Instrument Flying Manuals, Set of 2, Beam and Instrument Approach System 1943 A-30 It is presumed to be

It is presumed to be a WWII-era indicator used in aircraft of the Japanese Navy

So our assumption is that this item was offered prior to 1929

the SCR-274N was used in bombers B-17

which was likely for the microphone

Included ships/ship types are:

Instrument Flying Manuals, Set of 2, Beam and Instrument Approach System 1943 A-30 It is presumed to beThis is an original set of 2 training manuals for pilots of the US Army Air Force during WWII: Standard Beam Approach (TO 30 100E 1, March 1943, 28 pages) and Instrument Approach System (TO 30 100F 1, November 1943, 12 pages). These manuals are in good condition given their age. They came to us from the estate of a B 17 flight instructor.