# NTSB ANC99LA124: de Havilland DHC-2, N930TG, Iliamna, AK, August 25, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 25, 1999, 06:20 local (14:20 UTC) - Place: Iliamna, AK - Coordinates: 59.849296, -154.56015 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=59.8493&lon=-154.5601&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 5 uninjured - Status: Completed, report November 30, 2000 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 47322 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC99LA124 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/47322/pdf - Page: https://openairdocs.org/ntsb/ANC99LA124 ## Probable cause The pilot's selection of an unsuitable takeoff area, and an inadvertent stall. Factors associated with the accident were large wave/swells, and low light conditions (dawn). ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - On ground/water encounter with terrain/water, takeoff - roll/run - unsuitable terrain or takeoff/landing/taxi area - selected, pilot in command (cause) - terrain condition - large wave/swell (contributing factor) - light condition - dawn (contributing factor) - Loss of control - in flight, takeoff - initial climb - stall - inadvertent, pilot in command (cause) - In flight collision with terrain/water, takeoff - initial climb ## Analysis The certificated commercial pilot was attempting to takeoff from a lake with 2 feet tall, rolling swells. The pilot said that during the takeoff run, before a safe flying airspeed was attained, the airplane floats struck a large wave, and the airplane lifted off the water prematurely. He said that before he could react, the left wing stalled, and the airplane collided with the water. During the collision, the floats were torn off the airplane, and the airplane sank. The airplane sustained substantial damage to the fuselage, empennage, and wings. The closest official weather observation station is Iliamna. On August 25, 1999, at 0553, an Aviation Routine Weather Report (METAR) was reporting in part: Wind, 259 degrees (magnetic) at 7 knots; visibility, 10 statute miles; clouds, 7,500 feet broken; temperature, 51 degrees F; dew point, 46 degrees F; altimeter, 29.52 inHg. Official civil twilight for Iliamna was at 0610. ## Factual narrative On August 25, 1999, about 0620 Alaska daylight time, a float equipped DeHavilland DHC-2 airplane, N930TG, sustained substantial damage during takeoff from a remote lake, about 2 miles east of Iliamna, Alaska, at position 59 degrees 45 minutes north latitude, 154 degrees 22 minutes west longitude. The airplane was being operated as a visual flight rules (VFR) flight under Title 14, CFR Part 135, when the accident occurred. The pilot/owner was operating the airplane for his fishing guide business, Iliaska Lodge, Inc., of Iliamna. The certificated commercial pilot, and four passengers aboard, were not injured. Visual meteorological conditions prevailed, and company flight following procedures were in effect. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge on August 25, the pilot related that prior to his takeoff attempt, he noted that the lake surface had 2 feet tall, rolling swells. He said that during the takeoff run, before a safe flying airspeed was attained, the airplane floats struck a large wave, and the airplane lifted off the water prematurely. He said that before he could react, the left wing stalled, and the airplane collided with the water. During the collision, the floats were torn off the airplane, and the airplane sank. The airplane sustained substantial damage to the fuselage, empennage, and wings. In the Pilot/Operator report (NTSB form 6120.1/2) filed by the pilot, he wrote: "...I think the left flap and aileron partially retracted while the airplane was still on the step, prior to takeoff. Perhaps striking the larger swell caused the flap to retract." A Federal Aviation Administration (FAA) operations inspector, Anchorage Flight Standards District Office, traveled to the accident scene, and was present while the airplane was being recovered from the water. The inspector reported that no preaccident mechanical anomalies were noted with the airplane's flap or aileron systems. He added that the following day, prior to daylight conditions (dawn), he observed other operators departing with low light conditions which made it difficult to see the rolling swells. The closest official weather observation station is Iliamna. On August 25, 1999, at 0553, an Aviation Routine Weather Report (METAR) was reporting in part: Wind, 259 degrees (magnetic) at 7 knots; visibility, 10 statute miles; clouds, 7,500 feet broken; temperature, 51 degrees F; dew point, 46 degrees F; altimeter, 29.52 inHg. Official civil twilight for Iliamna was at 0610. ## Aircraft - Registration: [N930TG](https://openairdocs.org/deregistered/N930TG-2020-05-29), registration cancelled 2020-05-29, S/N 1041, built 1957 (OpenAirDocs) - Reported make and model: de Havilland DHC-2 - Registry model: [Dehavilland DHC-2 MK. I(L20A)](https://openairdocs.org/model/dehavilland-dhc-2-mk-i-l20a) (registry code 2808002) (OpenAirDocs) - Registry engine: [Pratt & Whitney R-985 series](https://openairdocs.org/engine/pratt-whitney-r-985-series) (registry code 52008, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 1041 - Airframe hours: 15661 - Engines: P&W R-985 450 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Registered owner: Arthur E. Gerken - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 20, 1999, 5 hours before - Departed: ILI, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 65; commercial, flight instructor; airplane ratings: single-engine land, single-engine sea, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 7,400 total, 2,500 in this make and model, 7,300 as pilot in command, 150 in the last 90 days, 75 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Dawn - Wind: 259° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: 7,500 ft broken - Temperature: 50 °F - Altimeter: 29.00 inHg ## 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 19990825024819A](https://openairdocs.org/incident/19990825024819A), Aug 25, 1999: Dhav DHC2*, Iliamna, AK, Substantial damage. (.19) On August 25, 1999, about 0615 Alaska daylight time, a float equipped Dehavilland DHC-2 airplane N930TG, sustained substantial damage during takeoff from… ## Other investigations on N930TG (2) 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 ANC17LA032](https://openairdocs.org/ntsb/ANC17LA032), Jun 18, 2017: Dehavilland DHC-2 (N930TG), Ketchikan, AK, substantial damage. Probable cause: The pilot's misjudgment of the takeoff distance needed to depart the lake, and his subsequent failure to maintain clearance from the water during a turn to avoid terrain, which resulted in impact… - [NTSB ANC03CA088](https://openairdocs.org/ntsb/ANC03CA088), Jun 25, 2003: de Havilland DHC-2 (N930TG), Iliamna, AK, substantial damage. Probable cause: The pilot's incorrect selection of the fuel selector valve position during takeoff which resulted in fuel starvation. A factor associated with the accident was inadequate transition training provided… 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.