Flight History
On 23 September 2005, a Piper PA-28R-180 Cherokee Arrow, registration G-OKAG, departed Stapleford Aerodrome near London for a private flight to Llandegla Airfield near Ruthin, Wales. The weather forecast indicated surface winds from 240° at 8 knots becoming northerly, with CAVOK conditions but occasional showers reducing visibility to 7,000 meters and cloudbase to 1,000 feet. The pilot flew at altitudes between 2,000 and 3,000 feet. Approximately 10 nautical miles from Llandegla, weather at the destination deteriorated, prompting the pilot to divert to the private airfield at Chirk.
Landing and Overrun
The pilot had contacted both Llandegla and Chirk airfields earlier to confirm availability and special instructions. At Chirk, the pilot performed an overhead join and an orbit to familiarize himself with the airfield, which he had not used before. The windsock indicated a surface wind of 230°/10 knots. After one circuit with full flaps, he conducted a go-around. On the second approach, with full flaps and an approach speed of 75 mph, the aircraft touched down within the first 60 meters of Runway 19, which was 500 meters long, 20 meters wide, with a grass surface and an uphill slope. When wheel brakes were applied, the aircraft skidded on the grass but remained directionally controllable. The pilot pumped the brake pedals, and with the upslope, the aircraft slowed but insufficient runway remained. Realizing a slow overrun was inevitable, he steered toward a wire fence to the right of a Portacabin, aiming for the least solid obstruction. Just before impact, he began isolating electrical services. The propeller and left wing struck the Portacabin, and as the aircraft slewed left, the right wing hit a fence post. The pilot and passenger were uninjured and vacated the aircraft through the normal exit after emergency shutdown.
Post-Accident Observations
After the accident, the pilot noticed that smoke from an industrial chimney adjacent to the airfield indicated a surface wind direction of about 270°. He was informed that local geography causes frequent wind direction variations at height. During a later visit, he observed the windsock showing a westerly direction while chimney smoke indicated a northerly wind.
Analysis
The pilot had obtained relevant information before departure and prudently diverted when destination weather worsened. Runway 19 length was 500 meters on long, wet grass with an ill-defined uphill slope. Variable wind may have resulted in little headwind component. The landing distance required for the aircraft weight and conditions was 340 meters based on a normal landing from 50 feet. According to CAA Safety Sense leaflet 7C, landing on long, wet grass on firm soil may require a 35% increase in landing distance, while very short, wet grass may require up to a 60% increase. Thus, the actual landing distance needed could have been between 459 and 544 meters, marginal for the available runway. The pilot was unable to stop the aircraft before the end.
Conclusions
While the pilot ensured he was fully apprised of relevant information for his destination and alternate airfields, the runway length for the surface conditions was marginal, and he was unable to stop the aircraft before the end of the runway.