investigating ALT CAP updating with target change

[Prof_Plumpy]

I have had a few issues with altitude/VNAV. 

 

Out of VHHX there is a max alt of 7000 feet untill 17nm past the VOR.  The plane will (mostly) settle at 7000 feet in CMD VNAV/TM mode.  ALT CAP and should stick at 7000

 

Now when you dial in a new alt and do nothing else, it will often start to climb by itself. One time dialled in a new alt increase and it started going down, probably as it was in a turn and thats the way the plane was going vertically at the time.   According to the normal ops page above it should hold until you engage ALT SELECT+VNAV.  

There is also a lag of a few seconds between hitting VNAV and anything happening.  

 

Back to OPs problem.  Did you enter data on pages 1/2/3? (Weights/ToD/Cruise info)

[richboy2307]

8 hours ago, Prof_Plumpy said:

I have had a few issues with altitude/VNAV. 

I have split your topic as its a separate issue to the one you had replied to.

8 hours ago, Prof_Plumpy said:

Out of VHHX there is a max alt of 7000 feet untill 17nm past the VOR.  The plane will (mostly) settle at 7000 feet in CMD VNAV/TM mode.  ALT CAP and should stick at 7000

 

Now when you dial in a new alt and do nothing else, it will often start to climb by itself. One time dialled in a new alt increase and it started going down, probably as it was in a turn and thats the way the plane was going vertically at the time.   According to the normal ops page above it should hold until you engage ALT SELECT+VNAV.  

Thanks we want to investigate this further. Was your AFCS ALT window indicating the mode as "ALT CAP" still when you changed the target? Or was this after it had already changed to ALT?

How were you changing the altitude target? click and drag or mouse wheel? Thanks!