[QUOTE=1920s Style “Death Ray”]
mittu that link doesn’t seem to be working.
[/QUOTE]
Indeed it doesn’t seem to allow you to download the file directly. Alternatively go to the Oops List and click on the A321CrossWind.wmv link.
Do auto-landing systems support crosswind conditions? Seems to me to be quite an art on itself, so I don´t know if a computer could do it reliably.*
- This goes just to show that even a hardcore aviation buff needs to get humble and ask questions some times.
[QUOTE=LSLGuy]
Fun factiod: Typically jets don’t have a formal maximum crosswind limitation. What they have instead is a “maximum demonstrated crosswind component”.
[/QUOTE]
I don’t think I’ve flown any aircraft that have a cross wind limit. It’s always been a maximum demonstrated crosswind, but as you say, anyone with half a brain treats it as a limit.
The Dash 8’s demonstrated crosswind is 36 knots which is just plenty in my opinion :).
[QUOTE=Ale]
Do auto-landing systems support crosswind conditions? Seems to me to be quite an art on itself, so I don´t know if a computer could do it reliably. …
[/QUOTE]
Yes, they can handle crosswinds, but only very light ones, < 10 knots being typical.
Typically autoland is only used in conditions where visibility is too poor to use manual landing. Visibility that low almost always comes from either fog, which generally implies light or no wind, or from blizzard conditions which implies a lot of wind & slippery runways to boot. For the former, we use autoland. For the latter we use “go land someplace else with better weather.”
[QUOTE=LSLGuy]
Visibility that low almost always comes from either fog, which generally implies light or no wind
[/QUOTE]
Unless you’re in Chicago - we’ve had dense pea-soup fog combined with winds 15-20 knots.
(It’s usually relatively warm, moist air coming off the big lake hitting cold land, or vice versa. Sort of like the mist that comes out of your freezer on a hot day when you’re getting ice cubes, but on a much larger scale.)
[QUOTE=1920s Style “Death Ray”]
Yeah, that’s a pretty famous example of how not to do it. First the dude overshoots finals on his turn so has to fly back to the centreline leaving himself with a very low turn to get lined up. In the end he actually touches down on the downwind wheels first and well to the right of the centreline.
[/QUOTE]
I’ve landed at Kai Tak. It’s not the kind of experience a passenger in a jumbo jet expects, or forgets. But I thought the last minute zig zag was to avoid the skyscrapers. Are you sure wind was a problem there?
If I remember correctly, the test for the A380 took place on an airport in Iceland, hence not the same than in K364’s video.
[QUOTE=Yeah]
I’ve landed at Kai Tak. It’s not the kind of experience a passenger in a jumbo jet expects, or forgets. But I thought the last minute zig zag was to avoid the skyscrapers. Are you sure wind was a problem there?
[/QUOTE]
Here’s a normal landing at Kai Tak. Note that the final turn is at around 500’ and it lines the aircraft up with the runway. In the other video I think the pilot has overshot the runway centreline when doing that 500’ turn which leaves him in a pretty poor position to land from and he then has to do another turn at 50’. In our company that would be cause for a missed approach. We are required to be lined up with the runway, on the correct glideslope and at the correct speed by 400’, otherwise we go around.
Although the wind was probably a factor, the landing was more because the wind was poorly handled.
[QUOTE=LSLGuy]
Minor item from waay up the thread … Somebody describes crabbing as using rudder to fly “sideways”. Wrong. A crab is fully coordinated straight flight through the air. The rudder is centered & the airplane is NOT flying sideways.
[/QUOTE]
Beat me to that. A “forward slip” (upwind wing low, tracking runway centerline, directionaly aligned with runway) is the uncordinated condition.
As a resident glider pilot, I’ll mention that nearly all gliders have a single main wheel. This makes crosswind landings, using the forward slip technique extreamly easy…course you still have to take care not to drag a wing.
Another point not mentioned is that the crosswind vector direction is highly dependant on landing airspeed. A 20 kt. 90 degree crosswind is much more of a issue for a cessna that would like to land at 50 kt. or so, than for a heavy that lands with 100kt. airspeed…at least as far as required crab angle is concerned.
As a glider pilot, landing at an alternate airport or waiting for more desireable wind direction may not be an option. Thus I may be aware of some less will known (and contriversial) techniques for dealing with crosswind.
One option, if forced to land a light aircraft in a heavy crosswind is to land at higher speed…half flaps, or no flaps may be considered. Some Cessnas have an issue with the verticle stabilizer being blanked in a hard slip with full flaps. Landing at higher speed can raise it’s own set of issues.
Another technique not mentioned so far is to land on the downwind edge of the runway, at a slight angle to the centerline…actually this can be quite an angle in the case of a light aircraft landing on a runway sized for 747s. Intentionally landing off the centerline is not typically considered by many pilots.
Finally, at uncontrolled airports there are often taxiways, etc. aligned at right angles to the runway. When the cross wind is strong enough to make them attractive, not much distance is needed to land. There are FAR and safety issues with this. In cases I am aware of, ground personnell were contacted by radio, and prevented access to the taxiway used for landing.
[QUOTE=Broomstick]
I also know that I could not do that safely with, say, a Citabria or an Ikarus, in those airplanes I’d have no choice but to divert. [bolding added]
[/QUOTE]
Who the hell names an airplane Ikarus? That just seems like asking for trouble.
[QUOTE=sturmhauke]
Who the hell names an airplane Ikarus? That just seems like asking for trouble.
[/QUOTE]
Those wacky Germans - if you think the name is funny you should read the pilot’s handbook. These have a sense of humor, let me tell you.
I am getting a little tired of the inevitable jokes and no, it does not have a lower service ceiling on hot, sunny days. But otherwise, it’s a fun airplane.
It also has very limited cross-wind capabilities. Low enough that a number of us currently flying it have seriously discussed the “land on the taxiway” scenario Kevbo mentioned. So far, though, no one has had to do that and we’re doing our best to avoid it. Suffice to say, I would not choose to fly it with a crosswind component greater than 10 knots and I’m very glad the landing gear handles side loads well. Not an overabundance of rudder on it - you definitely want to use a no-flap landing and a slip as the crab technique just isn’t sufficient when dealing with its upper limit on crosswinds. Fortunately, it is a high wing so you can get plenty of wing-tilt in there if you need it. Very strictly a fair-weather airplane.
[QUOTE=K364]
Here’s a video - just amazing that such a huge machine can be manipulated like a dirt bike!
[/QUOTE]
Is it my imagination, or am I seeing in these videos the rear landing gear sharply angled toward the direction of the anticipated side load?
[QUOTE=1920s Style “Death Ray”]
It’s always been a maximum demonstrated crosswind, but as you say, anyone with half a brain treats it as a limit.
[/QUOTE]
Or even some fraction of it, depending on experience. The max demonstrated crosswind component (not the total velocity, just the component across the runway0 is established by highly experienced test pilots pushing the airplane to the limit, mainly for the benefit of the company’s lawyers and not its customers. It does not mean that a weekend hobby pilot can comfortably expect to handle that much crosswind component, especially in gusts.
[QUOTE=Yeah]
I’ve landed at Kai Tak. It’s not the kind of experience a passenger in a jumbo jet expects, or forgets. But I thought the last minute zig zag was to avoid the skyscrapers. Are you sure wind was a problem there?
[/QUOTE]
Bit of both, I’m sure. There was only one runway, so if the wind was blowing straight across it, you either did some funky flying or went elsewhere to land. And there were some inconveniently located hills and mountains that prevented a straightforward approach even if the wind was from a good direction. The gallery at airliners.net has a selection of spectacular landings at Kai Tak - planespotters would camp out on likely days to catch burst tires, wingstrikes, tailstrikes, and other similar underwear-unfriendly events.
Pertinent to this discussion oops, it’s a bit sideways
an illustration of the low-wing problem not quite the worst-case scenario, but close
Kai-Tak was a mess of an airport.
When I was in the Air Force it was one of several “certification” airports. That meant that there was something weird, usually dangerous, that required special training and certification before you could fly there.
For Hong Kong it was the infamous “Hong Kong curve” - you would fly a normal instrument approach and then pick up visual cues (the checkerboards) that would have you make a right turn to line up with the runway. There were mountains to the left and buildings everywhere, not to mention the strong crosswinds. Those pictures on airliners.net have several Asian carriers that fly in there every day dragging pod engines on landing.
Closing that airport was a blessing to all things pilot-related.
RE: crosswind landings. LSL Guy nailed it (as usual) for the airliner side of things. With strong crosswinds you just set up a drift-kill heading on final to keep you lined up. This summer I had 70 knots of crosswind at 1500 feet going into Memphis. The controllers were having fits trying to vector everyone onto two parallel runways.
Someone earlier mentioned differential power. I’ve never used this in real life but I have tried it in the Beechjet 400A simulator. We had the crosswinds dialed up above the “max demonstrated”, and we found out why those WERE “max demonstrated”.
And for those of you who can’t view YouTube, I give you my own version of the Boeing crosswind video over on Google Video. (There’s some fun extra stuff at the beginning and the end).