NTSB Factual Report

HISTORY OF FLIGHT

On September 23, 2011, about 1930 Alaska daylight time, a single engine, turbine-powered, amphibious float-equipped de Havilland DHC-3T airplane, N361TT, sustained substantial damage during a go-around and subsequent low altitude maneuver at Heitman Lake, about 5 miles south-southwest of Kodiak, Alaska. The airplane was being operated by Paklook Air Inc., Kodiak, as a visual flight rules (VFR) on-demand air taxi flight, under the provisions of 14 Code of Federal Regulations Part 135, when the accident occurred. Of the three people aboard, the commercial pilot sustained fatal injuries, one passenger received serious injuries, and the remaining passenger received minor injuries. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The airplane departed Old Harbor, Alaska, bound for Kodiak, about 1905.

During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on September 23, an agent for the operator said that a passenger on the airplane reported that during a go-around on a lake, the airplane struck a tree on the shoreline and crashed. The passenger was able to make a cellphone call, and report the accident to authorities.

On September 24, the NTSB IIC and a Federal Aviation Administration (FAA) operations inspector from the Anchorage Flight Standards District Office (FSDO) examined the airplane at the crash site. The NTSB IIC noted evidence of the tree strike. The airplane collided with terrain in a steep, nose-low attitude, about 200 feet past the tree.

On September 24, during an interview with the NTSB IIC, the passenger in the rear passenger cabin said he boarded the airplane at Old Harbor. He said during the flight he knew that the airplane had descended and was flying over the surface of the lake. He did not know what had happened until he exited the wreckage.

On September 27, during an interview with the NTSB IIC, the front right seat passenger said that he was an employee of the company, and had accompanied the pilot to Old Harbor. At Old Harbor they picked up one passenger, and headed to Kodiak. He said that during the flight to Kodiak the pilot decided to land at Heitman Lake, for no particular reason. The passenger said after making an approach to the lake, but before touching down, the pilot decided to proceed to Kodiak without landing. He said the pilot flew low over the surface of the lake toward the “V” shaped notch at the east end of the lake. He said that as the airplane flew through the notch, he thought the left wing of the airplane had hit the hillside, but he didn’t see the tree. He said that after the initial impact the pilot reacted by pulling back hard on the control yoke and rolling the airplane to the right. As the airplane entered a steep climb, it began to shake, and he heard the stall warning horn come on. The airplane then rolled left before entering into a steep, nose down descent, which was followed by an impact with the ground.

INJURIES TO PERSONS

The pilot sustained fatal injuries. The right front seat passenger was seriously injured, and the passenger in the rear cabin received minor injuries.

DAMAGE TO AIRCRAFT

The airplane sustained substantial damage to the wings and fuselage.

PERSONNEL INFORMATION

The 49 year old pilot held a commercial pilot certificate, with ratings for airplane single-engine land, airplane single-engine sea, and instrument airplane. He was issued a second class FAA medical certificate on May 2, 2011, with limitations to wear corrective lenses for distance vision, and have lenses available for near vision.

In the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by the operator, the pilot's total aeronautical experience was listed as 3,000 hours, with 280 hours in the accident airplane make and model. He had flown 180 hours in the previous 90 days, including 6 hours the day of the accident. The accident flight was his third flight of the day. The pilot had completed a required biennial flight review or equivalent on July 1, 2011.

AIRCRAFT INFORMATION

The accident airplane was a de Havilland DHC-3, which was manufactured in 1952. The airplane had been modified under a supplemental type certificate (STC) SA 09866SC, for the installation of a 900 shaft horsepower, Honeywell TPE-331 turboprop engine by Texas Turbine Conversions, Inc., Denison, Texas. The engine was installed on June 6, 2003. The airplane was maintained under an Approved Airplane Inspection Program (AAIP), and at the most recent inspection, the engine had 3,424.0 hours. The airplane was also equipped with amphibious floats.

The last required inspection of the airplane was completed on June 10, 2011. Examinations of the airplane, engine, and propeller logbooks did not reveal any mechanical anomalies or concerns.

METEOROLOGICAL INFORMATION

The accident occurred during daylight hours. The closest weather reporting facility was at the Kodiak Airport, Kodiak, about 5 miles north-northeast of the accident site. The Meteorological Terminal Air Report (METAR) at 1953 ADT was reporting, in part: sky condition, broken at 4,500 feet; temperature, 48; dew point 43 degrees F; altimeter 29.34 inHg; wind 260 degrees true at 4 knots.

AIDS TO NAVIGATION

No aids to navigation were involved in this accident.

FLIGHT RECORDERS

The pilot had a Garmin GPSMAP 696, which was recovered from the wreckage. The Garmin GPS was examined at the NTSB Recorder Laboratory, and data recovered from it showed the track of the accident flight. Track data includes latitude, longitude, GPS altitude (height above ground), groundspeed, and track heading. The data points are 10-15 seconds apart.

The track data showed the airplane depart Old Harbor, en route to Kodiak. About 5 miles south-southwest of Kodiak, the airplane descended toward the west end of Heitman Lake. Once over the lake, the airplane turned toward the east end of the lake while descending. About midpoint on the lake, the last data point shows the airplane descending toward the surface of the lake, in the direction of the creek (outlet) at the east end of the lake, and the airplane had slowed to 64 knots of groundspeed. At the east end of the lake there is a creek outlet, with descending terrain beyond.

WRECKAGE AND IMPACT INFORMATION

All of the airplane's major components were found at the main wreckage site. The airplane wreckage was located on a hillside, on the north side of a creek originating from the east end of Heitman Lake. The wreckage was about 300 feet east of the lake. The lake’s elevation is about 900 feet above sea level, and the terrain is predominately rolling hills with sparse tree cover. The creek runs predominately west to east, and forms a “V” notch at the east end of the lake.

A single evergreen tree on the hillside, on the north side of the creek, about 20 vertical feet above the creek, is believed to be the initial point of impact. The tree was within the “V” notch created by the hills on either side of the creek. The terrain beyond the “V” notch descends steeply from the lake toward the Island’s coast. Orange paint chips were found at the base of the tree. The distance between the initial impact point and the main wreckage site was about 200 feet.

The airplane impacted the ground nose first in a near vertical attitude, creating an impact signature slightly larger than the diameter of the propeller. The left wing had broken away at the wing root, but remained with the airplane. The left wing leading edge had an impact mark, about 18 inches from the tip. The impact area on the wing was painted orange, and orange paint chips found at the base of the lone evergreen tree were physically matched with missing paint at the wing’s point of impact.

Aside from the single impact mark on the left wing the remainder of the leftwing leading edge, and the right wing leading edge were relatively undamaged.

The upper leading edges of the wing flaps were creased, consistent with the flaps being extended during impact.

The airplane impacted on its nose and the tip of both floats. The tips of both floats showed impact damage, and the retractable land wheels were retracted. The float support structure had collapsed.

The nose of the airplane had been crushed aft, and the engine and support structure intruded into the cockpit. The cockpit was open to the elements.

The aft passenger cabin was relatively intact, and the empennage was bent at the aft passenger cabin bulkhead. The tail was intact, however the left horizontal and elevator were pushed inward toward the fuselage when the wreckage landed on its left side.

Control continuity was established for all controls.

The engine had plastic folding of the exhaust manifold, and the propeller blades had extreme longitudinal bending, leading edge gouging, and torsional twisting.

There were no preaccident mechanical problems discovered during the NTSB IIC's on-scene wreckage examination.

MEDICAL AND PATHOLOGICAL INFORMATION

A postmortem examination of the pilot was conducted under the authority of the Alaska State Medical Examiner, 5455 Dr. MLK Jr. Avenue, Anchorage, Alaska. The cause of death was determined to be blunt force injury to the head, and the manner of death was accidental.

A toxicological examination was conducted by the FAA Civil Aeromedical Institute, Oklahoma City, Oklahoma, on January 24, 2012. The examination revealed the presence of Doxylamine (0.047 ug/ml) in the pilot's blood, and both dextrorphan and ranitidine in the pilot’s urine.

Ranitidine is an over the counter medication used for the suppression of gastric acid and reflux symptoms. It is not generally considered to be sedating.

Dextrorphan is a metabolite of Dextromethorphan, a cough suppressant. Dextromethorphan and Doxylamine are commonly found in over-the-counter cold medicines used for relief of cold and flu symptoms. Doxylamine is a sedating antihistamine with a therapeutic blood level range of 0.05-0.15ug/ml; the pilot’s level was just below therapeutic at the time of his death. This medication carries the warning that it may impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating heavy machinery).

The FAA recommends that pilots allow five dosing intervals to elapse (30 hours for dextromethorphan and doxylamine) from the time of the last dose of any sedating medication before returning to flying.

NTSB Probable Cause

The pilot’s failure to maintain clearance from a tree during a low altitude maneuver and his failure to maintain control of the airplane. Contributing to the accident was the pilot’s use of over-the-counter sedating medications.