Additional sideslip and additional crab all of which needs to be taken out at derotation, complicating directional control.
Ah, the rules of man, in this case the man is not keeping you down. Many of those rules are written in blood and they don't counter the laws of physics-they work every day.
I don't know what an FCOM is but they follow Boeings current guidance. Reduction to idle reverse or forward idle is their recommendation in the event of questionable directional stability on rollout. Maybe they figure you might grab the wrong side in the heat of the moment, impossible I know, but just saying. Last ditch effort? Do whatever it takes, it is always better to crash on an airport.

 

One more guy gets it!

PS I know I promised I wouldn't post here again but my god you guys are arguing physical law you obviously don't understand. I couldn't put it any clearer than showing you that sideslip into the wind video.

One last note, you don't have to wait to the flare to do it, when I used the technique it was about 2 miles out on final working with the engines to find what I was comfortable with. By a half mile I didn't touch those engines again until flare.

 

Just humor us poor old fools with multiple heavy jet type ratings. I'll let you and flyingchicken take the floor and 'splain it so even we can understand.

What manner of aerospace machinery are you performing these feats of domination over physical law with, if you don't mind my asking?

I'm always open to tips, but I just havn't been able to make much sense of it so far. Forgive my ignorance and carry on!

 

I have answered all of this, some of it multiple times through my posts on this thread. If you have a specific question about something that was said I would be glad to try and answer it, but I am not going to retype what I have already typed, sorry.

No matter how much we discuss it though, 5 minutes in a sim will explain it better than any book will do. Apply more thrust to the downwind engine, use the rudder to keep the ball centered (which will put the aircraft in a side slip) and leave the crab angle as is, watch the aircraft drift upwind. You will immediately recognize what has been discussed here, heck you can do it on flight sim right now on your computer if you have a way to use rudders.

Aircraft type is irrelevant in this case as we are talking nothing more of how forces apply to off centerline thrust. We could have the exact same discussion about boats and the result would be the same, unfortunately difficult to see as a boats engine arm off centerline is a matter of a couple feet.



PS The repeated mockery on each of your responses is getting a little old, and frankly is a bit childish.

 

Now, now, no need to get it in a wad, just curious which aircraft maker recommends this.
I don't have a computer sim, but I have been in lots of those big things on legs that move around and still can't make sense of what you are saying.

Aircraft type is somewhat important here, since none of the types I have ever flown used the procedure you seem so familiar with. It is, shall we say, foreign to my world.

 

There is no additional crab. Crab angle is actually reduced because of the sideslip. And getting that additional sideslip is the whole point of the manuver - its canceling out some of the crosswind component in order to track the centerline with less wing drop.

Don't worry, I'm not planning to, nor do I advocate the use of any unapproved procedures in normal ops. I do however believe we should keep as many tricks as we can up our sleeves for the day when everything comes apart.

Jungle, first time I've thought in depth about this technique is yesterday when I started reading this. I was initially just as skeptical as everyone, but after some thought, the principles behind appear sound. I also shared some of the same concerns as Phantom Flyer regarding the applicability to heavy jet a/c, as sideslipping swept wings can create some interesting interactions between yaw and roll, but so far can't think of anything worse than what happens in a max crosswind landing in the first place (and maybe even some advantages). I'm hoping to give it a try in the sim on my next recurrent and see how it goes.

PS. FCOMs are what scarebus calls their AOMs

 

This is a bit like saying loss of the upwind engine is going to improve your crosswind performance. I don't think so.

 

Shdw, don't take this personal. Now that I finally fully understand your technique (before it wasn't clear), here is an explaination as to why I do not like it.

In multi-engine prop aircraft, you learn day one that you don't fly them with asymmetric thrust and in a coordinated (ball centered) side-slip. You should be banking 2-3 degrees into the good engine with about 1/2 ball displacement into the good engine.

Here's why ...

1. You increase drag because the deflection of the fuselage and rudder with respect to the relative wind increases.

2. Unfortunately, because of the greater yawing moment due to the asymmetric thrust, you must deflect the rudder more so than if you were flying with symmetric thrust. Due to the sideslip, rudder deflection is parallel to the relative wind now and that makes it is less effective. The net result is that you need to use more rudder than otherwise necessary. You must counteract the yawing moment from asymmetric thrust and the natural weather vaning into the wind.

3. Since rudder authority is reduced (due to he relative wind being parallel to the rudder deflection), VMCA is going to increase. Depending on the type of aircraft, this could be very significant.

4. The relative wind striking the fuselage/tail on the reduced engine side, increases the yawing moment. This adds to the rudder problem. (see #2)

5. Extra drag is produced because of the rudder deflection and fuselage being deflected into the wind. (drag is increasing, but you are reducing power on an engine???)

6. Stall tendencies can be masked or changed because the airflow over the wing (on the side with the engine that has been increased) is partially blocked by the fuselage.

7. But the biggest reason I don't like this technique is this. If you suddenly lose the higher thrusted engine, you are going to instinctively push up the power on the remaining engine. When you do, and you have that rudder deflected into the once high powered engine, the increased yawing moment and associated roll is going to prove dangerous.

In a normal crab to forward-slip landing, you aren't as susceptible to an engine failure. In my current aircraft, the manufacturer recommends the crab to forward-slip procedure. Even the autopilot uses this method when flying autoland approaches. Even if you lose an engine at 50 feet or below, the autopilot can still autoland.

If flying your technique, I don't think you would have similar results if the unfortanate happened close to the ground.

 

Apparently it does.... however once on the ground if you pull reverse it starts working the wrong way.

One of my rules of thumb is that if I have one out, and given only a choice of direct crosswinds from either direction, if all other factors are equal, then I'll pick the direction with the crosswind on the side with the live engine, because once on the ground and reverse is pulled, the asymmetric reverse will pull you upwind rather than down.

 

Are you saying that if you have a left to right crosswind, if you pull the left engine thrust reverser, that the net effect is to get pulled upwind?

If so, you couldn't be more wrong. If you use reverse thrust, and the aircraft is pointed into the wind (regardless of one engine inoperative or not), the thrust vector is pointed downwind and behind you. Hence, you are pulled off the runway on the downwind side ... while pointed into the wind. I have a McD "Know Your Jet" advisory circular, 5 pages long, which warns pilots of exactly this.