Alaska B739 at Seattle on Dec 19th 2015, landed on taxiway

Last Update: June 11, 2020 / 14:08:04 GMT/Zulu time

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Incident Facts

Date of incident
Dec 19, 2015


Flight number

Aircraft Registration

Aircraft Type
Boeing 737-900

ICAO Type Designator

Airport ICAO Code

An Alaska Airlines Boeing 737-900, registration N477AS performing flight AS-27 from Chicago O'Hare,IL to Seattle,WA (USA) with 153 people on board, was on an ILS approach to runway 16R cleared to land on runway 16R, when tower offered a visual swing over to runway 16C, the crew opted to accept runway 16C but aligned with taxiway T in between runways 16R and 16C and continued for a safe landing on taxiway T at 08:31L (16:31Z), no other traffic was on taxiway T at that time. Tower, maintaining routine communication, cleared the aircraft to cross runway 16L, the crew read that clearance back after a slight hesitation and maintained routine communication, too.

Alaska Airlines confirmed their flight AS-27 landed on taxiway T on Dec 19th 2015, the occurrence is under investigation, further details can not be told due to the pending investigation.

The FAA reported, the occurrence is being investigated by the FAA.

On Feb 13th 2016 the NTSB announced that they have opened an investigation into the occurrence rated an incident. At the time of landing visual meteorologic conditions prevailed when the aircraft touched down on taxiway T instead of the intended runway 16C.

On Jun 10th 2020 the NTSB released their final report concluding the probable cause of the incident was:

the flight crew's misidentification of the taxiway as the landing runway.

The NTSB summarized the testimonies of both flight crew:

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.

KSEA 191753Z 16007KT 10SM FEW026 OVC038 04/02 A2992 RMK AO2 SLP141 60000 T00390022 10044 20028 51012 $
KSEA 191653Z 12008KT 10SM FEW022 03/02 A2991 RMK AO2 SLP137 T00330017 $
KSEA 191637Z 12010KT 10SM SCT022 03/02 A2991 RMK AO2 $
KSEA 191553Z 16007KT 10SM FEW016 BKN025 03/02 A2990 RMK AO2 SLP134 T00280017 $
KSEA 191523Z 14010KT 10SM FEW008 SCT016 OVC027 03/02 A2989 RMK AO2 $
KSEA 191453Z 15007KT 10SM SCT018 BKN029 04/03 A2989 RMK AO2 SLP129 60000 T00390028 53005 $
KSEA 191411Z 14009KT 9SM SCT003 BKN014 BKN029 04/03 A2988 RMK AO2 $
KSEA 191424Z 16007KT 10SM FEW003 SCT018 BKN025 04/03 A2988 RMK AO2 $
KSEA 191357Z 14007KT 1/2SM BR BKN005 OVC014 04/03 A2988 RMK AO2 SFC VIS 4 $
KSEA 191353Z 14007KT 7SM BKN005 OVC014 04/03 A2988 RMK AO2 RAE1255 SLP127 P0000 T00440028 $
KSEA 191342Z 15006KT 10SM FEW005 BKN016 OVC032 04/03 A2988 RMK AO2 RAE1255 P0000 $
Aircraft Registration Data
Registration mark
Country of Registration
United States
Date of Registration
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ICAO Aircraft Type
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Aircraft Address / Mode S Code (HEX)
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FbcefjkgnqeqkgAqcjpAic bpeeAlhAlbglAiihfcAmhgnqlhqcdfhdebplcm iAiqedAg ddfk mpljnjqhhkdpgeAjmpAggqmqjgfbd Subscribe to unlock
Incident Facts

Date of incident
Dec 19, 2015


Flight number

Aircraft Registration

Aircraft Type
Boeing 737-900

ICAO Type Designator

Airport ICAO Code

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