The Canadian Transportation Agency is holding an inquiry into two Air Transat flights held on the tarmac at Ottawa for hours in conditions passengers called "deplorable".
The flights from Brussels and Rome were diverted on 31 July amid bad weather in Montreal and Toronto.
The flights were stranded for between five and six hours without adequate air conditioning, food or water.
Passengers on one flight eventually rang emergency services.
The two international flights were among 20 diverted to Ottawa from Montreal and Toronto.
Air Transat said that numerous factors beyond its control, including long waits for fuel, had resulted in its inability to reduce the delay and allow passengers to disembark safely.
Airline CEO Jean-Francois Lemay said on Thursday that "something did not work well, obviously" on 31 July.
"I am not saying there is a fault or blame but there is a collective responsibility that has to be observed in these events."
Flight 507 pilot Yves St-Laurent testified before the CTA panel that the tarmac delay seemed like "the lesser evil" compared to the logistics of getting passengers off the aircraft and sending them through customs.
Pilots were consistently told the planes would be refuelled in short order.
"If we had known that the delay would be longer than three hours, the decisions would have been very different," Mr St-Laurent said.
PA
Flight staff said food and water were running low but that refreshments were available and temperatures seemed acceptable.
Travellers who gave statements or testified before the inquiry painted a very different picture.
Some described a growing frustration and panic fuelled by poor communication from airline staff.
More than one passenger testified during the public hearings that they felt they were seen simply as "luggage".
In a statement to the panel, Flight 507 passengers Alan and Patricia Abraham said they were initially told the delay in Ottawa would be just 45 minutes to refuel.
The couple said they were stranded for some hours in the stuffy plane, were given a small meal and only once offered a small glass of water.
"The bathroom had run out of toilet paper. One young boy became nauseous and was trying to make his way to the bathroom when he vomited in the aisle and all over several passengers two rows behind us," they said. "The stench was unbearable."
People on board Flight 157 from Brussels to Montreal were experiencing similar conditions to Flight 507.
At one point passengers chanted "open the door, open the door" to cabin crew. The cabin temperature reached upwards of 31C.
Passengers eventually rang 911 to complain of the heat and inability to disembark, and emergency responders came to their assistance and handed out water.
