An aircraft is intending to track from NDB ‘A’ to NDB ‘B’ on a track of 050° (T), heading 060° (T). If the RBI shows the relative bearing of ‘A’ to be 180° and the relative bearing of ‘B’ to be 330° then the aircraft is:
- A. Port of track and nearer ‘A’
- B. Port of track and nearer ‘B’
- C. Starboard of track and nearer ‘A’
- D. Starboard of track and nearer ‘B’
Think of it this way: the plane's heading is known, but the plane's actual track is not. Also the bearing from A to B is known-- it is the intended track.
Bearing from point A to plane = reciprocal of 60 + 180 = reciprocal of 240 = 60.
Bearing from point B to plane = reciprocal of 60 +330 = reciprocal of 390 = reciprocal of 030 = 210
Draw a sketch of A and B, with B 50 degrees from A. Draw the bearings from A and B to the plane-- the plane is located where these bearing lines cross-- and it will be clear that the plane is right of the intended track, and closer to B than A.
See diagram in other answer!
Whichever corner of the triangle is the larger angle-- the corner by point A or the corner by point B-- must correspond to the waypoint that is closest to the plane.