FAA Instrument Rating Airplane (IRA)Regulations and CurrencyMedium
A pilot's aircraft is equipped only with VOR navigation (no DME and no approved RNAV system) and plans an IFR flight at FL250. According to 14 CFR 91.205(f), what additional equipment must the aircraft have?
- AA second VOR receiver for redundancy
- BAn ADF receiver for cross-checking position
- CA weather radar or datalink weather display
- DDME or a suitable RNAV system
Show answer & explanationAnswer & explanation
Correct answer: D. DME or a suitable RNAV system
14 CFR 91.205(f) requires that a VOR-equipped civil aircraft operating IFR above FL240 have DME or a suitable RNAV system, since VOR/DME-based distance information becomes necessary at high altitudes where VOR station spacing increases.
Why the other options are wrong
- A. Incorrect — a second VOR is not the specific requirement under 91.205(f).
- B. Incorrect — ADF is not required by this regulation.
- C. Incorrect — weather radar is not an equipment mandate under 91.205(f).
DME/RNAV Above FL240 (91.205(f))
Civil aircraft using VOR for IFR navigation above FL240 must be equipped with DME or a suitable RNAV system.
- Applies specifically above FL240
- DME or RNAV satisfies the requirement
- Reflects wider VOR station spacing at high altitude
Memory trick: Above 24,000 feet, VOR alone isn't enough — bring DME or RNAV.