# NTSB SEA97IA040: McDonnell Douglas MD-80, N941AS, Seattle, WA, December 21, 1996 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: December 20, 1996, 20:45 local (Dec 21, 1996, 04:45 UTC) - Place: Seattle, WA - Coordinates: 47.439502, -122.279891 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.4395&lon=-122.2799&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 144 uninjured - Status: Completed, report March 31, 1998 - Report: Approved by Office Director - NTSB case key (mKey): 42516 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA97IA040 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/42516/pdf - Page: https://openairdocs.org/ntsb/SEA97IA040 ## Probable cause The failure of the left wing walker to verify the clearance between the left wing and the fuel truck during taxi, and his delay in signaling the lead marshaller to alert the pilot to stop the aircraft prior to impact. Factors contributing to the incident include congested ramp facilities, inadequate ramp markings, rain, and dark night conditions. ## Analysis The aircraft was taxiing into a gate area in close proximity to another parked aircraft, a fuel truck, a building, and a jetway. The end of the truck was overhanging into a designated safety zone. The left wing walker who was assisting in guiding the airplane into the ramp was standing in a position which allowed his view of the left wing tip to be obstructed by the fuel truck. The wing walker stated that he gave the emergency stop signal to the lead marshaler when he noticed that the left wing tip light disappeared behind the fuel truck. The lead marshaler immediately gave the stop signal to the pilot, but the airplane continued to roll during the pilot's reaction and braking. The left wing leading edge slat impacted the rear of the fuel truck and slat's skin was dented. Rain and dark night conditions prevailed at the time. The fuel truck had been struck in another incident by the same aircraft type while parked at the same gate. The gate's ramp was congested, and was marked by painted lines that were faded and difficult to discern under artificially-lighted, wet conditions at night. ## Factual narrative On December 20, 1996, about 2045 Pacific standard time, N941AS, a McDonnell Douglas MD-80 airplane, operating as Alaska Airlines Flight 255, collided with a fuel truck while attempting to taxi to the gate in Seattle, Washington, and received minor damage. An instrument flight rules flight plan had been filed and visual meteorological conditions prevailed in Seattle at the time. There were no injuries to the two flight crew members, three cabin attendants, 139 passengers, or any ground personnel. The scheduled air carrier flight, operating under 14 CFR 121, had departed from Los Angeles, California, and was destined for Seattle. An examination of the airplane revealed that the skin of the no. 5 leading edge slat, located near the tip of the left wing, was crushed aft and torn. An examination of the fuel truck revealed a small dent on the upper corner of the aft portion of the tank. According to written statements provided by Alaska Airlines ground personnel, the fuel truck was parked in the safety area of the adjacent gate to refuel another airplane. The aft portion of the truck was protruding into the safety area, designated by faded cross-hatched paint lines. The safety area is supposed to be an area that is to remain clear of any vehicles. A wing walker for the left wing was positioned several feet in front of the left wing tip, with the fuel truck parked in between the wing walker and the left wing of the taxiing airplane. The wing walker stated that he gave the signal to the marshaler to brake upon noticing the left wing tip navigation light "disappear behind the fuel truck." The airplane continued to move forward into the fuel truck as the brakes were applied, and the leading edge of the left wing struck the aft portion of the fuel truck. The wing walker also stated that the airplane taxied into the gate while its nose gear was off the centerline of the painted lead-in "J-line." The Safety Board inspected the J-line paint, as well as the paint markings used for the designated safety area; the markings appeared faded and were more difficult to discern in dark night, rain-soaked, artificially-lighted conditions than in dry, daylight conditions. Further investigation by the Safety Board revealed that the fuel truck had been previously struck by an Alaska Airlines MD-80 at the same gate, designated as "D-1", on January 5, 1996. Gate D-1 is the first in a linear series of gates utilized by Alaska Airlines. Because it is the first gate along the airline's designated corridor, it is surrounded on two sides of the airport terminal building structure, and on a third side by another gate, designated as gate D-2. The fourth, or "open" side is the only open area for an aircraft to enter the gate area. Because of the geometry of gate D-2 and the building structure, the J-lines, safety area lines, jetway, and ground equipment lines for gate D-1 are laid out at obtuse angles. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - On ground/water collision with object, taxi - object - vehicle (contributing factor) - remedial action - delayed, ground personnel (cause) - weather condition - rain (contributing factor) - clearance - not verified, ground personnel (cause) - light condition - dark night (contributing factor) - maneuver to avoid obstructions - not possible, pilot in command - airport facilities,ramp facilities - congested (contributing factor) - aircraft handling - inadequate, ground personnel (cause) - airport facilities,ramp facilities - inadequate (contributing factor) ## Aircraft - Registration: [N941AS](https://openairdocs.org/deregistered/N941AS-2012-11-19), registration cancelled 2012-11-19, S/N 49925, built 1989 (OpenAirDocs) - Reported make and model: McDonnell Douglas MD-80 - Registry model: [Mcdonnell Douglas DC-9-82(MD-82)](https://openairdocs.org/model/mcdonnell-douglas-dc-9-82-md-82) (registry code 3022082) (OpenAirDocs) - Registry engine: [Pratt & Whitney JT8D series](https://openairdocs.org/engine/pratt-whitney-jt8d-series) (registry code 52053, turbo-jet) (OpenAirDocs) - Category: Airplane - Serial number: 49925 - Airframe hours: 22423 - Engines: P&W JT8D-217 20800 lbs thrust turbo jet - Damage: Minor damage - Flight: Part 121 - Registered owner: Alaska Airlines, Inc. - Airworthiness certificate: Standard, Transport - Last inspection: AAIP, December 20, 1996, 0 hours before - Departed: LAX, LOS ANGELES, CA - Destination: SEA - Flight plan: IFR - Airport: SEA, Seattle-Tacoma Intl ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 47; flight engineer, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 15,529 total, 7,319 in this make and model, 9,824 as pilot in command, 114 in the last 90 days, 42 in the last 30 days, 6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night/dark ## 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 19961220045899I](https://openairdocs.org/incident/19961220045899I), Dec 20, 1996: Doug DC982, Seattle, WA, Minor damage. (-5) On December 20, 1996, about 2045 pacific standard time, N941AS, a Mcdonnell Douglas MD-80 airplane, operating as Alaska airlines flight 255, collided with… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; 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.