- Video report by ITV News Correspondent Paul Davies
The pilot in the Shoreham air disaster was flying too low and too slow to perform his stunt and failed to do the necessary escape manoeuvre before the crash that claimed 11 lives.
A final report into the 2015 tragedy found pilot Andrew Hill remained conscious throughout the flight but was untrained in escape manoeuvres, which would have still been possible before he plummeted into traffic.
Air accident investigators also called on the Department of Transport to sanction an independent review into the way flying displays in the UK are governed to increase safety levels.
They found a "lack of provisions" by the organisers to protect an area outside their control had increased the severity of the West Sussex disaster before the 52-year-old Mr Hill's loop-the-loop stunt went fatally wrong.
Responding to the report, the parents of victim Matthew Grimstone said the Civil Aviation Authority and the airshow organisers "have got much to answer for".
An aviation lawyer representing some of the victims said the crash was "a disaster waiting to happen and one that could have been avoided".
The report found Mr Hill, who survived the crash, had breached flying rules in the same aircraft at the previous year's airshow, travelling over a restricted area though he was not told to stop by the flight director.
Investigators also found the 1955 Hawker Hunter plane did not meet the requirements to fly.
Other key findings from the Air Accidents Investigation Branch (AAIB) report include:
- In the fatal 2015 flight Mr Hill failed to abandon the loop-the-loop stunt as he may have misinterpreted the speed and height required as the levels needed for a lighter aircraft.
- Mr Hill did not use full thrust into the manoeuvre so was travelling 40 knots too slow which meant he could only reach a height of 2700ft when 3500ft was required to pull off the stunt.
- Whether the Hawker Hunter plane lost thrust due to a technical issue could not be ruled out.
- Mr Hill could have still aborted the manoeuvre despite not being high enough or fast enough at the top of the manoeuvre.
- Mr Hill either did not think he needed an escape manoeuvre or did not know he could at the speed he was travelling, being unaware of the minimum speed required to abort it.
- The AAIB found Mr Hill had not practised or been trained in escape manoeuvres in the Hunter jet, while there was no details on them in the 1950s Hunter's vintage manual.
- The G-force on Mr Hill's body was not a factor in the accident while investigators confirmed he remained conscious and the aircraft responded to his controls during the whole flight.
- Mr Hill did not activate the ejector seat however the seat was activated due to damage to the cockpit upon crashing.
- Mr Hill confirmed in interviews related to an RAF Provost jet that he knew a safety manoeuvre must be used if the plane did not achieve the required safety height.
Mr Hill, from Sandon, Hertfordshire, is being investigated by Sussex Police for possible manslaughter.
Officers hope to submit a file of material to the Crown Prosecution Service before the next pre-inquest review on June 20.
Mr Hill was interviewed seven times by AAIB investigators but because of restrictions advised by his doctors they were not able to question him about his conduct during the flight.
Safety regulations at UK air show have already been tightened as a result of the 2015 disaster.
The chair of the Civil Aviation Authority, Dame Deirdre Hutton, said the CAA will "action as a priority" 10 safety recommendations contained in the final AAIB report, in addition to 21 previous recommendations she said "all of which we have acted on".
"We are fully committed to ensuring that all air shows take place safely, for the six million people who attend them each year in the UK and for the communities in which they take place," she said.
Organisers of the Shoreham airshow it is unlikely they will stage "the same or similar style event" in the future.
Colin Baker, one of the Shoreham air show directors, said "organisers always worked hard to ensure the event was both safe and successful" but said the findings in the report will require "further analysis and reflection".
The final report by the Air Accidents Investigation Branch (AAIB) sought to find how the disaster happened, what went wrong, and what safety measures could be brought in to protect future lives.
An earlier AAIB report had already found:
- The jet's ejection seat parts were in a "damaged condition"
- The seat cartridges - which had expired in 2014 - "posed a significant hazard" to emergency service crews
- Technical support for the jet ended once it was retired from military service
- A technical manual - written in the 1950s - had not been updated
- It was unclear whether the jet had a valid certificate allowing it to be flown