Navigation Equipment Flashcards

What is the primary function of a Distance Measuring Equipment (DME) system?

Answer: Measures slant range distance to a ground transponder

DME measures slant range (line-of-sight distance) between the aircraft and a ground transponder by timing interrogation/reply pulse pairs.

In an Inertial Navigation System (INS), what component detects rotational motion?

Answer: Gyroscope

Gyroscopes detect rotational motion (attitude changes) while accelerometers measure linear acceleration in an INS.

A VOR receiver measures the phase difference between which two signals?

Answer: 30 Hz reference and 30 Hz variable signals

VOR bearing is determined by comparing the phase of the 30 Hz omnidirectional reference signal against the 30 Hz variable phase signal.

What does a RAIM (Receiver Autonomous Integrity Monitoring) function do in a GPS receiver?

Answer: Detects faulty satellite data using redundant satellites

RAIM uses extra visible satellites beyond the minimum required to self-check GPS integrity and alert crew if a satellite is providing erroneous data.

Which frequency band does a typical radio altimeter operate in?

Answer: C-band (4.2–4.4 GHz)

Radio altimeters operate in the C-band at 4.2–4.4 GHz, transmitting FM continuous-wave signals toward the ground to measure altitude above terrain.

What is the maximum theoretical range error caused by Selective Availability (SA) in GPS before it was disabled?

Answer: ±100 meters

Selective Availability intentionally degraded civilian GPS accuracy to approximately ±100 meters (95%) until it was disabled by presidential order in May 2000.

On a horizontal situation indicator (HSI), what does the course deviation indicator (CDI) needle represent when centered?

Answer: Aircraft is on the selected VOR radial or localizer course

A centered CDI needle on the HSI indicates the aircraft is on the selected VOR radial or localizer centerline course.