Originally Posted by
bravolima
this is the important answer! Have a look at the first waypoints on your FMC, perhaps
XXX 150/2000
XXY 175/3500
XYY 230/5000
YYY 250/10000
if you are between the second and the third waypoint already up to let me say 7000ft and you engage VNAV then AP will force ou down to 5000ft, thats why you dive.
Two things to do:
modify your waypoints [B]before take off[/B when you know you will engage very early VNAV
]XXX 150/2000A
XXY 175/3500A
XYY 230/5000A
YYY 250/10000A
behind the altitudes put an "A", stands for at or above; this means the given altitudes figure like minimums. By the way you can do this as well in the descent. Then you have to put a "B" behind the altitudes. Means at or below.