Two pilots were killed when their light aircraft went into a virtually uncontrollable spin during a flight by one of its new owners to familiarise himself with the plane, an investigation has found.
A report into the fatal crash by the Air Accident Investigation Unit (AAIU) found no mechanical or structural faults with the Bristell NG5 Spreadwing single-engine aircraft during an attempted stall recovery.
The two victims – Aidan Rowsome (58) from Kildare Town and Jim Price (70) from Ballinteer, Co. Dublin – suffered fatal injuries when the aircraft crashed near Belan, outside Athy, Co. Kildare, on June 13, 2019.
It had taken off earlier from an airfield in Kilrush, Co. Kildare, on a flight to familiarise Mr Rowsome with the aircraft. The aircraft had been bought by a syndicate and they asked Mr Price to help them familiarise them with the aircraft type.
There were no records to suggest Mr Rowsome had practised stalling in a Bristell NGF before the fatal flight. Two stall exercises were carried out during the flight from an altitude of around 3,300ft. However, the aircraft departed from a controlled flight during recovery from the second stall and started a rapid descent.
AAIU investigators said the plane entered a spiral dive before entering into a flat spin — where an aircraft rotates horizontally — before it hit the ground in a grass field approximately 5.2km south of Belan, Co. Kildare.
They estimated the aircraft was rolling at the rate of more than 180º per second during the flat spin and hit the ground at a speed of 82km/h. The two occupants were fatally injured while the aircraft was destroyed.
The AAIU report noted that recovery from a flat spin may be “extremely difficult and in some cases, impossible”. Other syndicate members told AAIU investigators that Mr Price had pointed out the importance of safe practices and carrying out thorough checks prior to stalling the aircraft.
They also said Mr Rowsome was very conservative in his handling of an aircraft and he was “somewhat cautious of even stalling an aircraft, but knew it was something he should become familiar with and that should be practised.”
The AAIU said there was nothing in the recorded data recovered from the aircraft which suggested unapproved manoeuvres were being deliberately performed. It said the manoeuvres performed after each stall indicated “an unexpected upset”.
It said it was possible that the pilots became disorientated during the spiral dive which may have compromised their ability to recover control of the flight. AAIU investigators concluded that vertical acceleration which peaked at over 5g force resulted in an excessive fuel-air mixture which caused the engine to stop.
Investigators also highlighted how the pilot’s operating handbook for the aircraft type contained incorrect information for determining its centre of gravity.
The AAIU said this meant the aircraft’s centre of gravity was outside published limits at the time of the accident which may have caused it to be more unstable.
It said this could have made the aircraft “more susceptible to entry into a flat spin and more difficult to recover from such a spin”. The report said a small change in the location of a pilot or passenger could have a significant effect on the aircraft’s centre of gravity.
It observed that Mr Rowsome had unsuccessfully attempted to restart the engine during the flat spin and remarked that he might have undone his safety harness in an attempt to alter the aircraft’s centre of gravity.
The AAIU, which analysed four other accidents where a Bristell NG5 had entered a spin prior to crashing, noted that the aircraft manufacturer had issued two amendments to its operating instructions in August 2020 which contained incorrect information.
The aircraft’s manufacturer told the AAIU that it had conducted test flights in July 2021 which showed the aircraft was controllable up to a stall and had no tendency to enter into a spin even after exceeding limits in relation to its centre of gravity.
The AAIU issued a total of 10 safety recommendations, most of which applied to the aircraft’s manufacturer, BRM Aero.