On October 15, 2000, about 0035 Alaska daylight time, a Boeing 747-251F airplane, N629US, sustained minor damage during an aborted takeoff at the Ted Stevens Anchorage International Airport, Anchorage, Alaska. The airplane was being operated as an instrument (IFR) cargo flight to the John F. Kennedy International Airport, New York City, New York, under Title 14, CFR Part 121, when the incident occurred. The airplane was operated as Flight 904, by Northwest Airlines Inc., St. Paul, Minnesota. The captain, first officer, and second officer, were not injured. Visual meteorological conditions prevailed. An IFR flight plan was filed. Use your browsers 'back' function to return to synopsisReturn to Query Page
The airplane was departing runway 32 at the Ted Stevens Anchorage International airport. The captain reported that while taxiing to runway 32 for departure, the crew heard a "thump" type of noise. After discussion, the noise was attributed to the airplane tires running over a rut. The captain continued taxiing. During the takeoff roll, about 130 knots indicated airspeed (IAS), the captain heard and felt another "thump", followed by a substantial vibration. The captain said he aborted the takeoff about 148 knots IAS, and applied maximum braking and maximum reverse thrust. The airplane ran off the paved end of runway 32, into a clearway consisting of soft dirt, stopping about 486 feet beyond the paved end of the runway. Two omnidirectional approach lighting system (ODALS) fixtures, installed as lead-in lights for runway 14, were struck by the airplane as the landing gear wheels sank into the soft terrain.
Examination of the runway and airplane revealed a large amount of shredded tire debris on the runway, beginning about 1,500 feet from the beginning of runway 32. Gouge marks on the runway, consistent with tire wheel rims, were also visible on the runway. At the point of rest, the number 11, and number 12 tires, installed as the two aft tires on the right body landing gear assembly, were shredded and destroyed. Tires one through four, were inflated and undamaged. The number five tire was cut, torn and flat. Tires six, seven and eight, were flat. Tires nine and ten were still inflated. Tires 13, 14, 15, and 16, were flat. The nose wheel tires were undamaged and inflated. The airplane also received minor damage to the underside of the right flap assembly, damage to the right main landing gear hydraulic brake system, a landing gear door, and damage to the brake assemblies. There was no evidence of fire.
Beginning at the arrival threshold, runway 32 has 10,696 feet available. The captain elected to utilize runway 32 extension procedures. Aircraft with combined weight, stage length, or other condition, may request an extended departure from runway 32. The extension for runway 32 provides for a takeoff runway available (TORA), and an accelerate/stop distance available (ASDA) of 11,584 feet. An additional 1,000 feet of clearway is available at the departure end of the runway. Beyond the 1,000 feet of clearway, the terrain drops away sharply at the end of a small bluff, to a road below the bluff.
According to Northwest Airlines personnel, the airplane's gross weight is 817,000 pounds. The airplane's takeoff gross weight (TOGW) for the flight was 794,200 pounds. For takeoff operations on runway 32, the runway takeoff gross weight (RTOG) was 795,300 pounds. The RTOG is allowable weight for takeoff calculated by the operator. It takes into consideration numerous variables, including runway length, temperature, headwinds or tailwinds, obstructions, any inoperative brake systems, pressure altitude corrections, etc. The takeoff decision speed (V1) for the airplane was 165 knots. The rotation speed (VR) for the airplane was 174 knots.
Examination of data from the airplane's flight data recorder (FDR) indicated that in frame number 65267, the airspeed was 148.2 knots. Eight seconds later, at 166.7 knots, the number four engine thrust reverser deployed, and all engine thrust settings were decreasing. One second later, all of the thrust reversers indicated they were deployed, and all engine thrust was near idle. Over the next 24 seconds, all of the engine's thrust settings increased during reverse, and the airspeed slowed to below 50 knots.
At 0101, an Aviation Routine Weather Report (METAR) at Anchorage was reporting, in part: Wind, 260 degrees (true) at 03 knots; visibility, 10 statute miles; clouds and sky condition, 8,500 feet broken, 10,000 feet overcast; temperature, 38 degrees F; dew point, 36 degrees F; altimeter, 29.11 inHg.