Pilot Director Indicator as used with C-1 Autopilot, WWII B-29, B-24, B-17 (A) F9F Cougar when combined with the APA-44

when combined with the APA-44 computer

The main dial measures time

Overall width

The fluid is gone

Survey operations commenced in mid-1953 using a P2V Neptune aircraft

Pilot Director Indicator as used with C-1 Autopilot, WWII B-29, B-24, B-17 (A) F9F Cougar when combined with the APA-44The Pilot Director Indicator (PDI) was used during WWII in bombers of the US Army Air Force, including heavy bombers B 17 Flying Fortress, B 24 Liberator, and B 29 Superfortress and medium bombers B 25 Mitchell and B 26 Marauder, and US Navy's PBY5A Catalina and PB4Y Privateer. The PDI was located on the pilots instrument panel, and received signals from the bombardier to indicate his desired course changes, left or right, to obtain an accurate bomb