Incident Overview
A pilot experienced an unexpected descent shortly after takeoff from an airport near Cheyenne, Wyoming. According to the pilot's account, the flight began with a normal takeoff and climb to approximately 250 feet above ground level at 70 knots indicated airspeed. At that point, the aircraft encountered moderate turbulence, and the climb rate leveled off. The pilot checked the altimeter and vertical speed indicator, which indicated a descent, despite the airspeed and attitude suggesting the aircraft should be climbing. The pilot was unable to stop the descent, and the aircraft settled into an open field.
Weather Conditions
Before the flight, the pilot obtained a weather briefing that informed him of an approaching thunderstorm located 10 miles northwest of the airport. The thunderstorm passed over Cheyenne at 1907 Mountain Daylight Time and was reported to be of Level 1 intensity. Weather observations at Cheyenne showed variable winds: at 1959 MDT, winds were from 340 degrees at 25 knots with gusts to 38 knots; by 2052 MDT, winds had shifted to 020 degrees at 8 knots. The airport elevation was 6156 feet.
Flight Details
The pilot reported that after the onset of moderate turbulence and the leveling off of the climb, the flight instruments showed conflicting information. While the attitude and airspeed indicators implied a climbing flight path, the altimeter and vertical speed indicator displayed a descent. Despite efforts to correct the situation, the descent continued until the aircraft made contact with the ground in an open field. No further details about the aircraft, its occupants, or damage were provided in the initial report.