I think before the FAQ, the basic 1 range was only covered in rule 8.7 (Carrier-Based Aircraft) Appendix A, section 27 (Maritime Air Patrol).
No wonder the MAP rules were (and still are) misunderstood.
Regarding the Elimination question, it’s a good one and I am not 100% sure that Germany placing its own aircraft on MAP would eliminate the British seaplane.
Even if you have the option to leave aircraft on MAP more than one turn “until it chooses to end its patrol” (rule 8.7), Appendix A, section 27 says that aircraft on MAP is essentially patroling in circles, which explains the limited range.
Therefore, aircraft left on MAP virtually returns to base at some point, as it cannot fly for 6 month staight (a turn in Global War), even if this is not played on the actual game board.
Rule 8.7 also says that “On Enemy turn, an aircraft on Maritime Air Patrol defends against enemy units entering its sea zone”.
Should we consider that the British MAP would 100% be intercepted by the German MAP an eliminate it, because it would have at some point to enter the German-patrolled sea zone? I don’t know.
I think that a clearer case of Elimination would be if Germany puts a carrier with at least one aircraft between its only available landing spot, then the MAP seaplane would be eliminated (shot down when attempting to reach base to refuel, so to speak).