FAA Aircraft Dispatcher (ADX)Navigation and ATCHard
An aircraft is flying a published DME arc transition to an instrument approach. Which technique is used to maintain the aircraft on the arc while tracking around the fix?
- AAdjust heading in small increments (typically 5–10°) toward or away from the station as DME distance fluctuates from the arc
- BDescend at a constant rate while ignoring lateral position until intercepting the final approach course
- CTrack the arc using only VOR radial changes without reference to DME distance
- DFly a constant heading equal to the inbound course regardless of DME indications
Show answer & explanationAnswer & explanation
Correct answer: A. Adjust heading in small increments (typically 5–10°) toward or away from the station as DME distance fluctuates from the arc
The standard technique for flying a DME arc involves periodically adjusting heading by small bracket increments (commonly 5° or 10°) toward or away from the station to correct for any deviation in DME distance from the published arc, keeping the aircraft on the arc's circular path.
Why the other options are wrong
- B. Vertical descent management is separate from lateral tracking technique on the arc.
- C. DME distance, not radial changes alone, is the primary reference for maintaining the arc.
- D. A constant heading equal to the inbound course would not maintain a curved arc path.
DME Arc Tracking Technique
A method of flying a curved path at a constant distance from a VOR/DME station by making small heading corrections based on DME distance changes, commonly called the 'bracket' technique.
- Uses small heading changes (5°–10°) toward/away from station
- Corrects based on DME distance increasing or decreasing from published arc
- Often flown using the 'lead radial' technique to anticipate turns
- Common in DME arc transitions to instrument approaches
Memory trick: 'Bracket the arc like adjusting a steering wheel' — small nudges keep you on the curve.