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A320 strong crosswind landings in DIRECT Law.

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A320 strong crosswind landings in DIRECT Law.

Old 20th Apr 2019, 07:15
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A320 strong crosswind landings in DIRECT Law.

Hello all.

Just wondering if anyone has any tips/experience or advice about performing strong/max crosswind landings in direct law.

Some failures mean that A/THR can be available. Would you use it or strongly recommend manual thrust if the option? I also imagine in the flare holding into wind aileron ( more conventional) will be required.

Many thanks

Mooneyboy
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Old 20th Apr 2019, 08:52
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Hi mooneyboy,

I would say in all direct law cases, itís probably best to fly with manual thrust in order to make the pitch changes due to the pitch/power couple more predictable.

Iíve never had the chance to practice much in direct law but your logic seems sounds with into wind aileron. The main thing is Ďfly the outputí.

Caveat: Iím no instructor, just a line pilot. Iím sure someone more qualified will be along soon to put their opinion across.

champ
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Old 20th Apr 2019, 17:13
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Find an into-wind runway would be my advice. However, I would think that it's instinctive, but you may need more aileron than you'd expect. Don't forget that you can land with up to 5 degrees of drift still on, which may help.
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Old 20th Apr 2019, 22:22
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Yes would definitely try and find into wind runway depending on conditions first. At least a little allowance on drift on landing.

Usually in the sim if direct law usually fairly typical winds of 10kts across are given, so normally large thrust variations arenít required so your not fighting against pitch/power couple too much.

If it is very gusty and you decide to go manual thrust depending on the failure would it be better in terms of controllability to go selected speed with the max VAPP+15 or leave it managed speed? You really want to re-trim as less as possible especially with the trim not quite as to hand as the B737.
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Old 21st Apr 2019, 05:57
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I've recently flown SIM exercises with some demanding failure scenarios.
​​​​​​- this aircraft can be flown like any other aircraft
- fly the output
Is very good advice. You need to bump the SS into a strong crosswind when de crabbing in normal law, in DCT just keep it there. Decrab late (below 10) and ground comes in soon enough that you won't tell the difference.

Steady pitch and well trimmed is the key to get it done nicely. My personal conviction is that wind additives just make handling more unusual and demanding. Together with scaring one's self too much, I've recognized that as performance degradation traits. 😬

​​
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Old 21st Apr 2019, 13:38
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FD
. You need to bump the SS into a strong crosswind when de crabbing in normal law, in DCT just keep it there
Actually it should be other way round. In normal law while decrabing the yaw doesn't cause roll because of spoiler deployment to keep wings level same as in engine failure. It can be seen in the simulator in auto land with strong cross wind. Direct law is like conventional aircraft where bank is bank, you need to prevent wing rising with stick into the wind.
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Old 21st Apr 2019, 15:02
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Spot on Vilas.
I always love your well founded comments
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Old 21st Apr 2019, 17:22
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Sorry folks, in strong crosswind i.e. 20 kt component or more, when aligning with rudder to centerline a nudge (and release) on the stick is required to keep the wings level. Otherwise the upwind wing goes up and you get blown off. That is for pure crab technique. Normal law will contain the roll, but not prevent it.

Comparing pre-programmed autoland mode to reactive normal law is not fair play. 😉

We agree and apologies for poor grammar of the previous post that in DCT you need to put an aileron and keep it with SS deflection to achieve the same desired result.

Last edited by FlightDetent; 21st Apr 2019 at 18:01.
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Old 21st Apr 2019, 17:42
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It's been a while since I've flown the A320, but I spent 10 years as a captain on it. As I remember in direct law it flys just like a normal airplane. I really don't see what the problem is landing in a crosswind in normal law. Fly it in a crab down to the flare, then decrab at touchdown. Just pretend you are in a Boeing. Simple.
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Old 21st Apr 2019, 19:06
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Thankyou for all your responses and input.

Seems to be agreement that in the decrab will be holding SS in DCT Law ( just like the Boeing).

Flight detent and Vilas Iíve seen youíve made many knowledgable contributions to this tech forum so Iím guessing ( could be wrong) that you do sim work or very experienced on the airbus.

Have you ( or anyone else) come across many cases where max crosswind landings ( or over 20kts) have been carried out in the sim in dct law for training or recurrent? If yes what advice or tips would you have or any major gotchas? Is it something that should be practiced more?

Im sure the cause of the DCT law landing could change the controllability and difficulty ie ELAC 1+2 fault resulting in no ailerons vs RA1+2 fault.

Is this demonstrated for real by airbus during testing?



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Old 21st Apr 2019, 20:51
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Mooneyboy , I think you might be overthinking it a bit. Whatever you fly, in whatever state, you just need to apply whatever control inputs are required to get it going where you want...

If itís banking during decrab, you just put enough aileron is required to stop it - be it in Direct or Normal Law.

Weíre pilots, not robots after all...

Having said that, x-wind + Direct Law is an interesting scenario for the next sim...
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Old 22nd Apr 2019, 09:54
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Normal law will contain the roll, but not prevent it.
FD
The issue is about anticipatory aileron in put which is rate of roll demand. Airbus recommends you to use necessary side stick inputs to keep wings level.
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Old 22nd Apr 2019, 13:22
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@vilas Separated by common second language, me thinks. 👍

Mooneyboy do not overthink it. You won't nail the first one anyway, and by the third one you'll get the grip, DCT law or not. Both ways it is a benign aeroplane. Congrats on the rating!

I heard of a Kingdom in the Middle where FAC1+2 and OEI raw data to CAT I minima is the proving stone for capt upgrades, with 25 cross and light turbulence. If I have had enough SIM time for meat mincers like that, my skills would be sharper.

Last edited by FlightDetent; 25th Apr 2019 at 19:48.
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Old 24th Apr 2019, 15:45
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Thanks flightdetent.

I have done a fair few DCT law landings over the years and not an issue so far. Hopefully a strong crosswind wonít present too much of an issue.

Thanks for for the info.
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