FAA Commercial Pilot Airplane (CAX)Aircraft SystemsHard
While cruising at FL250 in a pressurized airplane, the cabin altitude warning light illuminates and horn sounds. This warning most likely indicates that:
- Acabin altitude has climbed above the maximum allowable value, indicating a loss of pressurization control
- Bthe landing gear has failed to retract properly after takeoff
- Cthe turbocharger has just reached its critical altitude
- Dthe outflow valve has failed fully closed, causing overpressurization of the cabin
Show answer & explanationAnswer & explanation
Correct answer: A. cabin altitude has climbed above the maximum allowable value, indicating a loss of pressurization control
A cabin altitude warning system alerts the pilot when the cabin altitude rises above a preset threshold (commonly around 10,000–12,500 feet depending on the aircraft), signaling that the pressurization system is no longer maintaining a safe cabin environment and prompting crew action such as donning oxygen and initiating an emergency descent.
Why the other options are wrong
- B. Landing gear position has no connection to the cabin pressurization warning system.
- C. Critical altitude relates to turbocharger manifold pressure capability, not cabin pressurization warnings.
- D. An outflow valve failed closed would cause overpressurization, not a high cabin altitude warning.
Cabin Altitude Warning System
A pressurization safety system that alerts the pilot when cabin altitude exceeds a preset limit, indicating loss of pressurization.
- Triggers oxygen mask use and emergency descent procedures
- Cabin altitude, not aircraft altitude, is the sensed parameter
- Distinct from an overpressurization (safety valve) failure
Memory trick: Horn blares when the cabin climbs too high, not the plane.