SEA00LA083

NTSB accident investigation · de Havilland U-6A · Kenmore, WA · May 3, 2000

Accident · No injuriesLimited investigationFinal report
Date
May 3, 2000, 10:50 local (17:50 UTC)
Place
Kenmore, WA
Injuries
2 uninjured
Damage
Substantial damage
Phase of flight
Landing
Aircraft
N8523de Havilland U-6A
Weather
Visual (VMC) · Day
Status
Completed · report May 9, 2001
Report
Approved by Office Director
Case key
49167

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

The pilot's failure to maintain control of the aircraft during the landing roll. Contributing factors were the power wave created by the nearby yacht, the rough water conditions, and the pilot's loss of visual contact with the wave during the rollout.

Sequence of events

NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.

Dragged wing,rotor,pod,float or tail/skidLanding - roll
Airport facilities,runway/landing area condition - large wave/swellFactor
Aircraft control - not maintainedPilot in commandCause
Visual/aural detectionPilot in commandFactor

Analysis

The pilot was landing to the south on Lake Washington in between a buoy and a yacht. The yacht was making approximately 2 to 3 knots speed heading south. Winds were out of the south at 13 knots, gusting to 17 knots resulting in choppy water surface conditions. As the floatplane touched down, the yacht powered up creating a large bow wave. The aircraft contacted the wave during its southerly rollout and while decelerating in a nose high attitude. The encounter resulted in the aircraft's right wing contacting the water. Forward visibility was restricted as the nose of the aircraft was raised during the landing on water.

Factual narrative

On May 3, 2000, approximately 1050 Pacific daylight time, a DeHavilland U-6A Beaver floatplane, N8523, registered to and being flown by a commercial pilot, was substantially damaged when the aircraft's right wingtip contacted the water during the landing roll at Kenmore Air Harbor seaplane base (north Lake Washington), Kenmore, Washington. The pilot and passenger were uninjured. Visual meteorological conditions prevailed and no flight plan had been filed. Winds were out of the south at 13 knots, gusting to 17 knots. The flight, which was personal, was operated under 14CFR91, and originated from Anacortes, Washington, approximately 1010.

The pilot reported that he was landing to the south on Lake Washington in between a buoy and a yacht. The yacht was making approximately 2 to 3 knots speed heading south. He further stated that just as he "arrived at the predetermined touch down point, the yacht at almost the same moment applied full power, creating a large bow wave and instead of passing over the anticipated 4 to 6 inch wave, my left float hit a 2 to 3 foot wave, raising the left float and rocking the aircraft, causing my right wing to clip the bow wave. At the same moment I applied power, bringing the aircraft to a normal position."

Additionally, the pilot related that "when rotating a Beaver just prior to touch down forward visibility is cut off for a period of approximately 30 seconds until the aircraft settles in the water. At that time the pilot's visibility is limited to the left side and 90 degrees to the right. Therefore the power (bow) wave was not visible until approximately 5 seconds prior to impact." The aircraft remained upright and taxied to Kenmore Air Harbor. Post-crash examination revealed extensive skin wrinkling on the right wing surface.

A commercial pilot with DeHavilland Beaver experience reported that the water at the north end of Lake Washington was choppy the day of the accident due to the strong southerly winds. He also confirmed that when landing in such circumstances, and once the pilot has engaged the floats in the water, back pressure on the control column is applied to decelerate the aircraft as quickly as possible. This raises the nose of the aircraft and further obstructs forward vision, as the accident pilot described earlier.

Aircraft

Registration
N8523
Reported as
de Havilland U-6A
Category
Airplane
Serial number
57-6161
Engine
P&W R985-AN39A, 450 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Registered owner
Yeager, Philip, J.
Airworthiness certificate
Standard, Normal
Last inspection
Annual · June 18, 1999 · 21 hours before
Departed
WA03 · Anacortes, WA
Destination
WA57
Airport
WA57 · Kenmore Air Harbour Spb

Flight crew

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
70
Certificate
Commercial
Airplane ratings
Single-engine sea, Single-engine land, Multi-engine land
Instrument ratings
Airplane
Medical
Class 3, Valid Medical--w/ waivers/lim
Seat
Left
Flight hours
5,000 total · 70 in this make and model · 3,000 as pilot in command

Weather

Conditions
Visual (VMC) · Day
Wind
180° at 13 knots, gusting 17
Visibility
10 statute miles
Lowest ceiling
9,000 ft broken
Temperature
52 °F, dew point 46 °F
Altimeter
29.00 inHg
Observed at
BFI, 12 nm away