- Date
- September 11, 1999, 11:45 local (19:45 UTC)
- Place
- Anchorage, AK
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Initial climb
- Aircraft
- N4BZDiehl Interstate S-4
- Weather
- Visual (VMC) · Day
- Status
- Completed · report January 18, 2001
- Report
- Approved by Office Director
- NTSB office
- Alaska Regional Office
- FAA report
- 19990911025419A
- Case key
- 47332
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The pilot's inadequate planning/decision, and his failure to maintain directional control of the airplane. Factors in the accident were a short runway/lake area for departure, and the pilot's extension of the landing gear steering system (water rudders) during the takeoff run.
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.
Analysis
The pilot was taking off from a private lake in a homebuilt/experimental float equipped airplane. While waiting for a departure clearance, he was taxiing in a tight left turn in a cove located at the west end of the lake. The water rudders were extended and displaced to the left. The pilot said the water rudders are stiff when they are deployed. After receiving his clearance, he began his departure from the cove. During the takeoff run, he left the water rudders extended. When the airplane became airborne, he said the airplane continued to turn left. He was unable to prevent the airplane from colliding with a small boat dock, and the top of a small boat. The airplane then collided with trees along the edge of the lake. An FAA inspector said the distance from the cove used for departure to the dock was about 500 feet. The distance from the dock to the trees was about 100 feet. In the Pilot/Operator report (NTSB form 6120.1/2) submitted by the pilot, he stated, in part: '...At rotation, could not control P-Factor of engine with max right rudder.' The pilot also indicated there was no mechanical malfunction/failure.
Factual narrative
On September 11, 1999, about 1145 Alaska daylight time, a float equipped homebuilt/experimental William Diehl, Interstate S-4 airplane, N4BZ, sustained substantial damage while taking off from a private lake, at Anchorage, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight when the accident occurred. The airplane was operated by the pilot. The private certificated pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed.
During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on September 13, 1999, the pilot reported he was departing from Sand Lake toward the east. While waiting for a departure clearance, he was taxiing in a tight left turn in a cove located at the west end of the lake. The water rudders were extended and displaced to the left. The pilot said the water rudders are stiff when they are deployed. After receiving his clearance, he began his departure from the cove. During the takeoff run, he left the water rudders extended. When the airplane became airborne, he said the airplane continued to turn left. He was unable to prevent the airplane from colliding with a small boat dock, and the top of a small boat. The airplane then collided with trees along the edge of the lake.
In the Pilot/Operator report (NTSB form 6120.1/2) submitted by the pilot, he stated, in part: "...At rotation, could not control P-Factor of engine with max right rudder." The pilot also indicated there was no mechanical malfunction/failure.
A Federal Aviation Administration (FAA) airworthiness inspector, Anchorage Flight Standards District Office (FSDO), reported that he inspected the airplane at the accident scene. The airplane received damage to the left wing, the left wing lift strut, and the left float. The inspector said the distance from the cove used for departure to the dock was about 500 feet. The distance from the dock to the trees was about 100 feet.
Aircraft
- Registration
- N4BZ
- Reported as
- Diehl Interstate S-4 (INTERSTATE)
- Category
- Airplane, amateur-built
- Serial number
- 004
- Engine
- Lycoming O-320, 160 lbs thrust, reciprocating
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Registered owner
- David D. Kyzer
- Airworthiness certificate
- Special, Experimental (Special)
- Last inspection
- Annual · July 28, 1999 · 12 hours before
- Destination
- Butterfly Lake, AK
- Airport
- Sand Lake, runway 9, 500 × ft, water
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 51
- Certificate
- Private
- Airplane ratings
- Single-engine land, Single-engine sea
- Instrument ratings
- Airplane
- Medical
- Class 3, Valid Medical--w/ waivers/lim
- Seat
- Left
- Flight hours
- 900 total · 33 in this make and model · 20 in the last 30 days
Weather
- Conditions
- Visual (VMC) · Day
- Visibility
- 30 statute miles
- Lowest ceiling
- None
- Temperature
- 50 °F
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.
Other investigations on N4BZ · 1
Matched to the same aircraft by N-number and date.