SEA98LA132
SEA98LA132

On July 12, 1998, approximately 1130 mountain daylight time, a Grumman-American AA-5B, N28299, registered to Catherine Haas, and being operated/flown by a private pilot, was substantially damaged when the aircraft collided with terrain following an impact with a fence post shortly after takeoff at Chico Hot Springs, Montana. The pilot and two passengers sustained no injuries while the remaining passenger sustained minor injuries. Visual meteorological conditions prevailed and no flight plan had been filed. The flight, which was personal, was to have been operated under 14CFR91, and was destined for Gallatin Field, Bozeman, Montana, located approximately 35 nautical miles northwest.

The pilot reported that with an air temperature of 75 to 80 degrees Fahrenheit and a wind of 15 to 20 knots down the runway these conditions "favored a takeoff to the south." After back-taxiing to the departure end of the runway, a paved highway (refer to DIAGRAM I and ATTACHMENT I), he completed a run-up, adjusted the mixture and began his takeoff to the south.

The pilot reported that he lifted off at 70 knots indicated airspeed and then executed a climbing left crosswind turn during which he "felt some light turbulence and the indicated airspeed dropped about 20 knots." The stall warning horn activated and the pilot "lower(ed) the nose a little and reduce(d) the turn rate to follow descending terrain. However, the stall horn continued to sound intermittently and the airspeed did not come up." The aircraft's left wing outboard leading edge (refer to photograph 1) then impacted a fence post. The aircraft then impacted terrain and slid to a stop (refer to photograph 2).

The hotel operations manager, who was responsible for insuring the roadway serving as runway 14/32 was properly blocked off and manned prior to aircraft use, provided a statement regarding his involvement in the pre-departure events of the accident. He reported speaking with the pilot "about taking off into the wind rather than with the wind." The pilot stated "that he wanted to taxi to the north end of the runway and then take-off towards Chico." The manager explained that "this was not normally allowed" but he would allow it if that was what the pilot wished. The manager also informed the pilot about "the tricky cross winds coming across the runway, and the obvious mountain at the end of the runway" (refer to ATTACHMENT S-I).

The takeoff on the road provides approximately 4,400 feet of straight, paved surface available and, when executed to the south provides an uphill gradient towards rapidly upsloping terrain (refer to DIAGRAM I). Additionally, the Montana Airport Directory (1994) provides a graphic overview of the airstrip including a length of 6,000 feet, a width of 35 feet, and remarks "Land to South. Takeoff to North." (Refer to ATTACHMENT I).

Meteorological conditions reported for Livingston, Montana, 23 nautical miles north, at 1154 MDT were as follows:

Surface temperature: 81 deg F. Wind Direction: 210 deg mag. Wind Speed: 21 knots Wind gusts: 28 knots Altimeter: 30.05 inches mercury Livingston elevation: 4,656 feet above sea level

The calculated density altitude at Livingston under these conditions was 7,014 feet. The estimated density altitude at the accident site (5,280 feet above sea level), based upon the same temperature and altimeter setting at Livingston, was 7,784 feet.

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