A commercial airline pilot landed on the central taxiway instead of the runway at Seattle-Tacoma International Airport earlier this month, and now officials are investigating to determine whether the landing was an accident.

The pilot of an Alaska Airlines Boeing 737 inbound from Chicago made the mistake on Dec. 19, reported The Puget Sound Business Journal. There were no other aircraft on the taxiway when the plane landed, and the results would have been disastrous if there was.

Several minutes before landing at around 8:30 a.m. local time, air traffic control tower notified the pilot that he was clear to land on runway 16 Center, though the flight was originally scheduled to land on 16 Right. However, minutes later, instead of landing on either runway, the pilot landed on the central taxiway, which lies in between both of them.

From an aerial view, the difference between the taxiway, which is used to by pilots to move their planes around the airport, and the runway is negligible, if at all noticeable. However, safety experts assert that pilots have been trained to be able to tell the difference and avoid the taxiway as they land, according to USA Today.

"This is not a new problem at Sea-Tac. There have been cases going back to the 1990s of aircraft inadvertently landing on what's called 'taxiway tango,'" aviation safety expert Todd Curtis said, adding that the landing instructions for Sea-Tac warn pilots about the potential for confusion on taxiways.

"So although this was a dangerous condition, a condition that should be avoided, it's something that can be learned from," Curtis said.

Sea-Tac officials say that the last time it happened was in 2004, before the addition of the third runway, making this the fourth time an incident has occurred in the airport's history. The markings and size of the taxiway are different than those of the actual runways, which include distinct markings.

However, the incident happened several days after workers finished paving the central runway, which could have played a role in the improper landing.

Regardless, the FAA and Alaska Airlines have launched investigations, reported NBC's Washington affiliate KING-TV. Depending on the findings, FAA could order Sea-Tac Airport to make changes if it's deemed necessary.