|Quoting c5load (Thread starter):|
He will say, "15, 20, time" then after a few seconds the pilot will say go. What does this mean?
Could be an acceleration check - I've heard of the military using this for fighters, so they might use it for cargo aircraft as well. Basically, you calculate how long it should take you to get to a certain speed, and if you hit that speed at or before that time (or, alternatively, if the time comes and you are at or above that speed), you know that your engines are performing the way they should be (or better), which in turn means that your V-speed calculations are good. If you don't have the acceleration you think you do, and you try and abort just before V1, you may not have enough room to stop, since you used up more runway that you thought you would to get up to V1 (if that makes sense). Thus, failing to reach that speed in the allotted time would be cause for an abort.
But it seems to me that if you wanted a really good answer, couldn't you just ask the flight engineer?