Admiral Murfin's Wind.
Admiral Murfin said the wind must have been stronger than forecast and blew the Electra off course to the Southeast. He was partly right; it probably was stronger than forecast.
Let us suppose that the Electra intercepted the 157/337 line of position bearing 157T at 200nm South of Howland. Presuming it was not a gross navigational error on the part of the crew, what wind would cause them to be so far off course? We can calculate the wind by plotting triangles of velocity comprising the air-position and the supposed ground-position after a suitable time interval, then measure the resulting wind-vector.
A flight-plan is prepared for the direct track based on the Electra performance, the forecast wind and the flight profile specified by Lockheed, giving heading, groundspeed and drift. A suitable time interval is the elapsed time between Waypoint 4 and Howland, amended by Earhart's position report at 159 degrees East longitude near to the Nukumanu Island group and Noonan's calculated actual wind for the flight up to that point (23kts).
The result is an ETA at Howland (or the 157/337 line of position through Howland) of 19:10GCT (07:40L) which is very close to the time of Earhart's report, 'We must be on you...', at 19:12GCT (07:42L). This just means that our flight-plan is similar to that by Noonan using the forecast wind. If Earhart's report is based on Noonan's recent observation of the sunrise and calculation of the Sun line of position, we can conclude that the headwind component was as forecast but alternatively, what crosswind would put them South of track?
The elapsed time from Waypoint 4 at 07:14GCT to Howland at 19:10GCT is 11hr 56min. Using the air-distance and drift angle, the air-position at 19:10GCT can be plotted (as if flown in still air). The line joining the air-position and Howland is the forecast wind vector, that is the effect of the forecast wind 068T/15kts during 11hrs 56mins, approximately 185nm.
Next draw the track from WP4 to the supposed DR position bearing 157T at 200 nm South of Howland, giving about 9 degrees of right drift (7+2). The line joining the air-position to the DR position is the new wind vector 295nm in 11hr 56min giving a wind of 25kts from direction 016T. This is Admiral Murfin's great wind, stronger than forecast but more particularly from the North Northeast giving a strong crosswind.
From that point a search pattern 1 hour North and 2 hours South will miss Baker Island and take Earhart and Noonan to the vicinity of Gardner Island.
But is this wind direction 016T/25kts plausible? What do you think?