NTSB Factual Report

On May 30, 2002, at 1715 mountain daylight time, a Cessna 170B, N4559C, piloted by a private pilot, sustained substantial damage during takeoff on runway 21 (5,223 feet by 75 feet, dry asphalt) at the Rock Springs/Sweetwater County Airport (RKS), Rock Springs, Wyoming, when the airplane departed the runway and impacted into a drainage ditch. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 CFR Part 91 without a flight plan. The pilot and two passengers on board the airplane reported no injuries. The local flight was originating at the time of the accident.

In his written statement, the pilot said that during takeoff roll, the winds swung from the west becoming a right crosswind. "Holding the right wing down, I felt I would be better off airborne, so [I] lifted the airplane off. [The] wind pushed me left of [the] runway. I kept trying to force [the] airplane to fly, but didn't have enough airspeed." The pilot said that he turned slightly left toward lower ground in an attempt to gain airspeed. The pilot said, "From [an] estimated height of 20-30 feet, [the] stall warning horn began blaring, airplane mushed into [the ground] - no breakover from stall."

The airport manager at RKS said the airplane came to rest in a drainage ditch approximately 1,000 feet southwest of the runway. An examination of the airplane revealed the airplane's cowling and firewall were crushed aft. The windscreen was broken out. The right cabin door was broken out. The right main landing gear was broken aft. The left wing, outboard of the strut, was twisted aft and bent upward. The left wing tip was broken aft longitudinally. The right wing was broken aft and downward at the wing root. The right wing tip was broken aft longitudinally. The empennage was twisted just forward of the horizontal stabilizer. The outer 8 inches of one propeller blade was broken off. The other propeller blade showed curling at the tip. Both blades showed torsional bending and chordwise scratches. Flight control continuity was confirmed. An examination of the engine, engine controls, and other airplane systems showed no anomalies.

At 1654, the Aviation Routine Weather Report (METAR) at RKS was clear skies, visibility 10 statute miles, temperature 82 degrees Fahrenheit (F), dew point 29 degrees F, winds 290 degrees at 13 knots with gusts to 24 knots, and an altimeter of 30.08 inches of Mercury.

At 1754, RKS METAR reported the winds as 270 degrees at 17 knots with gusts to 22 knots.

NTSB Probable Cause

the pilot's failure to maintain aircraft control during initial takeoff climb. A contributing factor was the gusty crosswind.