Aircraft Clock, 8 Day, Type A-13A-1, USAF 1965
Here is a fine specimen of a mechanical 8-day Aircraft Clock Type A-13A-1, made by Waltham Precision Instrument Company, part number 40091 with a manufacturing date of May 1965 for an order by the US Air Force. The A-13A-1 was used in a number of different aircraft during the 1960's and 1970's, including bomber B-52 Stratofortress, fighters F-100 Super Sabre and F-86 Sabrejet, and the trainer T-33.
From the Waltham Clock website:
With one-hour elapsed time feature and sweep hand. The start, stop and flyback of second and minute hands does not disturb time of day. The lever for adjusting rate is accessible without removing the clock movement from its case. Clocks contain an unbreakable, anti-magnetic cobalt alloy mainspring and an anti-magnetic temperature compensated hairspring to ensure accuracy. Mechanical clocks are stand-alone, time keeping instruments which are not affected by environmental extremes or system failure. Here is a link to Waltham's website describing the A-13A-1.
Here is a link to Ken Rockwell's website describing the A-13A-2 version of this clock.
The clock is in very good physical and cosmetic condition. The clock runs when wound, but has not been fully examined for accuracy and full functioning. Measures ~2 3/8" square and ~ 1 5/8" deep.