Pilots: why would flights be canceled due to cold?

Factual Questions
1

I grew up in Winnipeg, Manitoba, Canada, and so I was amused this morning to see the following headline: United Airlines cancels Winnipeg flights due to cold. This is the kind of headline that native Winnipeggers like myself take perverse pride in. “Oh, this? This is nothing! C’mon, you can’t handle a little cold?” (For the record, we’re talking about a daytime high of -18°F, and an overnight low of -29°F.)

I note, though, that none of the Canadian carriers cancelled their flights to Winnipeg. I had also been under the impression that colder air was denser, and so it was easier to take off & land in cold weather than in warm weather. So I guess my questions are:
[ol][]What are the Bad Things that can happen if you operate a jet airliner in very cold temperatures? []Sure the temperatures on the ground in Winnipeg are cold, but doesn’t the air at the cruising altitude get substantially colder than that?[]Is the type of aircraft that United operates to & from Winnipeg particularly susceptible to cold? They usually fly Embraer ERJs to & from the city (I flew YWG-ORD on one of them last Thursday, in fact). Maybe those Brazilian planes are particularly susceptible to cold?[]Are there modifications that the Canadian carriers might have made to their planes so that their planes are less susceptible to cold?[/ol]The information in the article is pretty sparse, but any speculation is welcome on the causes of this.

2

It is pretty sparse. Lack of functioning de-icing equipment at the airport? Break-down of snow-clearing machinery for the runways?

3

Interesting. Once an aircraft gets to 30,000 feet altitude the temp is usually around -30°F. So aircraft can certainly fly at such temps.

Icing shouldn’t be a problem at those cold temps. Was it snowing? Just read the story and icing could have been an issue. Deicing fluids don’t work every well at extreme cold temps. BTW: One of the worse jobs ever is deicing an aircraft. I know. Hopefully things are much better than when I did it years ago.

Starting jet engines in such cold could be an issue. We use to put heaters in the intakes before engine start on very cold days. Once started the core of the engine would stay warm for a long time so a restart in flight shouldn’t be a problem.

4

Only Canadians would want to GO to Winnipeg when it’s that cold. United isn’t going to keep a damn near empty flight! :wink:

5

Freezing tires? Lubricants seizing up? Engines shrinking?

6

Here are some weather statistics from Winnipeg for yesterday. Note that it wasn’t actually snowing, as is often the case when it’s really really cold up in Winnipeg. Somehow I had gotten it into my head that de-icing is only really necessary when it’s near freezing, so that snow/ice can melt and refreeze onto the aircraft’s skin; if it’s sufficiently cold, it doesn’t seem like ice should stick to the outside of the aircraft. Is this not the case?

7

On ice sticking to the aircraft, the worst case is when liquid water freezes on the plane, similar to an ice storm. This only happens right around freezing.

Looking at your weather stats, I see that the barometric pressure was high, if it was both cold and low that can make it difficult to set the altimeter correctly. -30C would put it at 45 below standard atmosphere conditions, this table shows what errors would be, perhaps some airlines have rules limiting what they are allowed to fly into.

8

This isn’t likely the reason for United’s decision - but as an interesting point of interest my brother, who is an airline pilot, tells me airlines frequently tell passengers that delays are caused by weather because it is something they can relate & sympathize with. However the most frequent cause of delays is simply the air traffic controllers being overburdened by extremely tight schedules with no time continencies. But if the weather is at all rainy or snowy or whatever it is easier to just blame mother nature that day.

9

We were stuck once for a long time on the ground at O’Hare when it was -25F and a howling wind. The problem they had was that the fuel was congealing in the trucks. They had to fuel up a truck, take it to a garage, get it warm, then quickly out to the jet to fuel it. The workers themselves also had to be rotated out as they couldn’t be out in the wind and cold for very long.

Since very few flights at a time can be fueled up like this, delays and cancellations abounded.

Yeah, really cold weather, esp. with wind, can effectively shut an airport down.

10

Should not be too difficult to deal with this, if anticipated. And in Winnipeg, I’d presume that weather cold enough to cause this can be expected, several times each winter.

11

Are you talking about the diesel fuel for running the truck’s engine, or the jet fuel that they were transporting for the aircraft?

If the latter, how do aircraft deal with hours and hours of time spent at 35,000 feet, where the temperature is quite a bit lower than -25F? Wouldn’t the fuel congeal in the wing tanks?

12

Modern airliners are quite capable of dealing with these weather extremes, as are airports located in these areas. But if that flight to Winnipeg is going to be half empty or has no few business class passengers, the airline is going to be much more likely to cancel the flight due to weather. One reason you’ll see that full flight from Toronto to Winnipeg carry on, but a flight from the US get canceled.

BTW Jet A fuel STARTS to develop ice crystals at around -40C, IIRC.

13

But what’s that in Fahrenheit? :confused:

:wink:

14

Let me calculate that for you!

Breaks out abacus
consults tables
rents time on University computer
-40! :wink:

15

This is 20 yr old info, but I once heard that if a flight was canceled due to weather the airline can tell you to go pound salt, if the flight were canceled due to mechanical issues the airlines needed to accommodate the stranded passengers.

So if the airline can get away with blaming the weather, even if it is mechanical problems, it is off the hook for getting passengers stuff like hotel rooms.

16

I was waiting for my delayed flight to take off from Ottawa and the people at the check-in desk told me it was because of thunderstorms at the destination (Boston). I called my wife in Boston and who reported the weather was fine with not a cloud in sight. When I went back to the check-in desk with this they confirmed it was a mechanical problem with the airplane.

So…they lie.

17

One Christmas, I was on a flight heading to Saskatoon that had a connection in Winnipeg. When we landed in Winnipeg, they started de-icing the plane, then they found a mechanical problem, then by the time they fixed the mechanical problem they had to de-ice again…and by the time that was done, it was too late to take off so we had to spend the night in Winnipeg. D’oh!

18

You owe me a new keyboard!

“[r]ents time on University computer”
Really? How old are you anyway?
heh heh heh

19

Surely commercial carriers have radar altimeters these days, don’t they? The temperatures described are not unheard of in Montreal, in fact we are supposed to have them Thursday and Friday.

20

FAA says no, then you don’t go.

Canadian airplanes can if that is not in their rules.

High pressure & temperature in Alaska shut down airports & is not a big thing unless it lasts for several days.

The altimeters can be adjusted only so far. This does not happen so often or in so many places that the builders of altimeters are not willing to go to the trouble & the expense of getting it certified. It is a mechanical device after all that has a very long proven service life that is no where finished. IMO

A US carrier can not go into or leave, IIRC, an airport that is out of adjustable range. FAA says so. Other styles of altimeters do not matter.

Maybe soon, with the GPS systems et/al & better digital stuff, the old style altimeter will be a non issue. It will always be an issue until a manufacture can make and certify a system to replace it. Major time & money that.

And remember who you are dealing with… uh huh, If you can’t make the feds believe it, it ain’t gonna happen.

It does not cause the big carriers enough per year to make it worthwhile them getting into a pissing match with the FAA. that is seldom worth the effort & is usually about more important issues. ( money )

Auto landing systems do not rely so much on the old mechanical altimeters but that does not negate the rule that is still in effect.

Or I could be totally wrong.

I’ll stand here & cheer you on if YOU want to take the FAA on.

Or you can just always fly on foreign carriers that don’t have to follow the US rules. Well they do while in the US but when in Canada or Colombia, then the rules are different.

They will be better anyway according to most comments from US people about the crappy US carriers.

You always have a choice.