Over the years there has been a great deal of speculation and debate about whether the approach to the advanced LOP employed what is known as an “offset.” When trying to find an island using only a Line of Position, it makes sense to deliberately “offset” your approach to one side or the other. This deliberate error removes the doubt about which way you should turn when you get to the line.

However, in Earhart’s case, the intention was never to use only the advanced LOP to find the island. Radio Direction Finding was supposed to provide guidance for the final approach and the phrase “We must be on you...” implies a straight-in approach to a specific spot where the island was expected to be. Of course, no one can say for sure, but we see nothing to indicate that an offset was used and some evidence that an offset was not employed.

See map at LOP Map and discussion of LOP navigation at Navigation FAQ.