Is a Dutch Roll Dangerous? What Passengers Should Know About the Recent Southwest Incident

20.06.2024 - 16:57 / travelandleisure.com

The Boeing 737 Max is back in the news after the plane was involved in a “Dutch roll” on a Southwest Airlines flight from Phoenix to Oakland in May. The incident caused significant structural damage and is raising further safety questions about the aircraft.

The National Transportation Safety Board (NTSB) is investigating the event that only came to light in the past week, the agency said on X. The incident caused damage to “structural components” on the plane, the agency said, adding that it has yet to determine the length or severity of the movements.

A Southwest spokesperson said it was “participating in and supporting the investigation.” They directed further questions to the NTSB.

While no one was injured and it is too early to know what caused the Dutch roll, the incident comes at a tough time for Boeing and the Max. The Federal Aviation Administration (FAA) launched an audit of Boeing’s production lines after a door plug blew off a 737 Max 9 plane operated by Alaska Airlines in January. The planemaker is also barred from increasing production above 38 planes-per-month until the regulator signs off.

“A Dutch roll is a series of out-of-phase turns when the aircraft rolls in one direction and yaws [twists] in the other,” said Daniel Kwasi Adjekum, an assistant professor in the aviation department at the University of North Dakota. 

The motion is much like the “the rhythmical flowing motion of a Dutch skater on a frozen canal,” as Michael Cook put it in the book "Flight Dynamics Principles."

Dutch rolls can be caused by things like “wind or pilot commands,” Boeing said in a 2022 post.

The movements are not necessarily uncommon in flight. Acrobatic pilots sometimes perform them as part of their demonstrations at air shows, Adjekum said. They are, however, uncommon on commercial flights as most modern airplanes have yaw dampers that quickly correct for any unexpected movements.

Dutch rolls themselves are not necessarily dangerous but can be uncomfortable to fliers and cause nauseousness or airsickness.

Pilots are trained to handle Dutch rolls and return a plane to normal flight. 

“My only advice for passengers is always to be strapped in with their seat belts when seated to ensure their safety in case of such events,” said Adjekum.

Damage from Dutch rolls, as happened to the Southwest plane in question, is uncommon, former airline pilot and CEO of Safety Operating Systems John Cox told The Washington Post. He added that he has “more questions than answers” about the Southwest incident.

The latest incident occurred on Southwest flight 746 from Phoenix to Oakland while it was cruising at 34,000 feet at around 8 a.m. on May 25, the NTSB said.