The Shoreham air disaster was caused by the pilot failing to achieve sufficient height during a loop manoeuvre, accident investigators have concluded.
Eleven people were killed on August 22, 2015, when Andrew Hill, 52, crashed a vintage jet onto the A27 in West Sussex during an air show.
The speed that the 1955 Hawker Hunter entered the manoeuvre was too low and it failed to use maximum thrust, the final report by the Air Accidents Investigation Branch (AAIB) found.
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 Mr Hill either did not perceive it was necessary or did not realise it was possible, the AAIB said.
The pilot had not received formal training to escape the manoeuvre and had not had his competence to do so assessed, the report found.
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, AAIB principal inspector Julian Firth said.
He added that it was possible “the pilot recalled the wrong numbers, essentially mixing up the two aircraft.”
The severity of the outcome was found to be due to the “absence of provisions” to mitigate the effects of an aircraft crashing in an area outside the control of the air show organisers.
Mr Hill, from Sandon, Hertfordshire, survived the crash but suffered serious injuries. He is being investigated by Sussex Police for possible manslaughter.
He was interviewed on seven occasions by AAIB investigators but because of restrictions advised by his doctors they were not able to question him about his conduct during the flight, the AAIB said.
Mr Hill did not recall events between the evening of August 19 and regaining consciousness in hospital after the accident.
He was therefore able to describe his normal practice but not the events on the day of the crash.
The pilot was attempting a bent loop, in which the aircraft pitched up into a loop and then rolls before leaving the manoeuvre in a different direction to its entry.
His display authorisation permitted him to carry out 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 Mr Hill flew at just 185ft at a speed of just 310 knots, reaching 2,700ft at the top of the loop.
Cockpit footage during the flight showed Mr Hill “alert and active”, with no suggestion he had passed out, investigators said.
AAIB Julian Firth said: “The aircraft crashed because at the top of its aerobatic manoeuvre it was too low to complete it.
“The reason that the results of this crash were so disastrous is because measures to protect the public were not effective.”
A number of safety recommendations were made by the AAIB to the Civil Aviation Authority over improving air show safety.
These include reviewing arrangements for the regulation of ex-military aircraft.