The organisers of the Shoreham Airshow, where 11 people were killed, did not know the intended routine of the pilot whose Hawker Hunter jet crashed on to a road, accident investigators have said.
A special bulletin published by the Air Accidents Investigation Branch (AAIB) stated that it was not possible to identify potential hazards before the event on August 22 last year without being aware of where the pilot would fly.
The show's risk assessment did not "show the range of hazards presented by different display aircraft", according to the report.
A review of the documents commissioned by the AAIB found "a number of deficiencies compared to what would have been expected".
It was not clear that the people who conducted the work "had a full understanding" of its purpose.
Shoreham's flying display director (FDD) presented risk assessments to the Civil Aviation Authority (CAA) to seek permission for two displays following the disaster that "were not materially different from that for Shoreham", the AAIB said.
Investigators issued a recommendation calling for the CAA to "specify the safety management and other competencies" that flying show organisers must demonstrate.
The AAIB special bulletin found that during the 2014 Shoreham show, the Hawker Hunter carried out the majority of its aerobatic manoeuvres over public areas away from the airfield.
Event organisers did not instruct the pilot to stop the display as the "regulatory infringements" were either not detected or understood.
The report also stated that officials were aware that several hundred people had gathered in the area next to the A27 in West Sussex where the plane crashed to watch the display in previous years.
Signs and stewards were deployed to ask people to move on, but neither the organisers nor the police had requested the legal power to prevent them from being there for the show on August 22 last year, the AAIB said.
This year's event has been cancelled out of respect for those affected by the tragedy.
The pilot, Andrew Hill, 51, from Hertfordshire, was voluntarily interviewed under caution by police in connection with the accident.
He was thrown clear from the 1955 fighter-bomber and suffered life-threatening injuries but was discharged from hospital in September.
Steps taken in the immediate aftermath of the disaster - such as banning ex-military jets from performing aerobatics over land - remain in place until the publication of a full air accident report into what caused the crash.
The CAA has warned that a number of air shows will not go ahead this year unless they adopt new safety measures.
The tightened rules include enhanced risk assessments and tougher checks on the experience, skill and health of pilots.
The regulator is also increasing its charges for air show organisers to fund the move, with larger displays facing a potential rise from £2,695 to more than £20,000.
CAA chief executive Andrew Haines said: "We understand that people care passionately about air shows and we want all events to be a success, but we are also very clear that we will not compromise on safety."
Supporters of air shows have urged the CAA to mitigate the impact of the new charges.