Ukraine International Airlines Flight 752

Investigation

The Civil Aviation Organization of Iran (CAOI) reported shortly after the incident that a team of investigators had been sent to the crash site. President Volodymyr Zelenskyy instructed the Ukrainian General Prosecutor to open a criminal investigation into the crash. The Ukrainian government sent 45 investigators to assist with the inquiry into the shootdown of the airliner.

Under standard International Civil Aviation Organization (ICAO) rules, according to Annex 13 of the Chicago Convention, the United States National Transportation Safety Board (NTSB) would participate in the investigation, as they represented the state of the manufacturer of the aircraft. France's Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA) would participate as representatives of the state of manufacture of the aircraft's engines (a U.S.–France joint venture) and Ukraine's Ministry of Infrastructure would participate as representatives of the state in which the aircraft was registered. Given that there were tensions between these nations and Iran as part of the 2019–2021 Persian Gulf crisis, it was not known how these investigative organizations would be involved, although it was reported that Iran had said American, French and Ukrainian authorities would be involved.

The head of the commission for accidents in the CAOI said they received no emergency message from the aircraft before the crash. It was reported that the aircraft's black boxes (the cockpit voice recorder (CVR) and flight data recorder (FDR)) had been recovered, but the CAOI said it was not clear to which country the recorders would be sent so the data could be analyzed. The association said it would not hand over the black boxes to Boeing or to U.S. authorities. On 9 January, the black boxes were reported, by Iranian investigators, to have been damaged and that some parts of their memory may have been lost. Mary Schiavo, a former U.S. Department of Transportation inspector general, said no automated distress messages had been sent from the aircraft or by its crew.

On 9 January, the Swedish Accident Investigation Authority and Transportation Safety Board of Canada (TSB) were officially invited by the investigation team to participate in the probe on the crash. The NTSB, Ukraine, and Boeing were also invited to participate in the investigation. Due to American economic sanctions placed on Iran, U.S. investigators would need a special licence from the Treasury and the State Departments to travel there.

On 9 January, media reports showed bulldozers being used to clear the crash site. Some aircraft investigation experts expressed concerns about disturbing and damaging the crash site before a thorough investigation could be conducted. Iran denied bulldozing the evidence. On 10 January, the Iranian government granted Ukrainian investigators permission to investigate the flight recorders and Ukrainian investigators visited the crash site, with plans to download the recorders in Tehran. On 14 January, the head of the TSB, Kathy Fox, said there were signs that Iran would allow the TSB to participate in the downloading and analysis of data from the airplane's flight data recorder and cockpit voice recorder. On 23 January, the TSB announced that they had been invited by Iran to help with the flight recorders.

On 2 February, Ukrainian public TV aired a leaked recording of the information exchange between the Iranian pilot of an Aseman Airlines flight and an Iranian air traffic controller. The pilot stated in Persian that he saw "a series of flares like that of a missile" and later an explosion. Following the leak, Zelenskyy said the new evidence proved Iran was well aware from the very first moments that the Ukraine passenger airplane was brought down by a missile. The following day Iran ceased co-operation with Ukraine in its investigation into the disaster. Iran resumed co-operation on 15 February. In the final report about the crash, Iranian authorities gave a more complete transcript of the communication.

Cause of the crash

On 8 January, Iran's Road and Transportation Ministry released a statement that the aircraft burst into flames after a fire started in one of its engines, causing the pilot to lose control and crash into the ground. The airline opined that pilot error was impossible to be cited as the cause of the crash as the pilots had exclusively been trained for the Tehran flights for years, noting that Tehran Airport was "not a simple airport".

Iranian and Ukrainian government sources initially blamed mechanical issues aboard the aircraft for its crash. The Ukrainian government later retracted its statement and said anything was possible, refusing to rule out that the aircraft was hit by a missile. Zelensky said there should not be any speculation about the cause of the crash.

On 9 January, U.S. intelligence and defence officials said they believed the aircraft had been shot down by an Iranian Tor missile (NATO reporting name SA-15 "Gauntlet"), based on evidence from reconnaissance satellite imagery and radar data. Ukrainian authorities said a shootdown was one of the "main working theories", while Iranian authorities denied this, stating that allegations of a missile hit were "psychological warfare". British defence officials agreed with the American assessment of a shootdown. Prime Minister of Canada Justin Trudeau said evidence from multiple sources, including Canadian intelligence, suggested the aircraft was shot down by an Iranian missile. He added that "this may well have been unintentional". Iranian media described it as "an American lie", "a wrongful scenario by CIA and the Pentagon", and "an attempt to prevent Boeing stock from a free fall".

On 11 January, the Armed Forces of the Islamic Republic of Iran admitted they had shot down the airplane, having erroneously identified it as a hostile target. According to an early IRGC statement, when the airplane seemed to head toward a "sensitive military centre" of the IRGC, controllers mistook it for a "hostile target" and shot it down. Iran's Civil Aviation Organization disputed this timeline, arguing that the airplane was on the correct course all the time and there was no proven flight deviation. The CAOI's viewpoint was also supported by a Radio Canada International article that used public ADS-B flight tracking data. Iranian Brigadier general Amir Ali Hajizadeh of the IRGC Aerospace Defense said a missile operator in Bidganeh had acted independently, mistook the airplane for a U.S. cruise missile and shot it down. Hajizadeh also said the airplane was on-track and "made no mistake".

Western experts had previously noted that Flight 752 was flying near several sensitive Iranian ballistic missile facilities, including the Shahid Modarres missile base at Bidganeh near Malard, which the Iranians could have believed would be targets of retaliation for their attack a few hours earlier. The flight had been delayed by more than an hour because the captain had decided to offload some luggage as the aircraft was over its certified takeoff weight.

On 11 July 2020, the CAOI reported that Iran now blamed the missile strike that downed PS752 on "bad communication" and "poor alignment". According to the Iranians, the missile battery "had been relocated and was not properly reoriented" and the guilty parties did not include the higher-ranking chain of command officers. On 20 July, Canadian foreign minister François-Philippe Champagne rejected the finding by the CAOI that "human error" caused the launch of the missiles which destroyed the aircraft: "It cannot just be the result of a human error. There is no circumstance under (which) a civilian aircraft can be downed just by the result of human error in this day and age... All the facts and circumstances point to more than just a human error, so certainly we will continue to pursue vigorously the investigation."

Final report

On 17 March 2021, CAOI released the final report on the crash, which states the following:

A contributing factor was:

Ukraine's Minister of Foreign Affairs Dmytro Kuleba rejected the findings and criticized the report as "a collection of manipulations, the goal of which is not to establish the truth, but to whitewash the Islamic Republic of Iran." The Transportation Safety Board of Canada also criticized the report, saying that it did not provide an exact reason to why the IRGC fired its missiles at Flight 752.