United Airlines passengers faced a travel disaster last weekend when an onboard medical emergency forced an abrupt landing before the Boeing 777 was left immobile for 12 hours on a Canadian runway.

United Flight 179, which was carrying 250 passengers from Newark, New Jersey to Hong Kong, made its unplanned stop in Newfoundland before suffering mechanical issues. Several of the plane’s necessary exits had frozen shut and, upon a mechanic’s investigation and attempts, were unable to be repaired.

A United spokesperson, as cited by the Wall Street Journal, explained that the flight crew wasn’t allowed to release the passengers as they were in a foreign country and had not been cleared through customs. This was the start of their overnight stay, which officially began around 9:30 p.m. at CFB Goose Bay airport on Saturday.

Since the mechanic couldn’t fix the door issue, those boarded on the plane were forced to wait for a backup aircraft to arrive. Given the Newfoundland facility’s relatively remote location, they faced an extended wait period which led to major frustration. Some passengers contacted United Chief Executive Oscar Munoz after the captain reportedly gave out his email address over the intercom and said, “Send him an email right now and tell him how mad you are.”

Some passengers that emailed Munoz claimed that they still hadn’t received a response come Monday.