Expert: Shooting possible - but unproven

All 176 people on board were killed when a Ukrainian passenger plane crashed shortly after taking off from Tehran International Airport.

63 of the dead were Canadian citizens and, according to Trudeau, there are "intelligence from a number of sources, which include our allies and our own intelligence" indicating that the plane was shot down by Iranian air defense. At the same time, he emphasizes that it is too early to draw conclusions and make accusations.

Also, two US and one Iraqi source tell Newsweek magazine that the plane is believed to have been shot down by an air defense system that may have been active with enhanced readiness due to Iran's attacks on military bases in Iraq, which happened just hours before the plane crash.

Flight safety expert Hans Kjäll says there is a possibility that the shooting could be an Iranian mistake fueled by the escalated armed conflict with the United States.

"It is clear that there can be a certain panic feeling that the airport can be bombed when you get threats from outside and when you politicize the whole business," he says.

At the same time, the fact that the aircraft was even allowed to lift may have been a violation of the regulations set by the United Nations Aviation Organization ICAO on civilian flights in conflict zones, according to Kjäll.

For example, if an air defense unit is grouping near a civilian airport, it will take time to secure a separation where it is possible to distinguish harmless civilian flights from possible military threats, he says.

- Then you should have closed the airport for civilian traffic for a few days and said that we are grouping air defense.

- It seems to be total chaos if this were to be true, continues Kjäll.

Iran has the main responsibility for investigating the crash. After the plane's tachograph, so-called black boxes, were found, the chief of the Iranian aviation authority said that American aircraft manufacturer Boeing will not be allowed to investigate them - which dilutes the suspicions that the country is hiding something.

Ali Abedzadeh, head of Iran's aviation, completely rejects the details of a shooting, according to the Iranian semi-state news agency Isna.

Kjäll says that data from Canadian authorities are usually nuanced, but that it is unclear exactly what the sources behind them are if a downturn is. He also emphasizes that neither metallurgical investigations of wreckage nor other analyzes have been made yet, and that it is wise at present to consider pending the details of a shooting.

- What is the evidence that it is a downturn, when not even the black boxes are analyzed or published?