World War II - military
A complete telephone system connecting A.C. instructor in the front cockpit and his Flying Cadet student pilot in the rear cockpit, a distance of 3 ft., is used at Randolph Field, Texas giant training field. Telephone dial is the only part that's missing…and of course, no "busy signals".

A complete telephone system connecting A.C. instructor in the front cockpit and his Flying Cadet student pilot in the rear cockpit, a distance of 3 ft., is used at Randolph Field, Texas giant training field. Telephone dial is the only part that's missing…and of course, no "busy signals".

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