"With equipment freezing and equipment moving slower … the airlines' ability to move the planes from the airfield to the gate was impeded," Corrinne Madden, spokesperson for the Greater Toronto Airports Authority (GTAA), told CBCNews.ca Wednesday. "Because we only have so much space at the gates and on the runways and taxiways, the decision was made to stop arrivals of planes from North America [between 5:55 a.m. ET and 10 a.m. ET]."
Canadians might be used to cold weather, but temperatures as low as the –30 to –40 C with wind chill that Torontonians experienced Monday night and Tuesday are unusual for the city. That means many airlines that operate out of the transportation hub likely see little need to invest in modifications and specialized ground-support equipment that might help them operate more efficiently in cold weather and were caught off guard by Tuesday's deep freeze, said independent aviation expert Rick Erickson, who is based out of Calgary.
"We have carriers throughout the Canadian High Arctic that operate every single day for four to five months of the year in these kinds of conditions, so it's not as though it can't be done. It certainly can be. It's a question of having the right equipment in place to be able to handle it," he said.
"Some carriers, I'm thinking particularly the U.S. carriers, because they tend to buy equipment on a system-wide basis, they won't go and buy some extraordinary piece of equipment that's made to operate in –40 C because they never see –40 C in Tampa and Texas and California and anywhere else that they're flying in the continental United States."
Ground equipment sluggish in cold</p>
Unusually cold temperatures, icy conditions and high winds combined to create an atypical situation at Pearson, which is a major flight hub for North America and has to contend with many more flights than airports in some of Canada's other cold-weather climates.
Winnipeg has had similarly frigid temperatures for the past few weeks, but its airport gets only about a third of the traffic of Pearson so weather-related slowdowns there don't create the kind of backlogs that Toronto experienced this week, officials and industry experts said. (The cold weather did force the United Airlines-affiliated ExpressJet to cancel some flights out of Winnipeg last week, most likely, says Erickson, because it did not have the adequate ground equipment to deal with the –30 C temperatures the city was experiencing.)
It's not airplanes themselves that have problems in cold weather. They're used to flying in atmospheric temperatures of –50 C and colder and actually perform better in the cold air, which is denser and allows engines to generate more power and planes to take off quicker and more efficiently.
It's all the equipment that services the planes when they are on the ground that poses a problem when temperatures drop as low as they did in Toronto overnight from Monday to Tuesday.
In such conditions, everything slows down — including the employees working outside on the tarmac who are forced to wear cold-weather gear that makes it cumbersome to do their job efficiently.
"Tugs that are pushing airplanes around, they don't operate anywhere near as efficiently in –30 C as they do in 30 C, and the same thing with all of the folks [working] with their big mitties on and their big jackets and all the stuff they gotta do," said Erickson.
"Typically, we have a snowballing effect. It's not just one thing that's not working; it's a whole bunch of things that aren't working, and it just slows stuff down."
Hydraulic systems particularly vulnerable
The fluid and the tubing that make up the hydraulic systems that operate mechanical parts such as landing gear, cargo doors, baggage belts and the movable gates and bridges that ferry passengers to and from aircraft are particularly affected by the cold and risk freezing. Baggage trains and equipment used to transport and load and unload luggage also get sluggish.
"It's similar to driving around a late-model vehicle in the winter that doesn't like being cold for an extended period of time. Unless you can plug them in or shelter them in a warm environment, they aren't going to respond very well," said Chris Ferris, executive vice-president of First Air, which operates flights out of several northern communities, including Iqaluit, Yellowknife and Rankin Inlet.
"Yesterday [Tuesday] in Iqaluit, all of our ground equipment that we could possibly get indoors was indoors."
First Air frequently operates in temperatures of –40 C and below but has never had to institute a ground stop because of cold weather — although it did have to ground its fleet in Iqaluit on Tuesday because of the hurricane-strength winds the Nunavut capital experienced. Usually, the small airline has five ATR passenger aircraft based in Iqaluit and on some days will have up to four other jets arriving there from the south.
"Our weather limitations are more with regards to operating limits as far as visibility or cross winds," Ferris said. "If we have safe landing and takeoff and taxi conditions, then we're out there and making it work."
No landing bridges in North
First Air mitigates the effects of cold weather by using equipment such as large industrial blankets to warm engines and keep them free of snow and avoids using landing bridges altogether.
"We roll up the stairs, and everybody walks across the apron to the terminal," Ferris said. "That's one of the problems we don't have to face that you would have at some place like Pearson, where if the bridges can't get on and off the airplane, that's an issue. [With] some brands of bridges, there's been problems in the past — they're just not made for operating in extended periods of the cold."
First Air outfits all of its ground and maintenance workers in Canada Goose extreme-weather parkas to prevent frostbite from the –50 C and lower wind chills they regularly face, but that doesn't mean they aren't slowed by cold weather.
"You're carrying more weight; it's not as nimble or flexible," said Ferris. "Things that would be very easy to do in a T-shirt on a summer day take a little bit longer."
Ground crews at Pearson were also slowed by the cold temperatures Tuesday, but it was the ice covering the tarmac and equipment that proved the most treacherous, said Bill Trbovich, director of communications for the International Association of Machinists and Aerospace Workers, the union that represents Air Canada ground crew workers at the airport.
"You can't put road salt on the tarmac because road salt and aircraft do not react very well together, so as a result, it's very, very slippery," he said.
Icy tarmac a hazard for baggage equipment
Unusually strong winds helped freeze over the open tarmac quicker than usual and made it hard to move equipment around and slowed down the crews responsible for unloading baggage because they couldn't get the necessary traction for themselves or their equipment, Trbovich said.
"There's a fear that you can't put the brakes on," he said. "You don't want somebody sliding one of those pieces of equipment into the side of the aircraft because we've had people killed in the past where something slips and they get stuck between the fuselage and the end of the baggage unloader. And the chances of that increase when you haven't got good traction to stop."
It was in part the extra caution the icy conditions required that delayed the offloading of aircraft and caused a backlog at the gates, which was compounded by the high volume of traffic Pearson gets and the fact that several flights were diverted there from Ottawa and Montreal because of weather-related problems at those airports.
"Basically, the snowball got bigger as a result." said Trbovich.
'Right thing to do'
The mounting delays and slowdowns prompted the airlines to request the so-called ground stop, and the GTAA and Nav Canada, which operates Canada's civil air navigation system, agreed that temporarily suspending passenger flights due to arrive at Pearson from North American cities was the best way of preventing a bigger backlog during the peak morning period.
"It was something that was just obvious to all of us," said Nav Canada spokesperson Ron Singer. "We all agreed a ground stop program for four hours was the right thing to do."
Air Canada did not respond to a CBCNews.ca request for an interview.
On Wednesday, conditions at the airport had improved, but the tarmac was still icy, meaning ground operations would still be slower than usual and likely remain so until it gets warmer, Trbovich said.
"The best thing I can caution people is, just be patient. I know that's something you don't want to hear when you're trying to get to Cancun or some place nice and warm or you're trying to make a flight home, but the bottom line is, mother nature rules, and you have to act accordingly," he said.
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