Originally Posted by
Cough
[guess mode]
Because thats what sensor that could be bought off the shelf that was proven safety critical?
[/guess mode]
For Altitude and Speed select, Concorde used what look like bog-standard "35mm camera film rewind" knobs with fold-out cranks. In an era before digital-push-button FMC flight plan entries, it was probably nice to be able to whizz-whirr one's target altitude up to or down from 60K feet with a rapid crank.
(Concorde pros can comment)
http://www.concordesst.com/inside/co...tures/ap17.jpg
http://www.destoutz.ch/slides/typ_nm...ob_black_2.jpg
When it comes to the number of clicks per revolution in
today's knobs - some "human factors" engineer probably had to figure out the optimum number to allow fast adjustments (more clicks per turn), while retaining discrete spacing of clicks for fingertip precision (fewer clicks per turn).
And came up with "32-ish."