[1] The official primary cause for the accident was a gross structural failure of the aircraft's main spar, which was confirmed by amateur footage, photographs and eyewitness accounts.

The reason for the failure was not determined by the Board of Inquiry (BoI), but it was suggested by an accident investigator called in by Rolls-Royce[4] that the main cause was that the pilot, upon performing the planned aerobatic display, exceeded the prototype's briefed speed and turning rate limits.

[6] The Technical Officer of the Board of Inquiry identified a suspected fatigue failure of the inboard arm of the front bottom wing attachment main forging, and suggested vibration from the high airflow volumes required by the RR Conway 11 engines as a possible cause.

[7] The Royal Aircraft Establishment carried out a structural analysis of the wreckage and produced a report on 21 April 1960,[8] but no copy has been found in the public record.

Avro reportedly inspected for damage using an exceptionally small technician after each aerobatic flight, Rolls may not have been aware of this practice.