Emirates PERF INIT and SOP update

[PinkPony 171]

I am sure many here operate the -200LR/F/-300ER in the Emirates livery. Some of you may remember Luke Pabari being kind enough to share the default PERF INIT values used on the EK777 fleet in this topic, especially useful for those of us who enjoy operating as close to reality as possible.

 

http://forum.avsim.net/topic/393541-performance-initialisation-emirates-b777/

 

Some changes have recently taken place:

 

1. EK is now using 30% as the default CRZ CG across the entire 777 fleet. Previously 30% on 772/3, 20% on 77L/F and 17.5% on -300ER¹

 

 

2. EK did not purchase the TO-1 and TO-2 de-rates option. This is  is also selectable in the PMDG Aircraft Equipment FMC menu. Boeing calls this customer option TO-1/2 takeoff de-rate Delete. 

 

This means EK only uses the TO rating in conjunction with assumed temp on the -300ER/200LR/F.

 

Furthermore, as per guidance from GE regarding the GE90, operators were advised that full CLB thrust regardless of what the FMC defaulted to based on the assumed temperature entered, was preferable. Why? Although there naturally was increased wear and tear from always using full CLB thrust vs CLB-1 and CLB-2, less fuel would be used to CRZ ALT as the aircraft would reach its CRZ alt quicker over CLB-1 and CLB-2. And until recently the fuel savings were greater than the cost increase in wear and tear.

 

Thus, SOP until recently was for crews to always select CLB thrust while setting up the THRUST LIM regardless of what the FMC defaulted to, specifically anytime takeoff weight was greater than MLW. (used as a arbitrary number to define the SOP). This changed late last year to leaving the FMC selected CLB thrust default (Be it CLB, CLB1/2) regardless of takeoff weight.² Of course anytime a higher CLB thrust rating is operationally required due to SID climb gradients or other factors, the crew may select it as the deem necessary for the safe and efficent operation of the aircraft.

 

Two hypothetical -300ER examples on how it is done now.

 

351.5t takeoff (highest -300ER MTOW), TO-37C the FMC defaults to CLB thrust on the THRUST LIM page. In this case you leave CLB because thats what the FMC selected based off the TO thrust.

 

275t takeoff, TO-62C the FMC defaults to CLB-1. In this case you now leave CLB-1 even though takeoff weight is above MLW (previously this would have been above the SOP threshold for crews to select CLB. Unless of course it is operationally necessary to full CLB prior or following TO. 

 

I hope this gives some insight into the real world operation of the magnificent B777, and also comes to show how both the manufacturer of the aircraft and engines continue to make improvements and extremely experienced B777 operators such as EK continue learn new things about their products/workhorse after 20+ years of successful commercial operation. 

 

For those that didn't already know, EK is the only Boeing customer operating the entire B777 family. From -200/ER/LR/F/-300/ER. That being a total of 6 different B777 types!

 

¹ The reason it was lower on the -300ER and -200LR/F is because upon original service entry of the -300ER crews, were experiencing airframe vibration at low weights hight altitudes. Boeing's solution that was in place for pretty much the past 11-12 years was to set the default CRZ CG% to 7.5% to artificially lower the MAX CRZ altitude. EK and other operators quickly began experimenting with higher numbers and 17.5% was used until recently on the -300ER and 20% on the -200LR/F.

 

Note : Changing CRZ CG % from 7.5% to 30%  in the real aircraft results in a slightly higher MAX and OPT altitudes on the VNAV CRZ pages (Changing this value in the PMDG 777 does not result in any MAX and OPT altitude changes as the MAX and OPT numbers in the sim already reflect the 30% -300LR -200LR/F MAX and OPT altitudes and not the slightly lower ones introduced by the Boeing 7.5% default. (I verified this with the latest Boeing -300ER and -200LR/F FPPM revision).

 

²  Late in 2014, GE issued a advisory to all GE90 operators based in a specific geographic region. Spanning from the middle east to south east china.  GE realized that specific fine sand dust particles found primarily within this larger geographic region, in conjunction with the higher core temps associated with full CLB thrust climbs, was resulting in increased wear in specific hot section components of the GE90. Hence for GE90 operators in that geographic region, such as EK, experienced increased wear and tear costs which were offsetting the fuel savings obtained from full CLB thrust climbs. (Which was the original GE advisory to GE90 operators). Cathay Pacific is another operator who used to select full CLB thrust for every takeoff above MLW, regardless of what the FMC defaulted to. Operators not based in that geographic region and thus not frequently exposing their turbines to those sand dust particles continue to follow the original GE guideline as the fuel savings associated with reaching CRZ alt quicker are greater than the slightly increased wear and tear 

 

Leo Cal

[Seme 6]

Hi Leo,

 

While im only flying with my own virtual airline and own liveries, I have to say the this forum continues to surprise me. There are always people like you who want to share their knowledge to others in order to gain as real as it gets environment.

 

Amazing stuff, thank you for sharing! Always interesting to read such topics!

 

Cheers

[willultra99 8]

Great read.  Thanks for the info

[ddswh1pk0s 8]

Thanks a lot for this info, a great read!

[http404 22]

Great read, thanks for sharing.

 

I would like to add that, as of May 2015, EK has increased the Cost Index for all flight except for the ULRs to CI 200.

 

Initial increase was to CI 400, as fuel prices plunged, then brought down to 300, then 200. There was an endless debate on the forums regarding that decision.

 

ULR flights, across the Atlantic and Cargo flights are using a CI 66.

 

The change enables EK to enhance the OTP and protect connections. (If only it wasn't for the DESDI hold... )

 

Now to the PMDG:

 

the PMDG seems to burn less fuel than the fuel burn increase calculated by PFPX for the same burn bias.

 

For example: If you use a Cruise fuel burn bias of 96.5% for a default CI 66-70, planning for a higher CI of 200 would return more fuel than the PMDG would burn at that CI.

 

This is probably something that would be fine-tuned within the fuel burn logic of the PMDG.

 

To counter that effect, if I'm to plan for a CI 200 flight, I'd enter CI 350 into the FMS to be close to the fuel burn suggested by PFPX.

 

 

Enjoy your high-speed flights!

[Boeing or not going 578]

I read Emirates freighters are using CI 40-45.

 

Does anyone have info about takeoff preferences? Do they like to use flaps 5 or flaps 15? AF Cargo likes flaps 15

 

And are they using vnav descent or a selected speed and flight change?

 

David Lee