ANC16LA062

NTSB accident investigation · Dehavilland DHC-2 · Kodiak, AK · September 9, 2016

Accident · Serious injuriesClass 3 · LimitedFinal report
Date
September 9, 2016, 11:30 local (19:30 UTC)
Place
Kodiak, AK
Injuries
3 serious
Damage
Substantial damage
Phase of flight
Initial climb
Aircraft
N91AKDehavilland DHC-2
Defining event
Initial climb: Loss of control in flight
Weather
Visual (VMC) · Day
Status
Completed
Report
Approved by Office Director
Investigation class
Class 3
NTSB office
Alaska Regional Office
Parties
Federal Aviation Administration
FAA report
20160909017009A
Case key
93982

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 failure to maintain adequate airspeed during the initial climb and turn after takeoff, which resulted in an exceedance of the airplane's critical angle of attack and an aerodynamic stall.

Findings · 4

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Performance/control parameters: airspeedAircraft › Aircraft oper/perf/capability · Not attained/maintainedDehavilland DHC-2 MK. I(L20A): 1 caseAll aircraft: 1,681 casesProbable cause
Performance/control parameters: angle of attackAircraft › Aircraft oper/perf/capability · Not attained/maintainedDehavilland DHC-2 MK. I(L20A): 2 casesAll aircraft: 990 casesProbable cause
Terrain: mountainous/hilly terrainEnvironmental issues › Physical environment · Contributed to outcomeDehavilland DHC-2 MK. I(L20A): 1 caseAll aircraft: 329 casesProbable cause

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Analysis

The airline transport pilot was conducting a scheduled commuter flight between remote villages in a float-equipped airplane. After making an intermediate stop to drop off a company maintenance technician at a remote lake, the pilot back-taxied the airplane to the east in preparation for a westerly departure. He estimated the wind at 15 knots with increasing gusts to 25 knots from the west. Ground witnesses and passengers on board the airplane reported that the pilot initiated a takeoff to the west, toward an area of rising, tree-covered terrain. After becoming airborne, the airplane entered a left turn to avoid the terrain. The left turn steepened, and the airplane then entered a steep nose-down descent into the terrain. The pilot reported that he did not recall any preaccident mechanical problems with the airplane. Due to his injuries, he was unable to recall the events of the accident. Postaccident examination revealed no mechanical malfunctions or anomalies of the airplane. Given the witness accounts of the accident, it is likely that the pilot exceeded the airplane's critical angle of attack during the initial climb toward and subsequent turn away from rising terrain, which resulted in an aerodynamic stall and loss of control at an altitude too low for recovery.

Factual narrative

On September 9, 2016, about 1130 Alaska daylight time, a float-equipped, de Havilland DHC-2 (Beaver) airplane, N91AK, sustained substantial damage during a collision with water, following a loss of control shortly after takeoff from Uganik Lake, about 35 miles west-southwest of Kodiak, Alaska. The airplane was registered to Redemption, Inc., and operated as Flight 43 by Island Air, as a visual flight rules (VFR) scheduled commuter flight under the provisions of 14 Code of Federal Regulations (CFR) Part 135. Of the three occupants onboard, the airline transport pilot and two passengers all sustained serious injuries. Visual meteorological conditions prevailed, and company flight following procedures were in effect. Flight 43 originated in Kodiak about 1100, with a preplanned, intermediate stop at Uganik Lake, before continuing to the flights scheduled stops in Amook Bay and Zachar Bay, Alaska. According to the operator's director of maintenance the purpose for the intermediate stop at Uganik Lake was to drop off a maintenance technician. He added that another company owned a Cessna 185 that had landed at Uganik Lake earlier in the day and damaged a float, and the maintenance technician was called in to inspect the float prior to the airplane returning to Kodiak. He said that after landing, the accident pilot met the crew of the Cessna 185 on the western shore of Uganik Lake, where he dropped off the maintenance technician, and then he departed for Amook Bay. Witnesses reported seeing the accident airplane back-taxi to the east before it eventually turned around to start the takeoff run to the west, and towards an area of rising, tree-covered terrain. The witnesses consistently reported that after the airplane became airborne, it began a left turn to avoid the rising terrain ahead. As the airplane flew closer to the rising terrain, the left turn steepened, and the airplane began a steep nose down descent. The airplane subsequently struck the shallow waters on the western end of Uganik Lake, and it came to rest partially submerged. The airplane sustained substantial damage to the wings and fuselage. The witnesses to the accident reported gusty wind conditions, from the west, estimated to be between 15 to 25 knots. Due to injuries sustained in the accident, the pilot did not recall the accident sequence; however, he did remember back-taxiing the airplane to the east for a westerly departure. He also recalled variable wind conditions, estimated to be 15 knots, with increasing gusts to 25 knots from the west. The pilot stated that to the best of his knowledge there were no preimpact mechanical anomalies with the airplane. One of the two passengers reported that he was seated in the right front seat, and his wife was seated just behind the pilot on the left side of the airplane. He added that water conditions consisted of 8 to 12 inches of chop on the surface of the water as the pilot started his westerly takeoff run. He said that just after takeoff,the airplane climbed slower than what he was accustomed to from previous flights. He added that as the airplane continued to climb, he could see an area of rising terrain ahead of them. As the airplane approached the area of rising terrain, he said that the pilot turned the airplane very steeply to the left, and then the airplane nosed down abruptly and then began a nosed down, uncontrolled descent into the shallow water below. ADDITIONAL INFORMATION At the time of the accident, the pilot was using a Garmin GPSMAP 496 portable global positioning system (GPS) receiver, capable of storing route-of-flight data. The GPS data logs for September 9, 2016 supported the pilots, passengers, and witness accounts of the accident. A flight track map overlay, and tabular data corresponding to the accident flight are available in the public docket for this accident.

Aircraft

Registration
N91AK
Reported as
Dehavilland DHC-2
Category
Airplane
Serial number
737
Built
1954
Airframe hours
26,114
Engine
Pratt & Whittney R985, 450 horsepower, reciprocating
Damage
Substantial damage
Flight
Part 135
Operator
Island Air
Registered owner
Redemption Inc DBA
Airworthiness certificate
Standard, Normal
Last inspection
Annual · August 24, 2016
Departed
Kodiak, AK
Destination
AK81 · Amook Bay, AK
Flight plan
Company VFR
Equipment
Handheld GPS

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
31
Injuries
Serious
Certificate
Airline transport
Airplane ratings
Multi-engine land, Single-engine sea, Single-engine land
Instrument ratings
Airplane
Medical
Class 1, Without waivers/limitations
Last flight review
April 4, 2016
Seat
Left
Restraint
4-point
Flight hours
3,262 total · 364 in this make and model · 243 in the last 90 days · 82 in the last 30 days · 4 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Wind
270° at 15 knots, gusting 25
Visibility
10 statute miles
Lowest ceiling
None

Docket · 7

The files NTSB released with the investigation on October 9, 2020, on NTSB’s docket system: statements, records, photos and specialists’ reports. 10.4 MB in all.

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.