Preliminary NTSB Report – Lake Crash in OSH

NTSBPicture: Kathryn's Report

Preliminary Accident Report On Lake LA4-250 Crash In Oshkosh

NTSB

The NTSB has issued a preliminary accident report on the Lake LA 4 250 Crash which occured on July 27, on Lake Winnebago during the 2017 Airventure event. Leaving two occupants fatally injured and one first responder with minor injuries, we had initially reported of the crash with some natural delay. Identification: CEN17FA287 14 CFR Part 91: General Aviation Accident occurred Thursday, July 27, 2017 in Oshkosh, WI Aircraft: AEROFAB INC LAKE LA 4 250, registration: N1400P

On July 27, 2017, at 1943 central daylight time, an Aerofab INC. Lake LA-4-250 amphibious airplane, N1400P, impacted water during takeoff. The pilot and one passenger were fatally injured, and the pilot rated passenger received minor injuries. The airplane was substantially damaged. The airplane was registered to, and operated by a private individual as a 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed at the accident site about the time of the accident, and the flight was operated without a flight plan. The flight was originating from Vette/Blust Seaplane Base (96WI), Oshkosh, Wisconsin, and its destination was Southwest Regional Airport (MML), Marshall, Minnesota.

The airplane arrived at 96WI about 1230 on the day of the accident. The airplane landed on Lake Winnebago to the south of the seaplane base and the pilot requested assistance during taxi because the airplane was taking on water in the left wing sponson. Boats were utilized to assist the airplane to the dock area. The left wing sponson was subsequently drained of water and the sponson fuel tank, which was a separate tank isolated inside the sponson, was also emptied. The airplane was subsequently moored and the airplane appeared to sit normally in the water. No additional issues were noted with the airplane or sponson taking on water prior to the airplane departing for the accident flight.

Personnel present at 96WI expressed concern to the pilot regarding the rough water conditions later in the afternoon. At one point the pilot was taken out on the lake by boat to observe the conditions on the lake. A witness onboard the boat described the waves being 1 ½ to 2 ft at that time. The pilot then asked to be taken back to the dock and to have the airplane fueled. The airplane was refueled, but no fuel was put into either sponson tank.

The pilot later approached the sea base staff and indicated he was ready for departure. The harbor master towed the seaplane from the dock, through a narrow gap from the base to the bay referred to as “the cut”, and into the bay outside the sea base. The pilot told the harbor master he was going to start the engine as the plane was being towed through the cut, and the harbor master held up a finger to indicated not yet and to wait a minute. The pilot reportedly asked him to start the engines several more times as the airplane was still under tow before the tow rope had been disconnected, and the harbor master indicted to him to wait each time. Once the tow ropes were disconnected and the harbor master moved out of the way to the side, the pilot started the airplane engine and the airplane “went to full power within two seconds.”

The airplane began its takeoff run immediately from the bay and departed to the northwest. Video of the takeoff showed the airplane porpoised two to three times, the nose rose steeply out of the water, and the airplane rolled to the left and the left wing struck the water. The airplane subsequently spun to the left and the airplane settled back to the right as it turned approximately 180 degrees, and the right wing was driven into the water. The nose of the airplane entered the water and the airplane subsequently started to submerge. The pilot-rated passenger was able to extricate himself from the airplane and the other two occupants were extracted by first responders. Swells in the lake were described as 1 to 1 ½ feet high at the time of the accident.

Review of video and photo evidence documenting the takeoff revealed the airplane’s wing flaps were in the up position during takeoff. The flaps and flap lever were found in the “up” position during examination of the wreckage. The takeoff trim tab was in a position close to, or at, maximum up. The takeoff trim position indicator was within the green band range for takeoff near the neutral position. No preimpact anomalies preventing normal operation of the airplane were noted during the examination of the airframe and engine.

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1 Comment on "Preliminary NTSB Report – Lake Crash in OSH"

  1. Alex Clark | August 8, 2017 at 9:29 pm |

    A rough water take-off is a lot more challenging than many pilots would like to believe. The nose being tossed up and the plane prematurely leaving the water, ( only to stall and fall) is a common occurrence in certain wave conditions. This pilot was obviously in a big hurry. It was 7:40 in the evening and waiting would have been a good idea.

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