NTSB Identification: SEA06LA138.
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Accident occurred Monday, July 10, 2006 in Hamilton, MT
Probable Cause Approval Date: 02/28/2008
Aircraft: Cessna Citation 560, registration: N50CV
Injuries: 2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot reported that while he was executing a visual flight rules extended straight-in approach to a full-stop landing, he encountered 10 knot wind fluctuations. He therefore decided to increase his approach speed by 10 knots. In addition to the increased airspeed, the pilot flew a flatter than normal approach descent angle. Due to the increased airspeed and the flatter approach, the airplane floated longer than normal after the initiation of the landing flare. Instead of executing a go-around after it became obvious that the airplane would not settle to the runway near the normal touchdown point, the pilot elected to continue the landing sequence. Once the airplane touched down, the pilot was unable to get it stopped in the remaining runway, and it departed the end of the runway and experienced a nose gear collapse after encountering rough/uneven, swampy terrain. The expected landing distance for the airplane was calculated based upon the Vref plus ten airspeed of 108 knots, a landing gross weight of 11,000 pounds, and the reported ambient weather conditions. According to those extrapolated calculations, the landing distance would have been expected to be about 3,100 feet. This distance does not include the use of thrust reversers, as the Model 560 landing performance charts for dry hard surface runways do not take into consideration use of the thrust reversers. The performance section of the Model 560 FAA-Approved flight manual stated that the landing is to be proceeded by, "...a steady three degree angle approach down to the 50-foot height point with airspeed at Vref in the landing configuration." According to Cessna Aircraft, maintaining a flatter approach, or an airspeed above designated Vref, will extend the landing distance beyond what is published in the performance tables. Review of the archived aviation surface weather observations (METAR) for Ravalli County Airport revealed that the winds measured at 1053, eight minutes after the accident, were from 150 degrees at five knots. The wind observations recorded at 0953 indicated calm winds, and the recorded winds at 0853 were 220 degrees at four knots.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's failure to attain the proper touchdown point and to execute a go-around, which lead to an overrun of the runway surface. Contributing to the accident was his failure to maintain the correct landing approach speed (Vref), his failure to maintain the correct glide path, and the swampy and rough/uneven terrain the airplane encountered after departing the end of the runway. Full narrative available
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