Master Indicator, Type N-1 Compass System plus Service Manual B-29 The letters AC US ARMY

The letters AC US ARMY are embossed on its face

so this might have been intended for an installation where this functionality was disabled

This is an original 1960's-era Instrument Flight Manual for the Naval Air Training and Operating Procedures Standardization Program (aka NATOPS

we discovered that we

according to its markings

Master Indicator, Type N-1 Compass System plus Service Manual B-29 The letters AC US ARMYThis is a Master Indicator used in the N 1 Compass System by aircraft of the US Air Force during the 1950's and into the 1960's. The N 1 system is a remote indicating, gyro stabilized compass system designed for use in all latitudes, which is what made it unique at the time. The N 1 system was commonly used in early models of the US Air Force bomber B 52 Stratofortress, transport C 130 Hercules, and air tanker KC 135. It was installed at the