ANC13FA054

NTSB accident investigation · Dehavilland Beaver DHC-2 MK.1 · Petersburg, AK · June 4, 2013

Accident · FatalField investigationFinal report
Date
June 4, 2013, 15:31 local (23:31 UTC)
Place
Petersburg, AK
Injuries
1 fatal, 2 serious, 4 minor
Damage
Substantial damage
Phase of flight
Enroute
Aircraft
N616WDehavilland Beaver DHC-2 MK.1
Defining event
Enroute-cruise: Abrupt maneuver
Weather
Visual (VMC) · Day
Status
Completed · report June 2, 2014
Report
Approved by Office Director
NTSB office
Alaska Regional Office
Parties
Federal Aviation Administration, Pacific Wings LLC
FAA report
20130604009819A
Case key
87091

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 failure to maintain adequate altitude above the trees, and his subsequent failure to maintain adequate airspeed while maneuvering to avoid the trees, which resulted in an inadvertent aerodynamic stall/spin and an uncontrolled descent.

Findings · 3

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 BEAVER DHC-2 MK.1: 2 casesAll aircraft: 1,681 casesProbable cause
Terrain: mountainous/hilly terrainEnvironmental issues › Physical environment · Contributed to outcomeDehavilland BEAVER DHC-2 MK.1: 1 caseAll aircraft: 329 cases

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 pilot reported that the accident flight was his fourth flight and the third tour flight of the day in a float-equipped airplane. The weather had deteriorated throughout the day with lowering ceilings, light rain, and fog on the mountain ridges. The pilot said that when approaching a mountain pass, he initiated a climb by adding a "little bit" of flap (about 1 pump of the flap handle actuator) but did not adjust the engine power from the cruise power setting. He noted his airspeed at 80 knots, with a 200-feet-per-minute climb on the vertical speed indicator. He was having difficulty seeing over the cowling due to the nose-high attitude, when he suddenly noticed trees in his flight path. He initiated an immediate left turn; the airplane stalled, and began to drop, impacting the mountainous, tree-covered terrain. A passenger reported that the weather conditions at the time of the accident consisted of tufts of low clouds, and good visibility. They did not enter the clouds at any time during the flight. He reported that the airplane made a left turn, stalled, and then made a sharp left turn right before impact. The airplane seemed to be operating fine, and he heard no unusual sounds, other than the engine speed seemed to increase significantly right before impact. The pilot reported that there were no preaccident mechanical anomalies that would have precluded normal operation, and the postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.

Factual narrative

The airplane was a 1958 model year, de Havilland DHC-2 MK1 (Beaver). At the time of the accident the airplane had a total time in service of 34,909.3 flight hours. A review of the maintenance records revealed that the most recent annual inspection of the airframe and engine was on January 22, 2013, 76.1 flight hours before the accident. The airplane was equipped with a Pratt and Whitney R-985 radial engine that was rated at 450 horsepower.The engine was overhauled 1,015.6 hours before the accident. The airplane was equipped with Edo 4930 floats. According to the performance information section of the airplane's FAA approved flight manual, the stall speed for a DHC-2 airplane configured with the flaps in the up position, operating at 5,057 pounds (the estimated gross weight of the airplane at the time of the accident), ranges between 60 and 105 miles per hour, depending on bank angle. On June 4, 2013, about 1531 Alaska daylight time, a float-equipped de Havilland DHC-2 (Beaver) airplane, N616W, sustained substantial damage when it collided with mountainous, tree-covered terrain, about 14 miles east of Petersburg, Alaska. The airplane was being operated by Pacific Wings LLC, as a visual flight rules (VFR) sightseeing flight under the provisions of 14 Code of Federal Regulations, Part 135, when the accident occurred. Of the seven people on board, the certificated airline transport pilot and three passengers sustained minor injuries, two passengers sustained serious injuries, and one passenger was fatally injured. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The flight originated at the Lloyd R. Roundtree Seaplane Facility, at the Petersburg Harbor, Petersburg, about 1519. The flight was a sightseeing flight for cruise ship passengers, and the passengers cruise ship was docked in Petersburg. As part of their company flight following procedures, Pacific Wings incorporates Spidertracks, which provides company management personnel with a real-time, moving map display of the airplane's progress. During an interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on June 6, the operator's director of operations reported that after returning from a flight, he was alerted that the flight track for the accident airplane had stopped transmitting along the anticipated route to LeConte Glacier. Inquiring of the company flight follower, and unable to establish radio contact with the pilot, he initiated a search for the missing airplane. He said the 45 minute tour flight had a standard route, but pilots were allowed to alter that route based on weather conditions. About 1547, approximately 16 minutes after the accident, the United States Coast Guard (USCG) Alaska received a 406 Mhz emergency locator transmitter (ELT) signal assigned to the accident airplane. At approximately 1614, after being notified of an overdue airplane, and after learning about reports of an emergencylocator transmitter (ELT) signal along the accident pilot's anticipated flight route, search and rescue personnel from the U.S. Coast Guard Air Station Sitka, began a search for the missing airplane. About 1816, the crew of a U.S. Coast Guard HH-60 helicopter located the airplane's wreckage in an area of mountainous, tree-covered terrain. A rescue swimmer was lowered to the accident site and discovered that one of the airplane's occupants died at the scene, and six others had survived the crash. The six survivors were hoisted aboard the HH-60 helicopter, and then transported to Petersburg. During an interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on June 6, the pilot stated that the accident flight was his fourth flight of the day, and his third tour flight that day. He said that weather conditions had deteriorated throughout the day with a ceiling of approximately 2,000 feet, light rain, and fog along the mountain ridges. He had departed from the Petersburg harbor en route to LeConte Glacier, via Horn Cliffs. He reported that while approaching a mountain pass, en route to LeConte Glacier he initiated a climb by adding a "little bit" of flap, approximately 1 pump of the flap handle actuator, but did not adjust the engine power from the cruise power setting. He noted his airspeed at 80 knots, with a 200 feet per minute climb on the vertical speed indicator. He was having difficulty seeing over the cowling due to the nose high attitude as he entered the pass, when he noticed trees in his flight path. He initiated an immediate left hand turn; the airplane stalled, and began to drop, impacting the mountainous terrain. The pilot stated that there were no preaccident mechanical anomalies that would have precluded normal operation. During a telephone conversation with the NTSB IIC, on June 7 a passenger reported that they received a preflight safety briefing when they boarded the airplane. After departure they headed out across the water towards LeConte Glacier. He said that the airplane made a left turn, stalled, and then made a sharp left turn right before impact. He said that the weather conditions at the time of the accident consisted of tufts of low clouds, and good visibility. They did not enter the clouds at any time during the flight. He stated that the airplane seemed to be operating fine, and he heard no unusual sounds, other than the engine speed seemed to increase significantly just before impact. The closest weather reporting facility was Petersburg Airport, approximately 14 miles west of the accident site. At 1536, an aviation routine weather report (METAR) at Petersburg, Alaska, reported wind, calm, visibility, 2 1/2 statute miles with light rain and mist, scattered clouds at 500 feet, broken clouds at 1,300 feet, overcast clouds at 1,800 feet, temperature, 52 degrees F; dewpoint 48 degrees F; altimeter, 30.03 inHG. The pilot, age 39, held an airline transport pilot certificate with an airplanemuilti-engine land rating, and commercial privileges for single-engine land and single-engine sea. He also held a type rating for a Hawker Siddeley HS-125 airplane. His most recent first class medical certificate was issued on April 24, 2013, with the limitation not valid for any class after October 24, 2013. According to the Pilot/Operator Aircraft Accident Report, (NTSB Form 6120.1) submitted by the operator, his total aeronautical experience was about 4,841 flight hours, of which about 1,465 were in same make and model as the accident airplane. In the preceding 90 and 30 days prior to the accident, the pilot flew a total of 114.1 and 45.7 flight hours. His most recent CFR Part 135.293 check ride was on February 5, 2013. A Federal Aviation Administration (FAA) operations inspector from the Juneau Flight Standards District Office (FSDO) administered the check ride in an amphibious float-equipped Cessna 185 airplane. Assisted by the United States Coast Guard, and two volunteers from Juneau Mountain Rescue, the NTSB IIC, along with an Alaska State Trooper, reached the accident site on the afternoon of June 5. The on-scene examination revealed that the airplane impacted in a near vertical attitude, on a tree covered 37 degree slope, at an elevation of about 912 feet mean sea level. The nose of the airplane was on approximately a 30 degree heading, and uphill (All headings/ bearings noted in this report are magnetic). The average heights of the trees surrounding the accident site were in excess of 200 feet tall. All of the airplanes major components were found at the main wreckage site. An area believed to be the initial impact point was marked by a broken treetop approximately 80 feet from the main wreckage site. Approximately 4 feet of the outboard section of the right wing was found at the base of the tree. The airplane's right wing separated into 3 sections, with the largest section remaining attached to the aft wing attach point, but separating from the forward wing attach point. Extensive spanwise leading edge aft crushing was present. The wing's flight control surfaces separated from their respective attach points. The airplane's severed left wing was suspended in the tall trees almost directly above the main wreckage site, and exhibited spanwise leading edge aft crushing, with multiple elliptical impact areas. The wing's flight control surfaces remained attached to their respective attach points. The left wing lift strut remained attached to the wing, but separated at the fuselage. The airplane impacted on its nose and the tips of both floats. The tips of both floats showed impact damage, and the float support structure collapsed. Extensive impact damage was evident to the airplane's firewall and right side of the cockpit area. The forward right-hand door remained attached to its attach points, but the door post and forward fuselage exhibited crushing damage. The empennage was bent to the right, approximately 90 degrees just forward of thehorizontal stabilizer. The left horizontal stabilizer exhibited leading edge aft crushing with two elliptical impact areas. The right horizontal stabilizer was relatively undamaged. The left elevator separated at the outboard attach point but remained attached at the inboard attach point. The right elevator remained attached to its respective attach points. The cowling was crushed upwards and aft. The engine assembly separated from the engine firewall and had impact damage to the front and underside.The exhaust tube had malleable bending and folding, producing sharp creases that were not cracked or broken along the creases. The propeller and hub remained attached to the engine crankshaft. Two of the three propeller blades exhibited extensive bending and torsional "S" twisting. The third propeller blade exhibited extensive leading edge gouges, substantial torsional "S" twisting and chordwise scratching. Due to impact damage, control continuity could not be established at the accident site. The on-scene examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.

Aircraft

Registration
N616W
Reported as
Dehavilland Beaver DHC-2 MK.1
Category
Airplane
Serial number
1290
Airframe hours
34,909
Engine
P&W R-985 SERIES, 450 horsepower, reciprocating
Damage
Substantial damage
Flight
Part 135
Operator
Pacific Wings LLC
Registered owner
Sunrise Aviation Inc
Airworthiness certificate
Standard, Normal
Last inspection
Annual · January 22, 2013
Departed
Petersburg, AK
Destination
Petersburg, AK
Flight plan
Company VFR
Equipment
Satellite tracking device

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
39
Injuries
Minor
Certificates
Commercial, 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
February 5, 2013
Seat
Left
Flight hours
4,841 total · 1,465 in this make and model · 3,971 as pilot in command · 114 in the last 90 days · 46 in the last 30 days · 6 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Wind
Calm
Visibility
2 statute miles
Temperature
52 °F, dew point 48 °F
Altimeter
30.03 inHg
Observed at
PAPG, 12 nm away

Docket · 5

The files NTSB released with the investigation on May 21, 2014, on NTSB’s docket system: statements, records, photos and specialists’ reports. 4.5 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.

Other investigations on N616W · 2

Matched to the same aircraft by N-number and date.