Unit 2 Review Worksheet– Navigation Systems

1a. What does ADF stand for?

Automatic Direction Finder.

1b. What does VOR stand for?

VHF Omnirange / VHF Omnidirectional Range.

1c. What does RMI stand for?

Radio Magnetic Indicator.

1d. What does CDI stand for?

Course Deviation Indicator.

1e. What does ILS stand for?

Instrument Landing System.

1f. What does LOC stand for?

Localizer.

1g. What does GS stand for?

Glide Slope.

1h. What does MB stand for?

Marker Beacon.

1i. What does DME stand for?

Distance Measuring Equipment.

1j. What does HSI stand for?

Horizontal Situation Indicator.

1k. What does GPS stand for?

Global Positioning System

1l. What does GNSS stand for?

Global Navigation Satellite System

1m. What does WAAS stand for?

Wide Area Augmentation System

1n. What does LAAS stand for?

Local Area Augmentation System.

1o. What does LPV stand for?

Localizer Performance with Vertical Guidance

1p. What does RNAV stand for?

Area Navigation

1q. What does EFIS stand for?

Electronic Flight Instrument System.

1r. What does PFD stand for?

Primary Flight Display.

1s. What does MFD stand for?

Multi-Function Display

2. What is the difference between the aircraft’s course and heading?

Heading is the direction the aircraft nose faces in relation to north.

Course is the intended route or line of travel in relation to north.

Explanation: Heading is about where the aircraft is pointed. Course is about the route the aircraft is supposed to follow.

3. Which navigation system can be used with commercial AM broadcast radio stations?

ADF.

Explanation: ADF works in the low/medium frequency range and can receive NDBs and AM broadcast stations.

4. When installing an ADF antenna what additional step is required that is not necessary with other antenna installations?

The ADF system must be checked and calibrated for accurate bearing indication.

Explanation: ADF bearing can be affected by interference and aircraft structure, so the system needs to be verified after installation.

5. What antennas are used with an ADF?

• Loop antenna

• Sense antenna

Explanation: The loop antenna is directional. The sense antenna is omnidirectional. Together, they allow the ADF to point correctly toward the station.

6. What is the difference between an CDI and a RMI?

• CDI: Shows how far off a selected course the aircraft is.

• RMI: Shows aircraft heading and magnetic bearing to a station.

Explanation: A CDI is mainly for course deviation. An RMI combines heading information with needles that point toward a navigation station.

7. Which is the primary advantage of a VOR system over a ADF system?

VOR is more accurate than ADF.

Explanation: VOR gives a more stable navigation signal. ADF is more likely to wander because it is more affected by interference.

8. What other navigation system uses the same antenna as the VOR system?

ILS/localizer.

Explanation: VOR and ILS/localizer use the VHF NAV frequency range, so they can use the same NAV antenna system.

9. How are VOR and LOC assigned frequencies differentiated?

• VOR: Even digit after the decimal

• ILS/localizer: Odd digit after the decimal

Explanation: VOR and ILS/localizer share part of the VHF NAV band. The digit after the decimal helps identify which type of system the frequency belongs to.

10. How often must the VOR be operationally checked for IFR equipped aircraft?

Every 30 days.

Explanation: An IFR aircraft using VOR navigation must have the VOR checked within the required time period so the pilot knows the system is accurate enough for IFR use.

11. What are the two signals transmitted by a VOR station?

• Reference phase signal

• Variable phase signal

Explanation: The receiver compares these two signals to determine the aircraft’s bearing or radial from the station.

12. How does the NAV receiver determine the radial the aircraft is currently on?

It compares the phase difference between the reference and variable signals.

Explanation: Each radial has a different phase relationship. The receiver reads that difference and turns it into radial information.

13. How does a CDI indicate if an aircraft is on course?

The needle is centered.

Explanation: The CDI needle shows the aircraft’s relationship to the selected course. Centered means the aircraft is on that course.

14. What indication will tell the pilot that they are off course?

The CDI needle is deflected left or right.

Explanation: A deflected needle means the selected course is to one side of the aircraft.

15. How should the pilot fly the aircraft to get back on course?

Fly toward the needle.

Explanation: The needle shows where the selected course is. Turning toward the needle brings the aircraft back toward the course line.

16. What is the significance of a red NAV flag on the CDI?

The navigation signal is lost or unreliable.

Explanation: A NAV flag means the CDI information should not be trusted for navigation.

17. How many degrees off course are you from the selected VOR radial when the CDI needle is one dot off?

2 degrees.

Explanation: On a VOR CDI, each dot equals 2 degrees of course deviation.

18. Which indicators will show the aircraft’s current heading (2 answers)

• RMI

• HSI

Explanation: Both instruments have a compass card that shows aircraft heading. The HSI uses the lubber line, and the RMI uses the rotating compass card.

19. What factors determine the category of an ILS approach?

• Decision Height

• Runway Visual Range

Explanation: ILS categories are based on how low the aircraft can descend and how much runway visibility is required.

20. What three radio systems make up the ILS system?

• Localizer

• Glide slope

• Marker beacon

Explanation: Localizer gives lateral guidance. Glide slope gives vertical guidance. Marker beacon gives distance/position information during the approach.

21. Of the above systems, which one is tuned by the pilot?

a. Localizer

b. Glide slope

c. Marker beacon

Localizer.

Explanation: The pilot selects the localizer frequency. The glide slope is paired with that frequency and tunes automatically.

22. Describe how an aircraft gets left and right guidance form a localizer?

The localizer sends two signal lobes down the runway, and the receiver compares them to determine whether the aircraft is left or right of centerline.

Explanation: When the signals are balanced, the aircraft is on the runway centerline. If one side is stronger, the indicator shows a left or right correction.

23. How is localizer guidance provided to the pilot?

It is displayed on a CDI or HSI.

Explanation: The pilot follows the needle to stay lined up with the runway centerline.

24. How is the glide slope receiver tuned?

It is automatically tuned when the matching localizer frequency is selected.

Explanation: The glide slope frequency is paired with the localizer frequency, so the pilot does not tune it separately.

25. How does the aircraft receive vertical guidance from the glide slope receiver?

Through vertical deviation shown on a CDI or HSI.

Explanation: The glide slope indication shows whether the aircraft is above, below, or on the descent path.

26. What is indicated by a red “G/S” flag on the CDI?

The glide slope signal is lost or unreliable.

Explanation: The G/S flag means the vertical guidance should not be used.

27. Which navigation receiver is tuned to 75Mhz?

Marker beacon receiver.

Explanation: Marker beacons all transmit on 75 MHz.

28. What are the lights and tones used for the different marker beacons?

• Outer marker: 400 Hz, blue light

• Middle marker: 1300 Hz, amber light

• Inner marker: 3000 Hz, white light

Explanation: Each marker has a different tone and light color so the pilot can identify which marker was crossed.

29. How is a DME tuned?

DME is tuned through its paired navigation frequency, such as VOR, localizer, or ILS.

Explanation: DME channels are paired with other NAV systems, so selecting the paired NAV frequency selects the matching DME.

30. Define Jitter.

Jitter is random spacing between DME request pulses.

Explanation: The aircraft uses that random spacing to recognize its own reply from the ground station.

31. Define Squitter.

Squitter is a DME ground-station transmission sent when there are no aircraft interrogations.

Explanation: It keeps the DME station active and ready for aircraft requests.

32. How does a DME transmitter calculate the aircraft’s distance from the ground station?

It times how long it takes for an interrogation to receive a reply, then converts that time delay into distance.

Explanation: DME distance is based on radio travel time. The distance shown is slant range, which includes altitude as part of the straight-line distance to the station.

33. What are the 6 GNSS constellations used for navigation?

• GPS

• BeiDou / BDS

• Galileo

• GLONASS

• NavIC

• QZSS

Explanation: These are the major satellite navigation constellations used for GNSS positioning.

34. What are the three segments of the GNSS?

• Space

• Control

• User

Explanation: Space is the satellites. Control is the ground monitoring system. User is the receiver equipment.

35. How many GPS satellites need to be tracked to provide a location?

At least 3 satellites.

Explanation: Three satellites can provide a basic horizontal position.

36. How many GPS satellites need to be tracked to provide altitude information?

At least 4 satellites.

Explanation: Altitude requires a 3D position fix, so the receiver needs another satellite

37. What two systems are used to improve the accuracy of GPS navigation?

• WAAS

• LAAS

Explanation: Both systems provide correction information to improve GPS accuracy.

38. What is an LPV approach and how does it compare to an ILS approach?

LPV means Localizer Performance with Vertical Guidance. It is a WAAS-based approach that comes close to a CAT I ILS approach.

Explanation: LPV provides lateral and vertical guidance like an ILS, but it uses GPS/WAAS instead of runway-based localizer and glide slope transmitters.

39. What navigation sources can be used by an RNAV system?

• VOR/DME

• DME

• INS

• Satellite navigation

• Ground systems

• Onboard systems

Explanation: RNAV can use different navigation inputs to build routes that are more direct than flying station-to-station.

40. What systems require a NAV data base update every 28 days?

Systems that use electronic navigation databases, such as FMS, RNAV, and GPS-based navigation systems.

Explanation: These systems depend on stored navigation data, so the database has to stay current for accurate navigation