@propertee64
“A very good question David. But I know speculation isn't on your agenda......!”
Well, not off the agenda totally for we are discussing “hypothetically” and in a discussion, ideas can be put forward.
There are a lot of “if’s” for the success of the Navigation
Firstly, Greg47 has suggested that Noonan would be able to get a sextant reading, a Westing, from the sun and presumably the Latitude from an almanac but they did not get to Howland so that idea does not produce the outcome of a landing at HOW.
Secondly, the sunrise was at HOW at 6:15 am Local time but at that GMT time of 1745GMT Earhart is on the radio saying they are 200 miles out and they would be lucky to see an indistinct glow of light far ahead. If Noonan had seen the sunrise clearly and timed the seconds before 1745GMT they would know how many miles to run to HOW in a lateral sense.
Thirdly, for an “Offset Approach”….where Noonan has the Electra purposely aimed off the track at a known distance from a “sunline’ onto a new course to reach the sunline and then fly down it (or up it) until reaching HOW.
Forthly… using the DF Equipment.
The peculiar thing is that at 1745GMT she stated 200 miles out “approximately” and then at 1815GMT “ 100 miles out, making the G/S 200 mph. Then at 1912GMT “Must be on you” the G/S has still been 200 mph. No success.
Due to circumstances, the Navigation failed, we can positively say that even though Noonan’s reputation was excellent, the circumstances made the navigation to Howland, difficult and impossible.
Ever since the report of “cloudy and overcast” at 1415GMT and subsequent overcast and cloudy reports, there had to be doubt as to whether they were going to make it. From the standards of the day, DED-reckoning would produce a maximum of a lateral 10% error either side of the target, even “if” the “reckoned” distance was correct. By my reckoning they still have 800 miles to run at 1415GMT so a 10% error delivers a possible 80 miles either side of HOW.
In the back of Earhart’s mind is The Contingency Plan. The question of the Fuel Reserve arises. On my plot, the fuel remaining at 1912GMT after a constant speed of 155 mph TAS since leaving the ONTARIO is 340 USG. At 2014GMT after searching for one hour, the fuel remaining is 303 USG.
Here is speculation for you: What if the Diversion Fuel for the Contingency Plan was a figure of 300 USG ?