Federal officials are investigating why a Southwest Airlines flight recently experienced a rare, potentially dangerous back-and-forth rocking known as a “Dutch roll” midflight.
The incident happened on the morning of May 25 on a Southwest Airline flight traveling from Phoenix to Oakland, according to a notice from the Federal Aviation Administration. The plane, a Boeing 737 Max 8, was carrying 181 people when the aircraft experienced a Dutch roll at 34,000 feet of altitude, officials said.
“A Dutch roll is a coupled oscillation in an airplane’s yaw and roll axes, inherent to the flight dynamics of all conventional airplanes,” according to the National Transportation Safety Board. Aviation safety analyst and former airline pilot Kathleen Bangs described it to CNN as “a very uncomfortable movement” in which passengers “feel the tail swinging around.”
No injuries were reported in the incident.
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Shem Malmquist, a commercial pilot and instructor at Florida Tech, told NPR that Dutch rolls are “pretty rare on modern airplanes” because planes and their systems are designed to prevent them. He emphasized the importance of training for pilots to know how to respond to such situations.
“Obviously in this case they were” trained, he said, according to NPR. “That training is really, really critical.”
It was not clear what caused the issue on the Southwest flight. In a statement obtained by Bloomberg News, the FAA noted, “Other airlines have not reported similar issues.”
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Airline officials did maintenance on the plane after it safely landed and found “damage to structural components,” according to the NTSB. It was not immediately clear if the damage was caused by the Dutch roll or if it might have caused the plane to experience the rocking.
The NTSB said it will use data downloaded from the plane’s digital flight data recorder to determine the length and severity of the incident. The agency expects to release a preliminary report later this month.
The incident happened as Boeing faces scrutiny following a series of safety incidents — including one that saw a door plug blow off a Boeing 737 Max 9 jetliner midflight in January. Authorities continue to investigate.