Accident Overview
On July 7, 2016, at approximately 1155 mountain daylight time, a Gulfstream American Corporation AA-5A aircraft, registration N26908, sustained substantial damage during a forced landing following a departure from Cheyenne Regional Airport/Jerry Olson Field (KCYS), Cheyenne, Wyoming. The flight, conducted under 14 Code of Federal Regulations Part 91 as an instructional flight, was en route to Eppley Airfield (KOMA), Omaha, Nebraska. Visual meteorological conditions prevailed, and a visual flight rules flight plan had been filed. Both the flight instructor and student pilot were uninjured.
Pilot Statements
The flight instructor reported that the takeoff was normal. However, at the departure end of the runway, between 300 and 400 feet above ground level, the wind began blowing from all directions, making control difficult. Unable to maintain altitude, the instructor elected to land the airplane on a road adjacent to a school. During the landing roll, he maneuvered to avoid striking construction workers ahead; the right wing contacted a construction sign, resulting in substantial damage. The instructor noted no mechanical issues with the aircraft or engine.
Weather Conditions
A weather study conducted by a National Transportation Safety Board meteorologist examined conditions. National Weather Service charts showed a low pressure system over southeast Wyoming and a mid-level trough just west of the accident site. Winds at the 700-hPa level were westerly around 10 knots, while at the 500-hPa level they increased to 60 knots. No AIRMETs, SIGMETs, or center weather advisories were valid for the accident location at the time. One pilot report in the area indicated moderate chop between 6,500 and 8,500 feet mean sea level. The terminal aerodrome forecast valid at the time predicted winds from 300 degrees at 12 knots, gusting to 20 knots.
Cheyenne Regional Airport, the closest official weather station (2 miles south-southeast of the accident site), reported at 1153 wind from 090 degrees at 9 knots with clear skies. A subsequent observation at 1208 recorded wind from 090 degrees at 7 knots. The nearest non-official surface observation site (5 miles west) reported at 1215 wind from 274 degrees with gusts to 19 knots. Weather radar depicted a dry-line boundary at the accident site at the time, which would have caused changes in wind speed and direction with altitude, corresponding to increased low-level turbulence and wind shear.
Weather Briefing
A review of official weather briefing sources indicated that the flight instructor contacted Lockheed Martin Flight Service at 0853 the morning of the accident and received an abbreviated briefing for the flight from Rock Springs, Wyoming, to Cheyenne, Wyoming. No record existed of the instructor receiving or retrieving any additional weather information before the accident flight.