \_\_\_\_

Air transport \_\_\_\_

Business \_\_\_\_

Corporate \_\_\_\_

Military \_\_\_\_

**Do you have experience with the following:**

-   **Glass cockpit?** Yes No

-   **FMS?** Yes No

-   **moving map displays?** Yes No

If yes, what are the specific moving map display(s) you are most
familiar with?

**This** **page left blank intentionally.**

Symbol Questionnaire

Part 1. Symbol Recall

A. General

The purpose of this task is to determine whether symbols being proposed
for use on paper and electronic terminal procedure charts (e.g., SIDS,
STARs) are understandable. For each shape below, identify it and
indicate your level of confidence in your response. Some of the symbols
are unusual, so you may not recognize all the symbols. Write "?" if you
do not know or can't tell.

+-----+--------------+--------------------------------------------------+
| 1   | ![](         | Symbol Type (or ?):                              |
| .   | media/image1 | \_\_\_\_\_\_\_\_                                 |
|     | 1.png){width | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | ="0.34375in" |                                                  |
|     | heig         | 1 2 3 4 5 6 7\                                   |
|     | ht="0.25in"} | **Low Medium High**                              |
|     |              |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 2   | ![]          | Symbol Type (or ?):                              |
| .   | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 12.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.3229166 |                                                  |
|     | 666666667in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="0.45833333 |                                                  |
|     | 33333333in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 3   | ![]          | Symbol Type (or ?):                              |
| .   | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 29.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.3333333 |                                                  |
|     | 333333333in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="0.30208333 |                                                  |
|     | 33333333in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 4   | ![           | Symbol Type (or ?):                              |
| .   | ](media/imag | \_\_\_\_\_\_\_\_                                 |
|     | e7.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.5625in" |                                                  |
|     | height       | 1 2 3 4 5 6 7\                                   |
|     | ="0.36458333 | **Low Medium High**                              |
|     | 33333333in"} |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 5   | ![]          | Symbol Type (or ?):                              |
| .   | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 19.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="1.0986111 |                                                  |
|     | 111111112in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="0.83194444 |                                                  |
|     | 44444445in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 6   | ![           | Symbol Type (or ?):                              |
| .   | ](media/imag | \_\_\_\_\_\_\_\_                                 |
|     | e9.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.3854166 |                                                  |
|     | 666666667in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="0.39583333 |                                                  |
|     | 33333333in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 7   | ![]          | Symbol Type (or ?):                              |
| .   | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 14.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.2604166 |                                                  |
|     | 666666667in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="1.83333333 |                                                  |
|     | 33333333in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 8   | ![]          | Symbol Type (or ?):                              |
| .   | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 13.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.4479166 |                                                  |
|     | 666666667in" | 1 2 3 4 5 6 7\                                   |
|     | height=      | **Low Medium High**                              |
|     | "0.46875in"} |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 9   | ![]          | Symbol Type (or ?):                              |
| .   | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 28.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.4166666 |                                                  |
|     | 666666667in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="0.41666666 |                                                  |
|     | 66666667in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 1   | ![]          | Symbol Type (or ?):                              |
| 0.  | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 10.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.2708333 |                                                  |
|     | 333333333in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="0.26041666 |                                                  |
|     | 66666667in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 1   | ![]          | Symbol Type (or ?):                              |
| 1.  | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 16.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.2604166 |                                                  |
|     | 666666667in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="1.83333333 |                                                  |
|     | 33333333in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 1   | !            | Symbol Type (or ?):                              |
| 2.  | [](media/ima | \_\_\_\_\_\_\_\_                                 |
|     | ge15.png){wi | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | dth="0.25in" |                                                  |
|     | height       | 1 2 3 4 5 6 7\                                   |
|     | ="1.83333333 | **Low Medium High**                              |
|     | 33333333in"} |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 1   | ![           | Symbol Type (or ?):                              |
| 3.  | ](media/imag | \_\_\_\_\_\_\_\_                                 |
|     | e8.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.6041666 |                                                  |
|     | 666666666in" | 1 2 3 4 5 6 7\                                   |
|     | height=      | **Low Medium High**                              |
|     | "0.208333333 |                                                  |
|     | 33333334in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 1   | !            | Symbol Type (or ?):                              |
| 4.  | [](media/ima | \_\_\_\_\_\_\_\_                                 |
|     | ge6.png){wid | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | th="0.375in" |                                                  |
|     | height       | 1 2 3 4 5 6 7\                                   |
|     | ="0.36458333 | **Low Medium High**                              |
|     | 33333333in"} |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 1   | ![]          | Symbol Type (or ?):                              |
| 5.  | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 18.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="1.0625in" |                                                  |
|     | height       | 1 2 3 4 5 6 7\                                   |
|     | ="0.47916666 | **Low Medium High**                              |
|     | 66666667in"} |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 1   | ![]          | Symbol Type (or ?):                              |
| 6.  | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 20.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="1.0993055 |                                                  |
|     | 555555555in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="1.20347222 |                                                  |
|     | 22222223in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 1   | ![]          | Symbol Type (or ?):                              |
| 7.  | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 21.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="1.0979166 |                                                  |
|     | 666666667in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="0.60069444 |                                                  |
|     | 44444444in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 1   | ![](         | Symbol Type (or ?):                              |
| 8.  | media/image1 | \_\_\_\_\_\_\_\_                                 |
|     | 7.png){width | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | ="0.17708333 |                                                  |
|     | 333333334in" | 1 2 3 4 5 6 7\                                   |
|     | height=      | **Low Medium High**                              |
|     | "0.177083333 |                                                  |
|     | 33333334in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+

B. Airport Identification

Each of the following shapes may be used to represent an airport. For
each symbol, identify the *type* of airport the symbol represents and
indicate your level of confidence in your response. Write "?" if you do
not know or can't tell.

+-----+--------------+--------------------------------------------------+
| 1   | ![]          | Airport Type (or Can't Tell):                    |
| .   | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 26.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.2916666 |                                                  |
|     | 666666667in" | 1 2 3 4 5 6 7\                                   |
|     | height=      | **Low Medium High**                              |
|     | "0.28125in"} |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 2   | ![]          | Airport Type (or Can't Tell):                    |
| .   | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 22.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.3958333 |                                                  |
|     | 333333333in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="0.38541666 |                                                  |
|     | 66666667in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 3   | ![]          | Airport Type (or Can't Tell):                    |
| .   | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 24.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.3125in" |                                                  |
|     | height       | 1 2 3 4 5 6 7\                                   |
|     | ="0.29166666 | **Low Medium High**                              |
|     | 66666667in"} |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 4   | ![]          | Airport Type (or Can't Tell):                    |
| .   | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 31.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.3541666 |                                                  |
|     | 666666667in" | 1 2 3 4 5 6 7\                                   |
|     | heigh        | **Low Medium High**                              |
|     | t="0.375in"} |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 5   | ![           | Airport Type (or Can't Tell):                    |
| .   | ](media/imag | \_\_\_\_\_\_\_\_                                 |
|     | e30.png){wid | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | th="0.375in" |                                                  |
|     | height       | 1 2 3 4 5 6 7\                                   |
|     | ="0.36458333 | **Low Medium High**                              |
|     | 33333333in"} |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 6   | ![](         | Airport Type (or Can't Tell):                    |
| .   | media/image2 | \_\_\_\_\_\_\_\_                                 |
|     | 7.png){width | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | ="0.40625in" |                                                  |
|     | height       | 1 2 3 4 5 6 7\                                   |
|     | ="0.38541666 | **Low Medium High**                              |
|     | 66666667in"} |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 7   | ![           | Airport Type (or Can't Tell):                    |
| .   | ](media/imag | \_\_\_\_\_\_\_\_                                 |
|     | e25.png){wid | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | th="0.375in" |                                                  |
|     | height       | 1 2 3 4 5 6 7\                                   |
|     | ="0.35416666 | **Low Medium High**                              |
|     | 66666667in"} |                                                  |
|     |              | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+
| 8   | ![]          | Airport Type (or Can't Tell):                    |
| .   | (media/image | \_\_\_\_\_\_\_\_                                 |
|     | 23.png){widt | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ |
|     | h="0.3333333 |                                                  |
|     | 333333333in" | 1 2 3 4 5 6 7\                                   |
|     | height       | **Low Medium High**                              |
|     | ="0.32291666 |                                                  |
|     | 66666667in"} | **Confidence Confidence Confidence**             |
+-----+--------------+--------------------------------------------------+

Part 2. Navigation Aids

A. Symbol Alone

The purpose of this task is to determine whether symbols being proposed
for navigation aids are understandable. Each of the symbol shapes below
may be used to represent a navigation aid. For each shape, identify it
and indicate your level of confidence in your response. Include as much
detail as you can in your answer (e.g., try to distinguish between VORs
and VORDMEs). Circle only one.

+----+-------------+--------------------------------------------------+
| 1. | ![](medi    | a\) DME only c) VOR only e) VORTAC               |
|    | a/image44.p |                                                  |
|    | ng){width=" | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | 0.239583333 |                                                  |
|    | 33333334in" | \-\-\-\-\-\-\                                    |
|    | height="0   | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | .2083333333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333334in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 2. | ![](med     | a\) DME only c) VOR only e) VORTAC               |
|    | ia/image36. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.33333333 |                                                  |
|    | 33333333in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.260416666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666667in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 3. | ![](medi    | a\) DME only c) VOR only e) VORTAC               |
|    | a/image33.p |                                                  |
|    | ng){width=" | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | 0.229166666 |                                                  |
|    | 66666666in" | \-\-\-\-\-\-\                                    |
|    | height="0   | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | .1979166666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666666in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 4. | ![](        | a\) DME only c) VOR only e) VORTAC               |
|    | media/image |                                                  |
|    | 39.png){wid | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | th="0.25in" |                                                  |
|    | height="0   | \-\-\-\-\-\-\                                    |
|    | .2083333333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333334in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 5. | ![](med     | a\) DME only c) VOR only e) VORTAC               |
|    | ia/image41. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.26041666 |                                                  |
|    | 66666667in" | \-\-\-\-\-\-\                                    |
|    | height="0   | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | .2291666666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666666in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+

B. Symbol with Additional Information

Each row below presents information that represents a navigation aid.
The information may be the one or more of the following: symbol shape,
identifier, frequency, or channel.

Based on the information provided, provide your best guess as to what
the navigation aid is and indicate your level of confidence in your
response. The navigation aid may be a DME only, TACAN only, VOR only,
VORDME, or VORTAC. Include as much detail as you can in your answer
(e.g., try to distinguish between VORs and VORDMEs). Note: The
identifiers, channels, and frequencies here are fictional. Any overlap
with real navigation aids is coincidental.

+----+-------------+--------------------------------------------------+
| 1. | ![](med     | a\) DME only c) VOR only e) VORTAC               |
|    | ia/image42. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.55208333 |                                                  |
|    | 33333334in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.260416666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666667in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 2. | ![](m       | a\) DME only c) VOR only e) VORTAC               |
|    | edia/image6 |                                                  |
|    | 4.png){widt | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | h="0.625in" |                                                  |
|    | height="    | \-\-\-\-\-\-\                                    |
|    | 0.260416666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666667in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 3. | ![](med     | a\) DME only c) VOR only e) VORTAC               |
|    | ia/image65. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.54166666 |                                                  |
|    | 66666666in" | \-\-\-\-\-\-\                                    |
|    | heigh       | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | t="0.25in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 4. | ![](med     | a\) DME only c) VOR only e) VORTAC               |
|    | ia/image66. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.34375in" |                                                  |
|    | height="0   | \-\-\-\-\-\-\                                    |
|    | .1145833333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333333in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 5. | ![](med     | a\) DME only c) VOR only e) VORTAC               |
|    | ia/image43. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.79166666 |                                                  |
|    | 66666666in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.270833333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333333in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 6. | ![](med     | a\) DME only c) VOR only e) VORTAC               |
|    | ia/image34. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.33333333 |                                                  |
|    | 33333333in" | \-\-\-\-\-\-\                                    |
|    | height="0   | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | .1354166666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666666in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 7. | ![](med     | a\) DME only c) VOR only e) VORTAC               |
|    | ia/image67. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.59375in" |                                                  |
|    | height="    | \-\-\-\-\-\-\                                    |
|    | 0.270833333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333333in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 8. | ![](med     | a\) DME only c) VOR only e) VORTAC               |
|    | ia/image68. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.57291666 |                                                  |
|    | 66666666in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.260416666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666667in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 9. | ![]         | a\) DME only c) VOR only e) VORTAC               |
|    | (media/imag |                                                  |
|    | e37.png){wi | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | dth="0.5in" |                                                  |
|    | height="0   | \-\-\-\-\-\-\                                    |
|    | .1666666666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666666in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 10 | ![](me      | a\) DME only c) VOR only e) VORTAC               |
| .  | dia/image69 |                                                  |
|    | .png){width | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | ="0.5625in" |                                                  |
|    | height="    | \-\-\-\-\-\-\                                    |
|    | 0.260416666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666667in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 11 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image70. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.28125in" |                                                  |
|    | height="0   | \-\-\-\-\-\-\                                    |
|    | .1354166666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666666in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 12 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image71. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.72916666 |                                                  |
|    | 66666666in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.270833333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333333in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 13 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image35. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.58333333 |                                                  |
|    | 33333334in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.21875in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 14 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image72. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.90625in" |                                                  |
|    | height="    | \-\-\-\-\-\-\                                    |
|    | 0.270833333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333333in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 15 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image73. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.47916666 |                                                  |
|    | 66666667in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.291666666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666667in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 16 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image38. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.79166666 |                                                  |
|    | 66666666in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.270833333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333333in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 17 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image74. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.73958333 |                                                  |
|    | 33333334in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.270833333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333333in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 18 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image75. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.90625in" |                                                  |
|    | height="0   | \-\-\-\-\-\-\                                    |
|    | .2395833333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333334in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 19 | ![](        | a\) DME only c) VOR only e) VORTAC               |
| .  | media/image |                                                  |
|    | 32.png){wid | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | th="0.75in" |                                                  |
|    | height="    | \-\-\-\-\-\-\                                    |
|    | 0.260416666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666667in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 20 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image40. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.77083333 |                                                  |
|    | 33333334in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.260416666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666667in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 21 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image76. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.78125in" |                                                  |
|    | height="    | \-\-\-\-\-\-\                                    |
|    | 0.28125in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    |             | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 22 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image77. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.55208333 |                                                  |
|    | 33333334in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.260416666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666667in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 23 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image78. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.79166666 |                                                  |
|    | 66666666in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.291666666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666667in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 24 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image79. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.54166666 |                                                  |
|    | 66666666in" | \-\-\-\-\-\-\                                    |
|    | height="0   | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | .1354166666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666666in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 25 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image80. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.89583333 |                                                  |
|    | 33333334in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.260416666 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 6666667in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 26 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image81. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.51041666 |                                                  |
|    | 66666666in" | \-\-\-\-\-\-\                                    |
|    | height="0   | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | .2395833333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333334in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 27 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image82. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.89583333 |                                                  |
|    | 33333334in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.270833333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333333in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+
| 28 | ![](med     | a\) DME only c) VOR only e) VORTAC               |
| .  | ia/image83. |                                                  |
|    | png){width= | b\) TACAN only d) VORDME f) Can't Tell (?)       |
|    | "0.88541666 |                                                  |
|    | 66666666in" | \-\-\-\-\-\-\                                    |
|    | height="    | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 0.270833333 | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\ |
|    | 3333333in"} | -\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- |
|    |             |                                                  |
|    |             | 1 2 3 4 5 6 7\                                   |
|    |             | **Low Medium High**                              |
|    |             |                                                  |
|    |             | **Confidence Confidence Confidence**             |
+----+-------------+--------------------------------------------------+

Part 3. Symbol Classification

We are interested in the relationships that pilots see among navigation
aids. Eight navigation aids are listed. Your task is to divide the
symbol types below into groups, according to the instructions. Name each
group to explain the rule you used to divide the symbols into groups.

1\. Divide the symbols below into **2** groups.

a)  DME

b)  Fix

c)  NDB

d)  TACAN

e)  VOR

f)  VORDME

g)  VORTAC

h)  Waypoint

  ----------------------------------- -----------------------------------
  Group 1                             Group 2

  Name:                               Name:

                                      
  ----------------------------------- -----------------------------------

2\. Divide the symbols below into **3** groups.

a)  DME

b)  Fix

c)  NDB

d)  TACAN

e)  VOR

f)  VORDME

g)  VORTAC

h)  Waypoint

  ----------------------- ----------------------- -----------------------
  Group 1                 Group 2                 Group 3

  Name:                   Name:                   Name:

                                                  
  ----------------------- ----------------------- -----------------------

3\. Divide the symbols below into **4** groups.

a)  DME

b)  Fix

c)  NDB

d)  TACAN

e)  VOR

f)  VORDME

g)  VORTAC

h)  Waypoint

  ----------------- ----------------- ----------------- -----------------
  Group 1           Group 2           Group 3           Group 4

  Name:             Name:             Name:             Name:

                                                        
  ----------------- ----------------- ----------------- -----------------

2\. Divide the symbols below into **5** groups.

a)  DME

b)  Fix

c)  NDB

d)  TACAN

e)  VOR

f)  VORDME

g)  VORTAC

h)  Waypoint

  -------------- -------------- -------------- -------------- --------------
  Group 1        Group 2        Group 3        Group 4        Group 5

  Name:          Name:          Name:          Name:          Name:

                                                              
  -------------- -------------- -------------- -------------- --------------

Part 4. Line Styles

The purpose of this task is to determine whether line style conventions
used on paper charts and moving map displays are understandable.

A. Paper Chart Styles

On a **paper chart**, solid thick, medium, and thin lines and dashed
long, medium, and short lines are used to convey different paths. For
each path described below, select the line style(s) that you think best
describe how it appears **when it appears on the plan view of a paper
chart**.

+-----+-----------------------------------------------------------------+
| 1   | **A radial or a bearing line that defines an intersection** is  |
| .   | represented by a:                                               |
|     |                                                                 |
|     | a)  solid, thick line ![](media/image45.png){width="1.34375in"  |
|     |     height="0.14583333333333334in"}                             |
|     |                                                                 |
|     | b)  solid, medium line                                          |
|     |     ![](media/image46.png){width="1.3020833333333333in"         |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | c)  solid, thin line ![](media/image47.png){width="1.3125in"    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | d)  dashed, long line                                           |
|     |     ![](media/image48.png){width="1.3333333333333333in"         |
|     |     height="0.13541666666666666in"}                             |
|     |                                                                 |
|     | e)  dashed, medium line                                         |
|     |     ![](media/image49.png){width="1.34375in"                    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | f)  dashed, short line                                          |
|     |     ![](media/image50.png){width="1.3229166666666667in"         |
|     |     height="0.10416666666666667in"}                             |
|     |                                                                 |
|     | g)  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | h)  Don't know                                                  |
+-----+-----------------------------------------------------------------+
| 2   | **The procedure path** is represented by a:                     |
| .   |                                                                 |
|     | a.  solid, thick line ![](media/image45.png){width="1.34375in"  |
|     |     height="0.14583333333333334in"}                             |
|     |                                                                 |
|     | b.  solid, medium line                                          |
|     |     ![](media/image46.png){width="1.3020833333333333in"         |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | c.  solid, thin line ![](media/image47.png){width="1.3125in"    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | d.  dashed, long line                                           |
|     |     ![](media/image48.png){width="1.3333333333333333in"         |
|     |     height="0.13541666666666666in"}                             |
|     |                                                                 |
|     | e.  dashed, medium line                                         |
|     |     ![](media/image49.png){width="1.34375in"                    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | f.  dashed, short line                                          |
|     |     ![](media/image50.png){width="1.3229166666666667in"         |
|     |     height="0.10416666666666667in"}                             |
|     |                                                                 |
|     | g.  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | h.  Don't know                                                  |
+-----+-----------------------------------------------------------------+
| 3   | A **missed approach path** is represented by a:                 |
| .   |                                                                 |
|     | a.  solid, thick line ![](media/image45.png){width="1.34375in"  |
|     |     height="0.14583333333333334in"}                             |
|     |                                                                 |
|     | b.  solid, medium line                                          |
|     |     ![](media/image46.png){width="1.3020833333333333in"         |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | c.  solid, thin line ![](media/image47.png){width="1.3125in"    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | d.  dashed, long line                                           |
|     |     ![](media/image48.png){width="1.3333333333333333in"         |
|     |     height="0.13541666666666666in"}                             |
|     |                                                                 |
|     | e.  dashed, medium line                                         |
|     |     ![](media/image49.png){width="1.34375in"                    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | f.  dashed, short line                                          |
|     |     ![](media/image50.png){width="1.3229166666666667in"         |
|     |     height="0.10416666666666667in"}                             |
|     |                                                                 |
|     | g.  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | h.  Don't know                                                  |
+-----+-----------------------------------------------------------------+
| 4   | A **transition path** is represented by a:                      |
| .   |                                                                 |
|     | a.  solid, thick line ![](media/image45.png){width="1.34375in"  |
|     |     height="0.14583333333333334in"}                             |
|     |                                                                 |
|     | b.  solid, medium line                                          |
|     |     ![](media/image46.png){width="1.3020833333333333in"         |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | c.  solid, thin line ![](media/image47.png){width="1.3125in"    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | d.  dashed, long line                                           |
|     |     ![](media/image48.png){width="1.3333333333333333in"         |
|     |     height="0.13541666666666666in"}                             |
|     |                                                                 |
|     | e.  dashed, medium line                                         |
|     |     ![](media/image49.png){width="1.34375in"                    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | f.  dashed, short line                                          |
|     |     ![](media/image50.png){width="1.3229166666666667in"         |
|     |     height="0.10416666666666667in"}                             |
|     |                                                                 |
|     | g.  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | h.  Don't know                                                  |
+-----+-----------------------------------------------------------------+
| 5   | A **visual flight path** is represented by a:                   |
| .   |                                                                 |
|     | a.  solid, thick line ![](media/image45.png){width="1.34375in"  |
|     |     height="0.14583333333333334in"}                             |
|     |                                                                 |
|     | b.  solid, medium line                                          |
|     |     ![](media/image46.png){width="1.3020833333333333in"         |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | c.  solid, thin line ![](media/image47.png){width="1.3125in"    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | d.  dashed, long line                                           |
|     |     ![](media/image48.png){width="1.3333333333333333in"         |
|     |     height="0.13541666666666666in"}                             |
|     |                                                                 |
|     | e.  dashed, medium line                                         |
|     |     ![](media/image49.png){width="1.34375in"                    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | f.  dashed, short line                                          |
|     |     ![](media/image50.png){width="1.3229166666666667in"         |
|     |     height="0.10416666666666667in"}                             |
|     |                                                                 |
|     | g.  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | h.  Don't know                                                  |
+-----+-----------------------------------------------------------------+
| 6   | **Other conditional routes** are represented by a:              |
| .   |                                                                 |
|     | a.  solid, thick line ![](media/image45.png){width="1.34375in"  |
|     |     height="0.14583333333333334in"}                             |
|     |                                                                 |
|     | b.  solid, medium line                                          |
|     |     ![](media/image46.png){width="1.3020833333333333in"         |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | c.  solid, thin line ![](media/image47.png){width="1.3125in"    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | d.  dashed, long line                                           |
|     |     ![](media/image48.png){width="1.3333333333333333in"         |
|     |     height="0.13541666666666666in"}                             |
|     |                                                                 |
|     | e.  dashed, medium line                                         |
|     |     ![](media/image49.png){width="1.34375in"                    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | f.  dashed, short line                                          |
|     |     ![](media/image50.png){width="1.3229166666666667in"         |
|     |     height="0.10416666666666667in"}                             |
|     |                                                                 |
|     | g.  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | h.  Don't know                                                  |
+-----+-----------------------------------------------------------------+
| 7   | **Airways** are represented by a:                               |
| .   |                                                                 |
|     | a.  solid, thick line ![](media/image45.png){width="1.34375in"  |
|     |     height="0.14583333333333334in"}                             |
|     |                                                                 |
|     | b.  solid, medium line                                          |
|     |     ![](media/image46.png){width="1.3020833333333333in"         |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | c.  solid, thin line ![](media/image47.png){width="1.3125in"    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | d.  dashed, long line                                           |
|     |     ![](media/image48.png){width="1.3333333333333333in"         |
|     |     height="0.13541666666666666in"}                             |
|     |                                                                 |
|     | e.  dashed, medium line                                         |
|     |     ![](media/image49.png){width="1.34375in"                    |
|     |     height="0.11458333333333333in"}                             |
|     |                                                                 |
|     | f.  dashed, short line                                          |
|     |     ![](media/image50.png){width="1.3229166666666667in"         |
|     |     height="0.10416666666666667in"}                             |
|     |                                                                 |
|     | g.  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | h.  Don't know                                                  |
+-----+-----------------------------------------------------------------+

B. Moving Map Display Styles (Skip this section if you are not familiar
with moving map displays)

On a **moving map display**, solid thick, medium, and thin lines and
dashed lines are used to convey different paths. For each path described
below, select the line style(s) that you think best describe how it
appears **when it appears on a moving map display**.

+-----+-----------------------------------------------------------------+
| 1   | The **missed approach path** is represented by a:               |
| .   |                                                                 |
|     | h)  solid, thick line                                           |
|     |                                                                 |
|     | i)  solid, medium line                                          |
|     |                                                                 |
|     | j)  solid, thin line                                            |
|     |                                                                 |
|     | k)  dashed line                                                 |
|     |                                                                 |
|     | l)  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | m)  No specific meaning                                         |
|     |                                                                 |
|     | n)  Don't know                                                  |
+-----+-----------------------------------------------------------------+
| 2   | **Airways** are represented by a:                               |
| .   |                                                                 |
|     | a)  solid, thick line                                           |
|     |                                                                 |
|     | b)  solid, medium line                                          |
|     |                                                                 |
|     | c)  solid, thin line                                            |
|     |                                                                 |
|     | d)  dashed line                                                 |
|     |                                                                 |
|     | e)  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | f)  No specific meaning                                         |
|     |                                                                 |
|     | g)  Don't know                                                  |
+-----+-----------------------------------------------------------------+
| 3   | The **alternate (non-activated) flight plan** is represented by |
| .   | a:                                                              |
|     |                                                                 |
|     | a)  solid, thick line                                           |
|     |                                                                 |
|     | b)  solid, medium line                                          |
|     |                                                                 |
|     | c)  solid, thin line                                            |
|     |                                                                 |
|     | d)  dashed line                                                 |
|     |                                                                 |
|     | e)  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | f)  No specific meaning                                         |
|     |                                                                 |
|     | g)  Don't know                                                  |
+-----+-----------------------------------------------------------------+
| 4   | A **state or country boundary** is represented by a             |
| .   |                                                                 |
|     | a)  solid, thick line                                           |
|     |                                                                 |
|     | b)  solid, medium line                                          |
|     |                                                                 |
|     | c)  solid, thin line                                            |
|     |                                                                 |
|     | d)  dashed line                                                 |
|     |                                                                 |
|     | e)  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | f)  No specific meaning                                         |
|     |                                                                 |
|     | g)  Don't know                                                  |
+-----+-----------------------------------------------------------------+
| 5   | The **active flight plan** is represented by a:                 |
| .   |                                                                 |
|     | a)  solid, thick line                                           |
|     |                                                                 |
|     | b)  solid, medium line                                          |
|     |                                                                 |
|     | c)  solid, thin line                                            |
|     |                                                                 |
|     | d)  dashed line                                                 |
|     |                                                                 |
|     | e)  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | f)  No specific meaning                                         |
|     |                                                                 |
|     | g)  Don't know                                                  |
+-----+-----------------------------------------------------------------+
| 6   | An **airspace boundary** is represented by a:                   |
| .   |                                                                 |
|     | a)  solid, thick line                                           |
|     |                                                                 |
|     | b)  solid, medium line                                          |
|     |                                                                 |
|     | c)  solid, thin line                                            |
|     |                                                                 |
|     | d)  dashed line                                                 |
|     |                                                                 |
|     | e)  Other \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_            |
|     |                                                                 |
|     | f)  No specific meaning                                         |
|     |                                                                 |
|     | g)  Don't know                                                  |
+-----+-----------------------------------------------------------------+

![](media/image84.jpeg){width="5.375in" height="8.25in"}

![](media/image85.jpeg){width="5.375in" height="8.25in"}

[]{#__RefHeading___Toc183840970 .anchor}Appendix B:\
Response Coding Method for the\
General-Symbol Identification Task

The purpose of this appendix is to explain the process used for coding
the raw response to the identification task for general symbols.

The raw responses to the symbol identification task produced multiple
unique responses. Some of these were simple variants of each other
(e.g., use of abbreviations) but some responses clearly represented a
different concept from other responses. The first step in the response
coding was to identify how many and which unique concepts were contained
in all of the individual responses.

To do this, the individual responses were first sorted alphabetically,
and duplicate responses were eliminated. The next step was to determine
which unique responses belonged together in one category. The
experimenters worked with the SAE G-10 Aeronautical Charting Committee
to develop the categories and to identify what responses belonged in
what category, particularly if there was some uncertainty. The final
result was a set of response categories that included all of the
individual responses. Note that there were typically a few unrelated
unique responses that were coded together in a miscellaneous response
category titled *Other*. A question-mark response was categorized as
*Can't Tell.* If there was no response at all, the cell was coded as
missing data.

Table 23 below is an excerpt from a raw data file for one of the
symbols, the low single obstruction symbol (i.e., item #10 from the
General Symbols section of the symbol identification task in
[Appendix A](#__RefHeading___Toc183840967)). For this symbol, the
response categories used were:

  ---- ------------------------------------------------------------------
  A    Obstruction

  B    Manmade Structures

  C    Terrain

  D    Other
  ---- ------------------------------------------------------------------

As shown in Table 23, responses containing the word *obstacle* were
placed in category A. Responses such as *multiple towers* and *antennae*
were placed in category B. Responses relating to terrain were placed in
the category C. These response category codes are shown under the column
titled *General Answer.* Note that some responses were coded in more
than one response category. For example the response from Participant
#32 mentions both *single tower* (a manmade structure, category B), and
*obstacle* response category A. Therefore that response was coded as "A,
B." The response from Participant #51 was coded as "A, C" because it
mentions both an obstacle and terrain.

For some symbols, the response was also coded in terms of whether
details about the symbol were mentioned or not. For example, for the
obstruction symbol, details about the mention of height and multiplicity
were also coded. The General Answer for the response was coded without
regard to the detail provided. For example, any response that said
*obstacle* or *obstruction* counted as an obstacle (A), even if the
detail was incorrect. The response from Participant #22 (in the first
row of Table 23) provides a specific example. The response given was
*obstacles* which was classified as the correct general answer (A) even
though the detail was not correct because more than one obstacle was
mentioned. Because the detail about multiplicity was incorrect,
Participant #22 did not get an "x" under the detail column titled
*Single*.

Similarly, the response *Obstruction \> 1000 AGL* (from Participant #39)
was classified as an obstacle (A) with correct mention of the *Single*
detail because the word *obstruction*, not *obstructions*, was used.
However, because the height detail reported was incorrect, the response
was not counted towards the reports of correct height detail (in the
column titled *Low*). The number of times incorrect detail was reported
was not analyzed.

  ------------- -------------------------------------- --------- -------- -------- ------------
                Obstruction - Low Single                                           

  Item \#       10                                                                  

  Participant   ![](media/image10.png){width="0.3in"   General   Single   Low      Confidence
  ID            height="0.26666666666666666in"}        Answer                      

  22            obstacles                              A                           5

  23            Obstruction below 1000\' AGL           A         x        x        6

  27            Building                               B         x                 6

  28            Localizer/Glidescope                   D                           4

  29            Unidentified man made structure        B         x                 6

  30            obstacle/obstruction                   A         x                 4

  31            Tower - Low Structure                  B         x        x        6

  32            single tower. obstacle                 A, B      x                 6

  33            obstruction                            A         x                  

  34            tower                                  B         x                 4

  35            obstruction - low height               A         x        x        5

  36            Obstacle                               A         x                 4

  37            obstacle                               A         x                 7

  38            Single obstruction shorter than 1000\' A         x        x        7
                AGL                                                                

  39            Obstruction \> 1000\' AGL              A         x                 7

  40            Twr                                    B         x                 5

  41            Tower                                  B         x                 6

  44            Terrain                                C                           7

  45            unidentified man made structure        B         x                 7

  46            Tower \<500\'                          B         x        x        7

  47            Man made obstruction in 400\'AGL with  B         x                  
                lights                                                             

  48            obstacle                               A         x                 6

  49            Antennae                               B                           5

  50            Tower                                  B         x                 5

  51            Obstacle on High Terrain               A, C      x                 6

  52            Single Obstruction                     A         x                 7

  53            Single manmade obstruction             A, B      x                 7
  ------------- -------------------------------------- --------- -------- -------- ------------

[]{#__RefHeading___Toc183841025 .anchor}Table 23. Excerpt of data for
low single obstruction symbol.

[]{#__RefHeading___Toc183840971 .anchor}Appendix C:\
Cluster Analysis Results

The tables below present the similarity matrices for the symbol
classification task. The navigation aids are listed in the columns and
rows of each matrix, and the number of times two navigation aids were
grouped together is shown in the cells. The upper and lower halves of
the matrices mirror each other, and cells along the diagonal indicate
how often the navigation aid was placed in a group by itself.

Dendrograms from the cluster analysis that depict the relationship among
navigation aids for that grouping are shown below each matrix. A
comparison of the dendrograms to the similarity matrices show the
relationships participants perceived among the navigation aids. An
explanation of how to interpret the dendrogram is included for the
classification of navigation aids into two groups. The other dendrograms
would be interpreted similarly.

Results for Classification into Two Groups

  -------------- --------- --------- --------- ----------- --------- ------------ ------------ --------------
                 **DME**   **Fix**   **NDB**   **TACAN**   **VOR**   **VORDME**   **VORTAC**   **Waypoint**

  **DME**        3         17        65        70          65        68           66           13

  **Fix**        17        \--       20        12          16        18           17           89

  **NDB**        65        20        \--       63          75        61           58           18

  **TACAN**      70        12        63        \--         74        73           76           12

  **VOR**        65        16        75        74          \--       68           65           16

  **VORDME**     68        18        61        73          68        \--          79           16

  **VORTAC**     66        17        58        76          65        79           \--          17

  **Waypoint**   13        89        18        12          16        16           17           \--
  -------------- --------- --------- --------- ----------- --------- ------------ ------------ --------------

![](media/image86.png){width="5.997916666666667in"
height="2.004861111111111in"}

The dendrogram for the classification of navigation aids into two groups
shows two main "clusters": one containing the fix and waypoint, and the
other consisting of the NDB, VOR, VORDME, VORTAC, TACAN, and DME. The
distance between clusters (i.e., the similarity between the items is
shown along the horizontal axis and highlights the "closeness" of the
fix and waypoint. Overall, the greatest number of clusters possible was
5 at a distance of 1: (1) fix and waypoint, (2) NDB and VOR, (3) VORDME
and VORTAC, (4) TACAN only, and (5) DME only. The distinctness of a
cluster is shown by the distance along the horizontal axis from the
point at which is comes into existence to the point at which it becomes
part of a larger cluster. Thus, pilots' categorizations showed that they
considered the NDB and VOR to be closely related, as were the VORDME and
VORTAC. At approximately a distance of 5, the VORDME and VORTAC joined
with the TACAN to form a cluster, and at a distance of 8, this cluster
was joined by the DME.

Results for Classification into Three Groups

  -------------- --------- --------- --------- ----------- --------- ------------ ------------ --------------
                 **DME**   **Fix**   **NDB**   **TACAN**   **VOR**   **VORDME**   **VORTAC**   **Waypoint**

  **DME**        9         11        29        38          39        26           24           8

  **Fix**        11        1         5         6           3         8            7            77

  **NDB**        29        5         11        14          56        17           14           6

  **TACAN**      38        6         14        \--         24        59           59           5

  **VOR**        39        3         56        24          \--       35           33           2

  **VORDME**     26        8         17        59          35        \--          65           8

  **VORTAC**     24        7         14        59          33        65           \--          8

  **Waypoint**   8         77        6         5           2         8            8            1
  -------------- --------- --------- --------- ----------- --------- ------------ ------------ --------------

![](media/image87.png){width="5.99375in" height="2.026388888888889in"}

Results for Classification into Four Groups

  -------------- --------- --------- --------- ----------- --------- ------------ ------------ --------------
                 **DME**   **Fix**   **NDB**   **TACAN**   **VOR**   **VORDME**   **VORTAC**   **Waypoint**

  **DME**        30        4         11        20          17        15           10           3

  **Fix**        4         4         3         2           0         2            4            72

  **NDB**        11        3         24        3           38        3            3            3

  **TACAN**      20        2         3         12          8         39           44           1

  **VOR**        17        0         38        8           \--       27           22           0

  **VORDME**     15        2         3         39          27        \--          70           1

  **VORTAC**     10        4         3         44          22        70           \--          2

  **Waypoint**   3         72        3         1           0         1            2            6
  -------------- --------- --------- --------- ----------- --------- ------------ ------------ --------------

![](media/image88.png){width="5.99375in" height="2.0in"}

Results for Classification into Five Groups

  -------------- --------- --------- --------- ----------- --------- ------------ ------------ --------------
                 **DME**   **Fix**   **NDB**   **TACAN**   **VOR**   **VORDME**   **VORTAC**   **Waypoint**

  **DME**        41        1         6         16          8         4            2            1

  **Fix**        1         12        0         1           1         3            3            57

  **NDB**        6         0         45        1           22        1            0            0

  **TACAN**      16        1         1         24          5         21           26           1

  **VOR**        8         1         22        5           26        13           11           0

  **VORDME**     4         3         1         21          13        8            55           1

  **VORTAC**     2         3         0         26          11        55           5            1

  **Waypoint**   1         57        0         1           0         1            1            15
  -------------- --------- --------- --------- ----------- --------- ------------ ------------ --------------

![](media/image89.png){width="5.998611111111111in"
height="2.0368055555555555in"}

##  {#section .unnumbered}

[^1]: The intention was to distinguish between private flights conducted
    for business purposes ("business") from flights conducted by a
    corporate flight department ("corporate"). However, it is not known
    whether this distinction was clear to participants.

[^2]: Pilots who did not sign the consent forms presumably thought they
    were ensuring their anonymity. However, the signed consent form,
    which assures that pilot that his/her participation is strictly
    confidential, is what gives us permission to use the data. The
    Institutional Review Board who reviewed the study procedure to
    ensure that participants are treated ethically requires the signed
    form. In addition, anonymity of the data was assured because the
    consent forms were separated from the rest of the data upon receipt.

[^3]: The overall response rate was difficult to track because the
    materials for the study were distributed freely at different venues
    via different methods. For example, the materials were provided to
    anyone who requested them at various meetings, regardless of whether
    the recipient was a qualified pilot. In some cases, a single
    individual at an organization was allowed to photocopy the
    materials, resulting in an unknown number of copies being
    distributed. In another case, the materials were left out on a desk
    for pilots to pick up, and it is not known how many of the surveys
    were actually taken.

[^4]: ADF (Automatic Direction Finder) is the name of the instrument on
    the aircraft that displays the location of the NDB relative to
    aircraft position, and is often mistakenly used to refer to the NDB
    instead.

[^5]: When the questionnaire was designed, the plan was to consider the
    symbol identifier as well as the frequency. These trials were
    included in the survey but they were deleted from the final analysis
    after consultation with the SAE G‑10 Aeronautical Charting committee
    because it was determined that the symbol identifier did not provide
    a reliable clue about the facility type.

[^6]: This was a 3x2 ANOVA with 3 levels of information (symbol alone,
    frequency alone, symbol + frequency) and 2 levels of chart provider
    (Jeppesen, NACO).

[^7]: Only 20 of the 96 participants reported that they primarily used
    NACO charts.