# NTSB SEA06LA033: McDonnell Douglas MD-83, N979AS, Seattle, WA, December 27, 2005 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 26, 2005, 16:35 local (Dec 27, 2005, 00:35 UTC) - Place: Seattle, WA - Coordinates: 47.44889, -122.309448 - Nearby events: https://openairdocs.org/map.md?lat=47.4489&lon=-122.3094&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 142 uninjured - Status: Completed, report August 29, 2006 - Report: Approved by Office Director - Parties: FAA FSDO - NTSB case key (mKey): 62990 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA06LA033 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/62990/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=62990 - Page: https://openairdocs.org/ntsb/SEA06LA033 ## Probable cause The ground personnel baggage handler failed to maintain clearance from the aircraft with cargo handling equipment during ground operations and inadvertently damaged the airplane's pressure bulkhead which subsequently decompressed during climb to cruise. ## Analysis The captain said that the airplane arrived late into Seattle, from its previous flight, and the new flight crew was waiting at the gate. After the airplane was chocked and the engines were shut down, the first officer immediately performed his preflight inspection. A ground baggage handler, who was driving a tug towing a train of baggage carts, said that he approached the airplane from aft to forward, but had to maneuver around another train of carts to get close to the belt loader. After loading the carts with baggage, he attempted to drive away. He stated, "I was hoping to make it out, but I felt my tug going against something. I immediately set my foot on the brakes and glanced at the body [in moderate rain] of the aircraft to see if there was any damage. It was a quick glance and I did not see any damage." He did not report the incident to anyone. The pilot said that the takeoff was normal. During the climb out, at approximately 26,000 feet, they heard a loud bang, and the cabin depressurized. He said that they put their oxygen masks on, and coordinated a descent to a lower altitude with Seattle Center. An uneventful landing was performed at Seattle-Tacoma International Airport, Seattle, Washington. Post landing examination of the fuselage revealed a 12 by 6 inch hole between the middle and forward cargo doors on the right side of the airplane. After the occurrence, the ground baggage handler confessed that he had "grazed the airplane" with a tug, while attempting to depart the vicinity of the airplane. ## Factual narrative On December 26, 2005, at approximately 1635 Pacific standard time, a McDonnell Douglas MD-83, N979AS, was substantially damaged when the airplane experienced a rapid cabin depressurization during climb out from Seattle, Washington. The airline transport pilot captain and first officer, the three flight crew members, and the 137 passengers were not injured. Alaska Airlines Inc. was operating the airplane under Title 14 CFR Part 121, as flight number 536. Visual meteorological conditions prevailed for the commercial cross-country flight that originated approximately 30 minutes before the accident. The flight was on an IFR clearance with a destination of Burbank, California. The captain said that the airplane arrived late into Seattle, from its previous flight, and the new flight crew was waiting at the gate. After the airplane was chocked and the engines were shut down, the first officer immediately performed his preflight inspection. A new (approximately one week on the job) ground baggage handler, who was driving a tug towing a train of baggage carts, said that he waited for a belt loader to be correctly positioned on the right side at the middle cargo door of the airplane. He said that he approached the airplane from aft to forward, but had to maneuver around another train of carts to get close to the belt loader. Once in position, he said the front of his tug was 4 to 5 feet away from the airplane. After loading the carts with baggage, he attempted to drive away. He said that he turned the tug's wheels as far as possible. He stated, "I was hoping to make it out, but I felt my tug going against something. I immediately set my foot on the brakes and glanced at the body [in moderate rain] of the aircraft to see if there was any damage. It was a quick glance and I did not see any damage." He said two other ground personnel came to assist him in maneuvering his tug away from the airplane. He did not report the incident to anyone. The pilot said that the takeoff was normal. During the climb out, at approximately 26,000 feet, they heard a loud bang, and the cabin depressurized. He said that they put their oxygen masks on, and coordinated a descent to a lower altitude with Seattle Center. An uneventful landing was performed at Seattle-Tacoma International Airport, Seattle, Washington. Post landing examination of the fuselage revealed a 12 by 6 inch hole between the middle and forward cargo doors on the right side of the airplane. After the occurrence, the ground baggage handler confessed that he had "grazed the airplane" with a tug, while attempting to depart the vicinity of the airplane. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Decompression, climb - to cruise - clearance - not maintained, ground personnel (cause) - fuselage,pressure bulkhead - punctured (cause) ## Aircraft - Registration: [N979AS](https://openairdocs.org/aircraft/N979AS), registered now, S/N 948126 (OpenAirDocs) - Reported make and model: McDonnell Douglas MD-83 - Registry model: [Let L-23 SUPER BLANIK](https://openairdocs.org/model/let-l-23-super-blanik) (registry code 1360308) (OpenAirDocs) - Category: Airplane - Serial number: 53471 - Airframe hours: 33530 - Engines: Pratt & Whitney JT8D-217A 20000 lbs thrust turbo fan; Pratt & Whitney JT8D-217A 20000 lbs thrust turbo fan - Damage: Substantial damage - Flight: Part 121 - Registered owner: Alaska Airlines Inc. - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, December 1, 2005 - Departed: SEA, Seattle, WA - Destination: BUR, Burbank, CA - Flight plan: IFR - Airport: SEA, Seattle-Tacoma Intern Arpt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; injuries: none; commercial, airline transport, flight engineer; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review July 1, 2005; seat: left; flight hours: 13,978 total, 162 in the last 90 days, 1 in the last 24 hours - Co-pilot; age 37; injuries: none; commercial, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review April 1, 2005; seat: rear; flight hours: 5,484 total, 210 in the last 90 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: 7,000 ft broken - Temperature: 50 °F, dew point 45 °F - Altimeter: 29.87 inHg - Observed at: SEA ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20051226030609A](https://openairdocs.org/incident/20051226030609A), Dec 26, 2005: Doug MD83, Seattle, WA, Substantial damage. (-23) Asaa flight 536 departed sea/tac enroute to burbank. Approximately 1625 PDT at FL 260 the flight crew experienced a loud bang followed by a rapid cabin… ## Docket (4 files) The files NTSB released with the investigation on April 17, 2006, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=62990. 550 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 410 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40259464&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Statement of Nathan Schuerch (item 2, .PDF, 61 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40259465&FileExtension=.PDF&FileName=Statement%20of%20Nathan%20Schuerch-Master.PDF - Belly Compartment of MD-80 (item 3, .PDF, 15 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40259466&FileExtension=.PDF&FileName=Belly%20Compartment%20of%20MD-80-Master.PDF - Image 1. View of damage to aircraft. (item 4, .PDF, 64 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40259467&FileExtension=.PDF&FileName=Image%201.%20%20View%20of%20damage%20to%20aircraft.-Master.PDF 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.