Gravity waves can scare you if you are near maximum FL (high weight) and the margin between VMO and VAPROT is small. In the updraft side, it makes you reduce target mach in order to reduce thrust and avoid overspeed. In this situations I hate soft altitude in the ALT CRZ mode. It makes the airplane gain some feet and increase the speed when you want quick A/THR reaction.
Then, just after you manage to recover the speed, with quite a low thrust, the downdraft side comes and everything changes to worse, the soft mode will again be late to react, some feet are lost, speed bleeds off, but in this circumstances, high altitude and low margin, gaining knots is much more difficult than losing them, so you can see the speed trend going well below green dot and the airplane seems unable to avoid the speed from decaying. And that damned soft altitude... Oh, wait, but we already have max CLB, and still unable to recover speed... Well, if then the pilot panics and decides to descend to a lower level (which is the best course of action), for Christ sake, don't let him pull for an OP DES!!!!!
Last edited by Microburst2002; 9th June 2012 at 15:06.