|Title:||Runway excursion on landing involving a Douglas DC-6B at an alpine airstrip north of Nuiqsut, Alaska, on September 25, 2001|
|Micro summary:||Runway excursion on landing involving this Douglas DC-6.|
|Event Time:||2001-09-25 at 1609 ADT|
|Publishing Agency:||National Transportation Safety Board (NTSB)|
|Site of event:||Nuiqsut, AK|
|Departure:||Ted Stevens Anchorage International Airport, Anchorage, Alaska, USA|
|Airplane Type(s):||Douglas DC-6B|
|Type of flight:||Cargo|
NTSB short summary:
The flightcrew's continued use of an unstabilized GPS approach. Factors associated with the accident were low ceilings, and the inadequate coordination between the crew.
The crew was conducting a GPS instrument approach in a Douglas DC-6B airplane under IFR conditions. Both pilots were certificated and type-rated in the Douglas DC-6B airplane. The first pilot, seated in the right seat, was one of the company's senior check airman, and possessed a right seat dependency endorsement. The second pilot, seated in the left seat, had less experience in the DC-6B airplane. It had been previously agreed that the second pilot would fly the leg of the flight on which the accident occurred. The first pilot reported that light snow showers were present, with visibility reported at 4 miles. During final approach as the airplane passed over the airstrip threshold, a higher than normal sink rate was encountered. He said that the initial touchdown was "firm," but was thought to be within acceptable tolerances. Just after touchdown, the left wing broke free from the airplane at the wing to fuselage attach point. The airplane veered to the left, continued off the left side of the 5,000 feet long by 75 feet runway, down an embankment, and came to rest in an area of wet, tundra-covered terrain. A postcrash fire heavily damaging the center section of the fuselage. The cockpit voice recorder (CVR) revealed that as the airplane progressed along the approach, the first pilot says: "You're only one mile from it....Take it on down ah three." As the airplane passes over the runway threshold, the first pilot says: "Keep that, keep that (expletive) power off.... Just push forward on the nose." The sound of impact is heard 4 seconds later. The minimum descent altitude (MDA) for the approach is 400 feet msl (383 feet agl). A contract weather observer reported lower ceilings, with about 1 mile visibility, over the approach end of the runway at the same time as the accident.
NTSB factual narrative text:
On September 25, 2001, about 1609 Alaska daylight time, a Douglas DC-6B airplane, N867TA, sustained substantial damage during landing at the Alpine Airstrip, located about 10 miles north of Nuiqsut, Alaska. The airplane was being operated as a visual flight rules (VFR) cargo flight under Title 14, CFR Part 121, when the accident occurred. The airplane was registered to and operated by Northern Air Cargo, Inc., Anchorage, Alaska. The two certificated airline transport pilots, and the flight engineer, sustained minor injures. Visual meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan was in effect. The flight originated at the Deadhorse Airport, Deadhorse, Alaska, about 1530.
During a telephone conversation with the National Transportation Safety Board investigator-in-charge on September 26, the director of operations for the operator reported that both of the pilots were certificated and type-rated in the accident airplane. He added that the first pilot, seated in the right seat, was one of the company's senior check airman, and possessed a right seat dependency endorsement. The second pilot, seated in the left seat, had less experience in the DC-6B airplane. The director of operations reported that prior to departure, both pilots had previously agreed that the second pilot would fly the leg of the flight on which the accident occurred.
During a telephone conversation with the National Transportation Safety Board investigator-in-charge on September 27, the first pilot related that the purpose of the flight was to deliver about 20,000 pounds of oil drilling equipment to a remote oil production site. He reported that light snow showers were present, with visibility reported at 4 miles. The first pilot stated that during final approach, as the airplane passed over the airstrip threshold, a higher than normal sink rate was encountered. He said that the initial touchdown was "firm," but was thought to be within acceptable tolerances. Just after touchdown, the left wing broke free from the airplane at the wing to fuselage attach point. The airplane veered to the left, continued off the left side of the 5,000 feet long by 100 feet wide runway, down an embankment, and came to rest in an area of wet, tundra-covered terrain. A postcrash fire ensued, heavily damaging the center section of the fuselage.
According to information recorded on the airplane's cockpit voice recorder (CVR), at 1552, prior to leaving their cruise altitude, the crew contacted the contract weather observer at the Alpine Airstrip, and requested current weather conditions. The weather observer responded, in part: "Ah currently visibility four miles with light snow and mist. Overcast one thousand two hundred. Temp minus three. Dew point missing."
At 1555, the second pilot briefed the first pilot and flight engineer on the anticipated GPS approach to runway 21, and included information concerning the missed approach procedures.
At 1558, Anchorage Air Route Traffic Control Center (ARTCC) cleared the accident airplane for the runway GPS 21 approach to the Alpine Airstrip, and advised the crew to contact the Alpine Common Traffic Advisory Frequency (CTAF) on 122.8.
At 1559, the crew contacted the contact weather observer on 122.8, and stated: "Alpine, Yukon six ninety, we're ah...ah ten minuets out... and we'll be landing runway two one." The contract weather observer acknowledged by stating: "Yukon six ninety this is Alpine ah your runway is clear, winds still currently ah two six zero, right at twelve knots, altimeter two niner five niner."
Between 1600:15 and 1606:25, the flight progressed in accordance with the published approach plate.
At 1606:35, the second pilot asked: "What are we landing... about one twenty three, one ten, something like that?" The flight engineer responds by saying: "Sounds good."
At 1606:40, the first pilot tells the second pilot: "Pull the power back to go down."
At 1607:12, the second pilot asks: "What do we have for landing speeds?"
At 1607:15, the flight engineer responds: "One twenty three, one ten."
At 1607:25, the first pilot states: "(Expletive) you're two miles from it. Where in the (expletive) is it? Take it down. I don't see the (expletive) yet.
At 1607:53, the first pilot states: " You're only one mile from it." "Take it on down ah three."
At 1608:31, the flight engineer states: "Lights right there."
At 1608:32, the second pilot says: "Okay, full flaps, final gear check." The flight engineer responds by saying: "Gear checks. Three wheels. Pressure quality. Before landing complete."
At 1608:49, the first pilot says: "Keep that, keep that (expletive) power off."
At 1608:51, the first pilot stated: "Just push forward on the nose."
At 1608:55, sound of impact, and end of recording.
A complete transcript of the CVR is included in this report.
The GPS 21 approach to runway 21 at the Alpine Airstrip is a Federal Aviation Administration (FAA) approved, private GPS approach, owned and operated by Phillips Petroleum, Inc. The FAA approved approach plate for the GPS 21 approach, while inbound on the 206 degree radial, allows airplanes to descend to 400 feet msl (383 feet agl) until the runway environment is observed, or until reaching the missed approach point, 0.7 miles from the runway. The minimum visibility required for the approach is 1 statue mile.
On September 25, at 1609, the contract weather observer located at the accident airstrip was reporting: Wind, 290 degrees (true) at 12 knots; visibility, 3 statute miles in light snow and mist; clouds and sky condition, 1,000 feet overcast; temperature, 28 degrees F; dew point, missing; altimeter, 29.59 inHg. In the remarks portion of his report, the weather observer reported lower conditions to the north-northeast, and visibility of 1 statute mile.
The Safety Board did not take custody of the airplane wreckage. The airplane's solid-state CVR was retained by Safety Board's Vehicle Recorders Division in Washington, D.C., and will be returned to the operator at a later date.
|Learning Keywords:||Operations - Airspace - Non-Precision Approach|
|Operations - Crew Resource Management|
|Operations - Runway Excursion|
|Operations - Unstabilized Approach|
|Consequence - Hull Loss|
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