Iran Aseman Airlines Flight 3704

The aircraft involved was an ATR 72-212 with MSN 391. It was registered EP-ATS and was delivered to Iran Aseman Airlines in 1993. No serious incidents were recorded during the 24 years of the aircraft's service in the airline.[4][5]

An Iranian source reported that the aircraft had recently resumed operations after being out of service for seven years due to a lack of spare parts and that it had technical problems during a flight some weeks before the crash. It was claimed that an Instagram post from Iran Aseman two months prior to the crash, that announced the aircraft was back in service, had been deleted after it crashed.[6]

At the time of the accident, Iran Aseman had six ATR aircraft in its fleet, of which three were in operation.[6]

It was initially reported that 59 passengers and six crew members were presumed to be on board.[6][7][8][4] It was later revealed that there were 60 passengers and six crew members aboard. The flight manifest was consisted of 65 adults and 1 child. There were 60 passengers, 2 security guards, 2 flight attendants and 2 flight crew members.[9]

The pilot of the flight was identified as 62-year old Hojatollah Foladi. He had accumulated a total flying hours of more than 17,000 hours, of which 12,000 hours were on the type. The pilot also had experience of flying in India from 2002 to 2007, before returning to Iran Aseman Airlines. At least 2 flights to Yasuj had been performed 3 months prior to the accident. His flying certificate was deemed as valid.[3][10]

The pilot not flying was identified as 36-year old First Officer Khevah Khalili with a total flying hours of approximately 1,800 flying hours, of which 197 hours were on the type.[3]

The aircraft was operating a domestic scheduled passenger flight from Iranian capital Tehran Mehrabad International Airport to Yasuj Airport in Yasuj, the capital of Kohgiluyeh and Boyer-Ahmad Province in southwest Iran.[11] The flight was supposed to take about 50 minutes. It was operated by Iran Aseman Airlines, the third largest airline in Iran. It took off from Tehran with 60 passengers and 6 crew members at about 04:35 UTC.[12][3]

At 05:49 UTC, as Flight 3704 approached Yasuj, the flight crew asked the meteorological information in Yasuj. Yasuj Tower later informed Flight 3704 about the weather condition and mentioned that the final approach path was clear. The flight later was cleared to descent to FL170 by Tehran and was handed over to Yasuj on 05:53 UTC.[3]

The crew stated that they would continue the approach with FL150. At 05:55, the crew reported that they were 25 miles from the destination airport. Yasuj Tower then told the pilot about the updated condition in Yasuj, stating that clouds were slowly moving to the south. Four minutes later, Yasuj asked the flight again and the crew responded that they failed to receive the signal of Distance Measuring Equipment (DME) from their navigational device. The crew then checked about the weather condition in the area again.[3]

At 06:04 UTC, Yasuj Tower lost communication contact with Flight 3704. Attempts had been made to re-establish communication with the aircraft but failed.[3]

According to flight tracking website Flightradar24, the last signal from the aircraft was received just before 05:56 UTC, when it was at an altitude of 16,975 feet (5,174 m) and was descending.[13]

Helicopters were deployed to search for the missing aircraft

Locals reported that they had heard the aircraft hit the mountain.[14] Iranian authorities in neighboring Shiraz and Isfahan province had deployed two of their helicopters to the crash site. A total of 12 search and rescue teams had been dispatched Mount Dena, but due to foggy conditions, rescue helicopters could not reach the crash site in the Zagros Mountains.[4][15][16] Mount Dena, the location of the crash site, is actually a mountain range within the Zagros Mountains; it is 80 kilometres (50 mi; 40 nmi) long with several peaks, the highest of which is 4,409 metres (14,465 ft) above sea level.

Spokesman from Iran Aseman Airlines initially stated that all 66 passengers and crews on board had been killed in the accident. However, this statement was later retracted by the airline and the airline later issued a statement saying that it could not "accurately and definitely confirm" that everyone had died in the crash.[17]

In response to the crash, crisis centres were set up in Tehran, Isfahan, Fars and Yasuj.[6] Weather conditions at the crash site, including snow and strong winds, were hampering search and rescue services.[4] The Red Crescent Society announced that a drone would be flown to the area due to the severe weather condition which prevented helicopters to reach the crash site. Search and rescue team announced on 19 February that at least 5 helicopters had been prepared for the search operation.[18] Troops with search dogs were deployed to hike the mountain and to search the area on foot. Search and rescue operation via air was stopped for the second time due to bad weather conditions.[19] Reports that the wreckage had been found at an elevation of 11,482 feet were refuted by officials from the Iranian Red Crescent and Iranian investigators.[20][21]

On 20 February, two helicopters from Islamic Revolutionary Guard Corps Air Force sighted the wreckage of the aircraft,[22][1] 30 metres (100 ft) below the peak of the mountains south of Noqol at an elevation of approximately 4,000 metres (13,000 ft).[1] Another military helicopter sighted the wreckage and pinpointed the crash site. The aircraft was completely obliterated, with large portion of the tail cone, the vertical stabilizer, the rudder and the empennage were found. Scattered bodies could be seen around the wreckage. No survivors were seen at the crash site. All 60 passengers and 6 crew members on board died.[3]

As helicopters were unable to land on the crash site, the recovery of the victims had to be done on foot. Officials stated that the bodies had to be carried on the rescuers' backs to the mountain foot.[23][24] The head of the country's emergency services said that the recovery of the victims would be challenging due to the adverse weather. As of 21 February, at least 32 bodies had been recovered from the crash site.[25][26]

On 3 March Iranian officials announced they had found the flight recorders.[27]

President of Iran Hassan Rouhani ordered Iranian Minister of Roads and Urban Development Abbas Ahmad Akhoundi to lead the investigation.[28] Iran Civil Aviation Organization (CAO) investigated the cause of the crash. The French BEA also sent 7 delegations to investigate the crash. The aircraft's manufacturer, ATR, sent 4 people to Iran to assist with the investigation.[29]

The preliminary report issued in March, 2018, states that while the aircraft was flying at an altitude of 15,000 feet, engine power was reduced causing the speed to drop significantly, and causing a descent towards 14,000 feet and causing a stall warning. In the area of the accident the minimum safe altitude was 15,500 feet, the mountains peaked at 14,460 feet and the flight plan called for the aircraft to maintain 17,000 feet.[30]

The authorities agreed that the main cause of the crash were icing conditions on the wings of the aircraft. However, there was no consensus among Iranian authorities on whom to blame. The investigation committee of the Civil Aviation Organization believed that the pilot had been aware of the lack of proper deicing on the aircraft, so he should not have entered the area with potential icing. However, Iranian judicial authorities and the special committee of the Islamic Consultative Assembly believed that the flight should not have been allowed in the first place, and blamed the Iran Aseman Airlines for the accident.[31]

According to the interim report issued one year after the accident, the probable main cause of the accident was human error, the actions of the crew resulting in dangerous conditions for the flight.[4]

Iranian Parliament investigation report on incident released on May 18, 2020, blamed Iranian Civil Aviation Organization and Aseman Airlines on the incident. The parliament report also accuses the manufacture of the airplane for not providing spare parts for repair of the aircraft.[32]

Iranian Minister of Roads and Urban Development Abbas Khoundi observed the search and rescue operation

On 23 February 2018, the Iran Civil Aviation Organization temporarily suspended the operation of Iran Aseman Airlines' ATR 72 aircraft.[33]

The search and rescue operation was viewed as "too long" by some family members, some were angered due to the incompetent handling of the disaster. On 19 February, more than 100 people reportedly protested outside a government building in Dena Kooh, demanding Iranian officials to step down due to the response on the disaster.[34]

Journalists have speculated that the economic sanctions against Iran which have prevented Iranian airlines from obtaining new planes and spare parts and forced them to operate aging aircraft may have contributed to the cause of the crash.[35]

• Iran Air Flight 277
• Iran Aseman Airlines Flight 6895
• American Eagle Flight 4184
• Scandinavian Airlines Flight 751

• Media related to Iran Aseman Airlines Flight 3704 at Wikimedia Commons
• Accident Investigation Report Issued 17 February 2019
• "Accident to the ATR72 registered EP-ATS and operated by Aseman Airlines on 18/02/2018 near Yasouj [Investigation led by AAIB / Islamic Republic of Iran]" – Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile
• "Accident de l’ATR72 immatriculé EP-ATS et exploité par Aseman Airlines survenu le 18/02/2018 près de Yasouj [Enquête menée par AAIB / République Islamique d'Iran]" – Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (in French)