Swiss crash investigators have found pilot error to have been the cause of the January 2005 fatal accident involving one of two prototypes of the Pilatus PC-21 aerobatic trainer.

On 13 January 2005, two Pilatus test pilots were practising an aerobatic display of the two PC-21 prototypes, one black (HB-HZA) one silver (HB-HZB) for exhibition at air shows and had taken off in formation at 16:33 from Buochs air field at Pilatus's facility in Stans, 12km (8miles) southeast of Lucerne. After take-off, both aircraft climbed to approximately 5,000ft (1,500m) before performing a series of aerobatic manoeuvres and low passes over the runway. During a shallow dive HB-HZB clipped the ground with its wing resulting in a crash with the ground at 300kt (555km/h), destroying the aircraft (pictured below).

PC-21 crash tail

The dossier produced by the Swiss aircraft accident investigation bureau BFU-CH, released to the public this week, concludes that the likely cause of the accident is pilot error. Specifically that the pilot "was very probably concentrating on the closing manoeuvre with the other aircraft and in the process, he did not pay attention to his height above the terrain.".

The report continues that the following factors may have contributed to the accident:
• The impairment of the vision of the pilot involved in the accident.
• The pressure of time and the multiple tasks imposed on the pilot.
• The difficulty of the manoeuvre which was being flown.
• The low level of training in formation flying.
• Non-compliance with the agreed altitudes and separations.

External link:
Read the official investigation report (No. u1909) by the Swiss aircraft accident investigation bureau concerning the accident of a Pilatus PC-21 (HB-HZB) on 13 January 2005 at Buochs aerodrome, Switzerland.