WestJet says a flight from London to Edmonton diverted to Iceland on Saturday after the crew discovered a "potential mechanical issue."
The pilots aboard the Boeing 767 declared an in-flight emergency about two hours after taking off from Gatwick Airport, but landed safely at Keflavik airport.
Dan Hayden, a passenger on the plane, said there was a large cracking noise about 90 minutes into the flight.
"We joked that an engine had gone. About 30 minutes later the pilot confirmed that it was an engine fault and they had been unable to resolve it, so we would land in Keflavik," Hayden said in an e-mail.
WestJet didn't disclose the nature of the mechanical issue, but said the plane would remain in Iceland for maintenance, and passengers would be put up in hotels and given meal vouchers until alternate arrangements could be made.
It wouldn't say how many people were onboard flight WS27, citing competition reasons.
WestJet spokeswoman Lauren Stewart said that declaring an emergency "does not necessarily mean an actual emergency has occurred," and is a measure taken "out of an abundance of caution."
Video of the jet's landing in Keflavik that was posted to YouTube appeared to show an uneventful daylight landing, although fire trucks with lights flashing could be seen near the runway.
WestJet flights to London's Gatwick airport began in May. According to the website www.planespotters.net the Boeing 767 that landed in Keflavik entered service in 1991 with Qantas.
WestJet CEO Gregg Saretsky said in July that issues with the used Boeing 767s that were added to the fleet for the London flights were partly to blame for the company's drop in earnings in the first quarter of 2016.
Saretsky said at the time that the company dealt with flight delays and cancellations, and that the problems were heightened because the aircraft were delivered 55 days late. But he said that "early teething pains" had been worked out.
Hayden, who was on his way from the UK to a wedding in Las Vegas, said they were still waiting for word about flights out of Iceland.
"We have a few days before the wedding, but we have no clothes to handle the cold temperatures here so we hope it's not a long stay," Hayden said.