Airbus THALES BOX. Loss of VDEV when in HDG mode

[Microburst2002]

Hi

I have noticed that in models with the THALES FMEGS, when we are in HDG because we are being vectored, the VDEV in the PFD and the PROG page dissapear (not immediately but at a few miles off the green line).

Perhaps it is a glitch but I haven't seen it in the looooong list of those "specificities". So I suspect it is like that per design, probably induced by some *#%&* lawyer.

Normally I don't need the VDEV, as I can calculate pretty accurately how many miles I need to land, but I like to compare with the FMS, and if there is a discrepancy I verify what is going on. Sometimes happens that I'm not considering some AT constraint, for instance.
Also is good to have it when my brain is not performing at its optimum. To put it short: I want to have the bl00dy VDEV. Why does THALES deny me what HONEYWELL has been giving me so long?

[A-3TWENTY]

This is just one of the problems. Thales FMGS is the worst crap I`ve ever flown in modern aircraft.

SHould be forbiden.

[fantom]

Isn't it because, in HDG, it does not know the track miles to run, whereas not in HDG it does?

[FE Hoppy]

Fantom, exactly.
Vertical deviation from what? If you're in HDG your not on track so the deviation from the vertical path is meaningless.

Lot's of other aircraft do the same.

[tubby linton]

3 Times Table Chart. 3X Free Multiplication Table Printable. (http://www.math-help-multiplication-tables.com/3-times-table-chart.html)

[mcdhu]

Love it Tubbs!!
PS 1 in 60 still works too!!

[flyingchanges]

If you are controlling the heading, you should also be controlling the altitude. Once off track, VNAV may not be a safe profile. I heard somewhere the next FMS update (737-800) for us was going to automatically disengage VNAV anytime LNAV is not active.

[tubby linton]

When I am given a heading in the descent i put the next altitude constraint waypoint into the box in the prog page and then just use three times the height plus a correction for head or tailwind. I have not been impressed with the blue bent arrow on the ND to show where I will level off

[Cough]

flyingchanges...

That's interesting because when I woz a lad on the 737 classic, thats exactly what it used to do. Then the FMC's were updated and we gained the capability (up to a restricted cross track distance).

Quite funny if it does go full circle!

[Microburst2002]

Since the first airbus boxes, VDEV is still there no matter what. The pilot has a brain capable of understanding that it is advisory only, since the track miles to touch down may differ.

The information that it gives is useful, even though you are off the green line.

Also, what is the point in using the DIR to radial inbound a fix in final if you will automatically loose the VDEV as soon as you pull HDG?

When you are in vectors and the WPT TO is a fix in final, VDEV is very useful too.

But THALES decided that we shouldn't have that info anymore. It is nonsense