VNav in TbM900

[cromsan]

The button of VNAV does not work, but in the FPlan I can read the different altitudes.

[okidokki]

What exactly does not work? Did you...

• put a lower altitude in the altitude pre-selector?
• confirm the altitudes in the flight plan? (i.e. select the altitude and press enter)
• activate the VNAV button within 5 minutes of the TOD? (afaik that is the limitation of the LR G1000)

These are the first things which come to my mind to check, but maybe I am misunderstanding your statement!?!?

[cromsan]

I see, at the right of some waypoints, the altitudes in blue above FAF, and I do not want to change them.

I press the VNAV button when I activate approach, but if I do not push  V/S and the feet of descend it does not descend; so I do not know the use of the VNAV button,

[okidokki]

The typical use of VNAV would be not so much for the approaches but rather for arrivals (I am not sure if the altitudes in the approach segment have any real effect on VNAV).

In the flightplan you need to scroll to the waypoint for which you want to have an altitude restriction. In the field to the right of the waypoint name you can enter the altitude you want to be at for this waypoint (don't forget to confirm by pressing the enter button). During the flight you would then use the steps I mentioned in my above post.

If you only wish to be at the correct altitude at the IAF, try entering the IAF as waypoint in your flight plan just before the arrival airport and input the altitude restriction there. This should also do the trick. It also helps to point the aircraft in the right direction after the "real" last waypoint in your flight plan.

[RobW05]

You need to have an altitude set for at least one waypoint in your active flight plan and the VNAV profile set up. Then you can activate VNAV within 5 minutes before the calculated TOD. Don't forget to also set your preselected altitude. 

[cromsan]

Thank you, okidokki; I try your information on next fly. I think my error was i do not activate the VNAV button within 5 minutes of TOD, only when I activate approach, and also press it several times, so I desactivate it.