I took a look at this one because it momentarily reminded me of the Rogue River "blimp" case, but quickly realized that there was about 3 months and 600 miles between them! I looked at it anyway.
Here are some issues with the Sandberg Pass entry that need correcting or clarifying:
The date of Feb 23 1949 is in question. This is the date that appears on a typed Incident #257 Checklist. It also appears on the Feb 1949 monthly list.
But there is another Incident #257 Checklist in the file, handwritten, containing the date Feb 28 1949! More significantly the same date, Feb 28, appears in the witness's signed typescript statement.
To complicate matters further, the Project Record Card has a hand correction from "Feb 28" to "Feb 23", whilst a letter from the DI, HQ 1st Fighter Wing, March AFB forwarding the witness interview statement has *possibly* been hand corrected (when and by whom?) to "Feb 28" - though *not* from "23", possibly from "27".
Presumably the date shown
a) on the witness statement (Feb 28),
b) on the hand-filled Checklist questionnaire which is probably the original of the typed version (Feb 28), and
c) on the March AFB letter (even though possibly hand-corrected)
should be the favoured date, not Feb 23.
The time given 10:30 pm PST is flat wrong. The time given in all documents is 2030 PST - 8:30 pm.
The "apparent size of his index finger at arm-length" is inaccurate and misleading. It implies a "sausage" maybe 8-10cm long at arm's length. He actually compared angular size to his "index and middle fingers" at arm's length. It's obvious from reading the file that this is intended to mean the angular length of the "sausage" was equal to the angular *width* of the two fingers held together (i.e., like a two-finger measure in a glass), so the estimated angular width is less than half that stated, maybe 3-4cm at arm's length.
The phrase "Time in sight: 20 seconds" does appear on the Checklist and elsewhere but again this is misleading if presented as a duration. It is an estimate of the total time the object was in view during *two* separate passes as it circled, but the pilot's statement is clear that the total duration was much longer. It was out of sight for at least "15 seconds" in between. It took "about 40 seconds for the object to take a 360 deg turn about my aircraft".
"Object circled plane in 360 degree and 150 degree turns". Presumably this is a typo for "360 degree and *180* degree turns"? The object approached head on from the N, circled, and left at 180 to the S.
The figure of 9000ft is also potentially misleading. The record card gives "10,000ft". The Checklist gives "9000 ft 20 degrees". In fact 9000 ft was the altitude of the T-11. The pilot estimated the object was 20 degrees above his horizon and about 1500 ft above his altitude. So in fact the reported estimate was 10,500 ft, not 9000ft - but of course the angular elevation of 20 deg (probably an overestimate) is the only value that has any real meaning in the circumstances.
It's a bit discouraging when such a minor report can have so many internal issues, and irritating to have to deal with them. But we may as well get it right.
As a final note, bear in mind that the first witness interview at March AFB did not happen until a month after the event, and there appears to be no earlier document or a reported sighting by anyone else that would.help calibrate his statement.. On the other hand he appears to have been judged fairly dependable by the DI, Major Crookes.