Iran's Civil Aviation Organization (CAO) says pilot error and excessive landing speed were the main causes of the Aria Qeshm plane crash in the city of Mashhad on July 24.
Of the 153 passengers and 15 crew, 16 people were killed when a Russian-built Ilyushin Il-62M, owned by a Kazakh company and leased by Iran's Aria Qeshm company, overshot the runway after touchdown and smashed through a perimeter wall.
The incident also saw 31 people injured who were immediately taken to nearby hospitals for treatment.
Faramarz Sarvi, the director of the CAO Flight Standards Department, said that after more than 4,200 hours of investigation and based on information retrieved from the plane's black boxes, officials found that human error, not equipment failure, had led to the tragic incident.
“Because of the high-speed, the pilot apparently lost control of the plane upon landing, causing it to run off the runway,” said Sarvi, adding that both the plane and its crew had passed all pre-flight safety inspections before take-off.
Sarvi rejected reports suggesting that the crew were involved in a heated argument at the time of the crash, although the cockpit voice recorder indicated to distractive conversations between the pilot and Mehdi Dadpey, the airline's managing director, who was onboard.
He added that this was a breach of proper cockpit management and played a significant role in the crash.
The incident was the second major airline catastrophe to have befallen Iran in a period of 10 days.
On July 15, an airliner went down near Jannat-abad village, killing all 168 people onboard. The plane, a Russian-made Tupolev Tu-154M belonging to Iran's Caspian Airlines, was flying from Tehran to Yerevan in Armenia.
SBB/DT/ZAP/MD
a similar aircraft with a different airline
Investigators with Iran's Civil Aviation Organization (CAO) have concluded that pilot error was to blame for last month's crash of Aria Air Flight 1525. The Ilyushin Il-62 ran off the runway at Mashad and struck a wall while landing, killing 17 people and wounding 30.

The CAO Flight Standards Department's deputy director Faramarz Sarvi stated that the aircraft had been traveling at excessive speed. Sarvi added that lack of crew cooperation was also suspected, but denied reports that the pilots had been arguing when the accident occurred. However, the ''Aviation Herald'' claims that the cockpit voice recorder showed they had been.

"Because of the high-speed, the pilot apparently lost control of the plane upon landing, causing it to veer off the runway," said Sarvi. He further stated that the crew did not answer warnings from the tower to slow down and that there was no equipment failure. Both aircraft and crew had passed safety checks prior to the plane taking off.

Sarvi stated that around 4,200 hours of investigations were conducted.