What is this???

An early mechanical pedometer.

The 'weight' works as a pendulum, which is sprung loaded, the tension of which is adjustable depending upon whether a person is walking or running.

The end of the spring strip attached to the arm of the weight, rides over a ratchet wheel one way, and nudges the gear train coming back again - so moving the hands.

This one is unusual in having a sub-dial, most only have the outer chapter.

The value depends who is bidding on the day, but I struggled to get £10GBP for a similar fully functional one I got rid of recently.
The sub dial may make it worth something to a collector, but I personally wouldn't go near it!

Probably the only thing it would measure in an aircraft, is severe turbulence, a lousy landing or someone pacing the flight deck or passenger cabin!

John