Originally Posted by
Adolphus Coors
Not according to our manuals. The de-crab method is aircraft parallel to center line with enough aileron to land with the wings level. It maybe different for your company or fleet. I have never seen anyone fly an approach in a side-slip which as you stated would require more power. I have seen the majority of the pilots I fly with apply a side-slip just prior to the flare which does not require more power. Your de-crab method is what we call the side-slip method.
Originally Posted by
Adolphus Coors
I'm pretty sure I'm not "missing the technique of the de-crab," as yoy say.
Mr. Coors (nice!),
Your company manuals may say whatever they say but they don't change basic aero. If you've got a crosswind to land in and you want to track the runway centerline through rollout, two things must happen.
1 - You've got to align the aircraft fuselage/gear with the runway with rudder.
2 - Since #1 will remove the portion of the aircraft's flight vector that was countering the crosswind, you must now drop the upwind wing with aileron to counter the drift.
I know you know both those things. Call it a "de-crab" or "side slip", whatever. Maybe whoever wrote your company manuals never landed in a significant crosswind. There's no way rudder to align and "enough aileron to land wings level" will hack it. It may work to some extent on a large majority of mild to moderate crosswinds due to the forgiving nature of most aircraft designs and a nice, wide, dry runway with lots of friction. However, you’re either not completely aligning with the runway and putting extra wear on your tires or you’re landing with a downwind vector that needs to be countered with steering once you’re on the runway. Either way, you’re not really dealing with the crosswind completely and kind of just hoping for the best. Try doing it in crosswinds approaching the design limits of the aircraft on a wet or snow covered runway and the drift induced by the lack of aileron may become a significant problem. Just my two cents on that.
It's not like company's are inventing new ways to land in crosswinds. You've got to align the aircraft with the runway with rudder and kill drift with upwind aileron - period-dot. When you put those flight controls in is really what we're all talking about (and apparently what you call the maneuver). I've landed 757, 767, A320/319, 737 and MD-11s performing the above maneuver in the flare with no problem. I prefer to do it that way. Now, thanks to Fedex company policy, I must establish those control inputs (they call it an “align maneuver”) no later than 100’ AGL. I’ve warmed up to doing it this way but I’d still prefer to do it in the flare. You’ve never seen someone fly an approach in a side slip because that’s not the way your company chooses to land their aircraft. When you do it at 200-ish feet, it absolutely induces extra drag that must be countered with additional power.
Cheers.
Last edited by Adlerdriver; 03-07-2008 at 02:14 PM.