A330 FMS perf data vs PFD

[TGoncalves 13]

Hello there!

 

I've noticed that during cockpit prep the manouvering speeds shown on takeoff perf are related with actual GW rather then the expected TOW calculated by FMS taking into account the fuel and ZFW inserted by the flight crew on INIT A. I've mentioned this on another topic, A330 first impressions. But as I did more runs with multiple variables I noticed that even while FMS is calculating this data related to actual GW, it does not come up with the right figures with higher weights. In this example I did a MTOW (block fuel 60.5, takeoff fuel +/- 60). For 233 Tons, green dot should be 247kt, but the fms computed 237kt. (or did the development team took into account the impact of eng fail/shut down have on green dot? I dont think thats the case but we never know)

Please login to display this image.

 

Yet, after takeoff the displayed green dot on PFD was correct.

After that I checked the perf appr page, where it should display the manouvering speeds assuming landing weight but it was showing the speeds for the actual weight.

In this case, for the expected landing weight of 182 (notice the landing fuel of 8.9Tons), green dot should be 216kt.

 

Please login to display this image.

 

Additional to that, above 20000', as the green dot on PFD increases 1kt per 1000', so did the FMS landing predictions as well as the other manouvering speeds.

 

Please login to display this image.

 

Also, with higher gross weights, it seems the VLS is the same as green dot when in fact is not the same.

 

And so I turn back for a landing with overweight eheh

All went well, just noticed a bug on the target speed range as follows

 

Please login to display this image.

 

 

In all cases, the Vls seem well, only the F, S, O have the issue

Thank you all for the hard work!

[masterhawk 799]

It' a known problem. Not easy to fix.