What happened?

Ukraine International Airlines flight 752 took off at 6.12am on 8 January after nearly an hour’s delay at Tehran’s Imam Khomeini International Airport. It gained altitude heading west, reaching nearly 8,000ft, according to flight-tracking data.

Video footage and eyewitnesses, including the crew of another flight passing above it, depicted the plane engulfed in flames before it crashed into countryside south-west of the Iranian capital at 6.18am, causing a massive explosion.

Play Video Video purportedly shows moment Ukrainian passenger plane plummets near Tehran

The aircraft’s black boxes have been recovered, giving investigators access to data and cockpit communications, though some parts of their memory had been damaged in the crash.

Who was on board?

Of the 176 people onboard, 78 were Iranian, 57 were Canadian and 11 were Ukrainian (including nine crew members), along with 10 Swedes, seven Afghans, four Britons and three German nationals. There was some confusion over the nationality of those killed, with many holding dual citizenship.

Facebook Twitter Pinterest Tributes at Boryspil International Airport in Kyiv to some of the victims of the Iran plane crash. Photograph: Pavlo_Bagmut/Ukrinform/Barcroft Media

What was the cause?

Iran has admitted its military unintentionally shot down the plane, after days of rejecting western intelligence reports that pointed to its responsibility.

A military statement on state TV on 11 January blamed “human error” for the incident. It was followed by an apology from Iran’s president and condolences from the supreme leader, Ayatollah Ali Khamenei.

Footage had earlier emerged on 9 January showing the moment the jet was shot down:

Play Video 0:31 Iran video appears to show missile striking Ukrainian plane – video

Unverified images posted on social media by an Iranian activist earlier in the day showed the remains of what could be a missile from a Tor-M1 system that he said was found near the plane’s crash site:

Facebook Twitter Pinterest Images circulating online of what an Iranian activist said was a missile head photographed near the crash site.

What is the Tor-M1?

Facebook Twitter Pinterest A Tor-M1 system displayed at a 2009 military parade in Tehran. Photograph: Raheb Homavandi/Reuters

The Tor is a short-range “point defence” system that integrates the missile launcher and radar into a single tracked vehicle. It is designed to be mobile and lethal against targets at altitudes up to 6,000 metres (20,000 feet) and at ranges of 12 km (7.5 miles).

Russia delivered 29 Tor-M1s to Iran in 2007 as part of a $700m contract signed in December 2005. Iran has displayed the missiles in military parades as well. Nato refers to the system as the SA-15 Gauntlet.

It is believed the US system that detected the supposed missile launches is the Space Based Infrared System, a network of about 10 satellites operated by the US Air Force’s Space Command, first launched in 2011.

What sort of plane was it?

The plane was a Boeing 737-800 model, the most popular aircraft in the world, used by airlines from Ryanair to American Airlines. The short-haul plane is the predecessor to the 737 Max, the model that was grounded after two fatal crashes in 2018 and 2019.

What is the context?

The crash occurred a few hours after Iran launched a ballistic missile attack against Iraqi military bases housing US troops, amid a confrontation with the US over its killing of the Iranian general Qassem Suleimani in a drone strike in Iraq last week.