Leicester City helicopter crash: Aircraft 'spun' after take-off
Video footage of the helicopter carrying the Leicester City owner shows it spinning moments before it crashed killing him and four others.
Vichai Srivaddhanaprabha died along with two members of his staff, the pilot and a passenger in the crash outside the King Power Stadium.
The video shows the aircraft going into a spin, which experts said suggests a problem with the tail rotor.
Investigators would not comment on the video or causes of Saturday's crash.
The widely shared footage, taken inside the stadium, shows the AgustaWestland AW169 climbing normally for about 40 seconds, before it pauses and goes into a downward spin.
Aviation expert David Learmount said the video showed the aircraft completed an "awkward" take-off without issue before getting into difficulty.
"At lift-off you can't see anything that's abnormal, but it's an awkward job climbing out of a stadium because ideally you want some forward speed as well as continuing to climb," Mr Learmount said.
"The pilot climbed very nearly vertically until he was above the height of the stadium and then started to turn to the right - it was very shortly after that control was lost.
"Just after he did a manoeuvre that seemed to be intended, he lost control."
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Mr Learmount said if the tail rotor was the problem, the pilot's options were limited to simply shutting power off to the rotors.
"That leaves you with no power - if you have no power you have to go down," he said.
"This action - bringing both rotors back to idle - has to be done incredibly quickly.
"If you shut the power down rapidly enough, you can keep the rotor spinning and that effectively puts the helicopter into a glide.
"If you've already started spinning, trying to do all of this is very nearly impossible."
All five occupants of the helicopter were pronounced dead at the scene of the crash.
As well as Mr Vichai, Nusara Suknamai, Kaveporn Punpare, and pilots and partners Eric Swaffer and Izabela Roza Lechowicz also died.
Police have said Ms Lechowicz was a passenger at the time of the crash.
The Air Accidents Investigation Branch (AAIB) is already examining the flight recorders, which were retrieved the day after the crash.
It said it was "too early" to comment on the video or the possible causes of the crash and said it "will consider a wealth of evidence, and the video is just one element".
A spokesperson for Leonardo, the Italian company which manufacturers the AW169, said it was working closely with the AAIB and British authorities.
So far it has not issued any new safety advice relating to the AW169 in light of the crash.
On Wednesday, coroners for Leicester said formal identification of 60-year-old Mr Vichai had taken place, along with 32-year-old Ms Nusara, 46-year-old Ms Lechowicz and 53-year-old Mr Swaffer.
Identification of the fifth victim was still in progress and no date for inquests have been set yet, police said.
A huge display of floral and footballing tributes have been left outside the stadium and a steady stream of people have signed a book of condolence since it opened on Tuesday.
Families of those who died, players and members of the wider Leicester community have also visited the scene.
A minute's silence will be held and black armbands will be worn by players at all Premier League matches this weekend as a mark of respect, the Premier League has confirmed.
Leicester players will also travel by road to their game at Cardiff on Saturday rather than fly, as it was felt insensitive to go by plane given the circumstances of Mr Vichai's death.