Gary,As I said, there is no evidence that Noonan carried a second sextant on the Earhart flight, no witnesses, no documents and no photographs. No marine sextant is listed on the Luke field inventory. Noonan's letter would not be admissible evidence in a court of law to prove that a second sextant was carried on the Earhart flight because it is too remote in time and the circumstances are too different. In fact, the letter itself shows the circumstances are not the same, as Noonan wrote "Due to the spacious chart room and large chart table aboard the Clipper, the navigation equipment need not be so severely limited as in smaller planes..." and no one can dispute that the Electra is a "smaller plane" compared to the S-42. And note, Noonan did NOT say in the letter, "I always carry a marine sextant as a 'preventer.'" And Noonan made no mention of a marine sextant in his article published a year later. (BTW, as to Noonan's experience at sea, ships commonly carried only one sextant.) (Although there is such a thing as "habit evidence," this one letter comes nowhere close to the requirements to prove an action based on a "habit.")
Please take this as a compliment. If I ever commit a crime I'm hiring you as my lawyer. I'm confident you would find a reason to prove I wasn't even at the scene.
To Jeff's latest post.... In the case of a very long trip would you not take a second sextant anyway as a backup? Your point about it likely being an FN habit is likely bang on. Navigation was FN's career. In fact on a clipper he probably needed the "preventer" less than he needed it on the global trip with AE.
Could they have crammed in an additional sextant, probably, but looking at all the things that Earhart removed from the plane, including even papers and her Colt pistol, a second sextant would seem pretty low on Earhart's priority list. We pilots want two of everything, two engines, two spark plugs in each cylinder, two magnetos on each engine, two fuel pumps, two navcoms, two GPSs, etc., but there is a limit. How about two life rafts, two parachutes for each person, two coffee pots, two "potties?"
By 1937 the Pioneer octant had been perfected and was carried in thousands of Air Force and Navy planes, virtually unchanged, through the end of WW2. Bubble octants are extremely simple and reliable instruments. Bubble octants were used on trans-oceanic airline flights through the 1970's and commonly on Air Force planes until less than ten years ago, (I believe that there are still some Air Force planes with them.) In all of these uses, only ONE octant was carried in each airplane, no "preventer" in B-17s, no "preventer" in Boeing 707s, no "preventer" in B-47s, no "preventer" in C-130s, and no "preventer" in B-52s, and none of these planes were limited by space and weight constraints like the Electra. No second octant was carried in any of these planes because they are so simple and reliable.
So, like I said, there is no evidence to prove that a marine sextant was carried on the Electra, the burden of proof is on those who make that claim.
Are you saying that if FN lost, misplaced, broke or had his primary sextant stolen then he would have been able to get it replaced easily anywhere on the world trip? Are you also saying that unless it was recorded somewhere in evidence then he couldn't possibly have had it with him? And aren't all the aircraft you list as having "no preventer" loaded up with modern, electronic nav equipment that have backup systems? Doesn't that mean the bubble octant in those aircraft is the backup to the backup? Whereas for FN it was his primary method of navigation?
Please excuse my ignorance of aeronautics and navigation practices.
As to whether celestial was simply a backup to a backup in modern times, here is a link to information about a book about B-52 navigators in the 60's and 70's written by the president of the Air Force Navigators Association. The book is Flying From the Black Hole
and I recommend it. This review should be enough to answer your question. Here are parts of it:
About midway through the course, celestial with an MA-2 sextant replaced
radar as the primary fix technique. "Becoming proficient in night and
day celestial was at the heart of navigator school;
accomplished, the student was on the home stretch. For most men, the
celestial phases were the most satisfying part of their entire training
— deliciously elemental disciplines that relied almost wholly on an
individual's wits for success."
Their flying classroom was the T-29, a military version of a twin piston
engine airliner. It had 14 work stations, each with a table, instrument
panel, and radar scope. Students shared five periscopic driftmeters and
four astrodomes. Three or four instructors supervised. The work
environment was difficult: "constant and very fatiguing engine and
slipstream noise, bumpy air, poor cabin lighting, student congestion in
the aisles upsetting tight shooting schedules, balky observation dome
making one even more late for the precomputed shot that
couldn't wait, and the inevitable, pitiless instructor hovering over a
shoulder -- red pencil at the ready."
[The reason for the safety harness was to keep the navigator from being blown out of the pressureized plane if the dome failed as had happened several times.]
Although B-52s carried the usual radio navigation equipment, it wasn't
used much. SAC's assumption was that in the event of nuclear war all
U.S. and Soviet stations would be down, so only celestial and radar
would be usable for fixes
. It was the EWO (electronic warfare officer)
who actually took the sextant shots. He had initially qualified as a
navigator, wasn't busy during the celestial legs of the mission, and his
station was closer to the sextant port on the B-52's upper deck. The nav
would give him the precomputed azimuth and altitude of the body, then
reduce the sight. It did seem a little unfair that he did the hard work
while the EWO got the fun part of the job.