NTSB Factual Report

On January 19, 2004, at 1138 Pacific standard time, the flight crew of a de Havilland DHC-8, C-GTAQ, inadvertently landed on Taxiway Tango at Seattle-Tacoma International Airport, Seattle, Washington. There were no injuries to the Captain, First Officer, Flight Attendant, or any of the 32 passengers. There was no damage to the aircraft, which is owned and operated by Air Canada Jazz. The 14 CFR Part 129 scheduled air carrier flight, which departed Vancouver, British Columbia, Canada, about 35 minutes prior to the incident, was landing in visual meteorological conditions. The aircraft had been on an IFR flight plan.

According to the flight crew, they were cleared by Seattle Center for a visual approach to Runway 16 Right. They contacted Seattle-Tacoma Tower when they were near Elliot Bay, and were cleared to land on Runway 16 Right, number two behind a 737 that was then touching down. Because of the distance between their position and the preceding 737, neither flight crew member saw the aircraft they were sequenced behind. The Captain, who was flying at the time, therefore aligned the aircraft with what he felt sure was Runway 16 Right. He then continued on the approach, and completed what to him seemed to be an uneventful landing. Soon after the aircraft touched down, the tower advised the flight crew that they had landed on Taxiway Tango.

The Captain said that when they lined up on final approach, there was an overcast over the approach end of the runway (which was dry), bright sunshine to the south of the airport, and a glare on the runway surface. According to him, this caused the area around the approach end of the runway to appear as one dark color (shadow), making it hard to differentiate between Runway 16 Right and Taxiway Tango. He further stated that he had been into Seattle-Tacoma Airport many times before, and was aware of the large "X" just off the north end of Taxiway Tango. But, according to the Captain, because of the contrast between the runway glare and the dark area around the approach end, he did not notice that he had flown over the "X" just prior to touchdown.

In a later discussion with the Investigator-In-Charge (IIC), the Captain stated that it was his opinion that lights on the aforementioned "X" along with some form of spaced-interval visual clues painted directly on Taxiway Tango would probably have alerted him to the misidentification of the landing surface in time to execute a safe go-around.

The Safety Board's investigation of the incident revealed that this was the third known instance of a flight crew landing on this taxiway after mistaking it for Runway 16 Right. In addition, it was determined that in at least two other instances prior to the Air Canada Jazz incident, and one subsequent to the Air Canada Jazz incident, flight crews that had been cleared to land on Runway 16 Right lined up on Taxiway Tango, and maintained their approach to a point where they came close to landing on Taxiway Tango, but instead made either a last second go-around or a sidestep to landing on the active runway.

The first of the reported events occurred at 1145 Pacific standard time, on December 2, 2000. The aircraft was a Cessna 208 operated by Harbor Air as scheduled passenger flight number 4506. At the time of the event, the aircraft was being operated under visual flight rules (VFR), and had been cleared for a visual approach to Runway 16 Right. The surface observation at the time reported 10 miles visibility, and the lowest ceiling was a broken layer 2,200 feet above the ground (AGL).

The second reported event took place at 1620 Pacific standard time, on March 14, 2003. The aircraft was an American Airlines MD-80, being operated as scheduled passenger flight number 1763. The flight crew involved in this event had been established on the localizer for an instrument landing system (ILS) approach to Runway 16 Right, but transitioned to visual navigation once they broke out of the overcast about 3,500 feet AGL and about five miles from the runway. According to the information collected from the flight data recorder immediately after that 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 Tango (at that time designated Taxiway Charlie). Neither the Captain nor the First Officer were aware they had landed on the taxiway until advised by the tower. At the time of this event the visibility was reported as 10 miles, and the lowest ceiling was a 6,000 foot broken layer, with a 3,000 foot scattered layer below. A rain shower had recently moved through the area, and south of the field rays of sunlight were shining through holes in the clouds, resulting in a glare from the wet paved surfaces.

The third reported taxiway-landing was the Air Canada Jazz (regional) de Havilland DHC-8 that is the subject of this incident report.

The first of the three known events where flight crews came close to landing on Taxiway Tango, but ultimately took other actions, occurred in December of 1999. Because the data related to this event comes from the voluntary Air Safety Reporting System (ASRS), the information available is limited to the aircraft being a scheduled Part 121 air carrier passenger flight that landed between 0601 and 1200 on that day. The aircraft was a Boeing 737-800. According to the Captain of this flight, who filed the ASRS report, he was executing a visual approach to Runway 16 Right on a clear bright morning, when he suddenly realized that he had inadvertently lined up on Taxiway Charlie (Tango). Although he was on short final at the time, he was able to sidestep to the active runway. He further stated that of the three individuals on the flight deck, himself, the First Officer, and another captain in the jump seat, he was the only one who recognized the fact that they were about to land on the taxiway.

The second event wherein a flight crew nearly landed on Taxiway Tango occurred on January 10, 2004, at 1345 Pacific standard time. The aircraft was a Boeing 737-400 being operated by Alaska Airlines as a scheduled passenger flight. During this event an FAA Avionics Inspector was riding in the jumpseat when the flight crew was cleared for a visual approach to Runway 16 Right while they were approximately 10 miles north of the airport. After being cleared for the visual, the flight crew inadvertently lined up to land on Taxiway Tango. When the aircraft was about 300 feet AGL, on "very short final," the inspector pointed out to the crew that they were about to land on the taxiway. The flight crew then executed a go-around and completed a VFR closed pattern to land on the active runway. At the time of the event there was a 5,000 foot overcast, 10 miles visibility, and according to the FAA inspector, no glare or reflection from the area around the airport.

The third near-landing event on Taxiway Tango occurred on February 24, 2004, at approximately 0930 Pacific standard time. The aircraft was a Boeing 737-300 operated by Southwest Airlines as a scheduled passenger flight. According to the flight crew, while they were west of the airport, the flight was cleared for the Bay Visual Approach to Runway 16 Right. The First Officer, who was flying at the time, made a right turn over Elliott Bay and lined up on what he believed to be Runway 16 Right. When the aircraft was about one-half mile from the end of the taxiway, the first officer noticed an X located just off the northern end of the taxiway. Upon realizing he was lined up on the wrong surface he initiated a sidestep to Runway 16 Right. He subsequently completed an uneventful landing on Runway 16 Right, and taxied to the gate for a normal deplanement of the passengers. At the time of the event, the airport's paved surfaces were wet from a recent rain shower, and the Captain, who was backing up the First Officer during the approach, did not realize the aircraft was lined up on the taxiway until the First Officer initiated the sidestep maneuver.

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 sun glare and shadows around the runway/taxiway environment, and visual illusions created by the airport surface environment.