A Qatari A350 gets TCAS RA over Iran as a Caspian MD83 gets too close due an autopilot malfunction
A Qatar Airways A350’s TCAS Resolution Advisory triggered while the aircraft was cruising at 34,000ft due to a Caspian McDonnell Douglas MD-83 deviating altitude.
The Qatar Airways Airbus A350-1000, registration A7-ANO was performing flight QR-739 from Doha, Qatar to Los Angeles, USA, cruising at FL340 while the opposite direction Caspian Airlines McDonnell Douglas MD-83, registration EP-CAS performing flight from Tehran Mehrabad to Kish, Iran at FL330 about 50nm northwest of Isfahan, Iran.
Due to an autopilot malfunction, the Caspian MD83 climbed 400ft above the assigned altitude due to which triggered the Qatari A350’s TCAS RA to climb the aircraft to 550ft above.
It was widely reported that the Qatari A350 received a stall warning during the RA climb which was denied by the airline.
“At no point was there a speed or stall warning issued. In addition to this, we can confirm that the Qatar Airways pilots onboard operated in accordance with the manufacturer’s published procedures and guidelines for situations of this type.” - Qatar Airways Spokesperson
A Traffic Collision Avoiding System (TCAS) automatically detects a potential threat for the aircraft that could lead to a mid-air crash and take appropriate action to distance from the other aircraft automatically.
Under International Civil Aviation Organization (ICAO) regulations it's mandatory for all aircraft with a maximum take-off mass of over 5,700 kg (12,600 lb) or authorized to carry more than 19 passengers to have a type of airborne collision avoidance system installed.