KENAI, AK, USA
N95031
Cessna 152
The solo student pilot, on her first cross-country flight, was departing on runway 19R. Just after rotation, the airplane veered to the left, and went off the left side of the 7,575 feet long by 150 foot wide runway. The airplane came to rest in a ditch that borders the runway, and sustained substantial damage to the wings and fuselage. The pilot stated that prior to her being cleared for takeoff, a DeHavilland DHC-8 departed from the opposite direction on the same runway. She said that about 2 minutes elapsed between the larger aircraft's departure, and her departure. The Air Traffic Controller's Manual (FAA order 7110.65M) relating to wake turbulence application, states that a 3-minute interval be observed between departures of large and small aircraft, and the issuance of a wake turbulence advisory before clearing the aircraft for takeoff. The manual identifies a DeHavilland DHC-8 as a large turboprop aircraft, and a Cessna 152 as a small aircraft. Review of air-ground radio communications tapes revealed that the total time separation between the two departures was 1 minute, 49 seconds, with no issuance of a wake turbulence advisory.
On August 3, 1999, about 1519 Alaska daylight time, a wheel equipped Cessna 152 airplane, N95031, sustained substantial damage during takeoff from the Kenai Municipal Airport, Kenai, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country instructional flight when the accident occurred. The airplane was registered to the U.S. Air Force, and operated by the Elmendorf Air Force Base (AFB) Aero Club, Anchorage, Alaska. The solo student pilot was not injured. Visual meteorological conditions prevailed, and a VFR flight plan was filed. The flight originated at Elmendorf AFB, about 1410. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge on August 3, the pilot reported that she rented the airplane from the Elmendorf AFB Aero Club. She added that the purpose of the flight was to conduct her first solo cross-country flight between Anchorage, Kenai, and Homer, Alaska, and return to Anchorage. She said that while departing from the Kenai Municipal Airport, using runway 19R, the airplane encountered a left crosswind which caused it to veer to the left. She said that the airplane continued to veer to the left, and went off the left side of the 7,575 feet long by 150 feet wide runway. The airplane came to rest in a ditch that borders the runway, and sustained substantial damage to the wings and fuselage. In the Pilot/Operator report (NTSB form 6120.1/2) filed by the operator, the pilot supplied a statement about the accident. The pilot said that she taxied to the end of runway 19R, and informed the tower operator that she was ready for takeoff, and that she would wait for a DeHavilland DHC-8 that would be departing on the opposite direction runway 01L. She said that she watched where the DeHavilland DHC-8 became airborne, and watched the progress as it passed over her airplane. She said after about two minutes, the tower operator cleared her for takeoff. She taxied onto runway 19R, and started her takeoff roll. She wrote: "Noting 50 knots indicated airspeed, I rotated the nose up to the horizon. Very shortly thereafter it felt as if the aircraft lifted slightly in the air, as if there was a bubble I was trying to get over. The aircraft returned to the runway with the left wing positioned downward, and immediately the aircraft developed a strong left turn." Review of air-ground radio communications tapes maintained by the FAA at the Kenai air traffic control tower (ATCT), revealed that at 1514:31, the tower operator cleared the departing DeHavilland DHC-8 for departure on runway 01L. At 1516:20, the controller cleared the accident airplane for departure on runway 19R. The total time separation between the two departures was 1 minute, 49 seconds. No wake turbulence advisory was issued to the accident airplane's pilot before the airplane was cleared for takeoff. A transcript of the air-ground radio communications between the pilot, and Kenai ATCT local control, is included in this report. The Air Traffic Controller's Manual (FAA order 7110.65M), page 3-9-4, wake turbulence application, sub paragraph i, states: "Separate a small aircraft behind a large aircraft taking off or making a low/missed approach utilizing opposite direction takeoffs on the same runway by 3 minutes unless a pilot has initiated a request to deviate from the 3-minute interval. In the latter case, issue a wake turbulence advisory before clearing the aircraft for takeoff." The Air Traffic Controller's Manual (FAA order 7110.65M), page A-8, appendix A, identifies a DeHavilland DHC-8 as a large turboprop aircraft, and a Cessna 152 as a small aircraft. The Aeronautical Information Manual (AIM) refers to wake turbulence as: "A phenomena resulting from the passage of an aircraft through the atmosphere. The term includes vortices, thrust stream turbulence, jet blast, jet wash, propeller wash, and rotor wash both on the ground and in the air." The pilot reported that wind conditions at the time of the accident were from 180 degrees at 7 knots.
The loss of control due to wake turbulence, and the issuance of an improper takeoff clearance by air traffic control personnel. A factor associated with the accident was air traffic control personnel's failure to issue a safety advisory.
Source: NTSB Aviation Accident Database
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