AET Navigation Equipment 5 — Questions and Answers
Question 1: When testing a VOR receiver, an approved VOR test facility (VOT) should produce what indication on a correctly functioning receiver?
- 360° radial with FROM flag and centered CDI
- 000° radial with TO flag and centered CDI (Correct answer)
- 090° radial with FROM flag and full-scale CDI deflection
- 180° radial with TO flag and centered CDI
Correct answer: 000° radial with TO flag and centered CDI
A VOT transmits the 360° radial omnidirectionally; a properly functioning receiver tuned to a VOT should show 000° (or 360°) with a TO flag and a centered CDI within ±4°.
Question 2: What phenomenon causes GPS multipath errors?
- Satellite signals arriving via reflected paths in addition to direct path (Correct answer)
- Atmospheric bending of GPS signals near the horizon
- Ionospheric absorption of GPS carrier frequencies
- Doppler shift due to satellite orbital velocity
Correct answer: Satellite signals arriving via reflected paths in addition to direct path
Multipath error occurs when GPS signals reflect off terrain, buildings, or aircraft structures and arrive at the antenna via indirect paths, corrupting the direct-signal measurement.
Question 3: What does the term 'CDI sensitivity' refer to in area navigation (RNAV) operations?
- The gain setting of the VOR receiver RF amplifier
- The crosstrack distance represented by full-scale needle deflection (Correct answer)
- The rate at which the CDI updates its position display
- The minimum signal strength required to lock onto a course
Correct answer: The crosstrack distance represented by full-scale needle deflection
CDI sensitivity refers to the crosstrack distance (in nautical miles) that represents full-scale deflection; it scales from ±5 NM en route to ±0.3 NM during approach.
Question 4: What is the primary advantage of a Ring Laser Gyroscope (RLG) over a conventional mechanical gyroscope in navigation systems?
- Lower cost and simpler construction
- No moving parts, resulting in higher reliability and faster startup (Correct answer)
- Higher accuracy at low rotation rates
- Immunity to magnetic field interference
Correct answer: No moving parts, resulting in higher reliability and faster startup
Ring Laser Gyroscopes have no moving parts, which eliminates wear and bearing friction, providing greater reliability, faster alignment, and longer service life than mechanical gyros.
Question 5: During an ILS approach, a glideslope pointer above center on the ADI/flight director indicates the aircraft is:
- Above the glideslope — fly down
- Below the glideslope — fly up (Correct answer)
- On the glideslope — maintain current rate
- Glideslope signal unreliable — go around
Correct answer: Below the glideslope — fly up
A glideslope deviation pointer above center means the glideslope beam is above the aircraft, so the aircraft is below the glideslope and must climb (fly up) to intercept it.
Question 6: What is the purpose of IRS (Inertial Reference System) alignment and why must it be performed stationary?
- To calibrate barometric sensors against a known field elevation
- To establish a precise north reference and initial position before computing navigation (Correct answer)
- To synchronize the IRS clock with GPS time signals
- To zero out accumulated drift errors from the previous flight
Correct answer: To establish a precise north reference and initial position before computing navigation
IRS alignment uses Earth's rotation sensed by the gyros to determine true north and must be done stationary because any movement during alignment introduces position and heading errors.
Question 7: What is the significance of the 'cone of silence' associated with a VOR ground station?
- An area where VOR signals are strongest and most accurate
- A zone directly above the station where the signal is unreliable or absent (Correct answer)
- The protected airspace where other transmitters cannot interfere
- The angular range where the reference and variable phases are identical
Correct answer: A zone directly above the station where the signal is unreliable or absent
The cone of silence is the roughly conical area directly above a VOR station where the signal is extremely weak or absent due to the antenna's radiation pattern, causing unreliable bearing indications.
AET Navigation Equipment 5
When testing a VOR receiver, an approved VOR test facility (VOT) should produce what indication on a correctly functioning receiver?