Sign in to follow this  
MarkW

somehow lost VNAV mid flight

Recommended Posts

Just in the last few hours of an atlantic crossing and I decided to load the Descent Forecast (flightplan from PFPX and weather from ASN).  After I did this all of the computed altitudes were blanked out and in the progress page the ETA and Fuel values were flashing.  I could never get them back and ended up manually working out my descent and using V/S.  Just wondering if this is normal behavior or some issue with my sim.  thanks.

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

Just wondering if this is normal behavior or some issue with my sim. thanks.

It doesn't sound like normal behavior. I have requested and loaded descent forecasts hundreds of time and never seen this. Was there any message on the CDU prior to this happening? Like maybe VERT PATH FULL.

Share this post


Link to post
Share on other sites

a similar topic was posted some time ago  and it turned out it was because of a speed/altitude restriction in the STAR that was not possible to meet in conjunction with the updated econ descent speed. for example the STAR required 280 and the calculated econ descent was 330.

modifying the descent speed on the vnav page to something like 280 made it all work again.

 

maybe when you updated the forecast it modified your descent speed to an unusable value such as this.

 

the thread was here; http://www.avsim.com/topic/495968-vnav-disconnect-flying-the-coorz3-out-of-kden/

 

cheers!

-andy crosby

Share this post


Link to post
Share on other sites

a similar topic was posted some time ago  and it turned out it was because of a speed/altitude restriction in the STAR that was not possible to meet in conjunction with the updated econ descent speed. for example the STAR required 280 and the calculated econ descent was 330.

modifying the descent speed on the vnav page to something like 280 made it all work again.

 

maybe when you updated the forecast it modified your descent speed to an unusable value such as this.

 

the thread was here; http://www.avsim.com/topic/495968-vnav-disconnect-flying-the-coorz3-out-of-kden/

 

cheers!

-andy crosby

 

Great catch, thanks for this comment, that sounds reasonable.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this