Instrument Systems Flashcards

What is the primary purpose of a Traffic Collision Avoidance System (TCAS)?

Answer: Detect nearby transponder-equipped aircraft and issue resolution advisories to avoid collision

TCAS interrogates transponders of nearby aircraft to determine relative position and issues Traffic Advisories (TAs) and Resolution Advisories (RAs) to prevent mid-air collisions.

What altitude is typically displayed on the TCAS/RA display relative to own aircraft?

Answer: Relative altitude in hundreds of feet above or below own aircraft

TCAS traffic symbols display relative altitude in hundreds of feet above (+) or below (−) the own aircraft's current altitude.

What is the function of a Ground Proximity Warning System (GPWS)?

Answer: Alert the crew when aircraft flight parameters indicate dangerous proximity to terrain

GPWS monitors parameters like sink rate, terrain clearance, gear/flap configuration, and airspeed to generate aural and visual warnings before controlled flight into terrain (CFIT).

Enhanced GPWS (EGPWS) adds which major capability over basic GPWS?

Answer: A worldwide terrain database for look-ahead terrain alerting

EGPWS adds a worldwide terrain elevation database to provide look-ahead terrain alerting, warning of obstacles ahead of the aircraft before they are sensed by reactive modes.

What does a radio altimeter measure?

Answer: True altitude above the terrain directly below the aircraft

A radio altimeter (radar altimeter) transmits radio waves downward and measures the round-trip time to determine exact height above ground level (AGL).

At what height AGL does the radio altimeter Decision Height (DH) alert typically trigger during an ILS approach?

Answer: At the pilot-set DH/DA value, typically 200 ft AGL for a Cat I ILS

The radio altimeter triggers the DH alert at the crew-selected decision height — typically 200 ft AGL for a Category I ILS approach.