Definition
A non-directional radio beacon (NDB) located on the airport itself, used as the final approach fix for an NDB instrument approach. Because the beacon sits on the field, station passage over the NDB marks arrival at the missed approach point, and no separate final approach fix is published off-airport.
Plain English
An NDB navigation beacon that is physically on the airport grounds. Flying over it tells you that you have reached the runway area, so it serves as the point where you either see the runway and land, or go missed.
Context Anchor
Seen on NDB approach charts and in instrument approach procedure descriptions.
Derivation
Beacon originally meant a signal used to guide or warn people, such as a light or fire on high ground. In aviation, an NDB is a radio beacon: it sends out a signal an aircraft can use to find the station.
Why Pilots Care
The on-airport location simplifies the final approach segment and affects how the missed approach is flown compared with an off-airport NDB.
Intuition Check
Do not assume “on-airport” means the beacon is on the runway centerline or at the runway end. It means the NDB facility is located on the airport and must be used exactly as shown on the procedure.
Example Sentence 1
Because this is an on-airport NDB facility, we'll start the missed approach the moment we get station passage if the runway isn't in sight.
Example Sentence 2
Because the procedure used an on-airport NDB facility, the final approach fix was located at the airport itself.