A Software Bug Caused Two Alaska Airlines Flights to Suffer Tailstrikes on the Same Morning

In aviation, a “tail strike” is an unfortunate incident in which a plane’s tail literally strikes the runway, the ground, or another stationary object. Typically, such episodes will occur during take off or landing and, typically, they’re not considered dangerous. However, that’s not always the case, and they have been known to cause real damage to planes.

Well, here’s some less than comforting news: earlier this week, it was reported that a bizarre incident had occurred at Seattle-Tacoma International Airport in late January. During the incident, two tail strikes occurred on the same morning, only minutes apart—both involving Boeing aircraft operated by Alaska Airlines. The incident grounded both flights and forced a temporary shutdown of Alaska’s flight activity nationwide.

Horrifyingly, investigators have now discovered that a software glitch was responsible for the incident. According to the Seattle Times, the tailstrikes occurred largely as the result of a bug in a program sold by a Swedish firm called DynamicSource. The program is supposed to deliver “crucial weight and balance data” that pilots enter into their flight computers to help determine stuff like “how much thrust the engines will provide and at what speed the jet will be ready to lift off.” In this case, the tool delivered faulty data that “seriously undervalued [the] weights for the airplanes.” The Times reports:

…the data [delivered] was on the order of 20,000 to 30,000 pounds light. With the total weight of those jets at 150,000 to 170,000 pounds, the error was enough to skew the engine thrust and speed settings. Both planes headed down the runway with less power and at lower speed than they should have. And with the jets judged lighter than they actually were, the pilots rotated too early.

Gizmodo reached out to Alaska Airlines for more information and will update this story if they respond.

Pretty much everybody is a little afraid of flying. Why wouldn’t you be? You’re being shot across the sky in a metal tube, tens of thousands of feet in the air. Despite everything we know about the statistics, that whole situation just doesn’t exactly scream “safe.” Still, knowing the backend digital infrastructure the airline industry is enough to make you want to travel by Megabus for the rest of your life.