Created Monday, Aug 29th 2022 17:38Z, last updated Monday, Aug 29th 2022 17:38Z
A Mahan Air Airbus A310-300, registration EP-MNP performing flight
W5-112 from Tehran Imam Khomeini (Iran) to Istanbul (Turkey) with 166 people on board, had safely landed on Ataturk Airport's runway 05 and taxied to the apron, stand S6, but failed to stop on the stand, about 30 meters past the stand broke through a concrete barrier topped by a railing causing the nose gear to collapse, the nose fell onto the roof of a bus driving along the road underneath. No injuries occurred.
No passengers were on board of the bus, the driver was the sole occupant of the bus and remained uninjured.
Passengers reported following the accident the captain announced they had suffered a hydraulic failure resulting in the failure of the brakes.
Airport officials commented the crew shut the engines down when the aircraft reached the parking position and encountered the failure of the brakes. Had the bus not been there by pure coincidence the outcome of the accident could have been far worse.
On Aug 29th 2022 the Turkish UAB released their final report in Turkish only (Editorial note: to serve the purpose of global prevention of the repeat of causes leading to an occurrence an additional timely release of all occurrence reports in the only world spanning aviation language English would be necessary, a Turkish only release does not achieve this purpose as set by ICAO annex 13 and just forces many aviators to waste much more time and effort each in trying to understand the circumstances leading to the occurrence. Aviators operating internationally are required to read/speak English besides their local language, investigators need to be able to read/write/speak English to communicate with their counterparts all around the globe).
The UAB concluded the probable causes of the accident were:
After successful landing on runway 05 during taxi an intense leak in the yellow hydraulic system occurred causing the loss of the brake accumulators.
The aircraft continued taxi with the green hydraulic system in normal braking mode.
The crew can not monitor the availability of the parking brake mode provided by the yellow system, the pressure in the park brake accumulators can not be adequately observed.
After arriving at the stand the aircraft was stopped with the green hydraulic system and park brake applied.
The main reason for the accident was the cockpit crew not applying brake pedal pressure as set in the standard operating procedures when the aircraft began to move despite park brake set.
A contributing factor was a defect in the PBOV (parking brake operating valve).
Excerpt of Aerodrome parking and docking chart (Graphics: AIP Turkey):
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