I am starting this topic for discussion of recent points raised in other threads possibly affecting the Radio Direction Finder Analysis and, marginally, the Post-Loss Radio Signals analysis. Most of the points arose in the Lambrecht Search topic for reasons not germane here.
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3) In recent posts Art Johnson has offered information as to the crossing of bearings, and as to the customary practice of adding bands of increasing uncertainty with distance instead of merely drawing single lines. This information is quite clear, and it seems there is opportunity to make a different chart showing area intersections rather than line crossings. However (and here I venture "Where There Be Serpents" as far as my own knowledge goes) I believe the "standard" uncertainty would apply generally to well-received signals that persist long enough to get "good" fixes, and may not be the whole story? Some of the earlier Research Papers and other TIGHAR material suggest that for very weak and/or fluctuating signals there are other possible effects (atmospheric, etc.) that could shift a bearing by larger amounts, even tens of degrees. OK, I will shut up now, as I'm well past my limits.
Have at it if you will, people!
Allan,
Gary LaPook has uploaded a chart
to another thread using his estimates of possible bearing accuracy range:
http://tighar.org/smf/index.php?action=dlattach;topic=944.0;attach=4235I cropped his chart to show what I was speaking of:
(You could just expand Gary's chart to 200% and scroll down to the intersections.)
If I were drawing a chart for navigation, it would just project the lines from the locations for Oahu, Midway and Wake. It would just cover the area around the crossings...

What you have now is a pentagon with boundary 1. being the short piece of green line crossing in the Baker island area.
Boundary 2. (going clockwise) would be the yellow line from Howland that passes NE of Gardner and Tokelau.
Boundary 3. would be the green line passing SE of Tokelau.
Boundary 4. would be the purple line (from Wake) that goes off the bottom of that chart.
Boundary 5. is the yellow line (from Howland) between the purple 4. and green 1.
Now you have the five sided (pentagon) area that is about five to six hundred miles wide in the area of Tokelau and perhaps eleven to twelve hundred miles tall (down to the 'off the bottom of the chart' intersection of purple 4. and green 3) and you would place greater weight to the middle of this shape.
If you accept the hypothesis that they began to follow their 'LOP' of 157° down from the area of Howland Island, you would also have to place a limit on that eleven hundred mile vertical dimension of the pentagon by the fuel they had available. Meaning that even Tokelau Island might have been beyond their maximum possible range. Tuvalu Island would be outside that pentagon and since the Radio use depends on dry land, this limits your search to islands within your pentagon.
Gary's estimate of bearing +/- error is no doubt a lot closer than my inital +/- 1° taken from
a 1936 Report that no doubt depended upon perfect conditions. (The
example given resulted in excess of 20° error when combined with their faulty compass.)
It has been my practical experience that bearings were usually within 1° and less often +/- 3° or more, but this is based on using relatively modern airborne equipment, not ancient ground based HF/DF equipment.
I will accept Gary's estimates of Bearing errors (+/- 10° from Hawaii & Wake; (+/- 21.25°) from Howland) for the conditions existing at the time even considering that as a dedicated
Crashed n'Sunker he is of the opinion that NO Post-Loss Radio signals
at all could be possible.