As passengers become increasingly frustrated with the high costs of plane travel, some Canadian airlines are making no apologies, telling consumers more service fees are on the horizon.

According to new numbers released Thursday, 4.2 million passengers flew with Canada’s two largest air carriers, Air Canada and WestJet, in March. That number is up 14 per cent over last year.

The trend is expected to continue into the busy summer vacation months.

But air carriers aren’t making concerted efforts to get passengers on board. In fact, it’s seemingly the opposite. Air Canada earned $122 million in profits in the first quarter of 2015.

The hefty sum was in part due to lower fuel costs, but the airline said its non-fare revenue per passenger increased 15 per cent, thanks to additional costs such as cancellation fees, preferred seating, and checked baggage fees. WestJet also posted a quarterly record due to falling fuel prices and higher fees.

Now, after letting the rule slide for years, Air Canada announced it will now begin cracking down on carry-on bag sizes.

“We will have additional staff at check-in and security to quickly confirm and tag carry-on bags that meet Air Canada’s existing carry-on dimensions as ‘approved,’” the airline said.

If the luggage is found oversized or overweight, passengers will be charged to check it.

The enforcement of the carry-on rule kicks in on Monday in Toronto. Air Canada says it will then begin weighing and measuring bags at airports across the rest of the country in June.

Aviation experts say it isn’t a money grab, but standard practice -- and a safety matter.

“It can affect the weight and the balance of the aircraft,” said Phyl Durdey. “It also causes a delay. If the bags don’t fit in the overhead bins, then they have to be moved down to the cargo.”

Airlines are posting record profits and benefit from low fuel costs. And soon will be increasing fees for extra bags, preferred seating, WiFi and food.

The changes come at a time when airline passengers are becoming increasingly frustrated with flying.

“We’re going in to the wrong direction, and consumers are actually telling we’re going in the wrong direction,” said Dean Headley, a marketing professor at Wichita State University.

And what about receiving more bang for your buck? There’s no guarantee. A new U.S. study found that on-time airline arrival rates fell to 76 per cent last year. Lost, stolen or delayed bags jumped by 13 per cent.

Delays are becoming an issue in the United States. On Wednesday, a passenger angry about his overbooked Charlotte, N.C.-Jamaica flight took his frustration to new heights: He stripped down naked in protest.

With files by CTV’s Peter Akman and The Canadian Press