I went flying for a little bit this morning. It's kind of hazy, so I went up more to heat up the engine oil than anything else.
My home `drome is uncontrolled (no tower). There was not enough traffic this morning so that there would be more than one airplane in the pattern at a time. So pilots were really free to land on the runway of their choice.
There is only one runway, so pilots have a choice of landing in either direction. The wind was blowing at 7kts, right down the runway. The airport has an AWOS (computerized local weather) and it has a prominent windsock.
I saw more pilots land downwind than upwind.
This is really stupid, in my view. For reasons of basic physics.
Let's say that your airplane touches down at 43kts. (For the sake of convenience, I'll use knots for this discussion.) You should remember the formula for kinetic energy: E = 0.5M x V^2. The square of 43 is 1,849.
So say you do a proper landing and you land upwind into that 7 kt wind. Your touchdown speed is 36kts. Square that and the velocity component is 1,296.
Now if you land downwind, your touchdown speed is 50kts. The velocity component is 2,500.
In other words, by landing downwind, you land with nearly twice as much energy, energy that mostly has to be bled off. Sure, you can pull the throttle to idle and try to coast down to taxi speed, but now you have that wind behind you, pushing you.
Land downwind and you need to use brakes more, you'll use more runway and, if something goes bad when you touch down, you're moving a lot faster and you're more likely to bend something.
Doing that in a nosewheel airplane is not terribly smart. Doing it in a taildragger (and I saw two piltos do it) borders on moronic. And the slower your airplane's no-wind touchdown speed is, the more moronic it is.
Why make the laws of physics work against you?
(Obviously, this applies to airports with flat runways and good approaches. There are airports where a downwind landing is a better choice. But my home field isn't one of them.)
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Saturday, September 20, 2014
8 comments:
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To say nothing of some gormless head-in-the Instruments klutz landing long. If he does everything wrong, he could end up doing a head on.
ReplyDeleteI did my private pilot rating work on Bowman Field in Louisville KY...it had nice paved runways, but harked back to the early grass days...so it was a honking big square field from the green-grass days when you had a "runway" for every degree of the compass.
LOL. Landed with a ten-knot tailwind once when I was still a newish pilot (and came in hot to boot) and used virtually every foot of that runway while glazing the brakes trying to get it stopped. Learned a lesson that day that I figured anyone who has ever done it would learn in spades. Can't imagine why people still do it when it's so easy to just fly downwind and make the right approach.
ReplyDeleteWow, Murphy, that sounds familiar. I decided to save a little time once and land north with a south wind at KABI. Got the east runway so I'd just roll long and it's a short taxi to the FBO...
ReplyDeleteIt turned out that an Archer will just float a remarkable distance with a nice tailwind. Before that I would never have believed I could come close to peeing in my pants landing on such a long runway with an Archer. Low time + Confidence = Education. Unfortunately, a lot of the education comes with a good chance of injury or property damage.
I think all of us have once (or twice) thouhgt it would work ... thankfully, we lived. It ain't worth it (especially on an insturment approach to an uncontrolled airfield). Had that happen once !
ReplyDeleteThere is an altiport in the French alps where take-off and landing are necessarily in opposite directions.
ReplyDeleteBeen there, done that!
Stu, the approach plates for a few of the DEW-line radar stations carry a version the following note, "WARNING: Successful go around after the missed approach point improbable." They are flying an approach onto a gravel, uphill strip with a near vertical surface at the end (and, in a couple of cases, parked aircraft there too).
ReplyDeleteStu, there are lots of one-way airports in the mountains -- Aspen, Telluride and Sun Valley f'rinstance. The shorter ones generally have a slope that helps with the wind direction.
ReplyDelete@Stu:
ReplyDeleteCourchevel, in the Savoie region of the Alps, I believe that airport is. There are abundant YouTube videos of it.
A couple of times a mountaintop finish of a stage of the Tour de France has been held there.
LRod
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