Aviation Accident Summaries

Aviation Accident Summary CEN12LA441

Elkader, IA, USA

Aircraft #1

N1127X

PIPER PA-32-300

Analysis

The pilot reported that the airplane touched down on the first third of the wet grass runway, but the braking action was ineffective. He stated that because of the ineffective braking action and the short runway length, he applied full engine power to abort the landing. He reported that although the airplane initially cleared trees located off the departure end of the runway, it was inexplicably pushed down into the tree line. The airplane came to rest in a 100-foot deep wooded ravine located off the departure end of the runway. The pilot noted that there were no preaccident mechanical malfunctions or failures that would have precluded normal operation of the airplane. Based on the available weather radar data and witness observations, localized instrument flight rule conditions likely existed due to thunderstorms and heavy rain in the vicinity of the airport. An on-site investigation found tire marks on the grass runway consistent with the tire width of the accident airplane. The first of these tire marks was more than halfway down the 1,705-foot-long runway, about 741 feet from the departure end. These tire tracks continued past the departure threshold until a point where the terrain sloped away from the runway elevation, indicating that the airplane had not become airborne on the usable runway. The physical evidence was consistent with the airplane running off the end of the runway before descending into treetops that were at or below the runway elevation. Review of available performance data indicated that the expected landing distance for a wet grass runway would be in excess of 748 feet. The landing performance calculations established that there was sufficient runway available for a ground roll if the pilot had touched down within the first half of the runway.

Factual Information

On July 14, 2012, about 1021 central daylight time, a Piper model PA-32-300 airplane, N1127X, was substantially damaged while landing at the Elkader Airport (I27) near Elkader, Iowa. The private pilot sustained minor injuries. The passenger sustained serious injuries. The airplane was registered to and operated by Wild River Flying Club, LLC, under the provisions of 14 Code of Federal Regulations Part 91 without a flight plan. Day instrument meteorological conditions prevailed at the time of the accident. The personal flight originated from L.O. Simenstad Municipal Airport (KOEO), Osceola, Wisconsin, at 0910. The pilot reported that as the flight approached the intended destination he descended from 5,500 feet to 2,000 feet mean sea level in order to remain clear of clouds. The flight subsequently encountered light rain and reduced forward visibilities. The pilot eventually performed a 180-degree turn while he considered diverting to an alternate airport. He stated that during the turn he noticed that the weather had closed-in behind him; however, as he continued the turn he was able to establish visual contact with the intended destination because the clouds had moved past the airport. He overflew the airport before entering a left traffic pattern for runway 17 on the upwind leg. He stated that the airplane touched down within the first third of the runway with the wing flaps fully extended. The pilot reported that braking action was ineffective after touchdown due to the wet grass runway condition. Because of the ineffective braking action and the short runway length (1,705 feet), the pilot applied full engine power to abort the landing. He reported that although the airplane initially cleared trees located off the departure end of the runway, it was inexplicably pushed down into the tree line. (The treetops were at or below the runway elevation, due to sloping terrain located off the end of the runway.) The airplane came to rest in a 100-foot deep wooded ravine. The fuselage and both wings were substantially damaged during the accident. The pilot noted that there were no preimpact mechanical malfunctions or failures that would have precluded normal operation of the airplane. Witnesses located at the destination airport reported that the airplane first overflew the airport at approximately 1020, at which time there was heavy rain and lightning. A few minutes later the witnesses heard the airplane attempting to land on runway 17; however, they were subsequently unable to locate the airplane as they drove the length of the runway. Based on the available weather radar data and the witness observations, localized instrument flight rule (IFR) conditions existed due to the thunderstorms and heavy rain affecting the destination airport. The closest weather observing station was at Prairie du Chien Municipal Airport (KPDC), located about 15 miles northeast of the accident site. At 1035, the KPDC automated surface observing system reported the following weather conditions: wind 130 degrees at 7 knots; visibility 3 miles with light rain; scattered clouds at 1,100 feet above ground level (agl), a broken ceiling at 3,800 feet agl, and a overcast ceiling at 4,900 feet agl; temperature 20 degrees Celsius; dew point 20 degrees Celsius; altimeter setting 30.04 inches of mercury. An on-site investigation was completed by local law enforcement and inspectors with the Federal Aviation Administration. Their investigation revealed that there were visible tracks located on the grass runway that were consistent with the tire width of the accident airplane. According to photographs and direct measurements, the first visible tire marks were located about 741 feet from the departure end of runway 17. These tire tracks continued past the departure threshold until a point where the terrain sloped away from the runway elevation. A global positioning system (GPS) handheld device was found at the accident site. The plotted GPS data suggested that the airplane landed about halfway down the 1,705 foot long runway; however, the exact touchdown point could not be inferred from the track data. The GPS data indicated that the airplane's groundspeed was 46 knots and 45 knots when it was 638 feet and 180 feet from the departure threshold, respectively. These groundspeeds were not consistent with the airplane decelerating during a landing roll. The final GPS data point was located about 195 feet past the departure threshold. The pilot reported that the airplane's weight was 2,858 pounds at time of the accident. According to the Piper PA-32-300 Pilot's Operating Manual (POM), the stall speed is 50 knots with the wing flaps fully extended to 40-degrees. The landing ground roll for a paved, level, and dry surfaced runway with no headwind and using maximum braking is about 575 feet. The POM does not provide landing distances for grass or wet surfaces; however, Civil Aviation Authority research indicates that ground rolls increase 30-percent to 40-percent when landing on wet grass runways. Therefore, the expected landing roll distance on a level, wet grass runway without a headwind and using maximum braking would be between 748 feet and 805 feet.

Probable Cause and Findings

The pilot's failure to attain the proper touchdown point while landing on the wet grass runway.

 

Source: NTSB Aviation Accident Database

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