If ground speed airspeed turns out to be in error, then wouldn't that have caused Noonan to possibly calclate the wrong wind corrections too?
Now why the navigation itself might have failed, that is a different story. I am inclined to believe that they were entering cloudy conditions after spotting the Ontario that worsened as time went on. If we assume that to be true, they might have used DR all the remainder of the trip (1277 miles). As daybreak came, even if the conditions improved from overcast, the stars might have been impossible to spot. So I think it is quite possible that they did not find another reference after spotting the Ontario. What is the magic number again? 10% of 1277 miles? Does this suggest that they were off by a maximum of 127 miles? That is quite a large hole if you ask me. Forced to guess, I would say they were at a minimum of 40 miles off target since they did not spot the Itasca mast or the smoke she was laying out for them that stretch out 10 miles (although I would still like to hear an estimate of how high that smoke rose in the 8mph cross wind).
I guess you missed my prior post, here is the relevant portion:
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"The whole reason that Earhart hauled Noonan all the way around the world was so that he could get fixes to eliminate any errors that would have resulted from dead reckoning alone. This was also the reason, in the original planning, to take two navigators for the leg from Hawaii to Howland so that they could use their skill and equipment to find that Island. Note also, that they had recognized and decided that even the much shorter leg from Hawaii to Howland (only 1900 SM instead of 2556 SM) was too long to complete with only dead reckoning. If Earhart wanted to dead reckon that leg then there was no reason to incur the expenses of having two navigators on board, Earhart could have done the dead reckoning herself as she had done when flying solo across the Atlantic and when flying solo from Hawaii to California. All the planning for the World Flight was based on the knowledge that dead reckoning was not sufficiently accurate for the most difficult leg of the flight, that of locating Howland, coming either from Hawaii or from Lae. The original plan was for Noonan to leave the flight at Howland and Manning to leave at Darwin with Earhart flying the rest of the flight solo. This is conclusive proof that they knew that finding Howland was THE most critical part of the entire around the world flight
I have attached Earhart's June 30, 1937 radiogram. It requested weather information because "
FN MUST HAVE STAR SIGHTS."
In prior posts I have demonstrated how Noonan computed a "point of no return" (PNR) which allowed them to fly until 1407 Z and to within 817 SM of Howland and still be able to return to Lae. Since it is highly likely that Noonan knew of the location of the Rabaul airport after talking to the people at the Lae airport that was 400 SM along the course line to Howland. (And also, very likely, Noonan and Earhart had talked to pilots arriving from Rabaul.) Noonan would have calculated a PNR for a departure from Lae with a return to Rabaul. Since Rabaul was closer to Howland, this PNR would also be closer to Howland. Doing this calculation we find the PNR occurs at 1526 Z, 1901 SM from Lae, only 655 SM short of Howland (only 55 SM short of Tabiteuea in the Gilberts) and only three hours and forty-five minutes before the 1912 Z radio report of "must be on you" from Earhart. So if Noonan had not been able to get fixes they could have turned around and returned safely to Lae or Rabaul from nearly over the Gilberts and try again another day.
Do we know that Noonan knew how to calculate a PNR and that his practice was to do this calculation? Yes. On the departure from Hawaii to Howland on March 20th they took aboard an extra 75 gallons of fuel to allow a return to Hawaii after flying for 8 hours on the leg to Howland. This meant that they would have flown 1320 SM and would have come as close 580 SM to howland before turning around. This extra fuel was taken aboard after Noonan calculated the PNR based on having to fight a headwind on the return leg to Hawaii, this is the standard PNR computation...
So now the creators of this "Monte Carlo Simulation" take the position that in spite of all the expense and careful preparation and Noonan's prior careful calculations including calculating PNRs that after all that, flying almost all the way around the world, that at the critical moment Earhart and Noonan just decided to ignore all the prior planning and just said "AHHHH, let's just go for it!"
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The point of no return was far past the Ontario, almost to the Gilbert Islands and they could have turned around and returned to a safe airport until the PNR. In the past Earhart had turned around and she planned on that possibility on the originally planned flight from Hawaii to Howland so there is no reason to think they wouldn't do it this time if Noonan couldn't get star sights.
gl