Some Porter Airlines customers say they are having difficulty trusting the carrier with their travel plans after a series of last-minute flight cancellations over the month of July.

Quincy Korte-King said her flights from Ottawa to Toronto and Toronto to Chicago were cancelled and bumped back five hours on July 28. Then, on her way back on July 31, her flight from Toronto to Chicago was cancelled as well.

"The first time around I thought it happens, it's part of travelling," she said.

"Then the second time around it was a little bit ridiculous — not only that my third flight was cancelled … but they weren't actually telling me 'oh you're a loyal customer, let us give you a free voucher or let us help you get on an earlier flight.'"

The least you could've done is put me on the flight directly before/after. Instead I'll be in YTZ for 4 hours 😑 would be faster to train... <a href="https://t.co/krTgzpFDis">pic.twitter.com/krTgzpFDis</a> —@quincykk

Korte-King said she ended up with a five hour layover at the Billy Bishop Toronto City Airport, which was packed with other customers experiencing similar delays.

She said they didn't provide a meal voucher or even allow her to get priority on the next flight to Ottawa since she'd already experienced cancellations.

"I'm pretty disappointed. I'm a loyal Porter flyer. I live in New York, my family lives in Ottawa," she said. "So I use them a lot."

I don't really want to go fly Porter again, because of the experience. - Quincy Korte-King

Korte-King said she wasn't given any reason for the cancellations and only received a $150 voucher for a trip worth $400.

"I don't really want to go fly Porter again, because of the experience," she said. "So I am trying to get them to give me the money as a refund instead of a flight voucher."

Wedding anniversary road-trip

On July 16, Richard Bootsma and his wife Carolyn Bissett had booked a flight with Porter from Ottawa to Newark, connecting in Toronto. They found out their flight was cancelled two hours before takeoff while waiting in the security line.

They'd been rebooked for a flight the next day, which would have cut their three-day vacation in New York City to mark their 10th wedding anniversary too short to make it worth the travel.

"We hadn't planned for this at all, we had non-refundable hotels booked, we had shows booked. We kind of had the whole thing mapped out," Bootsma said.

"We actually had to jump in our car that morning and basically wing it and try to find our way there."​

Richard Bootsma holds a printed version of the notice of his flight cancellation from July 16, 2017. (Matthew Kupfer/CBC)

Bootsma said it was frustrating that they couldn't travel the same day and they weren't given a clear explanation for why the flight couldn't go ahead.

The couple was refunded the full cost of the trip — about $950 — and Porter offered $50 vouchers for future flights, though it's unlikely the couple will redeem them, Bootsma said.

"The circumstances of it being a 10-year anniversary, [there was] no reason for the cancellation and no guarantee to get us there in any time that would've made the trip worthwhile anymore," he added. "Probably is going to make us a little leery to travel with them again. I think makes a good case for maybe travelling by rail the next time."

Airline apologizes

Porter Airlines said they could not pinpoint the factors that led to the specific flight cancellations or why passengers weren't communicated with more quickly when the delays happened.

Brad Cicero, a spokesperson for Porter Airlines, said the airline dealt with issues around crew availability and a military airspace closure over Trenton that may have contributed to delays and cancellations on those days.

"We work very hard to maintain a reputation as a service-oriented airline that's reliable for people and we want people to have that trust and that faith in us and we absolutely apologize whenever we're in a position where anyone was let down," he said.

Cicero said neither Bootsma and Bissett's experience or Korte-King's were what the airline wanted and that the vouchers were a gesture of goodwill.

Weather, ground delays lead to cancellations

Cicero said the apparent increase in cancellations this summer is related to longer ground delays and ground stops, which are ordered by air traffic control.

Those ground delays and stops are usually caused by weather, such as thunderstorms, and volumes of flights once weather clears, he added

The delays have increased to "unprecedented" levels, he said, with waits up to five and six hours becoming common, whereas delays between two and three hours used to be considered long.

Porter spokesperson Brad Cicero says there have been more delays and cancellations in the eastern U.S. than usual due to weather. (Gary Cameron/Reuters)

He said it affects the airline's trips to the eastern United States more than other regions.

"It's almost impossible to operate every flight because of the length of the delays. It puts strain on crews, they're only allowed to operate for a certain number of hours based on their schedules. That has a sort of repeat effect across the network," he said.

"That's definitely something we're seeing this summer moreso than any other."