New to A320

[awacs]

I have a question on the A320 cross wind landing technique. I'm coming from my last airplane, the B757. My question is: can the Airbus be landed in a full crab on the the runway like the Boeing? If so, what is the limit if any?

Thank you,

Awacs

[S speed]

Max 5 degrees crab angle at touch down.

[vilas]

My question is: can the Airbus be landed in a full crab on the the runway like the Boeing? If so, what is the limit if any?

Any aircraft can be landed in crab but it's not recommended. Are you sure Boeing recommends to land in full crab? In extreme circumstances Airbus recommend Max 5° crab and 5° bank.

[Banana Joe]

Boeing recommends to remove half the drift during flare when landing on wet or slippery runways. Boeing also state, in their FCTM, that the aircraft is certified and can withstand landing fully crabbed up to the certified crosswind guidelines. It can be done also on a dry runway, but it is not recommended. It is not prohibited either.

[Uplinker]

Just out of interest; why do you want to land crabbed anyway?

[Banana Joe]

Personally I don't want to land crabbed but being aware the aircraft is capable to withstand it makes me relax during a crosswind landing. It's one thing less to worry for me, especially because I still haven't got nowhere near enough exposure to feel fully proficient.

[vilas]

Boeing recommends to remove half the drift during flare when landing on wet or slippery runways. Boeing also state, in their FCTM, that the aircraft is certified and can withstand landing fully crabbed up to the certified crosswind guidelines. It can be done also on a dry runway, but it is not recommended. It is not prohibited either.

Landing gear is designed for high vertical impact loads but not that much side stress which is imposed during a crabbed Landing on a dry runway. When you land crabbed on wet/slippery runway initially the aircraft skids along the and runway which reduces the speed and then straightens due to the CG arm. This reduces the side load considerably but this doesn't happen on dry runway. Here the full impact of the touch down speed is felt on the gear sideways. That's why all aircraft procedures recommend decrab before touchdown. Unless you are landing a B52 where the gear can be aligned with the runway.

[Banana Joe]

I agree with you, but the FCTM on my type says the airplane can land using crab only (zero sideslip) up to the landing crosswind guideline speeds. And for the reason you have written it goes on to say touchdown in a crab only condition is not recommended when landing on a dry runway in strong crosswinds.
Again, I am not planning on landing fully crabbed, but it's good to know the landing gear won't collapse if I fail to properly align the aircraft with the runway centreline.

Now the MD11, that looks scary...

[vilas]

And for the reason you have written it goes on to say touchdown in a crab only condition is not recommended when landing on a dry runway in strong crosswinds.

You will have crab only in strong crosswind only. On dry runway after flare some crab should be removed. What is forbidden may cause a problem the very first time and what is not recommended will cause problems after repetative abuse.

[Uplinker]

Oh I see Banana Joe, well I applaud your honesty.

I had lots of crosswind landing practice in various turbo props, but don’t worry; decrabbing is not difficult: Once you have flared and are waiting for the main(s) to touch, at around 10’, you gently but firmly push the nose round with the rudder pedals to align it along the runway, (and keep the wings level or slightly roll into wind as you swing round).

With practice it all becomes a simultaneous manoeuvre. (And cross wind landings are good fun to be honest ! )

[misd-agin]

If you align the plane with the runway, and keep the wings level, the plane will drift downwind, immediately. Bank angle is needed to track straight to avoid side loading the gear at touchdown.

[megan]

You Tube

[pineteam]

Originally Posted by misd-agin

If you align the plane with the runway, and keep the wings level, the plane will drift downwind, immediately. Bank angle is needed to track straight to avoid side loading the gear at touchdown.

Not on Airbus. It will actually slightly drift into wind when you decrab. I know it sounds weird but it’s explained in one of the Airbus Safety First magazine.
I will edit my post with the reference later.

***EDIT****
From Safety First #20 July 2015 page 23.
https://ibb.co/DfMmjJR

[Goldenrivett]

Not on Airbus. It will actually slightly drift into wind when you decrab.

That tiny effect occurs on all aircraft - not just Airbus. Airbus say that during the decrab, the force on the rudder is towards the upwind side of the runway.

[Uplinker]

Originally Posted by misd-agin

If you align the plane with the runway, and keep the wings level, the plane will drift downwind, immediately. Bank angle is needed to track straight to avoid side loading the gear at touchdown.

If you decrab just before the mains touch - a split second before - and I did also say you might need to roll into wind slightly - you won’t drift much. With practice, you can nail it.

Decrab too high and yes you might drift. Wait until immediately before the mains touch.


PS. (To the OP), In the first year of flying your first big jet, always volunteer for the challenging landings, (within your allowed limits). This is the time to learn, and not to worry if you don’t nail it every time. If you get it wrong, well, you are still new and people will cut you some slack. But if you avoid challenging landings now, then when you are so-called experienced but cannot land near max crosswind, then you will not be a good pilot.

PPS, Don’t be offended if the Captain does not allow you to land near your limits, but always ask if you can.

[misd-agin]

If you have any crab in equal to the amount of crosswind, day five degrees, the instant you reduce to 4.9 degrees with the wings level the plane will start to drift. And it increases at 4,8, 4.7, 4.6.... The decrabbing isn’t instantaneous. And your technique assumes you can also coordinate reaching touchdown point at the exact moment that you instantaneous go fly your crab angle to runway alignment. That’s impossible in real life. I’d love to see someone try that in 25 kt crosswinds. Wait a second...I have. It’s not pretty.

[Uplinker]

Maybe all the crosswind practice I had on Dash 8’s and 146’s helped, but I have done it many times - so it is not impossible - but yes the timing and coordination takes practice. (I have +11k hours)


PS, partial spoiler deployment (on Airbus FBW), also helps.

[vilas]

Originally Posted by misd-agin

If you have any crab in equal to the amount of crosswind, day five degrees, the instant you reduce to 4.9 degrees with the wings level the plane will start to drift. And it increases at 4,8, 4.7, 4.6.... The decrabbing isn’t instantaneous. And your technique assumes you can also coordinate reaching touchdown point at the exact moment that you instantaneous go fly your crab angle to runway alignment. That’s impossible in real life. I’d love to see someone try that in 25 kt crosswinds. Wait a second...I have. It’s not pretty.

I am afraid your conclusion is not true. Decrabing is not done little by little but in one smooth application of downind rudder before touchdown. As correctly pointed out by pineteam during decrab the aircraft rotates around the vertical axis which is slightly ahead of the CG. That pushes the aircraft towards upwind. Also the inertia keeps the aircraft moving straight ahead. During this time the aircraft should touch down. During this yaw Flight control laws prevent upwind wing from rising. But if you have decrabbed high and keep floating then it will start drifting downwind and that will need to be corrected by banking upwind wing up to maximum of 5°. If it cannot be managed with five degrees then missed approach must be initiated.