What went wrong? Veteran pilot explains Alaska Airlines mid-flight blowout

SEATTLE - Veteran pilot John Nance shared with FOX 13 News his theory as to what caused the blowout on the Alaska Airlines flight departing Portland.

"The fact is, this is terrifying, there’s no question," said Nance. "This, quite frankly, is unprecedented."

After reviewing footage and photos of the incident, Nance deduced the cause of the terrifying incident 16,000 feet up.

"This was a door of one sort or another that came open," said Nance. "The margins of where it left were clean, there was no tearing."

The former Alaska Airlines captain believes there was a problem with a pin inside that door.

"[There is] a provision made for additional doors if the client wants it," explained Nance. "Boeing puts those in there, and if they’re not going to be used, they put a plug in place."

The aviation expert says these pins aren’t viable to passengers sitting in the cabin because they are hidden in the aircraft’s walls.

"By and large, we’ve got thousands of these doors flying around all the time," said Nance. "Not just the plugs but, of course, the emergency exit doors. They do not come open because they’re engineered extremely well."

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Nance explained that inspecting these pins is a tedious process. Crews must take apart plane walls panel by panel.

"Then they have to put the insulation back in. That’s why it takes 4–5 hours per airplane," said Nance.