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-   -   Assymetrical Thrust proper tech in x-wind? (https://www.airlinepilotforums.com/technical/42739-assymetrical-thrust-proper-tech-x-wind.html)

capncrunch 08-09-2009 06:09 AM


Originally Posted by captscott26 (Post 658819)
In a large jet........NO NO NO NO NO!!!!!!!

I cant even believe some of the stuff I am reading here.......WOW!!!
If the xwind is that bad to make you think the only way to get the aircraft on the ground is to use assymetrical thrust it is definately time to talk about going somewhere else. I have flown biz jets as small as a citation, and airliners up to an A320, and several sizes in between, and I have never even considered this technique. As some have posted, the best, most comfortable, and safest method is to hold the crab to the flare then kick it out just before touchdown.

As in my case, we are talking about a B1900. Most of my flying was done in Alaska, in winter and in extreme conditions. I'm not referring to big shiny jets on dry runways.

iceman49 08-09-2009 06:26 AM

Was there any consideratin during a go-around if you had asymetrical thrust...never, ever heard of this technique...

capncrunch 08-09-2009 07:08 AM


Originally Posted by iceman49 (Post 658831)
Was there any consideratin during a go-around if you had asymetrical thrust...never, ever heard of this technique...

This is the last I am going to speak on the subject, we have pounded it into the ground.

Yes, those considerations were made. This maneuver is done at the last minute as a transition from crab to landing. The decision to land has already been made. Also, as I stated earlier, if the asymmetrical thrust was very significant, then the maneuver was not made. That in mind, if using the maneuver and a go-around was necessary, spool up was not an issue.

I understand you have never heard of this technique but not all of us at the majors came from the military or an RJ. There are a few of us who had to learn how to fly on short, icy runways where the wind blows hard. We had to have many tools in our bag and some were not in the manual.

Qtip 08-09-2009 08:11 AM


Originally Posted by chuckyt1 (Post 658721)
Never have used it in a jet but I used to use it in the Shorts 360 all the time. It was just a matter of "idleing" the downwind engine in the flare. Seemed to help in an airplane that was crosswind challenged.

Thats the way to do it: just before t-down reduce pwr on the dwnd engine.

joepilot 08-09-2009 09:08 AM

I'm seeing people on here agreeing with each other, but saying the opposite things. Just as a refresher, the aircraft tries to yaw into the wind on takeoff. Therefore it is always the upwind engine that you would want to carry more power on. The only time I can think of that you would want to use this technique on takeoff would be on a multi engine TAILWHEEL aircraft, and then only until you are fast enough for rudder effectiveness.

Joe

SmoothOnTop 08-09-2009 11:53 AM

use the force luke...

KC10 FATboy 08-09-2009 01:09 PM

I'm still trying to grasp with why you would want to do this in the first place. I've flown the B1900 in Alaska, but not on ice. I've also landed the aircraft at its maximum certified crosswind, in the sim and in the actual aircraft.

I do not see how pulling the upwind engine first (which would increase your yaw into the wind, thus increasing your crab) helps you? You are pulling the critical engine.

If someone wants to show me a force vector diagram so I can understand the technique, I would appreciate it.

chuckyt1 08-09-2009 05:07 PM

Downwind engine. It just adds a little more rudder. I've only done it in aircraft that had a crosswind limit, as opposed to a demonstrated xwind component.

It's done in the flare and has the same effect as applying rudder. It really does help on aircraft that have limited rudder authority.

Pulling the upwind engine would, as you said, make things worse.

BTW, when I said I didn't like the slip, I meant - I don't like the wing down method. When you make the crosswind correction at 500+ feet. Much prefer to do it in the flare from both a performance and pax comfort standpoint.

KC10 FATboy 08-09-2009 07:31 PM

What cracks me up about this thread is that people are saying to use the upwind engine and and downwind engine. So there is confusion among the people who think this technique is acceptable.

Lets recap.

If you pull the downwind engine, the aircraft yaws more downwind, and increasing the drift and increasing the side loading on the gear.

If you pull the upwind engine, the aircraft yaws more into the wind increasing the crab angle, which by default increases the side loading.

If you do this in the flare, there's probably not enough time to cause any significant increase in drift or crab. However, I don't see how this benefits you either because I don't see the difference in torque being helpful.

And for the guys flying the B1900, the one big lesson that was taught to me, and I learned myself the hardway, pulling the throttles all the way to idle while in the flare was very risky. The props never came off the govenors at the same time. That gets your attention very quickly.

I agree, there's no reason to apply the forward slip very early. Typically you will see pilots who aren't very good at crosswind landings puttng the controls in early. This just adds drag and causes a lot more corrections to be made that really aren't necessary.

chuckyt1 08-09-2009 07:55 PM


Originally Posted by KC10 FATboy (Post 659109)
Lets recap.

If you pull the downwind engine, the aircraft yaws more downwind, and increasing the drift and increasing the side loading on the gear.


If you do this in the flare, there's probably not enough time to cause any significant increase in drift or crab. However, I don't see how this benefits you either because I don't see the difference in torque being helpful.

Think of it as more rudder authority. It's a lot like rudder in the flare. Just a means of aligning the centerline of the aircraft with the runway. I have never used this technique with any turbojet but have with airplanes that are limited, so to speak...


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