FAA Aircraft Dispatcher (ADX)Flight Planning and PerformanceHard
For ETOPS flight planning, the 'critical fuel scenario' requires the dispatcher to calculate fuel assuming which combination of events occurs simultaneously at the most critical point along the route?
- AEngine failure only, with the cabin remaining pressurized
- BComplete electrical failure combined with loss of both engines
- CLoss of pressurization only, with normal engine operation continuing
- DEngine failure and loss of cabin pressurization occurring at the same time
Show answer & explanationAnswer & explanation
Correct answer: D. Engine failure and loss of cabin pressurization occurring at the same time
The ETOPS critical fuel scenario requires planning for the simultaneous occurrence of an engine failure and a decompression at the most critical point (typically the equal-time point), since this combination produces the highest fuel burn during a diversion at a lower, less efficient altitude.
Why the other options are wrong
- A. Considering only engine failure without decompression understates the worst-case fuel burn.
- B. Total loss of both engines is not the ETOPS diversion scenario, which assumes one engine remains operative.
- C. Considering only decompression ignores the more fuel-critical engine failure scenario.
ETOPS Critical Fuel Scenario
An ETOPS fuel planning requirement assuming an engine failure and cabin decompression occur simultaneously at the most critical point, requiring diversion at a lower altitude with higher fuel burn.
- Combines engine failure + decompression simultaneously
- Evaluated at the most critical point (often the equal-time point)
- Drives diversion altitude and fuel reserve calculations for ETOPS routes
Memory trick: 'Worst case: lose an engine AND the cabin, all at once, far from land.'