A United Airlines jet blows snow on a runway at O'Hare International Airport , Feb. 1, 2015, in Chicago.
Nam Y. Huh/AP
Airports view fighting mother nature as war against cancelled flights, with runways as the battlefield. Much like state highway departments do, they prepare for bad weather with well-choreographed plans to deal with whatever might happen.
It turns out that it takes quite a bit of snow to completely close an airport. Thanks to modern chemicals, gigantic snow-moving equipment, and really good planning, airports can keep runways and taxiways clear of snow long enough for some planes to take off and land.
The biggest priority is keeping ice from forming on runways. Snow and rain can be easily dealt with, but once ice bonds to the runway surface, it takes a lot of work to get back down to dry pavement. That means constant preparation and hard work.
Everything at an airport slows down when it snows. Runways where planes are normally taking off every 45 seconds now can only handle one every 90 seconds. Baggage handlers must move slower because of slippery conditions; planes must be actively deiced before taking off; and runways need to be shut down periodically so armies of trucks with giant plows and brushes can get them down to bare pavement.
What it means is that in a snowstorm, an airport’s ability to handle arriving and departing aircraft can be cut in half, or worse, which results in a lot of cancelled flights.
As for how the airports keep the runways clear in winter weather, it’s similar to how state highway departments keep the roads clear—though with some very different priorities and techniques.
For example, highway departments use salt-based chemicals to keep ice from forming on roads. They work really well, but cars in winter states can accumulate rust as a result. Corrosion and airplanes do not mix, so airports need specialized (and really expensive) formulas that don’t affect metal on the airframe.
Highways generally use steel-tipped snowplow blades which can cause potholes, but are much cheaper. Airports cannot have potholes on the runway for obvious reasons, so they use polyurethane blades that are gentler on the surface.
Like all things associated with aviation in this country, the process is heavily regulated by an FAA document called the Airport Winter Safety and Operations advisory circular. The 60-plus-page document advises airport operators on how to develop a snow and ice control plan, and tells them how to conduct runway friction surveys to determine if it’s safe for a plane to land or take off.
Industry groups like the American Association of Airport Executives are involved too, with airports in similar climates (Boston and New York, for example) working together to share best practices and knowledge.
Normal climate helps determine how well an airport can respond to winter events. Airports that get 3 inches of snow per year probably won’t buy 100 pieces of snow-moving equipment. That means that if they ever do have a big storm, one that would only inconvenience another airport in a snowier clime, that airport might be closed for a significant period of time because they simply couldn’t keep the runway clear.
Some airports get lots of heavy, wet snow and need to use plows to remove it. Other airports get dry, blowing snow, and can use what are effectively giant spinning brooms to clear the way. If it’s rain turning to snow, airports will use dry chemicals and less liquid so it doesn’t all wash away, and vice versa.
“Big airports that get every conceivable type of precipitation—like Kennedy [Airport in New York City]—you’ll wind up with a little bit of all of that,” says Robert Junge, a former manager of airport operations at JFK. “You keep an arsenal on hand and take out of your toolbox the component pieces you need for that event.”
Airports work with the FAA, the ultimate controller of all the aircraft, to temporarily close runways so they can be plowed. At Kennedy, Junge says, it takes two liquid dispensing trucks with 75-foot-wide spray booms to cover each runway in liquid product ahead of a storm. Sometimes a third is added to ensure adequate overlap.
As the storm progresses, massive teams will head out to remove snow from all the primary airport areas like runways and taxiways. At Kennedy, Junge says, it takes six massive plow trucks 45 minutes, dispensing 17,000 gallons of liquid chemicals along the way at some $8 per gallon. Once that 45-minute sweep is finished, much of the time the crews need to head back to the beginning because of snow that accumulates while they were working on the rest of the airport.
Kennedy has 12 miles of very wide runway, plus 45 miles of taxiway and countless miles of vehicle service roads, ramp areas and more. It must all be plowed, inspected and kept safe. That doesn’t even count all the parking lots, roadways, terminal access and more on the civilian side.
Runways might be closed for 10 to 12 minutes while the trucks are out, and planes will shift to an alternate runway for takeoff and landing. Then they’ll switch, continually rotating planes and plows as long as they can keep up.
Airport operations supervisors will follow the crews, ensuring that the runway is safe for aircraft and that no parts of the truck were left on the runway, or that any landing lights are damaged. They’ll make sure that the appropriate amount of liquid product was applied—too much can make the surface slippery. Too little does the same.
They also use measurement devices to determine the coefficient of friction of a runway. With that data, teams can ensure that they are effectively clearing the pavement and that it’s safe for planes to operate.
If the weather gets bad enough, an airport might need to plow a single runway every 15 minutes, letting a few planes land in between passes. Eventually, the plows simply can’t keep up and the airport needs to be closed entirely.
“Today, it’s very rare that runways close,” says Junge. “The trick is to try to keep crews on the runways during the storm.” The crews rotate, getting on and off a runway in eight to 12 minutes, then on to the next one, and then back to the first.
“The goal is to keep the airport open, stay ahead of the storm, and stay as safe and efficient as you can.”
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