# NTSB ANC01IA007: Boeing 747-251F, N629US, Anchorage, AK, October 15, 2000 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: October 15, 2000, 00:35 local (08:35 UTC) - Place: Anchorage, AK - Coordinates: 61.159622, -149.989273 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=61.1596&lon=-149.9893&mi=10 - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report July 2, 2001 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 50483 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC01IA007 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/50483/pdf - Page: https://openairdocs.org/ntsb/ANC01IA007 ## Probable cause Rupture and disintegration of main landing gear tires during the takeoff roll, and subsequent damage to the right main gear hydraulic brake system. ## Analysis A Boeing 747 cargo airplane began to taxi for departure. The crew hear a 'thump' type of noise, but attributed the noise 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 reached 166 knots before beginning to slow. The airplane ran off the paved end of the runway into a clearway consisting of soft dirt, stopping about 486 feet beyond the paved end of the runway as the landing gear wheels sank into the soft terrain. The runway had 11,584 feet of pavement available for use. About 1,500 feet from the beginning of the runway, a large amount of shredded tire debris, along with gouge marks consistent with tire wheel rims, were found 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 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. The airplane's takeoff gross weight for the flight was 794,200 pounds. For takeoff operations on the runway utilized, the runway takeoff gross weight was 795,300 pounds. ## Factual narrative 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. 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. ## Aircraft - Registration: [N629US](https://openairdocs.org/deregistered/N629US-2021-05-20), registration cancelled 2021-05-20, S/N 22388, built 1980 (OpenAirDocs) - Reported make and model: Boeing 747-251F - Registry model: [Boeing 747-251F](https://openairdocs.org/model/boeing-747-251f) (registry code 1384898) (OpenAirDocs) - Registry engine: [Pratt & Whitney JT9D series](https://openairdocs.org/engine/pratt-whitney-jt9d-series) (registry code 52054, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 22388 - Engines: P&W JT9D-7J 48000 lbs thrust turbo fan - Damage: Minor damage - Flight: Part 121 - Registered owner: Northwest Airlines Inc. - Airworthiness certificate: Standard, Transport - Departed: PANC - Destination: KJFK, NEW YORK, NY - Flight plan: IFR - Airport: PANC, Anchorage International, runway 32, 11,584 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; airline transport, flight engineer; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 5,225 total, 3,972 in this make and model, 1,854 as pilot in command, 85 in the last 90 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night/dark - Wind: 227° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: 8,500 ft broken - Temperature: 37 °F, dew point 36 °F - Altimeter: 29.00 inHg - Observed at: PAN ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20001015016649I](https://openairdocs.org/incident/20001015016649I), Oct 15, 2000: Boeing 747251F, Anchorage, AK, Minor damage. (-23) During the takeoff roll the crew experienced excessive airframe vibration and aborted the takeoff at 148 knots prior to reaching V1 speed of 164 knots.… ## Other investigations on N629US (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB ANC93IA188](https://openairdocs.org/ntsb/ANC93IA188), Sep 25, 1993: Boeing 747-200 (N629US), Anchorage, AK, incident, minor damage. Probable cause: FOREIGN OBJECT DAMAGE TO THE COMPRESSOR FORWARD FAN ASSEMBLY AS A RESULT OF THE INGESTION OF A BIRD. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.