As noted above by KH, AC operations at YYZ always seem to grind to an agonizingly painful halt as soon as there is a period of winter cold or a bit of snow. The airline knows it has a problem. It has discussed the issue in its annual report. Unfortunately, it refuses to accept the labour costs, or to invest in the infrastructure needed to resolve the servicing issue. Customers will accept the delays if the airline makes an effort to assist. Unfortunately, customers are often faced with limited information from the airline, and long delays when they seek assistance.

IMO a large part of the problem are the employees. Some don't show up to work when the weather is unpleasant and others drag their butts because it is "too cold". The temperature never even got close to -40C at YYZ so it wasn't about jet fuel freezing. The fuel facilities are no more delicate or temperature sensitive than what is available at other airports in Canada, and yet these airports keep going in colder weather. In all my years of flying I have been able to get through YEG, YWG , YUL, YQB etc. on colder and snowier days. Yes, I can appreciate that there may be some delays, but the constant meltdowns at YYZ during IROPS and the unreliability of the largest AC hub are a national embarrassment.

Part of the service response problem is the inadequate staffing. This gets back to the employees' attitudes. The airline has bare bones staffing now, such that when some of the employees don't show up for work, it can disrupt the service response. Too many don't show up when they are most needed. The few staff working get stressed and short tempered and then become rude and snarky. The airline needs to reach out to the employees and to train them and more importantly, the union needs to get a dose of reality that YYZ is in Canada and that it gets cold. If the employees are too fragile for the weather, then they should consider jobs elsewhere. Plenty of people in Canada work outdoors and they don't disappear when it is cold.