Disengaging VNAV when changing ARR proc resets speed to .84

[lanmancz]

Pretty much as the title says. I pinpointed in which situation this still happens and that is when the auto-disconnect happens when changing the ARR procedure before descent (as per ATC instructions for example). This disengages VNAV and sets speed to .84 instead of current/last planned. Disengaging VNAV manually works OK.

Also I have a question about this - shouldn't the VNAV stay untouched until I execute the change in FMC ? I realize that when changing the plan there might be a disco so thats why its disengaging but I can still hit ERASE and go back to original plan. I would expect that the current VNAV path would be affected only after I execute it, no ?

Edited May 23, 2016 by lanmancz

[Litjan]

Hi lanman,

you are correct, VNAV should stay engaged in the MOD phase - I will see what we can do about this.

Thanks about the .84 report - we had a couple cases where this happened that we fixed, it looks like we missed this one!

Jan