The crew of a Sukhoi Superjet 100-95 accidentally extended their aircraft’s landing gear in cruise, causing a loss of separation in the process.

The incident happened on the 21st of October this year. Rosaviatsia (the Russian aviation authority published some information on it more recently. It involved Azimuth Airlines flight A4-543, from Sochi International Airport (URSS) to Bryansk International (UUBP) in Russia. The flight had taken off from its origin airport without incident, getting to a cruise altitude of FL340.

INCIDENT: Sukhoi Superjet Extends Gear By Mistake!

Photo: Papas Dos, CC BY 2.0

The gear extension came from a seemingly unrelated issue with the Sukhoi Superjet. The pilots were dealing with an issue relating to their satellite navigation system. Their aircraft was presenting them with repeated messages because the signal kept getting lost. The crew were getting these signals on their FMS and engine and warning display (EWD).

Eventually, the Captain attempted to cancel these messages. Unfortunately, the Captain accidentally pressed a button for the alternate landing gear extension system of the Sukhoi Superjet. And the system worked, with the landing gear extending accordingly. At the time, the aircraft was cruising at 270 KIAS. But the maximum landing gear extension speed for the Sukhoi Superjet is 255 KIAS.


Sukhoi Superjet Reacts To Gear Extension

The crew were flying the aircraft using their autopilot. But it appears that the autopilot caused the aircraft to climb when the landing gear extended. The aircraft gained approximately 450 feet, before returning to its designated altitude (FL340). However, there was traffic in the opposite direction, at FL350. So the sudden climb of the Azimuth flight triggered a Short-Term Collision Warning at the air traffic controller’s desk.

Fortunately, there were no injuries to the occupants or other faults with the airliner, from this landing gear extension. After the event, the crew first requested a descent to FL290, before diverting to Rostov-on-Don International (URRP). The aircraft was about 90 miles away from Rostov at the time of the incident. The crew made a safe landing.

Rosaviatsia reported that the Sukhoi Superjet suffered no damage from its unplanned landing gear extension. Accordingly, it returned to service approximately 18 hours after the incident. It appears to be in regular service today. The aircraft is a Sukhoi SS100-95B, with tail number RA-89120. The jet is just over 3 years old, having first flown in October 2018. Azimuth Airlines calls it “Oka”