FAA Aircraft Dispatcher (ADX)Regulations (Part 121)Medium
A Part 121 operator schedules a turbine-powered airplane with 19 passenger seats on a route through mountainous terrain. Under 14 CFR 121.354, this airplane must be equipped with which system?
- AAn auxiliary power unit for emergency terrain climb-out
- BA weather radar system only, since terrain avoidance is a pilot judgment issue
- CA ground proximity warning system with a terrain awareness and warning function
- DNo terrain warning system, since the requirement applies only to jets over 30 seats
Show answer & explanationAnswer & explanation
Correct answer: C. A ground proximity warning system with a terrain awareness and warning function
14 CFR 121.354 requires turbine-powered airplanes with 10 or more passenger seats operated under Part 121 to be equipped with a ground proximity warning system that includes a terrain awareness and warning function (TAWS), regardless of route terrain.
Why the other options are wrong
- A. An APU has no role in terrain avoidance.
- B. Weather radar addresses precipitation and turbulence, not terrain proximity.
- D. The threshold is 10 seats, not 30, and this airplane exceeds it.
GPWS/TAWS Requirement (121.354)
Requires turbine-powered Part 121 airplanes with 10 or more passenger seats to carry a ground proximity warning system with terrain awareness.
- Applies regardless of specific route terrain
- Provides warnings for excessive descent rate, terrain closure, etc.
- Distinct equipment from weather radar and TCAS
Memory trick: Ten seats or more, GPWS keeps you off the mountain floor.