Jane Ferland was shocked when an Air Canada agent tried to push her suitcase into a metal measuring cart and it didn’t fit.

“This is an official carry-on, that’s why I bought it,” said a baffled Ferland, who was at Toronto’s Pearson airport to catch a flight home to Vancouver.

Last week, Air Canada started a surprise trial crackdown on oversized carry-on a month before it begins charging $25 for the first checked bag for domestic, economy class travel. The fear and the likely reality is that some travellers will try to overload their carry-on to beat the new fee.

But the crackdown is frustrating and confusing many passengers who are stunned when their bags that have made it on-board before, don’t make the cut and must be checked.

“I love my little bag and it was expensive,” said a disappointed Ferland.

Size matters

The bag's only crime was that it was just half an inch deeper than Air Canada’s nine-inch limit.

Ferland has a tag that came with her suitcase that states, “official carry-on.” But the fine print underneath warns the owner to check a specific airline’s rules. That’s because different carriers have different carry-on size restrictions.

Her bag would have passed a British Airways test; that airline allows a maximum depth of 10 inches.

Width and height limits also vary among carriers. For example, WestJet’s height limit is 21 inches, Air Canada's is 21.5 and Porter Airlines's limit is 22. Those measurements include a case's wheels and handle.

Canada's major airlines list their size restrictions on their web sites, which can be found here:

Flyer beware

Michael Warwick, the CEO of Betty Hemmings Leathergoods in Toronto, warns there’s a price to pay when travellers buy their on-board bags anywhere, especially at a big box store, without someone on staff to assist. He keeps a thick binder on hand with airlines’ carry-on restrictions across the globe.

CBC went shopping at a popular retail chain. We found that most carry-on luggage that appeared suitable did not list dimensions. When we measured the suitcases, we found many were slightly taller than Air Canada’s or WestJet’s size restrictions.

“You do need to check the details of [the bag] or at least have the retailer stand behind the product and guarantee that you can carry it on," said Warwick.

It seemed like a heavy handed approach - Jane Ferland, Air Canada passenger

Because of that extra half an inch, Ferland had to check her bag.

“It seemed like a heavy-handed approach for a first [offence]. A warning would have been, to me, the appropriate and polite thing to do," she said, adding that it cost her an extra 30 minutes to check her case and she almost missed her flight. If the new rules had kicked in, she also would have had to pay $25.

Ferland pointed out that Air Canada had already let her take her carry-on on board when she flew to Toronto from Vancouver, where no one was measuring luggage. She added that, on that first flight, her suitcase “fit lovely” in the overhead bin.

Position matters

Warwick said he understands why an airline would quibble over half an inch, at least when it comes to height. Different planes have different-sized overhead bins and therefore different size limits, and a minor half an inch could cause problems.

“Most airlines want you to put your bag in perpendicular to the compartment,” he explained, to save room. “But if your bag is too long, the door on the overhead is not going to close, thereby you’re going to have to turn the bag [sideways] and eat up most of the space.”

Whether travellers will now make the extra effort to measure their bags before they buy or pack may depend on the longevity and extent of Air Canada’s crackdown. For now, the trial is only at Pearson and airline spokesperson Peter Fitzpatrick said it's “open ended” and that the “next steps will be determined by the results.”

He added that the crackdown "is simply about ensuring the existing rules are followed in fairness to all."

WestJet, which will also start charging a similar first checked bag fee at the end of this month, is currently not planning any new carry-on crackdowns. But spokesperson Brie Ogle told CBC, “We must ensure that guests are holding to the allowable size to ensure that there is as much room for everyone as possible.”

Airlines also have weight restrictions. Air Canada allows a maximum of 22 pounds each for your main carry-on bag and a personal item like a briefcase. There’s no word yet if the airline may also start weighing what you plan to take on board.