# NTSB ANC99LA143: Diehl Interstate S-4, N4BZ, Anchorage, AK, September 11, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 11, 1999, 11:45 local (19:45 UTC) - Place: Anchorage, AK - Coordinates: 61.160453, -149.99002 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=61.1605&lon=-149.9900&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report January 18, 2001 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 47332 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC99LA143 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/47332/pdf - Page: https://openairdocs.org/ntsb/ANC99LA143 ## 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 In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, takeoff - initial climb - airport facilities,runway/landing area condition - short runway/landing area (contributing factor) - planning/decision - inadequate, pilot in command (cause) - landing gear,steering system - extended (contributing factor) - directional control - not maintained, pilot in command (cause) - In flight collision with object, takeoff - 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](https://openairdocs.org/deregistered/N4BZ-2013-11-04), registration cancelled 2013-11-04, S/N 004, built 1991 (OpenAirDocs) - Reported make and model: Diehl INTERSTATE S-4 (INTERSTATE) - Registry model: [Diehl William A S-4](https://openairdocs.org/model/diehl-william-a-s-4) (registry code 05618K4) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 004 - Engines: 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 ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 51; 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 (OpenAirDocs). - [Accident 19990911025419A](https://openairdocs.org/incident/19990911025419A), Sep 11, 1999: Amtr S4, Anchorage, AK, Substantial damage. 19) On September 11, 1999, about 1145 Alaska daylight time, a float equip ped homebuilt/experiemental william diehl, interstate S-4 airplane, N4BZ, sustained… ## Other investigations on N4BZ (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB ANC08CA118](https://openairdocs.org/ntsb/ANC08CA118), Sep 5, 2008: Diehl William A S-4 (N4BZ), Galena, AK, substantial damage. Probable cause: The pilot's failure to maintain pitch control of the airplane during takeoff, and the pilot's inadequate preflight inspection of the airplane. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.