Here’s What Can Cause a Terrifying ‘Dutch Roll’ During a Flight
After a recent incident on a Southwest Airlines flight, this aerodynamic phenomenon is making headlines.
A Dutch Roll sounds like a flaky croissant-style treat stuffed with soft cheese that you can only find in certain regions of Europe. But when encountering a Dutch roll, your mouth won't open to take a pleasant bite of pastry. It may open as you release a scream of terror, however. Passengers on a Southwest flight from Phoenix to Oakland on May 25, 2024 experienced this when the Boeing 737 Max 8 they were on did a Dutch roll. Although the plane landed safely, and no injuries were reported among the crew or passengers, the incident did result in damage to the aircraft.
According to a Bloomberg report, that's not the first dramatic incident to happen on a Southwest flight in recent months. Just one month before the Dutch roll, a different Boeing 737 Max 8 aircraft plummeted 4,000 feet per minute, coming just a few hundred feet from the ocean before leveling out off the coast of Hawaii. That incident happened after the plane unsuccessfully attempted to land during a storm.
In the May incident, Southwest Airlines did not report the Dutch roll or that the aircraft was damaged until June 7. This has led to the Federal Aviation Administration and the National Transportation Safety Board launching an investigation into Southwest Airlines.
"Following the event, SWA [Southwest Airlines] performed maintenance on the airplane and discovered damage to structural components," a statement from the NTSB said. "SWA notified the NTSB of the event and damage on June 7. The NTSB's Vehicle Recorder Laboratory in Washington has received data downloaded from the airplane's digital flight data recorder. Data from the recorder will aid investigators in determining the length and severity of the event."
So, what exactly is a Dutch roll, and why does it merit an official investigation? Let's get into it.
What is a Dutch roll?
According to the FAA, the Dutch roll "is a coupled lateral/directional oscillation that is usually dynamically stable but is unsafe in an aircraft because of the oscillatory nature."
If that feels like a complicated explanation, don't worry. It is. That definition is meant for people already familiar with aerodynamics and airplanes. A more straightforward explanation, gleaned from watching YouTube videos, is that when in a Dutch roll, the aircraft moves 'wrong' on two of its three axes—its lateral (side to side) and directional (left to right) axes. The movement of its lateral axis is called rolling, and the directional axis is called yawing.
In a Dutch roll, the yawing and rolling motions feed into each other, making the plane tip from side to side and move from left to right. According to the FAA, this causes the plane to move in a figure-eight motion, throwing off the plane's stability.
Why is it called a Dutch roll?
According to the Associated Press, the name comes from how similar the motion is to Dutch figure skaters' movements on the ice.
What causes a Dutch roll?
According to Boeing, "Dutch rolls are caused by any asymmetric input, such as wind or pilot commands, causing a series of oscillations that will continue until the movement fixes itself or the pilot corrects it."
The Dutch roll is considered a phenomenon—from the reports about the May Southwest incident, it appears that there was damage to the plane, causing errors with the plane's rudder. This damage could have contributed to the plane's inability to stabilize itself, causing the Dutch Roll.
Is a Dutch roll dangerous?
According to my new favorite YouTube creator, Mentour Pilot, the Dutch roll is "not inherently dangerous."
"It's a perfectly normal movement," Petter Hörnfeldt, the man behind Mentour Pilot, explains in his video of the Dutch Roll. Hörnfeldt has been a Boeing 737 flight instructor for over a decade and produces social media content educating people about aviation. "If the aircraft is well constructed, it should just oscillate itself out."
Basically, if a plane is well constructed, it should naturally rebalance itself. But Hörnfeldt explains that pilots can make decisions in response to the aircraft entering the Dutch roll that can further exacerbate the instability. If a pilot mishandles the Dutch roll, it can worsen and create dangerous circumstances within the cabin.
However, in most cases, the worst you'll experience from a Dutch roll is motion sickness.
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