He couldn’t break this seal!

A JFK-bound passenger flying high on duty-free liquor had to be duct-taped to his seat to stop a midair rampage — which included shouts that the plane was going down, sources said yesterday.

Gudmundur Karl Arthorsson, 46, tried to choke and grope several people and was spitting all over the cabin when passengers pounced on him about halfway into the Thursday flight from Reykjavik, Iceland.

“He drank an entire bottle of hard liquor two to three hours into the flight,” said Manhattan resident Andy Ellwood, who posted on his blog a photo of Arthorsson taped to his seat taken by his friend.

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Arthorsson looked so loaded, a flight attendant confiscated two liquor bottles, a source said.

The relentless drunk then “went into the seat pocket in front of him and began consuming a variety of mini bottles,” the source added.

His choice of booze included Grand Marnier, whiskey and schnapps, a source said.

Arthorsson was fairly calm until about 4 p.m., nearly two hours before the flight was scheduled to land.

He “became intoxicated, verbally abusive toward the flight crew as well as other passengers,” a police source said.

Two female passengers next to the alleged drunk, who was sitting in seat 23C, felt uncomfortable and asked the flight crew to switch seats, which two Guatemalan men agreed to do.

Then Arthorsson got violent.

“He tried to grope and strangle fellow passengers and they said absolutely not,” Ellwood said.

He tried to “choke the woman next to him” and was “screaming the plane was going to crash,” according to accounts from terrified passengers.

“Just think of a typical drunk, when he starts taking fighting poses,” a police source said, adding that Arthorsson appeared to be “completely out of his mind.”

The two Guatemalan men got fed up with Arthorsson’s antics and pinned him to his seat.

An off-duty captain helped the good Samaritans hold him down while Icelandair’s flight crew closed in with green duct tape and Flex cuffs, which they used to bind the man around the ankles and knees.

They duct-taped Arthorsson to his seat and gagged his big mouth — just for good measure.

“Police took him when the plane landed,” Ellwood said.

Arthorsson was so drunk that when cops hauled him off the jet at Kennedy Airport, he became terrified and yelled, “There’s a snake on my leg!” a law-enforcement source said.

He was taken to Jamaica Hospital and treated for alcohol poisoning.

Arthorsson, a citizen of Iceland, works in Trinidad and Tobago as a civil engineer, a law-enforcement source said.

The divorced boozehound was on his way to Jamaica to meet his fiancée, the source added.

Cops interviewed Arthorsson, the flight crew and several passengers.

While it’s a crime to be “drunk and disorderly” on a plane, federal authorities declined to prosecute the menace because passengers wouldn’t come forward to detail his threatening behavior, a source said.

Icelandair did not reply to a request for comment.

Additional reporting by Lorena Mongelli