V/S is a great mode. Smart pilots will use it when appropriate.
I use it exactly as BizPilotBrazil describe it, only in the 737 (although I am probably a couple of thousand feets higher, that he is in his Airbus
). Better to let the airspeed fluctuate a little bit, than huge variations in vertical speed. Thousands of other pilots use it like this as well. No, it is not described in the manual, but come on, do we need a procedure for every
technique available?
It's also great for acceleration in a light 737. Eg. when passing FL100 with an acceleration from 250 to say 290 climb speed, VNAV will shove the nose down to less that 500 fpm climb, followed by a pull up to say 3-4000 fpm when reaching climb speed, with such a G-load that you have to use muscle staining techniques to stay conscious! A better way is to set 300 knots (to prevent reduction from climb thrust) and V/S 1800 - 2000 and when passing 285, press VNAV. That way it will accelerate gently and and transition nicely (and with moderate G-loads) to a steady climb speed. Passengers are happier, and we are not flying fighter aircrafts.
Vice versa, it also works great for deceleration in descent, when you are not interested in almost leveling off to reduce, as Level Change does. Set a low speed to keep idle thrust and V/S for the desired deceleration vs. descent rate.
Another great use of V/S is if kept high during descent (for terrain or ATC issues) and coming coming a lot above the path. You already have the speed dialed back to clean maybe. Instead of level change and increasing speed, just dial in initially 5000 fpm V/S. The aircraft will get the nose down and accelerate much faster than with Level Change (thrust will stay at idle due to the low speed set). Gradually reduce the V/S when approaching VMO to stop the acceleration. Chances are that you now almost reached you next cleared level, so now you can press Level Change and watch the speed coming back again and vertical speed reducing to TCAS friendly levels. Great for step downs descent over mountainous terrain. Using this technique, you you will get down a lot faster that with any other autopilot mode and in the 737 you can catch up several thousand feet above the path, with out using speed brakes.
...oh and yes, for it to be safe, you actually have to look at the instruments and watch what the aircraft is doing, like a
competent pilot always would.
