JP 3-50 National Search and Rescue Manual Vol I - US Navy

Figure E-3. Common-Time Relative Bearings
reaches position 2 at the end of searchleg L1, which
has the greatest headwind component. To an observer
on the ship, the aircraft has gradually moved from a
position abeam of the ship (when overhead) to a
position behind the beam position a distance equal
to X (when at the end of searchleg L1).
(2) When the aircraft is on its crossleg, both the
vessel and the aircraft are moving in the same
direction, from position 2 to position 3. The
distance the aircraft travels as the ship moves from
position 2 to position 3 is not seen as relative
motion by an observer on the ship.
(3) When the aircraft turns from the crossleg onto
searchleg L2 at position 3, it appears to the
observer to be forward of the beam a distance equal
to Y. The aircraft will then gradually appear to
move back toward the beam position during its
inbound period, reaching the abeam position when
again passing overhead the vessel at position 4 in
Figure E-4.