Two Southwest planes collide at Sea-Tac

Two Southwest planes collided at Sea-Tac this morning before passengers or even the crew could board them.

Officials tell us the rear Boeing 737 rolled into the other plane by accident this morning.

The rear plane's body actually went under the horizontal stabilizer of the Southwest plane in front of it.

"It's something that should never happen,”  said Mike Cantrell, an airplane mechanic.

When we showed Cantrell the photo—he said he was surprised.

In his 30 years as an airplane mechanic, he's never seen anything like it.

"No excuse whatsoever and very expensive,” said Cantrell.

What was supposed to happen?

According to officials, the rear plane was supposed to be pushed out to the cargo gate.

But around 6:30 a.m. Monday, something went wrong.

"Aircraft are not allowed to just roll around aimlessly on the runway, by themselves, or the taxiway, obviously people were involved that didn't do their job,” said Cantrell.

And we found other collisions involving Southwest planes this summer.

A Southwest Airlines flight at Denver International Airport was reversing and made contact with a catering cart in August.

Also this last August, two Southwest Airlines planes clipped wings at the gate of Oakland’s airport.

KIRO