Less than an hour after taking off from Phoenix on May 25th, the plane experienced an uncontrolled side-to-side yawing motion known as a Dutch roll while cruising at 32,000 feet. The pilots of Southwest flight 746 were able to regain control and the plane landed safely in Oakland, according to a preliminary report from the FAA.

“A Dutch roll is definitely not something that we like to see,” said Shem Malmquist, a commercial pilot who flies the Boeing 777 and an instructor at Florida Tech.

The Boeing 737 Max 8 jet involved in the Dutch roll incident is less than two years old. According to the FAA, a post-flight inspection revealed damage to a backup power control unit, known as a PCU. That system controls rudder movements on the plane’s tail.