Sudden, dense fog in a complex spring climate caused the helicopter crash that killed Iranian President Ebrahim Raisi and several other officials earlier this year, according to the final report released by Iran's Armed Forces General Staff on September 1, IMNA reported.

"The main cause of the helicopter crash was determined to be the sudden formation of dense, upward-moving fog in the complex spring climate of the region, leading to the aircraft's collision with a mountain," the report concluded.

The “comprehensive investigation”, conducted by a team of military and civilian experts, examined all aspects of the incident, including the helicopter's maintenance history, flight path, and weather conditions on the day of the crash.

Questions have lingered for months following the death of former president Ebrahim Raisi, former foreign minister Hossein Amir Abdollahian, and several others who died on May 19 close to the border of Azerbaijan and Armenia following a meeting on the border with Azerbaijani President Ilham Aliyev. Rumours circulated inside and outside the Islamic Republic that Raisi’s helicopter was shot down by hostile actors, along with several other theories, however, the investigation has now denied these other explanations.  

According to the report, all maintenance and repair documents for the helicopter were found to be in line with defined standards. The flight path from Tabriz to the crash site was determined to be as planned, with no deviation from the set route.

Investigators recovered and analysed the pilot's handheld computer (iPad), which confirmed the correct flight path information. Remaining parts of the crashed helicopter, including engines, power transmission systems, and electronic equipment, were tested in specialised laboratories with no defects found that could have contributed to the crash.

The report stated that weather conditions on the day of the incident were consistent with the meteorological forecasts. Notably, no emergency messages were recorded from the pilot in the cockpit voice recorder (CVR) or flight data recorder (FDR).

Forensic examinations of the victims' bodies revealed no suspicious findings, and no signs of sabotage were found in the helicopter's components and systems.

The report also ruled out the possibility of the helicopter being targeted by offensive or defensive systems, electronic warfare, or magnetic fields and lasers.

On August 21, The General Staff of the Armed Forces of Iran refuted a news agency's report claiming that the helicopter of the late President Ebrahim Raisi crashed due to adverse weather conditions and excessive weight.

Shortly after the parliamentary vote, Fars News Agency released a report about the causes of the helicopter incident.

The agency cited “an informed security source” as saying that unfavourable weather conditions and the excessive weight of the helicopter were the two reasons for the crash.

The flight teams had been informed of weather conditions the night before and were supposed to complete the flight before 1:00 p.m. local time, but it was delayed due to the president’s meetings, according to the report.

“It is necessary for the media to coordinate with the [General Staff of the Armed Forces] when publishing defence, security, and law enforcement news, and to prioritise accuracy over speed to avoid providing opportunities for enemy abuse,” the General Staff said in a statement.

Ali Naderi, managing director of the Iranian government’s official news agency, IRNA, also reacted to the Fars News report.

He tweeted that the helicopter’s capacity was 12 people, carrying only eight when the crash occurred.

Also, the meteorological organisation had forecast poor weather conditions for 2:00 p.m. local time, but the flight would have landed at 13:45 as scheduled, he added.

“Is publishing stories contrary to official reports aimed at playing with people’s trust? … Why after a vote of confidence? Why an informed source?” Naderi wrote on X.

Following Raisi’s early death, snap presidential elections were called in the country with Masoud Pezeshkian winning the vote.

Raisi was married to Jamileh Alamolhoda, a PhD in philosophy and writer, whose father is cleric Ahmad Alamolhoda. They had two daughters.

Raisi was the custodian of the Imam Reza shrine in Mashhad and a close associate of Iran’s Supreme Leader Ayatollah Ali Khamenei. In November 2019, he was sanctioned by the US and EU for human rights violations.

In 2021, Raisi was listed among Time magazine’s 100 most influential people worldwide.