CLB Page empty after removing speed restrictions from CLB page

[KrisDev]

Hi,

I've noticed that after removing speed restrictions in Climb page (f.e. I got unrestricted climb from ATC and removed 250/10000 restriction from the climb page) my CLB page goes empty (pic 1) and I don't have my CRZ page anymore, it's showing the same data DES page, it's basically now a DES page (pic 2). It's not the first time I'm experiencing this, it happened to me in the past as well. I've tried inserting FL again, or just the altitude, tried editing CRZ FL in Performance page as well... Nothing works!

In addition, vertical profile is showing me that I'm above profile and it resets to 0 when I enter altitude in the FMC, but starts falling again.

Regards,
Kris

 

Edited February 26, 2021 by KrisDev

[Litjan]

Hi Kris,

yes, this is not the way it should be - often the 250/10.000 restriction gets erazed in the real plane to climb with a higher speed when still below 10.000 feet.

Unfortunately our VNAV code is pretty frail right now and doing things out of the ordinary can make it fail, like you observe. The same goes for changing cruise altitude, entering complex descent restrictions, and so on.

We plan to solidify the code some more - for now I would suggest to just enter the most "basic" profile and not modify it too much regarding the vertical profile.

If you want to fly faster below 100, just use selected modes to do so and disregard what the FMS tries to make you do ;-)

The combination we used in 95% of all climb scenarios was LNAV with CWS P - that way we could keep the pitch constant, i.e. 10 degrees for roughly 250kts, 5 degrees for roughly 300 kts (great for passenger comfort) and the speed would vary slightly.

Cheers, Jan

 

Edited February 26, 2021 by Litjan

[KrisDev]

Hi Jan,

Thanks for the tip! One more observation from the problem is that it's resetting the altitude on the VNAV profile once it passes the WPT. It goes to 0 and then starts decreasing till it reaches next WPT. Hope it will be helpful for the bug fixing in the future