NavList:

Joe
Re: your question 25th 01:38 -0800

I think you're hoping to apply ground based survey standards to air navigation.  Air navigation was never like that.  You have to equate the required watch accuracy to the overall accuracy of your navigation system.  1 second’s timing error equates to a 0.25 minutes of arc error in longitude.  For a jet bomber flying at 480 knots in the troposphere a 3nm error in a PL is very good.  On a bad day, 30nm is not unheard of.  In 1974 when an RAF Vulcan Crew won the celestial section of SAC’s Giant Voice competition against countless B52s, the crew’s average termination error from the two celestial stages was 1.6nm, which was almost unbelievable for the time.  

As you’ll be using an averaging mechanism, you’re looking for an accurate start-time rather than an accurate mid-time.  Therefore, you’ll have checked the run-time of your sextant and calculated the start time required to give you the correct mid-time.  The procedure as far as your watch was concerned was much as Paul Loubris describes it.  There was an accurate chronometer on the Ops checkout desk, which the Ops staff checked regularly using the telephone ‘speaking clock’.  You checked your Government issue aircrew watch against that, and that was about it.  If you were keen, you’d have rated your watch so you could make adjustments to time as the flight progressed, except most of the time it was unnecessary, because in every five man crew their was always one member who had on a previous tour bought a watch with an unlikely sounding name for a few dollars in a bazaar somewhere that was claimed to be the most accurate watch in the World and who insisted upon calling the start-time.

If you had no such crew member, you strapped your watch to your left wrist facing inside rather than outside.  Smith’s periscopic sextants had a clever little Perspex light tube which when you pressed a button on the sextant handle (left one I think) a tiny beam of light shone from the right handle onto the inside of your left wrist, so you could keep an eye on the time with your left eye while still holding onto the sextant with both hands and observing the body with your right eye.  It was all pretty basic by land survey standards but great fun for a young chap.  DaveP