The Air Accidents Investigation Branch’s final report into the Shoreham Airshow disaster – which killed 11 people and injured 13 when a jet smashed on to the A27 in West Sussex on August 22 2015 – has been published.
Here’s everything you need to know about it:
What’s the conclusion of the investigation?
That the crash was caused by the pilot flying a vintage jet too slow and too low during a loop manoeuvre.
Andrew Hill was attempting a bent loop, where the aircraft pitches up into a loop and then rolls before leaving the manoeuvre in a different direction to the one it entered in.
He was permitted to carry out the aerobatics at a minimum altitude of 500ft, and the normal technique would be to enter the loop at an airspeed of at least 350 knots and use maximum engine thrust to achieve a height of at least 3,500ft at the apex.
But Hill flew the 1955 Hawker Hunter at just 185ft at a speed of just 310 knots, reaching 2,700ft at the top of the loop.
How did it happen?
Cockpit footage during the flight showed Hill “alert and active”, with no suggestion he had passed out, investigators said.
AAIB principal inspector Julian Firth pointed out that the speed, height and thrust followed in the Hunter were “very similar” to another aircraft that the pilot had flown during displays in the run up to the Shoreham event, adding that it was possible “the pilot recalled the wrong numbers, essentially mixing up the two aircraft.”
Could more have been done by the pilot and the organisers?
Flight trials indicated the pilot could have pulled out of the stunt up to four seconds after the aircraft reached the top of the loop, but Hill either did not perceive it was necessary or did not realise it was possible, the AAIB said.
He had not received formal training to escape the manoeuvre and had not had his competence to do so assessed, the report found.
The severity of the outcome was found to be due to the “absence of provisions” to protect the public and mitigate the effects of an aircraft crashing in an area outside the control of the air show organisers.
What have the families said?
The parents of victim Matthew Grimstone, 23, said the Civil Aviation Authority (CAA) and the air show organisers “have got much to answer for”.
In a statement, they said: “Apart from anything that the pilot may have got wrong it is very evident the CAA and the Shoreham Air Show organisers have got much to answer for.
“Rules laid down by the CAA were quite clearly inadequate and those that were there were, in some cases, not fully adhered to by the air show organisers.”
What’s happened to the pilot?
The 52-year-old from Sandon, Hertfordshire, suffered serious injuries. He was interviewed on seven occasions by AAIB investigators, but he could not remember events between the evening of August 19 and regaining consciousness in hospital after the accident.
He was able to describe his normal practice, but not the events on the day of the crash.
He is now being investigated by Sussex Police for possible manslaughter.
What happens next?
The AAIB made a total of 32 safety recommendations for the CAA, including 10 in the final report. They include reviewing arrangements for the regulation of ex-military aircraft.
The CAA said it would act on them “as a priority”.
Sussex Police will now review the report with their independent experts and hopes to submit a file of material to the Crown Prosecution Service (CPS) before the next pre-inquest review on June 20.
Organisers of the Shoreham air show said it was unlikely they will stage “the same or similar style event” in the future.