# Why don't airport have heated runways to deal with winter conditions?

It is for years that I ask myself as a frequent flyer why there is no Airport using a system, like built-in electrical resistances on Runways to avoid Delays/Cancellations and even closing Airfields during winter? The costs of such a system would be for sure less than closing an Airfield for one day.

• Please specify for what temp and precipitation ranges you want the system to work. Please also consider how you are going to drain thawed water, unclog the drainage, check if the rwy is clear of ice and snowdrifts, and repair it in a snowstorm. – Deer Hunter Aug 25 '15 at 13:13
• The costs of such a system would be for sure less than closing an Airfield for one day. How confident are you of that statement? I am far from confident. Install it, maintain it for the 5 days in 365 you actually need it, then supply it with enough electricity to heat an entire runway? I am far from convinced that it would be anywhere near cheaper. – Simon Aug 25 '15 at 18:01
• Melting snow requires HUGE amounts of electricity. See what-if.xkcd.com/130 for reference – Antzi Aug 26 '15 at 16:09

Removing snow from runways is not the biggest problem. Snow can be ploughed from the runways pretty quickly. The problems occur:

• When it is snowing, especially in snow storms with strong winds and poor visibility. The wind and visibility are bigger problem than the snow laying on the runway and when the snow fall rate is such that the snow becomes a problem itself, the heating system would not be able to keep up melting it anyway.
• Due to snow and ice accumulating on aircraft preparing for take-off. Obviously heating runways would not help in this regard.
• Due to fog, which is much more common in winter. Again, heating runways would not help in this regard.

So runway heating would probably not help very often.

Also the runway has to be extremely strong, because aircraft have much higher weight on each tire than cars. A heating system with adequate durability would therefore be really expensive.

• Do they use salt/sand on runways like they do on streets? – TomMcW Aug 25 '15 at 18:19
• – usernumber Aug 26 '15 at 12:49

I don't know how to calculate it, but I am sure that heating a runway will use a lot of electricity. Imagine yourself on that runway with a 2Kw electric fire in snowy conditions. You would still be freezing, and the fire would have no effect on the runway surface. Even if you could do this, the heating might create fog above the runway.

I don't think runway conditions are the biggest problem in winter, because as long as it isn't snowing continuously, snow ploughs can clear a runway (salt isn't used because it would be damaging/corrosive to aircraft).

The problems in winter often are the other weather conditions such as strong crosswinds, poor visibility, low cloud base, because unless AutoLand is being used (available only on some aircraft/some airports), the pilot generally has to be able to see the runway when coming into land from an height typically of 200 feet.

• Good point. How did I only forgot? Yes, it takes awful lot of energy. Specific heat of melting of water is ~335 kJ/kg. 1 mm of precipitation means 1 kg per square metre, but snow has a lot of air in it, so it corresponds to 10-20 mm (so say 1 cm). Now for stronger snowing 20 cm/hour is possible and to melt that much, we'd need ~ 1.9 kW/m². Now a runway at larger airport may have, say, 160 000 m² and we are at about 300 MW. That's in the same ballpark as this snow-melting XKCD What If. – Jan Hudec Aug 25 '15 at 17:51
• Typical runway at a major hub is at least 150ft x 10,000ft and could be as large as say 200ft x 16,000ft. That gives areas for a single runway of 140,000 to 300,000 m^2. And that's just ONE runway; some hubs have as many as 10 runways! And it doesn't even count taxiways, parking aprons, freight ramps, emergency areas, runup pads, etc. Too bad Solar Freakin' Roadways are impractical! – Carlo Felicione Oct 31 '16 at 17:46

It seems to have been done on runways, taxiways and parking stands, though not by using electric resistors, as you suggest. See the following articles from the interwebz:

• There's a pretty important quote in the FAA article: "Airport officials remain generally opposed to the concept of heated runways because of the high energy costs. 'There isn't a compelling need for these systems in the industry,' said Chris Oswald." – Cody P Sep 8 '17 at 21:36
• This "answer" should be improved, as it is the reader needs to read several pages of text, and ends up with an unclear view of whether heating a runway is realistic. – mins Nov 30 '17 at 18:02