Concorde - Eye Datum device

[Shaggy Sheep Driver]

I've noticed on G-BOAC's flight deck an 'Eye Datum' device. It's a flat metal arm with a spectacle-shaped end with two eye-holes in it. It's stowed in a pocket on the LH side of the flight deck, but can be mounted into the side of the overhead panel so that it's poitioned in front of either pilot.

I presume it was for positioning the seat to the optimum position for the pilot, so that his eyes were in the correct place relative to the instruments and the view out the front.

Does anyone know if it was actually used in practice? I've never heard of such a device in any other aeroplane (has anyone else?). And interestingly, when it's in position, the eye holes are not in line - the 'outside' eye hole (left eye for the LHS, right eye for the RHS) is lower than the 'inside' eye hole. Why's this?

SSD

[SFCC]

All the commercial types I have flown have optimum eye position devices. Most consist of 3 balls, a common one and one for each seat . One simply positions the seat so that the ball nearest you obscures the reference ball behind it.
Simple and effective.

[wileydog3]

Didn't fly Concorde but did fly the sim for about 4 hours and yes, the balls are used to position for sitting height. And they were on the Boeings, McDougs and Airbi that I flew.

The sitting height is especially important when conducting Cat II and III operations...