# NTSB DCA16IA036: Boeing 737, N477AS, Seattle, WA, December 19, 2015 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: December 19, 2015, 08:31 local (16:31 UTC) - Place: Seattle, WA - Coordinates: 47.463611, -122.313331 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.4636&lon=-122.3133&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-flare/touchdown: Wrong surface or wrong airport](https://openairdocs.org/ntsb-events/284) - Highest injury: No injuries - Injuries: 153 uninjured - Status: Completed, report June 8, 2020 - Report: Approved by Office Director - NTSB office: Major Investigations Division - Parties: Federal Aviation Administration - NTSB case key (mKey): 92491 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA16IA036 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/92491/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=92491 - Page: https://openairdocs.org/ntsb/DCA16IA036 ## Probable cause the flight crew's misidentification of the taxiway as the landing runway. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Light condition: glare](https://openairdocs.org/ntsb-findings/03036030): Environmental issues › Conditions/weather/phenomena · Effect on personnel; cases with it: [Boeing 737-990ER, 1 case](https://openairdocs.org/ntsb-findings/03036030/cases.md?model=13848CE), [All aircraft, 109 cases](https://openairdocs.org/ntsb-findings/03036030/cases.md) - [Info processing/decision: identification/recognition](https://openairdocs.org/ntsb-findings/02041510): Personnel issues › Action/decision · Flight crew (probable cause); cases with it: [Boeing 737-990ER, 1 case](https://openairdocs.org/ntsb-findings/02041510/cases.md?model=13848CE), [All aircraft, 559 cases](https://openairdocs.org/ntsb-findings/02041510/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-flare/touchdown: Wrong surface or wrong airport](https://openairdocs.org/ntsb-events/284) (defining event); cases with it: [Boeing 737-990ER, 1 case](https://openairdocs.org/ntsb-events/284/sequence.md?model=13848CE), [All aircraft, 56 cases](https://openairdocs.org/ntsb-events/284/sequence.md) ## Analysis The flight crew inadvertently landed on a taxiway that ran parallel to the intended landing runway. About 5 miles from the runway and having been cleared to land on runway 16R, the tower controller asked if the flight would like to sidestep to runway 16C which had recently opened. The flight crew accepted and visually lined up with taxiway T, instead of the intended landing runway 16C. Although visual meteorological conditions were present, the sun was reflecting off taxiway T resulting in the flight crew visually focusing on it during landing. The flight crew and controller did not recognize the error until after landing. ## Factual narrative On December 19, 2015, about 0831 pacific standard time, Alaska Airlines flight 27, a Boeing 737 airplane, N477AS, landed on taxiway T instead of the intended runway 16C at the Seattle-Tacoma International Airport (SEA), Seattle, Washington. There were no injuries to the 153 passengers and crew onboard and the airplane was not damaged. The flight was conducted under the provisions of 14 Code of Federal Regulations Part 121 as a regularly scheduled passenger flight from Chicago O'Hare International Airport (ORD), Chicago, Illinois, to SEA. Visual meteorological conditions prevailed at the time of the incident. The captain reported that the descent and approach were normal. They had been cleared for the instrument landing system (ILS) approach to runway 16R. Just inside of 5 miles, the tower controller offered runway 16C that had recently opened. The captain lined up the airplane to land on what he believed was 16C. He noted that runways 16C and 16R and taxiway T were wet and reflected the morning sun, whereas 16L and the terminal were in a shadowed area and not readily visible. He further noted that the distance from 16L to 16C is less than the distance between 16C and 16R so it may appear that 16C is the left runway with taxiway T being the middle runway. The captain suggested that runway lead-in lights should remain on to prevent future similar events. The first officer reported that both pilots were focused on landing what they thought was runway 16C, but was taxiway T. Although the first officer had retuned the captain's ILS for 16C, he was puzzled that the flightpath indicator showed on-glideslope while the localizer showed off course. Although he casually mentioned the discrepancy, since they were visually aligned with the runway, he did not give it further attention. The first officer noted that he had been focused too much on secondary tasks and neglected the big picture of ensuring the airplane was lined up on the proper runway. ## Aircraft - Registration: [N477AS](https://openairdocs.org/aircraft/N477AS), registered now, S/N 40716, built 2015 (OpenAirDocs) - Reported make and model: BOEING 737 (990ER) - Registry model: [Boeing 737-990ER](https://openairdocs.org/model/boeing-737-990er) (registry code 13848CE) (OpenAirDocs) - Registry engine: [CFM International CFM56-7B27E series](https://openairdocs.org/engine/cfm-international-cfm56-7b27e-series) (registry code 13078, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 40716 - Year built: 2015 - Airframe hours: 1986 - Engines: CFM International CFM56-7B27E 27000 lbs thrust turbo fan; CFM International CFM56-7B27E 27000 lbs thrust turbo fan - Damage: No damage - Flight: Part 121 - Operator: Alaska Airlines Inc - Registered owner: Alaska Airlines - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, January 16, 2015, 1,986 hours before - Departed: ORD, CHICAGO, IL - Destination: SEA, Seattle, WA - Flight plan: IFR - Airport: SEA, Seattle-Tacoma Intl, runway 16C, 9,426 × 150 ft, concrete - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 58; injuries: none; commercial, airline transport, flight engineer; airplane ratings: single-engine sea, multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review June 12, 2015; seat: left; restraint: 5-point; flight hours: 21,882 total, 12,328 in this make and model - Co-pilot; age 41; injuries: none; airline transport, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review April 30, 2015; seat: right; restraint: 5-point; flight hours: 949 in this make and model ## Weather - Conditions: Visual (VMC), Dawn - Wind: 140° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: 2,500 ft broken - Temperature: 37 °F, dew point 36 °F - Altimeter: 29.89 inHg - Observed at: KSEA, 1 nm away ## 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 20151219023779I](https://openairdocs.org/incident/20151219023779I), Dec 19, 2015: 2015 Boeing 737-990ER, Seattle, WA, No damage. On Saturday, December 19, 2015, at 0831 pacific standard time, Alaska Airlines flight 27, a Boeing 737-990ER, was cleared to land on runway 16 Center (16C) at… ## Docket (5 files) The files NTSB released with the investigation on September 22, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=92491. 8.8 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120 (item 1, PDF, 11 pages, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12723127&FileExtension=pdf&FileName=6120%20(2)_Redacted-Rel.pdf - Captain's statement (item 2, PDF, 1 page, 900 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9533615&FileExtension=pdf&FileName=PIC%20Statement_Redacted-Rel.pdf - First officer's statement (item 3, PDF, 2 pages, 3.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9534159&FileExtension=pdf&FileName=FO%20Statement_Redacted-Rel.pdf - Flight data recorder - specialist's factual report (item 4, PDF, 10 pages, 6 photos, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=3597098&FileExtension=pdf&FileName=dca16ia036_v2_final_approved_report_for_myDMS-Rel.pdf - Flight data recorder - specialist's factual report - attachment 1 - tabular (zip/csv) (item 5, ZIP, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=3596483&FileExtension=zip&FileName=final_attachment_1-Rel.zip 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.