AAIB investigation to PIper PA-24-250 Comanche, N673SA
Runway excursion, Firs Farm Airfield, Newbury, Berkshire, 19 May 2017.
Summary:
The aircraft made an approach to a grass airfield during a heavy shower of rain. The approach speed was high and the pilot touched down with approximately 400 m of runway remaining. Aircraft performance tables give a corrected landing distance for a wet grass surface of 309 m. This figure is based on ‘short field technique’ which assumes the application of maximum braking. In this case the pilot braked hard but encountered wheel locking and was forced to reduce brake pressure to prevent a skid. The landing distance required would therefore have been significantly increased. Without short field technique applied the manufacturers documents indicate that landing distance might be doubled. At the end of the runway the prospective overrun had been planted with crops and so the pilot attempted a turn with higher than normal speed. During the turn the aircraft skidded and slid off the operating surface into the crops. The left hand undercarriage leg collapsed but both those on board exited the aircraft without injury. The pilot reported that, given the high speed and the incorrect touchdown point, he should have executed a go-around. CAA Safety Sense Leaflet 7c contains very useful information for GA performance planning.
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