Super80 Pro VNAV

[Rey Ramon]

I can not figure out why I can not get my VNAV on the super80 Pro to work. I think it worked one time. Usually when I press it, it reverts to vertical speed. What am I doing wrong? I've filled everything out in FMC completely. Any particular way to engage it?

[Harold Henderson]

Rey, I fought this battle, too. I ended up having to manually select CL mode before selecting the VNAV button, and that works almost all the time for me. I think I also found somewhere (probably at their forum) there is an altitude below which you can't engage the VNAV mode ... but don't remember what that is. May be why taking the extra time to select CL works for me.

Just a few other things:

1) I know you said you set everything in the FMC, but, just to confirm, did you select the departure runway?

2) Have you done the tutorial flight? Did it work then?

3) Check the forums - http://s80.flight1.net/forums/forum_top ... on-support

Good luck. It's a great airplane.

[Rey Ramon]

Departure runway is set. I did the tutorial flight, twice in fact. Once it worked (the only time it has) and once it did not work. Thanks for the input. I've had this plane for ever, but I've just completed my first two flights with it.

[Wayne Pierce]

I use this craft a lot and the VNAV will not engage until I am on the prescribed course and heading on LNAV and at a prescribed altitude ?. One has to manually fly upwards until it wants to work. Then it works fine for me.

WLP

FROM HH below, Also, the Normal Procedures section does call for manually selecting CLimb mode after takeoff BUT it does not give any guidance that I could find on WHEN to enable VNAV

[Harold Henderson]

and a few excerpts from the manual (reading it for the FIRST time, of course):

VNAV Engagement
The flight crew may couple the FMS VNAV
mode to the DFGS by pushing the VNAV
button on the FGCP as long as the following
conditions are satisfied:
 The following FMS data is present:
o Aircraft GWT, cost index,
cruise altitude.
o Aircraft position, CADC data,
IAS, Mach, SAT, TAT, pressure
altitude, and vertical speed.
o Roll and pitch attitudes.
o FGCP clearance altitude
(altitude preselect readout).
o Acceleration data.
o Vertical flight plan.
 Autopilot and/or Flight Director
engaged.
 TRP is not in TO, TO FLX, or GA mode.
 The autothrottles are engaged or will
be engaged within 5 seconds of
VNAV engagement.

Conditions resulting in VNAV
disengagement:
 The flight crew engages another
vertical mode such as VERT SPD.
 The armed mode becomes active,
such as G/S armed to G/S CAP.
 A loss of data sensor required for
VNAV.
 A loss of navigation data (position or
velocity).
 The Autopilot and both Flight
Directors are de-selected.
 The autothrottles are disengaged.
 The TRP mode is changed to TO or
TO FLX.

When VNAV is disengaged, the DFGS reverts
to ALT HLD from VNAV CRZ or VNAV LVL, and
IAS HLD from VNAV CLB or VNAV DES.



and from the Flight Management section:


PERF INIT PAGE
This page provides for insertion of
performance data into the FMC
performance calculations.
Dash prompts indicate helpful/optional
preflight entries. Box prompts indicate
required preflight entries before VNAV can
be used.


NOTE there is a box on Reserves!


Also, the Normal Procedures section does call for manually selecting CLimb mode after takeoff BUT it does not give any guidance that I could find on WHEN to enable VNAV.

[Rey Ramon]

Thanks for the advice. Finally took the super 80 out for a spin two days ago, and selecting the CL mode fixed the issue. You guys are the best!