• US officials have said an Iranian missile most likely downed a Ukrainian passenger jet that crashed Wednesday morning shortly after taking off from Tehran's main international airport.
  • Researchers told Business Insider that a combination of "poor training" and "panic" could have led Iranian personnel to fire a missile at the plane accidentally. Nearly half the plane's passengers were Iranian.
  • But other experts say the plane's flight path and data transmitted to radars would have indicated the aircraft was a passenger plane.
  • Iran denies the plane was brought down by a missile, instead blaming a technical failure.
  • Visit Business Insider's homepage for more stories.

Video footage that emerged Thursday showed the moment Western officials believe an Iranian surface-to-air missile detonated near a Ukrainian International Airlines jet carrying 176 people, puncturing the fuselage with thousands of shards of shrapnel and sending it crashing to the ground.

Iran has denied responsibility for bringing down the jet, blaming a technical failure and accusing the US of spreading a "big lie" by claiming a missile strike caused the crash, which killed everyone on board.

But Pentagon and intelligence officials told US media outlets that radar data appeared to pick up the firing of a short-range Iranian interceptor. Officials told Newsweek the missile was most likely a Russian-supplied Tor model.

Canadian Prime Minister Justin Trudeau has said intelligence pointed to an accidental missile strike.

User error

Discussion is now focusing on explaining why Iran may have brought down the plane. Nearly half of the people on the aircraft were Iranian, making it unlikely that the plane was deliberately targeted.

Instead, human error is the most likely explanation, said Justin Bronk, a research fellow in combat airpower and technology at the Royal United Services Institute, London.

Part of the wreckage from Ukraine International Airlines flight PS752, a Boeing 737-800 plane that crashed after taking off from Tehran's Imam Khomeini airport
Part of the wreckage from Ukraine International Airlines Flight 752, a Boeing 737-800 plane that crashed after taking off from the main Tehran airport.
Iran Press/Handout via REUTERS

"This was a completely avoidable tragedy which should never have happened if Iran's air defences were being managed and operated competently," he told Business Insider in an email. 

He said the Iranian crew operating the Tor system would most likely have been on high alert since the US assassination of Iran's top military commander, Qassem Soleimani, in Iraq.

In an article for the Times of London, Bronk argued that the crew, exhausted and braced for retaliation following the Iranian missile attacks that targeted US troops in Iraq hours earlier, most likely committed a tragic mistake.

"When the United States (or any air force) conducts strikes against a country that has air defence systems, those systems are often hit at the outset to clear the way," Bronk wrote.

"So the crew are likely to have been scared. Scared too of the consequences from their own regime and superiors if they missed a potential threat in the event of a US attack."

Iran plane crash
Rescue workers search the scene where the Ukrainian plane crashed on January 8 2020.
Mahmoud Hosseini/picture alliance via Getty Images

Portecting Tehran

Other experts cite data indicating the plane was traveling near an area about 12 miles northwest of Tehran's international airport, where a sensitive Iranian missile site is most likely protected by antiaircraft missile batteries.

Iran may have viewed the missile sites as targets for a counterstrike by the US, Michael Elleman, the director of the Non-proliferation and Nuclear Policy Program at the International Institute for Strategic Studies, told the Washington Post.

Pieter van Huis, a senior researcher at the open-source investigations organization Bellingcat, told Business Insider that the Iranian missile base the plane flew close to was just outside the city of Malard on the fringes of Tehran.

"From what we know, the military base at Malard is of great importance for Iran's missile development," he said.

"On 12 November, 2011, a big explosion there killed 17 Revolutionary Guard soldiers, including Hassan Tehrani Moghaddam, the 'father of the Islamic Republic's missile technology.'

"Iran had just launched an attack on the US, so any soldiers stationed there may have been extra nervous about an imminent attack by the Americans."

A major mistake

But questions still remain over how the jet could have been mistaken for a hostile aircraft. Bronk noted that the airliner would have been following a prefiled flight plan and emitting a transponder signal that would tell radar-receiving equipment the identity, position, and flight path of the aircraft.

The plane had also just taken off from a major international airport, and several other aircraft had taken a similar flight path from the airport in the early hours of Wednesday morning, in the wake of the Iranian strikes against the US, according to the flight data tracking site Flightradar24.

The New York Times reported that Tor missile launchers are operated by teams of about three to four people, tracking flights using radar data, but that distinguishing civilian flights from military ones can require skill and that mistakes can occur.

In an email to Business Insider, Bronk wrote that simple human error was most likely a key factor in the tragedy.

"The SA-15 crew would have had plenty of information available to them that would have told them this was a civilian airliner or at the very least, a very odd fit for an incoming threat," he wrote. Tor launchers are also known as SA-15s.

"A mix of oversights, poor training and confirmation bias in a tense situation is the best explanation I can see at this point," he added.

Van Huis agreed. "It normally is very easy for trained antiaircraft units to distinguish civilian airliners from military jets," he said. "Panic among soldiers and/or miscommunication must have played a role."