Alaska Airlines flight to San Diego returns to SEA after 'unusual vibration' from side of plane

An Alaska Airlines flight headed for San Diego returned to Seattle-Tacoma International Airport shortly after takeoff because of an "unusual vibration" coming from the left side of the plane.

A spokesperson for Alaska told FOX 13 News that Flight 558 returned to the airport and landed safely Monday morning. There were 176 customers and six crew members onboard.

The aircraft, a 3-year-old Boeing 737-900ER, was taken out of service while Alaska's safety team investigates.

Customers were rebooked on another flight for San Diego which was scheduled to arrive about 90 minutes late.