Cross Landing The Heavy Iron, Airbus jocks advice needed Options

[Harmattan96]

I have to say that after accumulating some 5000 landings in light training aircraft I have made my mind as to what works and what doesn't in a cross wind landing. But....

When it comes to flying the heavy rust buckets I am somewhat puzzled.
As everyone else, I have seen the test cams for crosswind certification of the B-777, those are some scary techniques being applied. I can only hope that this is done on purpose.
Now to the meat of the subject:
My understanding is that Airbus industries makes it a requirement that their aircraft be landed with a crab and a kick the nose straight on the flare and brace for impact. (Should I be wrong correct me promptly)
Why would that manufacturer of fine flying machines recommended this highly stressful method rather than the more gentle "wing low" method, which guarantees absolute control over the aircraft from touchdown and through the roll out.
Is it an engine ground clearance issue, is it something else, did I misunderstood things in the first place?

As I said firstly, I will not be convinced of one technique over the other, it is beyond late for this; but I am very curious as to why would this maker in particular would suggest this technique over another.

[c150student]

Dont quote me on this, but I think its mainly the engine ground clearance- for some aircraft those big jets arent far off the ground as it is, let alone when the aircraft is banked over to one side.

Secondly is the passenger comfort- flying with crosses controls (which is what is happening with the wing low method) means that the aircraft is out of balance and therefore not as comfortable for the passengers. But I dont think thats the main reason, as flying in an unbalanced aircraft is alot more comfortable than crashing...

So I think its mainly the engine ground clearance thing. Seeing as my engine is on the nose, I like to crab it to short finals, kick it out with rudder whilst simultaneously lowering the wing facing into the wind, entering a slip.

Oh, and for those who like links, heres an A.net topic I found on the subject: http://www.airliners.net/discussions/tech_...ad.main/144458/ Oh, and if you like, read the flamewar that starts later in that topic hehe

They also say you can slip a jet in, but only with a few degrees of bank.

[trijetflyermd11]

The engine clearance is the primary reason for the wings level landing technique. The B747 is landed in a similar manner. The MD11 on the other hand uses the low wing technique. Other than that the software on the FBW Airbuses don't like cross controls.

[Harmattan96]

Fly by wire and unhappy cross controlled computers, I had completely forgone this particular aspect of flying.
Thanks for that Tri jet.

[Ranger]

They also say you can slip a jet in, but only with a few degrees of bank.

Slipping a large, swept wing airplane is not a good idea. In the MD-11 it's a definite no-no. Slipping can lead to masking of the elevator. When you're within a couple of hundred feet of the ground you're running a huge and unnecessary risk. Having to do something like that also implies that you are not stable on the approach. The FAA is not impressed by that at all.

[AirRabbit]

OK. I’m going to try to NOT drag out my

As I have said many times here, all airplanes land the same way: from a level flight attitude. When you throw a in crosswind, nothing changes. You still need to land (i.e., “touch down”) with the airplane tracking down the runway, parallel to the runway centerline, preferably with the centerline between the MLG. Please note that “tracking down the runway” doesn’t mean drifting to the left or right – it means the airplane is moving down the runway, at least parallel with the runway centerline. Nothing changes EXCEPT that you have to control the tendency of the airplane to drift toward the downwind side of the runway.

You can fly final approach almost any way you wish – you can do it inverted if you desire - although that brings in some additional issues that are probably better kept for another thread. Some airplanes do not like to be “slipped;” and some pilots do not like to “slip” their airplanes. In large airplanes you can keep the wings level during the final approach, tracking across the ground along the extended runway centerline, while watching the runway out of the side of the forward windscreen – or, in large crosswinds, out of the side window (uh … if this is the case, you might want to consider waiting until the winds die down or go someplace else). OR, you can line up the airplane on the extended runway centerline, keep the airplane fuselage parallel with that centerline, and maintain your position across the ground during the approach by flying with a cross control application - aileron control INTO the wind, and rudder control as necessary (which will be opposite – thereby the name, cross control) to keep the airplane tracking the intended ground track.

Most people don’t like this second method. They don’t like it because the airplane is NOT in coordinated flight for the time you keep it this way. As Ranger said, this often leads to a compromise in the effectiveness of some of the aerodynamic control surfaces. Not good. Another reason it is not liked is that the little old lady in seat 2D is going to be uncomfortably jammed up against the window all the way down final. Remember, the airplane is banked, but it is not coordinated. As a result, people (and cargo) will tend to “slide down to the bottom of the bank angle.” OK. Maybe a small exaggeration … but you get my point.

The first way is much more preferable – pilots like it because the airplane stays coordinated until the very last moments. The airplane stays happy, in that all of its control surfaces get all the effectiveness they would like to have. And, it keeps that nice lady in 2D comfortable.

In the second example (the one with 2D’s face scrunched) the flare is initiated just as normal except that you’ll probably have to make an adjustment on the amount of aileron necessary to keep the airplane from drifting downwind (toward the runway side) as you enter ground effect, which is very likely going to reduce the amount of bank angle you have. You ARE going to have to be aware of the maximum angle of bank you are allowed here, because too much bank and you might wind up dragging the outboard engine pod (usually only applicable to 4-engine airplanes), the wing tip, or the trailing edge of the outboard flaps. BTW, any of this is frowned upon and is a definite “no-no.” As the airplane fuselage is already aligned with the runway centerline, and you have killed any drift tendencies with the bank angle, all you have to do is to flare to the level flight attitude – stay in the flare for not more than about 3 seconds while retarding the throttles to idle as the mains touchdown. Because of the bank angle, you might actually touch the upwind main gear prior to touching the downwind main gear. Not to worry. This is normal. Keep the crosswind controls active (maybe required to increase the displacement as the forward speed slows) and do so until taxi speed is reached.

In the first example (the PREFERRED one), you, the airplane, and 2D are all happy. You’re tracking across the ground, following the extended runway centerline, although the nose of the airplane is pointed more into the wind. Here, also, you do exactly as you do in any landing – when you get to the flare initiation point, you begin your flare to the level flight attitude. However, here, as you flare you begin to PRESSURE (not kick!) the downwind rudder to swing the nose around to line up with the runway. AS you do this, you’ll probably need a bit of aileron into the wind – just in case the wind is sufficient to displace the momentum of the airplane and start it drifting downwind – toward the side of the runway. Again, stay in the flare for not more than 3 seconds, bringing the throttles to idle as the main gear touches. Here, you may, or you may not have a bank angle – and, of course, if you do, no problem, you might touch the upwind main gear first, and you may not. It all depends on what bank you needed to keep from drifting. Also, you need to be aware of what that maximum bank angle is. Just because you gave 2D a nice ride down final, that is no reason to scare her by dragging the wing on the runway! And, here too, keep the crosswind controls active (maybe required to increase the displacement as the forward speed slows) and do so until taxi speed is reached.

[glnflwrs]

Gosh, he talks just like a CFI. Don't he?


(Love ya' bro.)

[Harmattan96]

OK. I’m going to try to NOT drag out my
(...)
And, here too, keep the crosswind controls active (maybe required to increase the displacement as the forward speed slows) and do so until taxi speed is reached.

Rabbit, did you steal this script from me, I wrote this thing myself a while back.
But all kidding aside, I think I lost you somewhere in regards to Airbus Industries and their recommended method. You eloquently touched up on all points of my now popular crosswind landing lesson plan, but no answer on Airbus. Did I miss something? I am English challenged afterall.

[AirRabbit]

Rabbit, did you steal this script from me, I wrote this thing myself a while back.
But all kidding aside, I think I lost you somewhere in regards to Airbus Industries and their recommended method. You eloquently touched up on all points of my now popular crosswind landing lesson plan, but no answer on Airbus. Did I miss something? I am English challenged afterall.

Hey Harmattan!!

My friend, if you are English-challenged, I would absolutely HATE for you to comment on my French-speaking abilities! How DO you say “zero” in French? Haha. And, if it did look like I stole "your script," I certainly didn't do it on purpose, and I would be pleased to relinquish all rights and forward to you all payments I've received as a result.

However, I do apologize; because, apparently I did skip right over your question regarding the French-built machines and whether or not they are required to land in a crab. I guess it largely centered on the way you phrased the question.

My understanding is that Airbus industries makes it a requirement that their aircraft be landed with a crab and kick the nose straight on the flare and brace for impact.

Because the “flare” ends with the “touchdown,” I thought you were describing the removal of the crab prior to touchdown (i.e., “during” the flare), which is the method I prefer for landing in a crosswind – although, as you probably noted, I go out of my way to talk about “pressuring” the nose around with rudder, rather than imply that one should “kick” the nose around with rudder. Kicking the rudder controls in an airplane cockpit is something that shouldn’t ever occur – except, of course, when at the gate with the engines shut down; and then, only if you need to get the blood flowing in your feet again after a multi-hour stint on your butt without moving. Right Ranger?

There ARE some who believe that you can land an airplane (that is, actually put the landing gear on the ground) while the airplane is “crabbed” into the wind – and for those who may not know, the term “crabbed” means the nose of the airplane remains pointed more or less toward the direction from which the wind is blowing, while the airplane is tracking across the ground in the direction of the runway heading (crabs, you see, are known for walking kind of “sideways”) when the MLG touchdown. When this happens, a considerable amount of torsion (twisting force) is placed on the landing gear, the wheels, tires, brakes, hydraulic seals, the struts, and just about anything else connected with the landing gear. I am fully aware that the designers know that pilots, being human, are going to do this (land in a crab) once in a while – and they probably build a bit more ruggedness into the design to help the gear mechanisms survive a bit longer. But the simple fact is that landing in any condition other than parallel to the runway centerline and tracking along, or parallel to, that centerline will cause unnecessary wear and tear on the landing gear. Large crab – large wear and tear. Small crab – smaller wear and tear – but wear and tear nonetheless. As I’ve said previously, the only airplane I’ve ever known that was DESIGNED to land in a crab was the B-52. That airplane had (and it still HAS) swiveling main landing gear – both forward and rear. This allowed the fuselage of the airplane to remain pointed into the wind, while the gear would be adjusted to a position parallel to the centerline of the runway. The airplane was landed in that configuration, without any torsion moment imparted to the gear and its mechanisms. As the airplane slowed, the swivel was gradually removed, bringing the fuselage back into a parallel position with respect to the runway centerline. It was a VERY weird thing to watch; but it worked like a champ. Really, pretty slick stuff! The B747 has body-mounted MLG that are “steerable” under hydraulic control – so they are probably more able to withstand landing in a crabbed condition, but it still isn’t recommended – AND, the wing-mounted MLG are fixed; so they would take the full brunt of that torsion. I also understand that the rear pair of wheels/tires on each MLG on the B777 are sterrable also under hydraulic control, although, to a lesser degree than the B747 body gear. Airplanes that have simple, dual gear (not tandem – fore/aft – configurations), like the B737, the B727, the A-320 family, the Regional jets, etc., are probably not quite as susceptible to torsion damage as 4-wheel/tire truck assemblies. However, again, I am not aware of any Boeing, Airbus, or Embraer (or anyone else for that matter) philosophy that says, “yeah, go ahead and land in a crab” let alone levy a requirement that they do so.

Most transport category airplanes DO have bank limits for landing; and it is usually somewhere between 7 and 11 degrees. Actually, 7 degrees is quite a bit for landing, and 11 degrees is a huge amount. Depending on the airplane, the limit is due to the potentials of striking the ground with outboard engine pod (usually limited to 4-engine airplanes), the wing tip, or the outboard portion of the trailing-edge flaps. If the airplane is flown as I think it should be (described in my earlier post), the crab is removed simultaneously with the initiation of the flare. The nose should be brought to the center-of the-runway position as the MLG touch down. Unless there is a really good crosswind blowing, this allows the airplane to retain some crab, although a decreasing amount, throughout the flare, and brings everything into alignment just as touchdown occurs, without having to require a bank angle. Yes there might be (and there usually IS) a requirement to have a bit of up-wind aileron control involved (resulting in a small cross-control condition), but depending on the size of the airplane and the amount of crosswind present, a good share of the time the crosswind does not have long enough to act on the airplane to get it to start drifting downwind before a polished pilot has it on the ground without getting into a bank. However, there is absolutely nothing wrong with having a small bank to keep that drift from developing.

I wish I could tell you that I’ve never landed an airplane in a crabbed condition. But, unfortunately, if a pilot ever tells you that, you can pretty much understand that he (or she) is talking through their hat! If you DO land in a crab, you try to make the crab angle as little as possible, touchdown as softly as possible, and learn from your mistakes so that you don’t do it again.

[Harmattan96]

Thanks for that Air Rabbit.
If I understand well, there is then hardly any differences between light trainers and heavy haulers, and I do see a LOT of very interesting techniques being used that quite frankly reveal a lot of the PIC's understanding, or lack thereof, in regards to basic structural physics.
By the way, you shall keep all payments received from the x-wind ground school. I get the distinct feeling that I might have been drinking warm milk out of a baby bottle while you were teaching all of those marvelous basic principles, I just hope you are glad to see that the newer generation of aviators embraces the old ways...

As for your French, you did say "zero" with the proper spelling, so you, might be better then you want to admit!
If you swing by South Florida, make sure that I buy the beer, we shall get you "edumacated" in the French tongue.

[Ranger]

we shall get you "edumacated" in the French tongue.

I'm not going to say it. Nope. Not me.

Gosh, it's hard being a nice guy.

[AirRabbit]

If you swing by South Florida, make sure that I buy the beer, we shall get you "edumacated" in the French tongue.

I'm not going to say it. Nope. Not me.
Gosh, it's hard being a nice guy.

Ahem ... well, a couple of things. First - the "French Tongue" thing... (I'm right there with ya, Ranger) I'm motivated to either "plead the 5th" or "drink a 5th" depending on what was behind that expression; and

Second - since "South Florida" is my old stompin' grounds, I have to ask ... where abouts in that area of the Sunshine State would you be located? Dade, Broward, or Monroe county? I'm very familiar with many of the neighborhoods around the Miami and Ft. Lauderdale airports ... and, since the French language is involved in the discussion, are you familiar with a glass-front building on the west side of Sheridan Drive, just off of NW 36th Street?

[Harmattan96]

Alright, Alright let's replace "tongue" with "language" so you fellows don't get any wild ideas about my cross dressing activities on sunday afternoon.....
Rabbit, I can't say that I am familiar with such a building in the Miami area, but then again, I follow Victor Airways for the most part, and my wife does the ground driving, I just enjoy the scenery.
As far as myself I claim residence on the other coast in Naples (Collier County that is).

[Ranger]

my cross dressing activities on sunday afternoon.....

I KNEW IT!!!!!!!

[learguy]

... and, since the French language is involved in the discussion, are you familiar with a glass-front building on the west side of Sheridan Drive, just off of NW 36th Street?

It could be known as the ATC for short?

[Harmattan96]

It could be known as the ATC for short?

Oh, yes indeed the Airbus Training Center building. That place is where It seems we misplace some if not all of our local FSDO ops inspectors.

[c150student]

Erm ok, so I went flying today, and changed from the crab to the slip on short final like I normally do (we had a 19 knot crosswind) and my new instructor took the controls, helped me land it, and then after we took off again, asked which instructor thought slipping it was ok. I'd always thought that it allowed the most control throughout the landing, rather than kicking it straight (I dont think we ever hit the centreline today- am quite sure I would have at least once had I slipped it in). He says it increases the drag and isnt the proper way to do it (only slip when trying to lose altitude). I can crab it (well, I think I can, his hands were on the controls every landing, which I must admit made me feel 'seperated' from the aircraft and slightly uncomfortable, but thats something else).

I went on the site Glen often links to (whittsflying) and they say that the slip is the best way, and the crab can cause damage. My instructor says a slip may result in a wing strike (I'm no ATPL holder, but a large angle of bank is needed to strike a wing on a high-wig aircraft especially. The guy on whittsflying says hes landed a cessna in a 45 knots 90 degree crosswind). I personally prefer crabbing onto short final and then slipping it onto the runway.

Any thoughts? Thanks (by the way, I know the c150 isnt heavy iron, but I thought I'd rather put it here rather than make a whole new topic on it).

[AirRabbit]

As far as myself I claim residence on the other coast in Naples (Collier County that is).

Ah, yes. I know it too, though not as well as the Dade, Broward, Monroe side.

It could be known as the ATC for short?

Hmmm ... as is often heard on the street corner in that neighborhood, "JES."

Oh, yes indeed the Airbus Training Center building. That place is where It seems we misplace some if not all of our local FSDO ops inspectors.

Really? They should be easy to spot. Just look for the guys looking up at all the "neat" models suspended from the ceiling!

Erm ok, so I went flying today, and changed from the crab to the slip on short final like I normally do (we had a 19 knot crosswind) and my new instructor took the controls, helped me land it, and then after we took off again, asked which instructor thought slipping it was ok. I'd always thought that it allowed the most control throughout the landing, rather than kicking it straight (I dont think we ever hit the centreline today- am quite sure I would have at least once had I slipped it in). He says it increases the drag and isnt the proper way to do it. I can crab it (well, I think I can, his hands were on the controls every landing, which I must admit made me feel 'seperated' from the aircraft and slightly uncomfortable, but thats something else).

Any thoughts? Thanks (by the way, I know the c150 isnt heavy iron, but I thought I'd rather put it here rather than make a whole new topic on it).

Sounds like I'd like your instructor! The way to minimize the tendency to drift toward the downwind side of the runway as you straighten out the airplane is to first, be sure that the center of the airplane is tracking down the extended center line of the runway (so if you're in a very big airplane, the cockpit is likely to be aligned with the center of the upwind side of the runway) and second, flare so that you wind up in a level flight attitude at a height of about a foot above the runway. Very importantly, AS you begin to flare, also begin to pressure the rudder to bring the nose around to line up with the runway, and, AT THE SAME TIME begin to feed in a little aileron toward the direction of the wind. There is nothing wrong with winding up with a cross-controlled slip right at the end (nose down the runway, upwind wing slightly down) because you're only a foot above the ground; AND you won't be in that condition for very long. Also, in larger airplanes, if the crosswind isn't too stout, just having the aileron into the wind may be enough without having to actually bank the airplane toward the wind. But, as I'm sure you've seen, there are plenty of times where landing even the biggest airplanes on the upwind landing gear first is not uncommon.

[Becky_KSTS]

Awesome advice. I really messed up my last x-wind landing in Monterey, Ca. (I didn't break anything but my ego) but I need to get a little more aggressive with the controls once I am "in the moment" just before tires meet the runway. Great post and great responses so we can all learn...this is what flightlevel350 is all about to me!

[c150student]

Airrabbit- thanks for that, it actually helped alot! I guess with some more practise I'll be able to master it (I wouldnt be allowed to solo in the winds I had yesterday anyway). Is the slip method still good though? I've heard lots of good things about that, and, like I said, I always used to do it that way--I know it looks like I'm looking for a "yes c150, thats still a good way, keep on doing it your way, its good" but now I'm asking because want to end up with the best techniques I can, to be the safest pilot I can be.

Thanks again. I love knowing this forum when I have questions like this