AGI-1

 AGI-1-fighter aircraft horizon, product "167". One of the first domestic air horizons.

Development history

It was developed in the late 50s of the XX century in the USSR. Health checks in various modes took place from 1957 to 1960. These tests proved the correct operation of the device in all flight modes, including corkscrew, after which the device began to be completed with serial aircraft.

However, this aircraft horizon required preliminary training of pilots before using it — due to the inverted pitch indication and reverse roll indication, which was not intuitively clear to the flight crew.

Accidents of Tu-104 aircraft led to the fact that in 1958, employees of the GosNII GA, in particular S. L. Belogorodsky, was proposed to modernize the AGI-1 air horizon, which is mainly used on highly maneuverable aircraft, so that it can be used on civil aircraft. This modernization solved another acute problem - it became possible to install a backup air horizon on civilian jet aircraft that would be able to operate in conditions of strong roll or at large pitch angles. The upgraded AGI-1C air horizon was used on Tu-104, Tu-114, and Tu-124 aircraft, Tu-134, IL-18, AN-12, etc. 

Usage

This device was installed on MiG-15, MiG-17, Yak-18, Yak-50, Yak-52, An-28, Su-7, Tu-124 and some others. Now preserved in the Yak-52 and An-28aircraft.

Incidents

On January 3 , 1976, a Tu-124 crashed. The reason was called the failure of the air horizon in conditions of poor visibility. All 61 people on board were killed.