NTSB Factual Report

On March 14, 2003, at 1620 Pacific standard time, an American Airlines DC-9-82, N298AA, landed on Taxiway Charlie at Seattle-Tacoma International Airport, Seattle, Washington. There were no injuries to the flight crew, the cabin crew, or any of the 105 passengers. The aircraft, which is owned and operated by American Airlines, Inc., was not damaged. All occupants exited the aircraft at the passenger terminal using normal means. The 14 CFR Part 121 scheduled domestic passenger flight, which departed Dallas-Fort Worth Airport at 1435 central standard time, was being operated in visual meteorological conditions at the time of the incident.

At the time the aircraft arrived in the area adjacent to Mount Rainer, the Bay Visual Approach was in effect, and according to American Airlines, during his pre-landing flight crew briefing, the Captain stated that he intended to execute the visual approach backed up by the ILS to Runway 16 Right. Because there was a ceiling over the final approach course, while the flight was tracking to the north on the east side of the airport, they were advised by the approach controller to expect the ILS to Runway 16 Right. The flight was then vectored to a 15 mile final and cleared for the ILS approach. About four to five miles from the end of the runway, at about 3,500 feet above the ground (AGL), the flight crew passed through the cloud deck, made visual contact with the runway environment, and transitioned to visual navigation. According to the information collected from the flight data recorder immediately after the event, the aircraft started a constant-rate deviation to the right of the localize approximately the same time as the aircraft passed 3,500 feet AGL. This deviation was the result of the flight crew maintaining a heading between 153 degrees and 156 degrees magnetic, which was taking them directly to the "approach end" of Taxiway Charlie. Neither the Captain nor the First Officer were aware they were lined up on the taxiway, and they did not know they had landed on the taxiway until advised by the tower. A rain shower had recently moved through the area, and although there was an overcast over the center and north end of the airport, south of the field rays of sunlight were shining through holes in the clouds, resulting in a glare from the wet paved surfaces.

During the investigation it was determined that during the four years prior to this event, there had been one other reported landing on Taxiway Charlie, and two reported instances where flight crews had lined up on the taxiway, but on short final had either executed a go-around or sidestepped to Runway 16 right. In May of 2000, the airport installed an "X" (about 12 feet across) about 150 feet off the north end of Taxiway Charlie, but the subject crew did not detect it on this approach. It was also noted that since January of 2001, there has been an entry in the United States Government Airport Facility Directory stating, "Do not mistake Txy C for a landing surface."

NTSB Probable Cause

The flight crew's misidentification of the parallel taxiway as the active runway, resulting in the flight crew executing a landing on the taxiway. Factors include sunglare from the wet paved surfaces, and a visual illusion created by the airport surface environment.