MONTREAL -- Transport Minister Marc Garneau said he was "surprised" and "disappointed" by legal action from Canadian airlines to quash new rules to beef up compensation for passengers subjected to delayed flights and damaged luggage.

"We feel that we have done our homework very, very carefully in consultation with the airlines and with other stakeholders," Garneau told reporters Monday, when the first phase of long-promised air travel regulations took effect.

"We feel that the passenger rights that we've put in place are going to stand up and that they're very fair to both passengers and to the airlines."

Air Canada and Porter Airlines Inc., along with 17 other applicants that include the International Air Transport Association -- which counts WestJet Airlines Ltd. among its 290-odd member airlines -- state in a court filing that mandatory compensation under the passenger bill of rights violates international standards and should be rendered invalid.

The June 28 court application argues that the passenger bill of rights contravenes the Montreal Convention, a multilateral treaty, by setting compensation amounts based on the length of the flight delay and "irrespective of the actual damage suffered."

Consumer advocates, however, say the rules do not go far enough, arguing that airlines' exemption from compensating customers in situations "outside of the airline's control" uses too broad a definition and amounts to a loophole.

A second batch of rules, set to roll out in December, imposes no obligation on airlines to pay customers for delays or cancellations if they were caused by mechanical problems discovered in a pre-flight check -- walking around the aircraft before takeoff looking for defects -- rather than during scheduled maintenance -- more thorough inspections required after 100 hours cumulatively in the air.

"Airlines understandably cannot be held responsible for acts of sabotage or medical emergencies, yet there are other circumstances listed as outside of carriers' control in the air passenger protection regulations that raise serious questions, such as labour disruptions and manufacturing defects in an aircraft," said advocacy group Flight Claim Canada in a release.

"The list is also non-exhaustive -- a gap that airlines will use to their advantage to the detriment of air passengers."

Garneau insisted terms are clearly defined, and reiterated that delays or cancellations following a pre-flight check do not, in his view, warrant, compensation.

"We believe that we've made it very clear what is within the airline's control and what is not within the airline's control," he said.

The new rules align roughly with those in the U.S., but do not match European Union standards that deem most mechanical defects within the airlines' control.

The first phase of regulations that came into force Monday require prompt updates and clear communication with passengers about their rights if their flight is delayed or cancelled.

Travellers can receive up to $2,400 if bumped from a flight and up to $2,100 for lost or damaged luggage.

In the event of a tarmac delay, aircraft must return to the gate after three hours. An extra 45 minutes is allowed if takeoff is likely.

During a tarmac delay, Passengers also must have access to washrooms, food and water, heating or cooling, and communication with people outside the plane free of charge, "if feasible," the Canadian Transportation Agency said.

The issue came to the forefront after a 2017 incident in which two Montreal-bound Air Transat jets were diverted to Ottawa due to bad weather and held on the tarmac for up to six hours, leading some passengers to call 911 for rescue.

Compensation of up to $1,000 for delays of nine hours or more will take effect in December.

On Monday, Garneau defended the postponement -- pushed for by airlines -- by pointing to the now four-month grounding of the Boeing 737 Max, after he said as recently as April the regulations would come down simultaneously in July.

"That has affected several airlines in Canada, and we recognize that that has put an additional burden on them in terms of their reservation systems and their operations," he said.

Garneau told reporters that "complex software" systems to handle the new passenger compensation rules also necessitated the delay.

Passenger Mary Alice Ernst, en route to Chicago from Montreal with her daughter Monday, said the traveller bill of rights was a breath of fresh air.

"Used to be, back in the day, they were really eager to please you, and provide those extra incidentals -- free hotel, things like that. Now they're not so quick to respond to those needs. They have excuses," she said of airlines. "We need this."

As of Monday, airlines must also outline clear rules around carriage of musical instruments.