Flagstaff, AZ, USA
N228BH
Beech C-99
The airplane veered off the runway and impacted a runway distance sign during the landing. The airplane was on final approach to the destination airport when the pilot extended the flaps and lost control of the airplane. The airplane slowed and drifted to the left. The pilot added power for a go-around; however, the airplane touched down to the left of the runway centerline approximately 1,000 feet from the approach end of the runway. The pilot reduced engine power, but the airplane continued to the left, exiting the runway surface where it impacted a runway distance marker. The airport manager observed a "moderate amount of rime ice" on the wing leading edges, propeller spinners, and airplane radome immediately after the accident. According to the pilot, the ice was approximately 1/8 inch in thickness. The pilot also reported no mechanical anomalies with the airplane. The FAA's advisory circular regarding icing indicates that even a small amount of ice on the leading edge of the wing can reduce the stall angle of attack and increase stall speed.
On November 29, 2001, at 0746 mountain standard time, a Beech C-99, N228BH, operated by Ameriflight, Inc., as flight 1862, veered off the runway and impacted a runway distance sign following a loss of control on approach to Flagstaff Pulliam Airport, Flagstaff, Arizona. The flight was operating under the provisions of 14 CFR Part 135 as a nonscheduled cargo operation. The commercial pilot, the sole occupant, was not injured; the airplane sustained substantial damage. Visual meteorological conditions prevailed, and an instrument flight plan had been filed. The flight originated from Phoenix, Arizona, at 0700, with a planned destination of Flagstaff. According to a statement provided by Ameriflight's Director of Operations (DO), the pilot conducted a visual approach to runway 21. While passing through 200 feet agl, he extended the flaps from 30 percent to 100 percent. The pilot felt as though the airplane was "getting slow and drifting uncontrollably to the left." The pilot applied power for a go-around, but the airplane touched down on the runway approximately 1,000 feet from the approach end. At the point of touchdown, the pilot reduced power, and the airplane swerved to the left. The airplane departed the runway, impacted a runway distance sign, and came to rest in the dirt approximately 3,000 feet from the approach end of the runway. According to the air traffic controller who cleared the airplane for landing, the pilot reported that he was on a "high left downwind." The controller issued the wind conditions to the pilot along with a landing clearance. He then observed the airplane touchdown with all three wheels on the runway, slightly to the left of centerline. The controller looked away momentarily to coordinate with another facility. When he looked at the airplane again, it had veered to the left, striking the 5,000-foot remaining marker. The airplane came to a stop approximately 50 feet left of the runway edge-line (200 feet from the runway centerline). The runway was 6,999 feet long and 150 feet wide, and is at an elevation of 7,011 feet mean seal level. The weather observation facility located at the airport reported that the wind was from 230 degrees at 6 knots; visibility was 10 statute miles; clouds were broken at 3,700 feet and 4,600 feet above ground level (agl) and overcast at 6,000 feet agl; temperature was -3 degrees Celsius; dew point was -11 degrees Celsius; and the altimeter setting was 29.94 inches of mercury. The airport manager reported observing a "moderate amount of rime ice" on the wing leading edges, propeller spinners, and airplane radome immediately after the accident. According to the pilot, the ice was approximately 1/8 inch in thickness. The pilot reported to the DO that he did not believe that there were any mechanical problems with the airplane, nor did he believe that the icing contributed to the loss of control. The commercial pilot had accumulated a total of 2,546 hours of flight time, of which 669 hours were in multiengine airplanes, and 158 hours were in the same make and model as the accident airplane. According to the Federal Aviation Administration Advisory Circular 91-74: Pilot Guide to Flight in Icing Conditions, "at very low angles of attack, there may be little or no effect of the ice on the coefficient of lift. Thus, when cruising at a low angle of attack (AOA), ice on the wing may have little effect on lift. However, note that the maximum coefficient of lift is significantly reduced by the ice, and the AOA at which it occurs (the stall angle) is much lower. Thus when slowing down and increasing the AOA for approach, the pilot may find that ice on the wing which had little effect on the lift in cruise now causes stall to occur at a lower AOA and higher speed. Even a thin layer of ice at the leading edge of a wing, especially if it is rough, can have a significant effect in increasing stall speed."
The pilot's failure to maintain adequate airspeed and his failure to maintain directional control. Contributing factors were the icing conditions, icing, and the improper use of the anti-ice/deicing equipment.
Source: NTSB Aviation Accident Database
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