[2] Flight 277 had taken off from Mehrabad International Airport, Tehran, at 18:15 local time (15:15 UTC), more than two hours later than scheduled because of poor weather at the destination.

The aircraft crashed near the village of Tarmani, around 15 kilometres (9 mi; 8 nmi) south-east of Urmia Airport, breaking into multiple sections.

[6][16] Rescue efforts were complicated by extremely heavy snow in the area, which was reportedly around 70 cm (28 in) deep at the crash site.

[2] Investigators believe the aircraft encountered severe icing conditions, which caused disruption of the airflow and loss of engine thrust.

The aircraft started to descend and entered a turn that momentarily reached 41° bank angle, causing the activation of the stick shaker.

[2] The report concluded that the main causes of the accident were severe icing conditions and inappropriate actions by the flight crew.

Obsolete on-board systems, absence of suitable simulators for adverse weather conditions, failure to follow standard operating procedures, and inadequate crew resource management were cited as contributing factors.