Accident Details
An air ambulance departed Steamboat Springs, Colorado, to pick up a patient in serious condition from Rawlins Municipal Airport/Harvey Field and transport them to Casper, Wyoming. While maneuvering for the final approach course of the VOR/GPS approach to runway 22, the pilot initiated a right turn outbound before turning inbound. On the inbound course, the airplane impacted mountainous terrain approximately 2.5 nautical miles east-northeast of the airport. The aircraft was configured for landing and struck the terrain wings level in a 45-degree nose-down dive, consistent with impact following an aerodynamic stall.
Weather Conditions
Approximately five minutes before the accident, Rawlins Municipal Airport reported broken ceilings at 1,100 and 1,800 feet above ground level, overcast at 3,100 feet, visibility 2.5 statute miles with light snow and mist, temperature 33 degrees Fahrenheit, dew point 30 degrees Fahrenheit, winds from 240 degrees at 3 knots, and altimeter 29.35 inches of mercury. The pilot received a weather briefing from Denver Flight Service before departure. The briefer indicated a band of light to moderate snow shower activity between Rock Springs and Rawlins, spreading northeast, and mentioned adverse conditions and flight precautions for occasional mountain or terrain obscurations. The pilot stated he planned to fly under instrument flight rules for the entire flight. The National Weather Service surface analysis showed a stationary front along the Rocky Mountains. An AIRMET advised occasional moderate rime or mixed icing in clouds and precipitation between the freezing level and flight level 220, with the freezing level at the surface. Witnesses near Rawlins reported surface weather conditions varying from freezing rain to heavy snow.
Aircraft Examination
An examination of the airplane revealed clear ice up to 1.5 inches thick adhering to the vertical stabilizer, left and right wings, right main landing gear tire, and right propeller. The ice contamination degraded the airplane's aerodynamic performance, leading to a stall. No anomalies were found in the airplane's systems.
Human Factors and Operational Considerations
A review of interviews and other materials found insufficient evidence that the company placed pressure on the pilot to take the flight; however, the review did not rule out the possibility of self-induced pressure. FAA Advisory Circular 135-15, Emergency Medical Services/Airplane, addresses subjects not practiced by the operator, including the recommendation to avoid flight in icing weather whenever possible.