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It is very common today for planes to land on snow (for example, in Antarctica). How are planes kept in control with so little friction against the ground? What is the procedure to perform this kind of landing? How much extra distance, on average, does an aircraft cover by landing on snow, compared to landing on dry pavement? (Video)

4 US Air Force Hercules aircraft at Willies field, Antarctica

4 US Air Force Hercules aircraft at Willies field, Antarctica Source

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It is very common for planes to land on snow (i.e. packed snow) or even ice runways.

How are planes kept in control with so less friction on ground?

Snow/ice friction is a function of the outside air temperature, so it depends. Another factor is whether the runway was packed, fresh snow - and the temperature the previous day. The colder it is, the more friction the snow will have (i.e. adequate braking). In warmer temperatures the snow will be slick (scarily slick at times - as in nil braking).

While flying a multi-engine airplane, one can use differential power. If you're flying a single-engine airplane - one is better off with small taps on the brake during slick conditions. If the OAT is relatively cold (well below freezing), braking can be pretty good.

What is the procedure to perform such kind of landing?

The procedure is the same as a standard landing. However, it is awfully nice to have good contrast on the snow to see the runway. Often runways that are pure snow/ice will be more visible than the surrounding terrain. At the very least - the runway will be outlined with some sort of runway markers.

And, on an average how much extra distance does an aircraft covers by landing on snow, as compared to landing on ground?

As I said before, it is really dependent upon the outside air temperature and the condition of the runway (i.e. packed snow or fresh snow).

For example, suppose there were fresh snow on a relatively warm day (30 degrees farenheight) and the snow is compacted (i.e. by humans) that day. Say, night-time temperatues drop to 0F, and the next day you land with an OAT of 30 to 35+F... that runway is going to be SLICK. However, if the temperatures were to stay at 0F - you would actually have decent braking. Even further, if the OAT dropped to -40 below...you will have excellent braking.

TLDR:

Snow conditions are always changing and braking/control of the airplane are dependent on those conditions. Snow-conditions are highly dependent on the outside air temperature and to some degree human-maintenance (for better or worse).

*source: Personal experience from flying in the Arctic.

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  • $\begingroup$ "Often runways that are pure snow/ice will be more visisble than the surrounding terrain."—runways are usually pure snow/ice because the terrain is completely snow/ice covered, in which case everything is white and you need good markings. $\endgroup$ – Jan Hudec Jun 22 '15 at 10:10
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    $\begingroup$ +1 for mentioning visibility problems. If all land below is white, it is hard to estimate altitude. $\endgroup$ – Peter Kämpf Jun 22 '15 at 12:20
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I'd quote from this source

Landing on snow itself is not a problem. The rudder is used for steering upon landing so control is no different than landing on a dry runway.

Getting stopped is where it can get alittle tricky. Careful use of reverse thrust and braking along with not making any turnoffs from the runway until sufficiently slowed are the name of the game.

A wise Capt once told me not to make any turns offs from a snowy/slippery runway until your slow enough that you have to actually add power to get off. Wise advice indeed.

and

Landing on wet or contaminated runways requires more close control over approach speeds. With a B747 you should accomplish touchdown on the runway at 1.000 ft from the approach end of the runway. The airplane should be flown firmly onto the runway at the aiming point. It's very important not to land long! The speedbrakes should be used immediately after the main gear contacts the runway, because they destroy lift, increase drag and, most important, increase main gear loading. It's necessary to use thrust reversers at high power as soon as possible because they are most effective at high speed.

Hope this answers your questions. TY

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  • $\begingroup$ I saw that link before asking this question, and was not convinced with the answers. Just see how complete and thorough is @fbynite's answer.And, the third post there is specifically for the B747-200 only. $\endgroup$ – anshabhi Jun 22 '15 at 10:23
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I only fly single engine aircraft. I have landed a number of time on snow and on ice. The two things I do differently is to 1) feather the touch-down with a slight power increase just before hand, and 2) "fly" the aircraft all the way to a near stop. That is to say that instead of steering the plane once on the ground, you treat it more like you are still in the air.

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