[FMS] Can't set Takeoff Ref Speed when APPROACH REF page is open on FO CDU

[daemotron]

I stumbled across this one on a turn-around (without rebooting Gizmo since I didn't need VNAV for that leg), and I'm not 100% sure this is really a bug or intended behaviour:

After updating RTE, PERF and N1 LIMIT pages (and executing everything of course), I had correct QRHs displayed, but I could not confirm them by clicking the RK 1/2/3. I had this already before, sometimes I could, sometimes not. Now this time I noticed I still had the APPROACH REF page open on the FO's CDU from the previous flight, and voila, as soon as I select any other page on the FO's CDU, I can set and confirm V1, VR and V2 (plus: re-selecting the APPROACH REF page on the FO's CDU will instantly clear the V1/VR/V2 selected):

I know this is sort of weird; normally it doesn't make sense to have VREF for approach set and V1/VR/V2 at the same time. Now the question is, what would the real aircraft do in such a situation?

 

 

Edited April 9, 2024 by daemotron

[Litjan]

Thanks for this interesting report!

We took some measures to avoid displaying takeoff speeds and approach speeds on the EADI speed tape at the same time. So this is probably whats kicking in, here. We figured that setting approach speeds would be a higher priority than setting take-off speeds, hence the bias.

Jan