A massive military aircraft flew over San Francisco on Tuesday afternoon, letting out a thunderous roar that shocked many residents in the area.

Thunderous Roar

The giant plane flew past the region at about 2:35 p.m., causing a disturbance and resulting in questions posted on Twitter since Fleet Week is still several months away. Residents believe it could have been a fighter jet before it was revealed that it was an Air Force KC-10 Extender, a large aerial refueling tanker aircraft.

The plane was part of the Travis Air Force Base 9th Air Refuelling Squadron. Officials authorized the aircraft to pass over the Bay Area as part of their tradition called a “fini flight.”

“We call it a ‘fini flight’ and it’s your final flight at this base before retirement or moving on to another unit. It’s kind of like a celebration flight or a send-off. They come back afterward and celebrate with their friends and family and other members of the unit,” Travis Air Force Base Public Affairs Officer Lt. Amelia Chromy said.

Chromy said the Tuesday flight was made in honor of someone within the Air Force who was moving to a different unit. She noted these kinds of flights can use any type of aircraft and can have more than one plane at a time, the San Francisco Gate reported.