Is a Dutch Roll dangerous? What passengers should know about the recent Southwest incident

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 raised further safety questions about the aircraft.

The National Transportation Safety Board (NTSB) is investigating the incident, which only came to light last week, the agency said on X. The incident caused damage to “structural components” of the aircraft, the agency said, adding that the duration and severity of the movements have not yet been determined.

A Southwest spokesman said they were “participating in and assisting with the investigation.” Further questions were directed to the NTSB.

Although no one was injured and it is too early to determine the cause of the rollover, the incident comes at a difficult time for Boeing and the Max. The Federal Aviation Administration (FAA) launched an audit of Boeing’s production lines after a door stopper on an Alaska Airlines 737 Max 9 broke off in January. Until the regulator approves the move, the planemaker is not allowed to increase production above 38 planes per month.

What is a Dutch Roll?

“A Dutch roll is a series of out-of-phase turns in which the aircraft rolls in one direction and yaws (turns) in the other,” said Daniel Kwasi Adjekum, assistant professor in the aeronautics department at the University of North Dakota.

The movement is very similar to “the rhythmic, flowing movement of a Dutch ice skater on a frozen canal,” as Michael Cook describes it in his book “Flight Dynamics Principles.”

“Dutch rolls,” for example, could be caused by “wind or pilot commands,” Boeing explained in a 2022 post.

The movements aren’t necessarily unusual in flight. Aerobatic pilots sometimes perform them as part of their displays at air shows, Adjekum said. But they’re unusual on commercial flights because most modern aircraft have yaw dampers that quickly compensate for unexpected movements.

What travelers should know

Dutch rolls themselves are not necessarily dangerous, but they can be uncomfortable for pilots and cause nausea or airsickness.

Pilots are trained to perform Dutch rolls and return an aircraft to normal flight.

“My only advice to passengers is to always wear their seatbelts in such cases to ensure their safety,” said Adjekum.

Damage caused by “Dutch rolls” such as those that occurred on the Southwest plane in question is unusual, former pilot and CEO of Safety Operating Systems John Cox told the Washington Post. He added that he had “more questions than answers” about the Southwest incident.

The most recent incident occurred at about 8 a.m. on May 25 on Southwest Flight 746 from Phoenix to Oakland when it was at an altitude of 34,000 feet, the NTSB said.