FAA Instrument Flight Instructor (FII)Instrument RegulationsEasy
A Part 91 pilot plans an IFR flight at FL270 in an airplane equipped with a single VOR receiver but no DME or RNAV system. Under 14 CFR 91.205(e), what must be added to the aircraft before this flight may be conducted?
- AA marker beacon receiver
- BA second VOR receiver for redundancy
- CDME or a suitable RNAV system
- DAn ADF receiver
Show answer & explanationAnswer & explanation
Correct answer: C. DME or a suitable RNAV system
14 CFR 91.205(e) requires that when operating IFR at or above FL240 using VOR navigation, the aircraft must also have DME or a suitable RNAV system installed and operable, because VOR stations become widely spaced at high altitude and DME/RNAV is needed for reliable position fixing.
Why the other options are wrong
- A. Marker beacon receivers relate to approach guidance, not high-altitude en route navigation.
- B. A second VOR is not the equipment specifically required by the regulation.
- D. ADF is not a requirement of 91.205(e) for high-altitude VOR operations.
High-Altitude DME/RNAV Requirement
14 CFR 91.205(e) requires DME or suitable RNAV equipment whenever VOR navigation is used for IFR flight at or above FL240.
- Applies at/above FL240 (24,000 ft MSL)
- Required only when VOR-based navigation is used
- A suitable RNAV system (e.g., IFR-approved GPS) satisfies the requirement
Memory trick: 'Above 240, DME or RNAV alone.'