The airline that left passengers stranded on the Ottawa airport's runway for hours last week says it tried its best to get them back in the air — but workers failed to give its two planes proper refuelling priority.

Air Transat is blaming "a confluence of factors beyond our control" for the lengthy delay of international Flights 157 and 507, both of which were diverted to the Macdonald-Cartier International Airport on July 31 due to bad weather in Montreal.

The airline's defence is found in the legal response it filed last Friday to the Canadian Transportation Agency, which has announced it will hold an inquiry into what went wrong that night.

The agency made Air Transat's response public Wednesday afternoon.

Hundreds of passengers were prevented from leaving the two planes after they touched down at around 5 p.m. in Ottawa last Monday.

One passenger, Laura Mah, told CBC News that food was being rationed, the cabin temperature was steadily rising, and people were being given almost no information about what was going on.

I'm sorry to hear that - it's up to the airline to determine whether to deplane or wait it out when a flight diverts. —@FlyYOW

The situation became so desperate that at least two passengers called 911.

Air Transat's timeline

Air Transat's legal filing contains the airline's own timeline of the events that transpired that day, starting at around 4 p.m. ET when crews were told that passing storms had closed the Montreal airport.

The two planes assumed a "standard holding pattern," and were at one point mistakenly told that the Montreal airport had reopened, before touching down in Ottawa an hour later.

Both aircraft held on the runway with no ground support whatsoever for approximately 90 minutes. - Air Transat

Both planes were then told to park on one of the airport's runways. At that time, about 20 to 30 other aircraft had already been diverted to Ottawa's airport, Air Transat said.

The two planes shut down their main engines and switched to auxiliary power units to keep the lights on and onboard ventilation systems in operation. However, the high temperatures, plus the number of passengers on board, meant temperatures steadily rose to above 23 C, Air Transat said.

Crews tried to get permission to refuel while on the runway, the airline said, but their requests were turned down. There was also a "critically-high demand" for air stairs, which could have allowed passengers to leave the plane, and ground power units, which could have kept the plane cool, the airline said.

"In total, both aircraft held on the runway with no ground support whatsoever for approximately 90 minutes," said Air Transat. "Deplaning in the above circumstances was therefore a physical impossibility."

Other planes jumped the queue

More than two hours after the planes arrived at the airport, Air Transat crews were told that refuelling would soon be underway — but according to the airline, the delays continued.

While they waited, other planes that had landed before Flights 157 and 507 touched down had refuelled and taken off, said Air Transat. Eventually, Flight 157 ran out of fuel and its auxiliary power units shut down. Soon afterwards, one passenger called 911, Air Transat said.

It was only then, said the airline, that air stairs were hooked up so that emergency crews could get in to the cabin.

At around 9 p.m., four hours after the two planes touched down — and "after practically all other diverted flights had been refuelled" — the two planes finally got their fuel, the airline said.

Flight 507 was then able to take off, but "fuel starvation" caused problems with Flight 157's onboard systems. It wasn't until six hours after it landed that 157 was able to go "wheels up," Air Transat said.

"Per the above, Air Transat submits that a confluence of factors beyond our control led directly to our inability to minimize the weather-related diversion delays of the affected flights, deplane passengers from stranded aircraft and provide minimal levels of comfort to our passengers onboard," the airline concluded in its response.

Refuelling not airport's responsibility

Some of the claims in Air Transat's response fly counter to what the Ottawa International Airport Authority said following the incident.

At the time, the authority said there was both a gate and air stairs available, and they were prepared to bring supplies beyond just bottled water to the stranded passengers — but never received clearance from Air Transat.

At no time did the Air Transat crew or its ground handler request fuelling assistance. -Ottawa International Airport Authority

Air Transat staff were also "uncommunicative" that night, the authority said in its initial statement.

In a follow-up statement Wednesday, the airport authority said that airlines like Air Transat would have their affairs managed at airports by "third party" ground handling firms, not airport staff.

Those firms' responsibilities include arranging refuelling services, the authority said.

"The airport does not determine the priority of refuelling activity. This is determined by the airlines who request refuelling through their ground handlers," the airport authority said in its statement.

Ottawa International Airport Authority spokeswoman Krista Kealey told CBC News that all refueling services are provided by 'third-party' workers — not airport authority employees. (Giacomo Panico/CBC)

"At no time did the Air Transat crew or its ground handler request fuelling assistance or a gate from the airport authority."

Airport authority spokesperson Krista Kealey also said that for diverting to the aircraft in question to the Ottawa airport, Air Transat would have been charged $2,000, plus an additional $3,000 if they decided to allow their passengers to disembark and use the airport's terminal.

The Canadian Transportation Agency has now scheduled a public hearing into the stranded passenger saga to take place Aug. 30 and Aug. 31 in Ottawa.

If it finds Air Transat did not abide by the terms of its international tariff — a document that sets out its obligations to its passengers — the CTA could order the airline to financially compensate the passengers on board the two planes.

The inquiry will not tackle "broader questions" about tarmac delays at Canadian airports, but rather the specific events that took place July 31 at the Ottawa airport, the CTA said.