Swoop, the low-cost carrier owned by WestJet, is apologizing to customers after cancelling 24 flights to the United States.

The Calgary-based airline was forced to cancel the flights while it waits for clearance to fly south of the border.

Curtis Stewart told CTV News he booked a direct flight to Las Vegas two months ago to celebrate his wife’s 50th birthday. The flight was cancelled Thursday—two days before the trip.

“It just gets me extremely angry,” he said. “Extremely angry that they don’t even have the authority to fly and they’re taking money and booking flights.”

Karen McIsaac, Swoop’s senior communications advisor, said the company received approval to sell flights.

Swoop is contacting customers directly “to help them with rebooking options or to provide full refunds to them,” McIsaac said.

Stewart—who paid extra for a bigger seat and other upgrades—is not sure whether he will get all his money back, but wants the airline to be held accountable.

“There has to be compensation. That’s the only way it can happen ... if the airlines actually have to pay a price.”

Swoop expects to begin flights to the United States by October 27.

With files from Amanda Anderson