An Azerbaijan Airlines Embraer E190 flying from the Azerbaijani capital Baku to Grozny, in Chechnya, crashed and caught fire at about 9:30am Moscow time at Aktau Airport in southwestern Kazakhstan on 25 December. The front of the plane burst into flames, while the tail remained intact, meaning 29 passengers escaped with their lives. There were 67 people on board in total.

The airline, as well as Russia’s civil aviation agency Rosaviatsia, originally said the crash was caused by a collision with a flock of birds, leading to a loss of navigation control.

But images of holes in the fuselage of the plane which crashed as it was flying from Baku to Grozny posted on social media shortly after the event occurred on Wednesday caused many bloggers and journalists to suggest that it had been hit by an anti-aircraft missile.

Experts including Friendly Avia Support Director Oleksandr Lanetskyi were quick to dismiss the bird story as “total nonsense” as more video evidence emerged from the crash site. “If birds come into contact with a plane, the worst thing that can happen is an engine shutdown. But there’s no way that would create holes in the fuselage or the tail. That has never happened before,” Lanetskyi says.

Their suspicions were finally confirmed on Thursday, when sources in the Azerbaijani government told Euronews that the plane was struck by a Russian ground-to-air missile, and reaffirmed on Friday, when Azerbaijan Airlines said in a statement cited by Reuters that the plane had experienced “external physical and technical interference”.

Azerbaijan’s Transport Minister Rashad Nabiyev said on Friday that surviving passengers had heard an explosion while flying over Grozny, while a flight attendant even sustained an arm injury when “something struck the plane” from outside, but added that the investigation into the crash continued.

The plane took off at 8am on Wednesday morning from Baku — 7am Moscow time — and was due to land in Grozny 80 minutes later. This coincided with an air raid warning over the North Caucasus. At about 8am, a surface-to-air missile launched from a Pantsir air defence system shot down a Ukrainian drone, the debris from which then struck a shopping mall in the city of Vladikavkaz, about 100km from Grozny Airport, Lanetskyi says.

Head of North Ossetia Sergey Menyaylo initially denied that a drone had struck the shopping centre, but later said that the Russian Defence Ministry had confirmed “drone attacks had affected a number of areas in the North Caucasus”.

Other reports say a drone also fell on the town of Malgobek, in the republic of Ingushetia, about 100km from Grozny. Khamzat Kadyrov, secretary of the Chechen Security Council and nephew of head of Chechnya Ramzan, wrote on Instagram that all attempts to attack the republic had been repelled.

“All air defence systems work on a friend-or-foe principle, using radar to determine whether it is a target or a civilian aircraft,” Lanetskyi explains, suggesting that everyone got a “dressing down” from Kadyrov after Chechnya’s air defences had failed to repel a number of recent drone attacks and had received orders to take down everything in the event of an air raid warning.

Russian military expert Alexey Kuznetsov* agrees. “After multiple attacks on Grozny, Ramzan Kadyrov was obviously furious at how ineffective the air defences had been and ordered tighter surveillance.”

During an air raid warning, civil aviation first declares airspace restrictions — referred to in Russia as “Operation Kovyor”, Lanetskyi says. This means that all aircraft that are on the ground must remain there, those that can immediately land must land, and those that cannot land must reach maximum altitude and leave the danger zone.

But it appears that the plane was not warned in time or given a window to land safely, and the reason for that is unclear, Lanetskyi says.

‘Complicated’ situation

Rosaviatsia, Russia’s civil aviation agency, confirmed on Friday that the situation around Grozny “in the hours of the plane crash” was “complicated”, with Grozny Airport introducing airspace restrictions due to “terrorist attacks by Ukrainian drones” and “heavy fog”, state news agency TASS reported.

Pavel Aksyonov, a military observer for BBC News Russian, says the holes could only have been made by projectiles flying at high speed. He thinks the damage is typical of an attack by an anti-aircraft missile, as happened with Flight MH17 that was shot down in the sky over eastern Ukraine in 2014, which was also hit by a number of projectiles.

But the Embraer appears to have suffered relatively little damage, Aksyonov notes. “It makes sense to assume, therefore, that the missile was not very large.”

Lanetskyi thinks the most plausible version is that the aircraft was hit twice by the Pantsir system, which almost always fires two missiles, though says this is just an assumption based on the information available to date. The Pantsir also fires relatively small missiles which create “a fairly diffuse ring of shrapnel”, Kuznetsov added.

Experts have also analysed the purported transcripts of the conversations between pilots and air traffic control published by Russian Telegram channels. If those are true, it’s clear that the aircraft’s GPS and other electronic systems started failing on the approach to Grozny Airport.

It looks like the aircraft then came into the range of Russia’s electronic warfare system, designed to jam and knock out Ukrainian drones.

“Neither air traffic control nor the pilots were notified of the air raid warning, or that the electronic warfare system and air defences were now operating, which raises the more general question of how safe Russian airspace even is now,” Lanetskyi notes.

The plane tried to land several times, Kuznetsov continues. “On one approach, ‘birds’ hit the aircraft hard, at which point the plane abruptly lost control and the pilot became inaudible,” he says.

Aksyonov believes the transcript of the conversation between air traffic control and the pilots is reliable and says there is no mention of firing from the ground. It is difficult to say whether the crew understood the plane had become an anti-aircraft target.

“It looks like the air defence operator confused the Embraer on his radar display with a drone and fired a missile at the plane. The crew mistook the hit for a collision with a flock of birds and decided to divert to an alternate airfield,” Kuznetsov said.

However, it remains unclear why the plane then headed to Kazakhstan, and didn’t land at a closer Russian airport or military airfield. Rosaviatsia said on Friday that Russia had suggested the pilot land at other airports, but he decided to head for Aktau, but its statement has not been confirmed by other sources.

What to expect now

A special commission should now establish the real cause of the disaster. A commission is usually made up of representatives from three countries: the one where the aircraft was built, the one where the airline is based, and the country where the incident occurred. In this case, that would mean Brazil, where Embraer is from, Azerbaijan and Kazakhstan.

“The Kazakh authorities have asked people to wait for the commission’s conclusion. It will have access to the flight recorders and radar data,” says Aksyonov.

Speaker of the Kazakh Senate Maulen Ashimbaev said on Thursday that representatives of “special bodies” from Russia would be involved in the commission. He also said it was “speculation” to say the aircraft had been shot down and that it was “wrong and unethical to voice such assessments”.

“How do they know it wasn’t?” Lanetskyi asks, surprised. “I can understand Rosaviatsia saying that, or officials refusing to comment until there is some preliminary version of events available.”

However, he agrees we may have to wait some time for the official version. Under the rules set out by the Interstate Aviation Committee, which governs air travel in various former Soviet states, including Russia, Azerbaijan and Kazakhstan, no official statement on the cause of a plane accident must be made for “at least 10 days”, and the investigation itself could last a year or more.

*Not his real name