Way no radio message saying thier heading to a different island? They knew they were in contact with the Itasca - multiple A's.
Ted Campbell
Yes,
if only there had been a couple more in-flight radio messages which included "continuing on the line 157" with ever-weakening signals than the last known transmission, the Niku hypothesis would not have so many detractors. In fact, Earhart and Noonan might have been rescued with a much more concerted search effort in the Phoenix group. I can only speculate why such signals were not sent, or received as the case may be ... I don't know.
That notwithstanding, my inclination is to believe Noonan knew it was Gardner when they found it.
With a star fix at some time before sunrise, and the LOP established at sunrise, I believe Noonan had a very good idea where they were and the course, time and distance required to reach Howland. Earhart's ability to hold that course while she fiddled with the radio for the balance of the flight to the Howland area would be critical to arrive on station, and I believe her course discipline suffered under these conditions (what the hell ... we will have Itasca to help guide us in...) along with the fatigue factor associated with such a long flight. They missed by a little, they knew they were close, but they simply could not see Howland when they arrived in the area and searched along their LOP, first to the NNW, then to the SSE. And this is a contingency I believe Noonan considered and had planned for prior to arriving in the area.
So I believe Plan B was enacted when "bingo" fuel was reached after searching along the LOP near Howland. This plan was to fly a SSE heading to the Phoenix Islands, knowing Baker was en route along that heading and that if they happened upon Baker, it would be a relatively easy navigational turnaround to get back to Howland with fuel to spare for another brief search. But they did not see Baker (I assume due to the same challenges in surface visibility as at Howland), and continued until they did see a much larger Gardner in the distance, more or less where Noonan expected it to be.
The post-loss radio signals deemed credible are either brief, or incomplete, or both. Betty herself acknowledges she didn't start writing down what she was hearing for some time after she was hearing it, and even then she confirmed she did not record every word she heard. So it is entirely plausible, if not likely, that Earhart
did mention Gardner and/or Phoenix, and it simply was not heard or recorded, or both.
As to why more in-flight signals were not heard after Plan B went in to effect, there are dozens of speculative possibilities. Maybe Amelia became exasperated at the onset of Plan B and while abandoning the Howland area, she switched to incorrect frequencies, did not double-check frequency? or began a debate with Noonan about the merits of Plan B as they began their flight away from Howland and was hoping they would soon see Baker, at which point she would broadcast again? Then not seeing Baker, she became even more exasperated and questioned Noonan about their navigational conundrum before trying to broadcast again, then saw an island in the distance, flew towards it ... oops, not an island ... then finally saw Gardner and made a pre-landing broadcast that was not picked up? or she saw fuel was extremely low so she prioritized the identification of a landing site and execution of the landing sequence, and never made a pre-landing broadcast? I don't know.
But I do believe Noonan had a Plan B, that plan involved the Phoenix Islands, and he made Amelia follow it to the letter.