When calculating V speeds for takeoff using performance calculator on EFB, they are inevitably different from the speeds that come up on CDU. There have been times when the difference is almost 10 Kts.
What is the recommendation in such case; use the CDU or perf calculator speed?
I’ve never had them be off by that much - that suggests something may not have been loaded into the CDU properly. Double check that you have the correct weights, TO flaps, and that you’ve set the N1 limit that the EFB produces. For me they’re almost always within 1-2kt of each other in most cases, except for V1 if the RWY is short. Double check your weights match up
That being said, typically you go with the EFB if there is a variance. A 10kt difference does suggest they’re both calculating off different things though.
I made it a habbit to click “calculate” twice. Often the first output is corrected then, at least for me.
I’ve been flying the 777 since the PC release and never had the EFB and FMC difference be greater than 1 knot, and most of the time they are completely the same.
As others said, check to be absolutely sure the aircraft weights are the same in the EFB and the FMC, that you have the same flaps set for both calculations, that the weather is the same, and that you have the correct runway set in both.
And set the flex temp…
Exactly. @xisumervoid Thats most likely the issue.
First select the TO/CLB suggested by the EFB (TO, TO1, TO2, and CLB, CLB1, CLB2) and then put the assumed temperature not the other way around.
I am sure that if you put the assumed temperature and the select the TO derates then it will wipe out the assumed temperature value to - - -
If you enter runway wind, runway slope and ground temperature (OAT) into FMC you will get similar or the same takeoff speeds. EFB takes this data from Metar when you import it, in FMC you need to enter these values manually.
Thanks - I saw the yt vid by 330driver and he put the temp suggested by EFB which in turn led to appropriate TO and CLB derates being selected automatically. This is the step I was doing incorrectly.
And the sequence is non-trivial which I learned the hard way, and Ffortuna posted above. When I was entering the temp first, top down as displayed on the CDU, then the derate, I got weird results. When I started selecting the derate first, then entering the temp, it all came together correctly. Was not a big difference really, but it’s nice to see it all hang together correctly!
do the engine covers open on this? also what is the “EE” and “Avionics” access doors? i opened both but couldn’t see what it was doing
Thanks all, the pointers really helped and now I am very well placed with V speeds on CDU and EFB being very close and matching in some cases.
I did my first intercontinental flight from EGLL to VIDP and with 4X feature being a great boon completed it in a lot shorter than predicted 8+ hours. When I finally landed, instead of the airport bustling with traffic, was empty as it seems I hit the sim object limit while flying across continents - which is a pity and something that must be addressed in 2024.
Did anyone see this strange value for trim before? I couldn’t import weather data, EFB was giving me errors about weather not available. I entered it manually based on ATIS. Wind was calm so I entered 000/00. I tried also 000/0 but the result was the same.
It’s happened to me once before, and a handful of others have reported it as well.
After I got the error, I intentionally re-flew the same route, using the same livery, same ZFW and weather and could not get it to recur.
Brake temperatur does not change after landing & hard braking…
I remember the glowing brake discs were one of the advertised features but it’s been quite a long time (maybe never?) since I’ve seen that works.
Is it only me that passed the fix or wasn’t it fixed yet for everyone?
Same here. Only works if you try it at the beginning of the flight, but after a flight upon landing the temperature does not change at all.
