Jun. 14—The crew of a Southwest Airlines flight from Phoenix to Oakland had to regain control of a Boeing 737-8 Max aircraft after it experienced a rare, midair Dutch roll last month, according to the Federal Aviation Administration, prompting the plane to be taken out of service.
But what exactly is the phenomenon?
A Dutch roll, named after the movements of traditional ice skaters, is when an airplane sways back and forth both laterally, called "rolling," and directionally, called "yawing," according to Boeing.
In other words, the plane's wing tips tilt up and down on either side (the rolling), while its nose and tail wobble left to right (the yawing).
The plane's nose makes a figure-eight motion as a result of the out-of-phase oscillations, according to the FAA. The rocking movement can cause airsickness.
The oscillations will continue until the movement eventually corrects itself or a pilot corrects it, according to Boeing.
Pilots are trained to handle the motion, which can be caused by any "asymmetric input," like wind or an action by the pilot. In the Southwest case, a preliminary inspection by the FAA found damage to a unit that supplies backup power to the rudder, which officials indicated could have led to the May 25, incident, the Associated Press reported.
The National Transportation Safety Board said Friday that it had opened an investigation into the incident. In a post on social media platform X, the agency said that maintenance on the plane performed by Southwest after the May 25 "inflight oscillation event" had revealed damage to structural components, which it reported to the NTSB on June 7.
The agency has received data from the plane's digital flight data recorder, which will "aid investigators in determining the length and severity of the event," the post said.
"The cockpit voice recorder, which is currently limited to two hours of audio, was overwritten and unavailable to investigators," the agency said.
A preliminary report is expected within 30 days, according to the NTSB.
The FAA said it was working with the NTSB and Boeing to investigate the incident, the Associated Press reported.
Reach Danielle Echeverria: [email protected]; Twitter: @DanielleEchev
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