An experienced amateur pilot nosedived his friend's aircraft into the ground following a mid-air mix-up over the controls, according to an official report.
The 49-year-old man "inadvertently" confused the joystick for the throttle, and vice versa, causing him to direct the aircraft downwards as he circled above a Co Longford airstrip.
The mix-up arose because in his own microlight aircraft the throttle was controlled by the left-hand, and the joystick - or control column - by the right, while the reverse applied in his friend's Savannah ultralight.
Both the pilot and the aircraft's 48-year-old owner, who was sitting in the left-hand cockpit seat, were seriously injured in the crash.
Both suffered broken bones and facial injuries, and the owner reported experiencing amnesia as a result of the sudden impact.
The Air Accident Investigation Unit, which inquired into the crash at Granard Airfield last April, said: "One way to familiarise oneself on the idiosyncrasies of different cockpit types, and indeed different aircraft types, is to carry out differences training with a qualified instructor. Had this been done in this particular case, it is likely that this accident would not have occurred."
The report noted that the owner of the aircraft had more than 100 hours' flying experience. The pilot had 600 hours but had only once before flown that particular microlight.
In an interview with the investigators, the pilot admitted to his mistake, describing his reaction at the controls as "instinctive". The report said impact was inevitable after the mix-up.
The report further noted that both men were flying under UK private pilot licences. Neither of them had sought permission to validate these in Ireland. The investigators said this was a matter for the respective licensing authorities.
