Crosswind ?

[biffo1963]

A question for the professionals here. On two separate landings this year (one at BGI in a 767, the other at LTN in a Dash 8-400 ) I've noticed the aircraft perform a pronounced swerve to the left after the main gear has touched down - both quickly corrected, but a bit of a surprise nonetheless. I've been flying for 40 years on and off but I can't recall ever being aware of this happening before. Since nothing was said on either occasion I assume it was routine. Is this just part of a standard crosswind landing technique, or are there other possibilities ? Just curious ! :)

[Rainboe]

Yes, crosswind landings. If you land with drift still applied to counter the crosswind (valid procedure and well within design parameters right up to the maximum crosswind limitation of the aeroplane), then when the landing gear touches down, the physical process of the offset gear makes the aeroplane swing into the direction of the runway, so you don't have to apply correction, it is done automatically. There are 3 ways to handle crosswinds:
1/ Apply an offset drift like you would in a rowing boat crossing a flowing river, push it off with rudder before landing to line up with the runway
2/ Crosscontrol with bank and yaw (awfully complicated and uncomfortable- can't be doing with that!)
3/ do 1/, but don't bother with pushing drift off. Tends to be a bit uncomfortable on touchdown and a bit harder on the landing gear.

You witnessed 3/. Most pilots tend to do 1/.....a bit more finesse to it. But nothing wrong with 3/!

As a matter of interest, I understand the giant Lockheed Galaxy had lots of main landing gear wheels and you could dial the drift on and 'steer' them, so you could land with drift on, but the wheels lined up with the runway, and just roll out like that. Wonderful idea and a great innovation, but............on the odd day when the wind is all over the place and changes from what you expect just before touchdown, it was very likely you might shoot off the side of the runway after touchdown! It is a deactivated system!

[Avman]

Quite standard with a stiff crosswind as the a/c is straightened up just prior or on touchdown. Will be much more noticeable if you're sitting at or near the back.

Edit: Beaten to it by a much more comprehensive explanation from an expert.

[Rainboe]

Less of the 'expert' please! I'll sue!

[biffo1963]

Thanks Rainboe for that very comprehensive explanation. Interesting too to hear about that system on the Galaxy - nice idea, but it sounds like another complication you guys probably don't need when you're already so busy ! :ok:

[G SXTY]

Just to add that the preferred technique in the Q400 is a combination of 1 and 2. The aircraft’s nose is pointed into wind sufficient to track the runway centreline, then somewhere between the 100’ and 50’ radalt calls, rudder is used to align the aircraft nose with the centreline, with opposite aileron to stop any drift across the runway. The aircraft thus lands with crossed controls, but as the technique is only used for the last few seconds of flight, it’s more comfortable down the back (and doesn’t require the driver to do too much thinking – always a good thing).

That’s the theory, anyway. In practice, landing the Q400 is generally a roll of the dice, with the result somewhere between mediocre and awful. Not an aeroplane for people with big egos. :)

[biffo1963]

Ah yes, I'm sure I remember reading somewhere else that the Q400 can be a difficult beast to land. You guys who do it on a daily basis have my admiration - personally I can't cope with anything larger than a Kirby Cadet Mk 3, and I can get that notably wrong too. :)

[WHBM]

As a matter of interest, I understand the giant Lockheed Galaxy had lots of main landing gear wheels and you could dial the drift on and 'steer' them, so you could land with drift on, but the wheels lined up with the runway, .........It is a deactivated system!Also tried out on the DC3 in the 1940s ("Crosswind landing gear"). Didn't work then, either. Give it another 20 years and someone else will have a go, I'm sure.

Regarding the original post, any time a passenger writes about rough landings you can guess it's either an MD-11 or a Q400. And here we have it again. Really makes you wonder when Bombardier will get round to sorting the Q400 out.

[Cunliffe]

I remember travelling in the first row of an F27 (Air UK?) going into Edinburgh on a windy day. The cabin door was left open and the aircraft was yawing left and right so that the runway kept appearing and disappearing in different directions. This continued right up to touchdown when the (lady) driver banged it down just as the centre line appeared dead ahead. Is this one of the three categories or something different altogether?

[Rainboe]

Optical illusion. The 'front row' of an F27 is actually quite far back behind the baggage holds. You are looking forward through a narrow window quite a long way away. The smallest sideways motion looks enormous. It's even worse from the back row, where I was sitting in Kenya. It looked as if we wouldn't even hit the runway let alone land.

[763 jock]

Me at work yesterday......:yuk: I wish!

YouTube - B777 Crosswinds (http://www.youtube.com/watch?v=EDfWXzd3Zfk)

[Cunliffe]

Thanks Rainboe
Wish I could get a forward view nowadays.

[liteswap]

Last time I tried landing like that in a crosswind with that amount of yaw on I shot off the side of the runway. But then, I was in a Cessna 152, and it was only my 10th landing or so. No damage done to self or plane so it counts as a good landing...