Too cold to fly
December 28, 2017 10:29 AM   Subscribe

Is there an official temperature below which they would automatically shut down an airport?

More specifically, is there a temperature below which it becomes impossible for a 747 to take off from the longest strip in JFK, EWR, or LGA, either due to lower air pressure, or the tires becoming frozen/brittle, or whatever other reason the plane might not work?

Assume ideal conditions otherwise, ie no snow, wind, or ice.
posted by Grither to Travel & Transportation (14 answers total) 3 users marked this as a favorite
 
All other things being equal, airplanes actually have an easier time getting off the ground when the air is colder: colder air is denser, and the amount of lift created for a given airspeed increases with the density of the air. Moreover, the extreme cold in the Northeast is actually due to high-pressure air from the Arctic, not low-pressure air.

To the broader question, though: airlines do occasionally cancel flights due to extreme cold. Back in January 2014, United cancelled all of its flights to Winnipeg, Manitoba (my hometown) for several days because of the extreme cold. The daytime highs during that particular cold snap were around -30 °C (-20 °F.) However, it was not clear precisely what factors led to this decision; it may have been partially due to bad weather elsewhere as well.
posted by Johnny Assay at 10:39 AM on December 28, 2017


Barometric altimeters are used to fly instrument approaches and require a correction factor for cold weather. Accordingly, the FAA has a list (PDF) of cold temperature restricted airports. Some more information here.
posted by exogenous at 10:46 AM on December 28, 2017


As far as I know, they only ground airplanes if they can't keep them from forming ice on the wings.

Boeing's airport planning guide for the 747 has engine start characteristics listed down to ~-50C, which makes sense since Jet-A1 freezes at -47, and Jet-B freezes at -60C making it hard to pump out of the tanks.
posted by Dr. Twist at 10:52 AM on December 28, 2017


as an addendum, aircraft rely on hydraulics for a bunch of functions, so the pour point of the hydraulic oil effectively sets the minimum temperature for the aircraft. for Skydrol LD4 that temperature is -60C.

that temperature also coincides with MIL-PRF-87257 fluids too
posted by Dr. Twist at 11:20 AM on December 28, 2017


It can be 40-60 below zero at 40,000 feet.

Planes fly into Antarctica all the time - my dad relates that it was about 30 below when his plane crashed there. More.
posted by Pogo_Fuzzybutt at 11:39 AM on December 28, 2017 [6 favorites]


Several good answers so far. Also think about the air temperature at cruising altitude. IIRC, when we flew to Russia to pick up my brother's adopted children, we flew at 38,000 feet and one of the channels on the seatback video screens showed external air temperature. I don't remember what the number was, but it was really fucking cold. (Quora shows -54.2C for 35,000 feet.) If the aircraft will operate at that temperature when flying, there's no reason why it wouldn't also operate at that temperature on the ground.
posted by Bruce H. at 11:41 AM on December 28, 2017


One important consideration: once the engines are running, they generate heat that heats the lubricant and hydraulic fluids. In some cases, turbines need to be preheated to get the lubricants up to operating temperature before spooling up. Then again, there are preheaters (internal and external) for exactly that purpose, so it shouldn't be a limiting factor.
posted by Alterscape at 12:08 PM on December 28, 2017


I think there's also something about the temperature at which the plane bits stop functioning, plus the difficulties of landing/taking off in very icy conditions (which are not the perfect conditions you specified, of course!) According to this article on flying in/out of Antarctica during the winter, and why it's pretty much never done, it can be so cold that jet fuel freezes into slush and hydraulic fluid turns into a gel. To get around this, apparently the smaller planes used for rescue rely on mechanical parts, but even then they freeze or get stuck together in the snow. Also, it's so cold than moisture in the air freezes and hangs like sand, blowing around in the wind.
posted by stillmoving at 12:10 PM on December 28, 2017 [1 favorite]


There have been perennial problems with Toronto Pearson Airport's de-icing machines; they can usually handle about 500 planes a day. One issue is that the de-icer does not do the whole plane so a build up of ice on brakes or the windshield need to be dealt with elsewhere, by which time the wings need to be de-iced again and then the brakes start to get a build up of ice ... one example.
posted by saucysault at 1:06 PM on December 28, 2017


Except for the ice problem (it also forms on the runways and makes them skating rinks) the cold did not stop flights in the Arctic when my dad was flying there in the eighties (using planes from WWII that still had visible bullet holes!) and temps were regularly -40 degrees C
posted by saucysault at 1:09 PM on December 28, 2017


It's -43°C (-45°F) in Yakutsk today (average for the season), and planes are still flying in and out. I've not seen it said anywhere that they're ever stopped by weather (record low is -64°C, I think also a global record), but possibly the airport would shut then.
posted by ambrosen at 1:13 PM on December 28, 2017


I have landed and taken off on 737s in Alaska when the ambient temperature has been -20 f.
posted by spitbull at 2:43 PM on December 28, 2017


Airports pretty much only shut down entirely for high winds. Takeoffs are allowed (depending on the operator's policy manual) down to zero visibility. Some consider it bad form to take off in pea soup fog, though, especially in a single engine plane since it's much easier to avoid killing people on the ground if your engine fails when you can see where you're going.

They will temporarily close runways while snow removal operations are active, but otherwise there's nothing stopping a foolhardy pilot from landing on a runway covered in several inches of ice if they believe they and their aircraft can handle the conditions.

Minimum operating temps for a given aircraft are found in the POH, but it varies widely by type. Most turbine aircraft are fine down to well below 0F.
posted by wierdo at 8:13 PM on December 28, 2017


I think you're referring to the news reports about Midway closing flights because of the cold. I bought into the clickbait too, as others have noted flights go into Antarctica all the time, so I was curious if there was some sort of hazard with having passengers potentially stuck on the runway or jetway at certain temperatures. Planes physically capable of flying and strange airport/airline consumer liabilities are two different things.

In any case, the articles indicated de-icing was the problem not the cold itself. "Planes grounded because of cold," are not just misleading headlines but wrong.
posted by geoff. at 2:44 PM on December 29, 2017


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