ANC99LA143

NTSB accident investigation · Diehl Interstate S-4 · Anchorage, AK · September 11, 1999

Accident · No injuriesLimited investigationFinal report
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.

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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.

Loss of control - in flightTakeoff - initial climb
Airport facilities,runway/landing area condition - short runway/landing areaFactor
Planning/decision - inadequatePilot in commandCause
Landing gear,steering system - extendedFactor
Directional control - not maintainedPilot in commandCause
In flight collision with objectTakeoff - initial climb
Object - other
Object - tree(s)

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.