Tuesday, September 07, 2010

Preliminary NTSB report for the Fairchild C-123K Provider crash in Alaska

by B. N. Sullivan

NTSB logoThe U.S. National Transportation Safety Board (NTSB) has issued a preliminary report regarding the crash of a Fairchild C-123K Provider in Alaska last month.  The accident occurred on the afternoon of August 1, 2010 when the aircraft impacted terrain at Denali National Park, Alaska.  All three people on board perished in the crash, and the aircraft was completely destroyed.

The aircraft (registration N709RR) was owned and operated by All West Freight, Inc. of Delta Junction, Alaska.  The accident flight, which was conducted under Part 91 rules, originated at the Wolf Lake Airport (4AK6), Palmer, Alaska, and was destined for Unalakleet Airport (PAUN), Unalakleet, Alaska.  No flight plan was filed.  Visual meteorological conditions prevailed.

The NTSB's preliminary report about the accident presents factual information about the accident flight, the crash site, and the crew.  No conclusions about probable cause are stated in the preliminary report.

The Accident Flight

According to the NTSB report, the purpose of the flight was to transport a large generator to Unalakleet.  The aircraft reportedly departed Wolf Lake at approximately 14:00L on August 1, 2010.  The pilot was not in contact with air traffic control (ATC) during the flight, and no radar service was provided. 

Quoting from the report:
At 1452, a witness, who was hunting about 10 miles south of Cantwell, Alaska, observed the airplane flying about 300-500 feet high above Parks Highway near mile-marker 195.  The witness, who is a certificated pilot, said the airplane was flying straight and level and headed north toward Denali National Park.  He stated that the landing gear and flaps were retracted and the engines were “really working” and “I felt the air vibrate as the airplane flew by.”

The witness did not observe any smoke trailing from the airplane or anything unusual.  He said the ceiling at the time was approximately 3,500 to 4,000 feet and the surrounding mountains were partially obscured.  The witness took two photos of the airplane and one of the mountain obscuration.  He provided a copy of these photos to the Safety Board, and they properly depict his observations.

Another witness, who was also a private pilot, was eating lunch on the deck at the Crow’s Nest, which is a restaurant on the hillside adjacent to the entrance into Denali National Park.  The witness first observed the airplane flying straight and level from her left to right near the main entrance area to the park.  Everything appeared to be normal.

The witness could not estimate the airplane’s altitude, but said it was in “slow flight” and in a 30 degree nose down descent.  There was no smoke trailing the airplane.  She then observed the airplane pitch straight up near vertical, stall, then roll left, and nose dive toward the ground.  The witness did not see the impact, but saw two large mushroom clouds after she lost sight of the airplane.  The weather at the time was “clear skies with a high ceiling.”  The witness took two photographs of the airplane.  The first photo shows the airplane in straight and level flight.  The second photo was taken several seconds later and showed the airplane inverted in a near vertical descent just above the tree line.

Numerous people observed the airplane flying low and slow over the park before it entered a steep left bank and then nosedive into the ground.  The sound of the engines was loud and an increase in pitch was heard right before impact.  Several of these witnesses also observed that the landing gear was retracted.
The Crash Site

The aircraft impacted wooded terrain near the main road into Denali Park. Quoting again from the report:
The airplane came to rest upright on a 060 degree heading at an elevation of 2,158 feet mean sea level (msl).  The wreckage was confined to an approximately 250-foot by 300-foot-wide area.

A post impact fire consumed most of the cockpit area, fuselage, inboard sections of the wings (around fuel tanks), both flaps, and damaged a majority of the tail section and outboard sections of the wings.  The post impact fire also started a small forest fire around the main wreckage and to an area adjacent to the accident site.

Examination of the airplane revealed that all major flight control surfaces were located at the site, including the two R2800 radial engines and the two jet-assist engines.  Flight control continuity was established for all flight control surfaces to the cockpit.  The left wing (including the aileron)exhibited impact and fire damage as did the right wing and aileron.  The vertical stabilizer, the rudder and rudder trim sustained impact and fire damage and came to rest on top of the cockpit area.  The right horizontal stabilizer exhibited fire and impact damage, and came to rest on top of the right wing.  A section of the right elevator remained attached to the stabilizer, but the fabric had burned away, exposing the metal framework.  The left horizontal stabilizer sustained extensive fire damage, and was found on the left side of the fuselage near where the left wing fuel tank was located.  A small section of elevator remained attached to the stabilizer.

The generator came to rest upright, and was in the center of the wreckage, which was consistent with the location of the cargo bay.  The nose gear was observed just forward and partially under the generator.  The ramp to the cargo bay and the main landing gear came to rest aft of the generator and exhibited fire and impact damage.

Both engines came to rest on their respective sides next to the cockpit. The left engine was upright, but partially buried in the ground and sustained impact and fire damage. A propeller blade remained attached, but was turned 180 degrees in the hub. The blade was intact and if orientated correctly, would be bent forward. The other two blades were buried in a small impact crater just forward of the engine. Both blades had separated at the hub and exhibited extensive leading edge damage and chordwise gouging and scoring. The left jet engine came to rest just forward of the left wing.

The right engine came to rest with the propeller hub buried about 2- 3 feet into the ground and sustained fire and impact damage.  A segment of one of the propeller blades was found on Park Road.  Another section of a blade was found just forward of the right wing, and another section of a blade was found in the impact crater near the propeller hub.  The right jet engine came to rest just aft of the right wing.
The Crew

There were three people on board the aircraft -- two pilots, and another person described by the NTSB as a passenger -- all of whom were fatally injured in the crash.

The pilot in command held a commercial pilot certificate for airplane single-engine land and sea, multi-engine land, rotorcraft-helicopter, and instrument airplane. He also held a type rating for the FA-C123, and was restricted to flights conducted under visual flight rules only. As of May, 2010 the pilot reported a total of 20,000 flight hours.

The co-pilot held a private pilot certificate for airplane single and multi-engine land, rotorcraft-helicopter, and instrument airplane.

The NTSB notes, "According to the type certificate data sheet (NO. A12NM), the airplane required a minimum of two crew; a pilot and copilot.  However, according to the FAA, the co-pilot was not required to hold a type rating in the airplane but was required to have some training in the airplane."

The investigation is continuing.

Here is the link to the preliminary accident report:  NTSB ID: ANC10FA067

RELATED: Click here to view all posts about the All West Freight C-123K Provider accident on Aircrew Buzz.