FAA Airline Transport Pilot (ATM)Transport Aerodynamics and High-Altitude OperationsEasy
A flight crew is planning a flight through RVSM airspace between FL290 and FL410. To receive RVSM operational approval, the airplane's altimetry system must maintain altimetry system error (ASE) within:
- A±200 feet
- B±300 feet
- C±100 feet
- D±500 feet
Show answer & explanationAnswer & explanation
Correct answer: A. ±200 feet
RVSM approval requires the altimetry system error (difference between indicated pressure altitude and true pressure altitude) to remain within ±200 feet. This tight tolerance is what allows ATC to safely apply the reduced 1,000-foot vertical separation between FL290 and FL410 instead of the normal 2,000 feet.
Why the other options are wrong
- B. ±300 ft would be too loose to safely support 1,000-ft separation.
- C. ±100 ft is tighter than the actual RVSM standard.
- D. ±500 ft is the pre-RVSM (non-RVSM) separation standard, not the ASE tolerance.
RVSM Altimetry System Error (ASE)
Reduced Vertical Separation Minimum airspace (FL290–FL410) requires aircraft altimetry systems to be accurate within ±200 feet to support 1,000-ft vertical separation.
- RVSM airspace spans FL290 to FL410
- ASE tolerance must be within ±200 feet
- Enables 1,000-ft vertical separation instead of 2,000-ft
Memory trick: RVSM = 'Really Very Small Margin' — 200 feet or bust