Originally Posted by
Enigma01
Mmmm i dont get it. I always thought it would just reduce speed to 210K by pitching up. How can it try to regain the path by ignoring my fmc vnav descend speed and pitching down (so increasing speed above 260K by piching more down) if it is in the vnav speed on the FMA???
Pegasus FMC.
Sorry still all unclear to me.
I can only speak for the 757, but in that aircraft in VNAV SPD the priority is speed. In PATH, when the auto throttle is unable to maintain speed within parameters, it reverts to speed. If you open the speed window and slow down, it prioritises that speed, the nose goes up and it departs the path in VNAV SPD. The only time path is prioritised is in descent logic with flap out: you get the option to descend in SPD: VNAV PATH.
On the LEGS page, the FMC decent speed is shown against all legs in small characters, unless a hard speed has been inserted (in large characters) - so it's reasonable to assume that VNAV SPD would follow that speed, leaving you the problem of getting back down to the path with speed brake, gear or just saying you can't do it (which is reasonable if its their fault you're high).
Of course the 737 might be quite different.