Communication and Navigation Systems Oral Exam Questions and Answers

October 19, 2026 · FAA sources checked October 19, 2026

These communication and navigation systems oral exam questions and answers follow AM.II.I. For O&P practice, identify the signal, the aircraft equipment, and the information shown to the crew.

What should my answer explain?

Our study tip: Separate communication, navigation, and surveillance functions before explaining a system. The elements below are all from AM.II.I; use the installed equipment’s instructions for maintenance and testing.

FAA-S-ACS-1, printed 34, PDF 39 · AM.II.I: Communication and Navigation Systems

Which ACS elements do these questions practice?

The table maps each study prompt to its knowledge element. It is not a prediction of assigned test questions.

Which oral exam questions can I practice?

These practice questions are built from ACS elements; they are not actual FAA test questions.

1. How does amplitude modulation put information on a radio carrier?

ACS: AM.II.I.K1

The information signal varies the carrier’s amplitude while the oscillator frequency stays consistent. At the receiver, demodulation removes the original information signal from the carrier.

FAA-H-8083-31B, Airframe, printed 11-31, PDF 634

2. Why can HF communication reach beyond line of sight while VHF is normally line of sight?

ACS: AM.II.I.K5

HF signals can refract from the ionosphere, extending their range beyond line of sight. As a result, transoceanic aircraft often use HF radios for voice communication. VHF space waves do not refract from the ionosphere and are limited to line-of-sight transmission.

FAA-H-8083-31B, Airframe, printed 11-30, PDF 633 · FAA-H-8083-31B, Airframe, printed 11-31, PDF 634

3. How does an aircraft’s VOR radial relate to its heading?

ACS: AM.II.I.K9

The radial identifies the aircraft’s location relative to the VOR station, regardless of the aircraft’s direction of flight. The aircraft does not have to be heading along that radial.

FAA-H-8083-31B, Airframe, printed 11-42, PDF 645

4. Why can DME slant distance differ from distance measured over the ground?

ACS: AM.II.I.K10

A traditional DME displays the distance from the ground-station antenna to the aircraft, called the slant distance. Because the aircraft is at altitude, the distance to the station from the point directly beneath the aircraft is shorter. Some modern DMEs can calculate and display that ground distance.

FAA-H-8083-31B, Airframe, printed 11-51, PDF 654 · FAA-H-8083-31B, Airframe, printed 11-52, PDF 655

5. What guidance do the ILS localizer and glideslope provide?

ACS: AM.II.I.K11

The localizer provides horizontal guidance to the runway centerline. The separate glideslope transmission provides vertical guidance down the proper slope to the touchdown point.

FAA-H-8083-31B, Airframe, printed 11-47, PDF 650

6. Where does a Mode C transponder get the altitude it reports to ATC?

ACS: AM.II.I.K21

The transponder gets pressure altitude from an electrically connected altitude encoder. In ALT or Mode C, the reply is modified with a code that places pressure altitude beside the aircraft’s target on the radar display.

FAA-H-8083-31B, Airframe, printed 11-54, PDF 657

7. How does a TCAS II resolution advisory differ from a traffic advisory?

ACS: AM.II.I.K13

A traffic advisory helps the pilot locate an intruder visually. TCAS II also analyzes projected flightpaths and, if a collision or near miss is imminent, issues a resolution advisory, an aural command to take a specific evasive action.

FAA-H-8083-31B, Airframe, printed 11-56, PDF 659

8. What information does ADS-B OUT broadcast?

ACS: AM.II.I.K20

ADS-B OUT combines GPS position with onboard flight-status information, including altitude, velocity, and time, and broadcasts it to other equipped aircraft and ground stations. The broadcasts use either 1090 ES, an expanded use of the 1090 MHz Mode S transponder protocol, or 978 MHz with a universal access transceiver (UAT).

FAA-H-8083-31B, Airframe, printed 11-57, PDF 660

9. How does a radio altimeter obtain height above the terrain?

ACS: AM.II.I.K19

The radio altimeter sends a signal toward the terrain beneath the aircraft and receives the reflection. The transceiver processes the signal’s elapsed travel time and frequency modulation to display height above ground level.

FAA-H-8083-31B, Airframe, printed 11-59, PDF 662 · FAA-H-8083-31B, Airframe, printed 11-60, PDF 663

10. What are the three GPS segments, and which equipment does the aircraft technician work with?

ACS: AM.II.I.K12

The segments are space, control, and user. The aircraft technician works with user equipment such as the GPS receiver, display, and antenna.

FAA-H-8083-31B, Airframe, printed 11-68, PDF 671

How do I rehearse the answer out loud?

Read the question, put the answer aside, and give a connected explanation. Then compare your answer with the cited FAA page and repeat the prompt. This is our study routine, not an FAA scoring rule.

For actual maintenance, use the applicable manufacturer’s instructions and aircraft-specific data. These short study answers are not complete maintenance procedures.

Which guide should I read next?

• Aircraft Instrument Systems Oral Exam Questions and Answers
• Aircraft Electrical Systems Oral Exam Questions and Answers
• Airframe Inspection Oral Exam Questions and Answers

Which sources support these answers?

Sources were checked on October 19, 2026. Handbook citations identify the printed and PDF pages.

• FAA-S-ACS-1
• FAA-H-8083-31B, Airframe

About this guide: drafted with AI from the FAA sources listed on this page and checked claim by claim against them. Not reviewed by an A&P mechanic or DME. How we make our guides