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N4065Z accident description

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Tail numberN4065Z
Accident dateAugust 14, 2002
Aircraft typePiper PA-18
LocationSkwentna, AK
Near 61.95 N, -151.166667 W
Additional details: None

NTSB description

HISTORY OF FLIGHT

On August 14, 2002, about 1539 Alaska daylight time, a wheel-equipped Piper PA-18 airplane, N4065Z, was destroyed during an in-flight collision with tree-covered terrain, about 1,500 feet west of the Skwentna Airport, Skwentna, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight when the accident occurred. The certificated private pilot, and the one passenger, received fatal injuries. Visual meteorological conditions prevailed, and a VFR flight plan was filed. The flight originated about 1445, from the Lake Hood Airstrip, Anchorage, Alaska, and was en route to Skwentna.

A family member reported that the pilot intended to fly to his remote cabin located near Skwentna on August 14, and return by 0800 on August 16. When the airplane did not arrive in Anchorage, the family member reported the airplane overdue on August 16, about 1722. At the request of the family, friends in Skwentna checked the pilot's cabin, and reported that there were no signs that anyone had been at the cabin recently. A review of the accident pilot's flight plan for the outbound portion of the flight on August 14, revealed that the pilot cancelled his flight plan at 1533, while still airborne, over the destination airport of Skwentna.

On August 16, about 2118, ground search personnel in Skwentna, aided by aerial search personnel, located the airplane wreckage along the anticipated final approach path to runway 27, at Skwentna.

During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on August 23, a resident of Skwentna who was familiar with the accident airplane, reported seeing the accident airplane on August 16, between 1530 and 1545, as it approached from the south-southeast. He said that when he noticed the airplane, he was working next to the Skwentna River, located about 1 mile south of the Skwentna airport. He added that he would routinely see the accident airplane in the area during the summer months. The witness reported that when he noticed the airplane, it seemed to be "flying very slow...slower than normal." The witness could not recall if the accident airplane's wing flaps were extended, or retracted. He added that once the airplane had passed by, he did not see or hear anything unusual, and was unaware that the airplane had crashed.

PERSONNEL INFORMATION

The pilot held a private pilot certificate with an airplane single-engine land rating. The most recent second-class medical certificate was issued to the pilot on April 10, 2002, and contained the limitation that the holder must wear corrective lenses.

No personal flight records were located for the pilot. On the pilot's application for medical certificate, dated April 10, 2002, the pilot indicated that his total aeronautical experience consisted of about 300 hours, of which 25 hours were accrued in the previous 6 months.

AIRCRAFT INFORMATION

No airframe or engine records were located for the accident airplane.

METEOROLOGICAL INFORMATION

The closest official weather observation station is located at the Skwentna Airport, in Skwentna. On August 14, 2002, at 1450, an automated weather observation system was reporting, in part: Wind, 290 degrees (true) at 7 knots; visibility, 35 statute miles; clouds, 5000 feet few, 15,000 feet scattered; temperature, 54 degrees F; dew point, 39 degrees F; altimeter, 29.78 inHg.

COMMUNICATIONS

On August 14, at 0757, the pilot contacted the preflight eight position of the Kenai, Alaska, Automated Flight Service Station (AFSS), and obtained a weather briefing for the flight from the Lake Hood Airstrip en route to Skwentna. The AFSS specialist provided the pilot with a standard weather briefing for the anticipated route of flight. At the conclusion of the weather briefing, the pilot filed a VFR flight plan, with an anticipated activation time of 1100. The pilot noted that his anticipated flight time to Skwentna would be one hour en route, with four hours of fuel, and two souls on board.

At 1221, the pilot contacted the preflight six position of the Kenai AFSS, and requested that his departure time be amended to 1330. The AFSS specialist amended the proposed takeoff to show 1330, and asked the pilot if he would like any weather briefing updates. The pilot declined any further weather updates, and stated: "No, I'll get that ah I'll get that later."

At 1451, after departing from the Lake Hood Airstrip, the pilot contacted the in-flight one position of the Kenai AFSS, and requested that his previously filed VFR flight plan be activated. The AFSS specialist confirmed that the flight plan was activated.

At 1532, the pilot contacted the in-flight one position of the Kenai AFSS, and said: "Cub six five zulu, we're five miles from Skwentna, request the uh latest Skwentna weather." The AFSS specialist on duty responded by saying: "Cub six five zulu, Kenai radio, Skwentna wind two niner zero, at seven knots, visibility three five, few clouds at five thousand, one five thousand scattered, temperature one niner, dew point six, altimeter three zero three eight, and no specials. Anything else sir we can do for you, over?" The pilot responded by saying: "Cub six five zulu, no thanks, that's fine, if you could cancel my VFR flight, appreciate it." At 1533, the AFSS specialist responded to the pilot's request by saying: "Cub six five zulu, flight plan closed." The accident pilot's last radio transmission was: "Cub six five zulu, roger."

A complete transcript of all preflight telephone and air to ground communications is included in the public docket for this accident.

WRECKAGE AND IMPACT INFORMATION

The NTSB IIC, a Federal Aviation Administration (FAA) operations inspector, and an Alaska State Trooper, examined the airplane wreckage at the accident site on August 17, 2002. The location of the airplane wreckage was within the city limits of Skwentna, about 50 feet north of a roadway used by residents of Skwentna. The airplane wreckage was not visible from the road due to thick vegetation.

The accident site consisted of thick-forested terrain, with trees extending upwards of 30 feet. The forest floor had numerous large fallen tree trunks and limbs, and soft, tundra-covered ground. The entire wreckage was found in a small opening in the trees, with all of the airplane's major components located at the main wreckage area. Examination of the trees surrounding the scene revealed two broken tree tops. Vertical scrape marks were visible on tree bark next to the site. A large tree adjacent to where the wreckage came to rest had extensive gash and chop marks, consistent with propeller slash marks.

The fuselage came to rest in an inverted and nose down attitude, with the nose of the airplane oriented on a 100 degree heading. (All headings/bearings noted in this report are oriented toward magnetic north.) The fuselage was extensively twisted and buckled. The top portion of the engine and propeller were buried in the soft, tundra-covered terrain. The cockpit area and instrument panel were crushed aft. The floor of the cabin was buckled upward, and the cabin roof area was buckled inward.

The left wing was inverted and torn free at the fuselage to wing attach points, and was displaced aft about 6 feet. It was buckled in a "U" shape, about mid-span, and draped around a tree, measuring about 12 inches in diameter. The left wing flap and aileron remained attached to the wing. The left fuel tank was ruptured.

The right wing remained attached to the fuselage, but sustained extensive leading edge aft crushing. The right wing flap and aileron remained attached to the wing.

The empennage was inverted. The rudder remained attached to the vertical stabilizer, and each had minor damage. The elevator remained attached to the horizontal stabilizer. The leading edge of the left horizontal stabilizer had spanwise crushing.

Due to impact damage, the flight controls could not be moved by their respective control mechanisms. The continuity of the flight control cables from the wings and empennage was established to the cabin area.

The accident scene had a pronounced odor of gasoline. The pilot's fuel selector valve was selected to the left fuel tank.

The propeller assembly was partially buried. The propeller assembly was excavated and examined. Both blades had extensive leading edge gouging and torsional twisting.

No evidence of any preimpact mechanical anomalies was discovered during the on-site investigation.

MEDICAL AND PATHOLOGICAL INFORMATION

A postmortem examination of the pilot was conducted under the authority of the Alaska State Medical Examiner, 4500 South Boniface Parkway, Anchorage, Alaska, on August 20, 2002. According to the medical examiner's report, the cause of death for the pilot was attributed to mechanical/positional asphyxia. The medical examiner who conducted the postmortem examination noted in the comments section of his autopsy report: "Autopsy and investigation reveals that the cause of death of this 43-year-old Caucasian male is due to mechanical/positional asphyxia due to airplane crash, decedent as pilot. The manner of death is accidental. Without significant blunt force injuries that would account for the rapid death, the most probable cause is death is mechanical/positional asphyxia. Another possible mechanism of death is a combination of blood loss due to skeletal fractures in a setting of significant exposure to environmental temperature with the crashed airplane. It is noted that the airplane crashed days before discovery."

Additionally, the medical examiner noted in his preliminary autopsy report concerning items found in the pilot's pants pocket. He wrote, in part: "...present in the same pocket is a plastic container with multiple fragments of a green-colored leafy substance consisting of approximately a small handful of substance or material."

The Federal Aviation Administration (FAA) Civil Aeromedical Institute (CAMI) conducted a toxicological examination on October 3, 2002. The examination revealed the presence of the following agents in the pilot's blood:

Tetrahydrocannabinol (Marijuana) Tetrahydrocannabinol carboxylic acid (Marijuana)

The following agents were found in the urine:

Tetrahydrocannabinol carboxylic acid (Marijuana) (0.0406 ug/ml, ug/g)

Tetrahydrocannabinol is the active substance in marijuana, and tetrahydrocannabinol carboxylic acid is the primary inactive metabolite of tetrahydrocannabinol.

SEARCH AND RESCUE

Various residents of Skwentna reported that on the day of the accident, between 1545 and 1600, they heard what one witness described as "a loud revving of an airplane's engine, then the sound of wood splintering." A number of Skwentna residents then began to search for the source of the noise. An extensive search of the area did not reveal any source of the reported noise. One witness noted that a supply barge that was being unloaded at the time of the accident was believed to be the source of the noise.

On August 16, about 1722, a family member reported that the accident airplane was overdue. Search personnel from the Anchorage squadron of the Civil Air Patrol, along with various privately owned aircraft, conducted an extensive search along the pilot's anticipated route of flight. At 2118, ground search personnel in Skwentna, aided by aerial search personnel, located the airplane wreckage along the anticipated approach path to runway 27.

Responding search and rescue personnel reported that there was no emergency locator transmitter (ELT) signal received from the airplane.

During the on-scene portion of the investigation, the NTSB IIC, and the FAA inspector, confirmed that upon arrival at the accident site, the ELT's three-position activation switch was selected to the "ARM" position. The ELT had broken free from its mounting base and was located loose within the cockpit area. Both the coaxial ELT antenna cable, and the remote cockpit mounted control switch wire, were found attached and intact. The ELT had broken free of the factory provided mounting tray at the quick release straps. The mounting plate was located adjacent to the right wing root, and just above the airplane's clamshell door. The ELT mounting tray was bent and distorted. On a piece of masking tape affixed to the side of the ELT case, a hand written note read: "ELT due 1-2002." When the ELT's three-position activation switch was placed in the "ON" position, an ELT signal was heard on frequency 121.5.

The ELT was sent to the manufacturer for disassembly and testing under supervision of the FAA.

TESTS AND RESEARCH

The ACK Technologies, Inc, ELT model ELT-01, was inspected and tested at the manufacturer's facility on January 15, 2003 under the supervision of an FAA avionics inspector from the San Jose, California, Flight Standards District Office (FSDO). This test revealed the G-switch, and all other components in the ELT, operated within prescribed parameters. A copy of the FAA avionics inspector's test report is included in the public docket for this accident.

The NTSB IIC recovered a GARMIN, model GPSMAP 195, hand held GPS unit from the accident site. The GPS unit was shipped to GARMIN International, Inc.

The technician who preformed the data extraction from the GPS unit reported that the accident airplane's recorded GPS track starts about 3 miles north of the Lake Hood Airstrip, at 1450, over Point McKenzie. The GPS track proceeds northwest, towards Skwentna. As the GPS track approaches the Skwentna airstrip from the southeast, the GPS track makes a gradual left turn, and proceeds southwest. When the GPS track is about 1 mile directly south of the airstrip, the GPS track then makes a turn to the right, and proceeds north, flying an apparent crosswind pattern over the departure end of runway 27, then making a right turn, and eventually entering a right downwind approach for runway 27. The GPS track then proceeds southeast bound, past the approach end of runway 27, and makes a gradual turn, consistent with a right base leg for landing on runway 27. As the right turn progresses, the rate of turn increases sharply. The last GPS track was recorded at 1539, with an indicated magnetic heading of 095 degrees.

WRECKAGE RELEASE

The National Transportation Safety Board released the wreckage to the owner's family, via a family friend, on August 18. The retained hand held GPS unit, along with the ELT, were released to the family on May 23, 2003.

(c) 2009-2011 Lee C. Baker. For informational purposes only.