FORT YUKON, AK, USA
N5143E
CESSNA 180B
THE PILOT AND A PASSENGER WERE DEPARTING A REMOTE LAKE IN A FLOAT EQUIPPED AIRPLANE AS THE RETURN PORTION OF A CROSS-COUNTRY PERSONAL FLIGHT AT THE CONCLUSION OF A HUNTING TRIP. DURING THE TAKEOFF, THE PILOT REPORTED USING 10 DEGREES OF FLAPS THAT HE LOWERED TO 20 DEGREES WHEN THE AIRPLANE WOULD NOT BREAK FREE FROM THE WATER SURFACE. THE WATER CONDITIONS WERE SMOOTH AND GLASSY. WHEN THE AIRPLANE DID NOT ACCELERATE PROPERLY, THE PILOT ABORTED THE TAKEOFF; HOWEVER, THE AIRPLANE'S FORWARD MOMENTUM CARRIED THE AIRCRAFT INTO THE LAKE SHORELINE. THE FRONT PORTION OF THE FLOATS CONTACTED THE TERRAIN AND THE AIRPLANE NOSED OVER. THE AIRCRAFT OWNER'S MANUAL RECOMMENDS USING 20 DEGREES OF FLAPS THROUGHOUT THE TAKEOFF. ADDITIONALLY, UNDER HEAVY LOADS AND GLASSY WATER CONDITIONS, AN ABRUPT APPLICATION OF BACK CONTROL PRESSURE MAY BE NECESSARY TO BREAK FREE OF THE WATER SURFACE.
On September 2, 1994, at 1100 Alaska daylight time, a float equipped Cessna 180B airplane, N5143E, owned and operated by the pilot-in-command, collided with terrain during an aborted takeoff at a remote lake approximately 145 miles north of Fort Yukon, Alaska. The private certificated pilot and one passenger, the sole occupants, were not injured and the airplane sustained substantial damage. The flight last departed Fairbanks, Alaska on September 1, 1994 and the intended destination was the lake on which the accident occurred. According to the pilot, visual meteorological conditions prevailed and a VFR flight plan was established with personal acquaintances. During a telephone interview on the morning of September 6, 1994, the pilot told the NTSB investigator-in-charge that the plane was loaded with five quarters of Caribou weighing 35 pounds each and the wing tanks contained 55 gallons of fuel. The pilot said that the wind was calm and the lake surface was as smooth as glass. The takeoff was commenced from the opposite end of the lake near the shoreline using 10 degrees of flap. As the airspeed approached 53 knots, he added another 10 to 15 degrees of flap but the plane "stuck to the water". Fearing that he would not be able to clear the approaching terrain, he aborted the takeoff. The plane continued forward with the tips of the floats contacting the shore and the plane nosing over onto its back. The "operating details/floatplane takeoff" section of the manufacturer's owner's manual states in part: "...Takeoff performance from water is much better with wing flaps 20 degrees throughout the takeoff run...Under heavy load and glassy water conditions, it may be advisable to apply abrupt back pressure for breaking away from the surface."
THE PILOT'S IMPROPER USE OF THE FLAPS AND FLIGHT CONTROLS, AND A DELAY IN ABORTING THE TAKEOFF. A FACTOR IN THE ACCIDENT WAS GLASSY WATER CONDITIONS.
Source: NTSB Aviation Accident Database
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