ADF/NDB tracking technique
| Homing | Tracking | |
|---|---|---|
| Needle | pinned on 0 index | constant offset from 0 index (inbound) or 180 index (outbound) |
| Offset means | none | wind correction |
| Crosswind result | curved path, downwind drift, longer distance | drift corrected |
- Outbound: correct opposite the direction needle points (needle near tail).
Intercepting a track:
- Fly heading parallel to desired track.
- Turn 90 degrees toward needle side.
- Hold until needle nears wing-tip (090 or 270 relative).
- Turn onto track.
- Example: south of 285 degree inbound track, needle at 030: turn to 015; turn onto 285 when needle opens to 270.
- Near station: shallower than 90 degrees; 90 overshoots track, drift can exceed a wide angle before turn finished.
Correcting drift once tracking:
- Needle deviates off 0/180 index while heading held: drifting.
- Turn back by chosen correction.
- Hold until needle returns to within 20 degrees of index.
- Halve that correction for new maintenance heading.
- Steady offset on steady heading: correction right.
Station passage:
- Overhead: needle swings back and forth, then snaps to 180 (beacon behind).
- Needle displacement per off-track distance grows sharply near beacon: see
one-in-sixty-off-course.
Trap: homing (chasing needle to 0) instead of tracking (steady wind-corrected offset) drifts downwind, lengthens flight.
References
- TP 1102 Instrument Flying: Homing to the Station, Intercepting a Track To/From a Station, Correcting for Drift, Station Passage, Intercept Angles
- FAA-H-8083-25 PHAK ch.16, ADF Homing, ADF Tracking To/From Station