UK Air Accidents Investigation Branch (AAIB) has identified pilot error as the cause for the deadly crash of the Hawker Hunter aircraft on 22 August 2015 while maneuvering for the Shoreham Air Show.
The aircraft was carrying out a manoeuvre involving both a pitching and rolling component, which commenced from a height lower than the pilot’s authorised minimum for aerobatics, at an airspeed below his stated minimum, and proceeded with less than maximum thrust.
This resulted in the aircraft achieving a height at the top of the manoeuvre less than the minimum required to complete it safely, at a speed that was slower than normal.
Although it was possible to abort the manoeuvre safely at this point, it appeared the pilot did not recognise that the aircraft was too low to complete the downward half of the manoeuvre. An analysis of human performance identified several credible explanations for this, including: not reading the altimeter due to workload, distraction or visual limitations such as contrast or glare; misreading the altimeter due to its presentation of height information; or incorrectly recalling the minimum height required at the apex.
Training and assessment procedures in place at the time of the accident did not prepare the pilot fully for the conduct of relevant escape manoeuvres in the Hunter.
The manoeuvre was continued and the aircraft struck the ground on the northern side of the westbound carriageway of the A27 close to the central reservation with a ground track at a slight angle to the direction of the road.
When it struck the ground it broke into four main sections. Fuel and fuel vapour released from the fuel tanks ignited. In its path were vehicles that were stationary at, or in the vicinity of, the traffic lights at the junction with the Old Shoreham Road, and pedestrians standing by the junction.
The pilot did not attempt to jettison the aircraft’s canopy or activate his ejection seat. However, disruption of the aircraft due to the impact activated the canopy jettison process and caused the ejection seat firing mechanism to initiate.
The seat firing sequence was not completed due to damage sustained by its firing mechanism during the impact. The seat was released from the aircraft and the pilot was released from the seat as a result of partial operation of the sequencing mechanism. Some of the pyrotechnic cartridges remained live and were a hazard to first responders until they were made safe.
The investigation found that the aircraft appeared to be operating normally and responding to pilot control inputs until it impacted the ground. Defects in the altimeter system would have resulted in the height indicated to the pilot being lower than the actual aircraft height at the apex of the manoeuvre.
The investigation identified the following causal factors in the accident:
- The aircraft did not achieve sufficient height at the apex of the accident manoeuvre to complete it before impacting the ground because the combination of low entry speed and low engine thrust in the upward half of the manoeuvre was insufficient.
- An escape manoeuvre was not carried out, despite the aircraft not achieving the required minimum apex height.
First flown in 1955, the Ex-Royal Airforce fighter aircraft registered G-BXFI crash fatally injured eleven road users and bystanders. A further 13 people, including the pilot, sustained other injuries.
Read the detailed report here.
Source: AAIB UK