Originally Posted by Permafrost_ATPL
Hi all,
2) If the RW is known to be slippery and you start drifting on the landing roll, do you just use rudder to correct? Brakes? Differential thrust?
3) What is the most effective way to brake on landing? My answer would be thrust reversers at first, then brakes become more effective as you slow down.
While I have an opinion on your question #1, I'll avoid getting too deep into that at the moment. However, I can say that the very LAST thing a pilot can do to attempt to control a "drift" toward the edge on a slippery runway is to use reverse thrust -- symmetrical OR asymmetrical. Reverse is your very best way to get the aircraft off into the dirt or mud or whatever borders the runway. If using reverse and you recognize a drift starting, immediately go to idle reverse thrust to see if that aids the problem -- if not, immediately go to idle forward thrust. (If you doubt that, simply plot the thrust vectors and verify for yourself that any reverse thrust not directed in parallel with the runway centerline will be pulling you toward the edge.) Any speed above about 60 - 70 knots is going to provide at least some aerodynamic control, (which should be used in all landings) and rudder pedal steering used below that if available. I agree with one of the earlier posts, not recommending the use of the tiller -- at least until forward speed is down to taxi speed.
Your other question is a bit mirkey ... the "most effective" braking is full brakes, maximum brake pedal deflection, as soon as the wheels are on the ground! Spoilers do help transfer weight to the wheels -- and they provide a modicum of additional form drag. Will you get hot (or warm) brakes doing this? Sure! But that IS the most "effective use" of brakes - changing kinetic energy into heat energy. Reverse thrust does help -- but it is far more effective at the higher airspeeds as has been said here a couple of times. On the other hand, if you're looking for the most cost effective use of the available methods to get the airplane stopped -- that is a different story. Assuming you have sufficient runway, spoilers as soon as you can (I prefer to wait until the airplane is on the ground -- or it will be soon), reverse thrust as soon as you can, and as much as you can - lessening the amount of reverse thrust as the forward speed slows (not doing much good and it avoids compressor stalls), and the judicious use of wheel brakes after reaching something below 100 knots.