744 FMC flight plan wind usage
 

My first question is normally a computer flight plan ( Jeppesen and many others) are based on "ECNO" speed mode or "LRC" speed mode ?

If wind modifications, wind mixing and winds and step climbs and Cost Index are conducted during cruise, which speed mode should pilot select on VNAV page ?

I understand that "ECNO" is a defult mode for FMC, if forecast winds for fuel remain at destination is necessary to re-calculateste, LRC and MCP speed mode will have the this functions?

Thanks & Regards,

I'm sorry if this does not answer your question(s) greenband, but you've not worded them very clearly:

Anyway here goes:

1.Normally a computerised (or manual for that matter) flight plan will be based on whatever the flight planner/ crew decide and select when the plan is being created. That can mean anything from fixed MACH, LRC, MRC, a company standard speed or even ECON (no such thing as ECNO??).
Factors that will influence the choice range from route/ schedule/ timings/ payload/ fuel cost ......

2. Whatever is appropriate! You should note that COST INDEX relates to ECON speed. A flight plan produced using ECON as the default will have been produced with a specific COST INDEX associated. This cost index would normally be input to allow ECON to default correctly. It can of course be modified as appropriate to adjust timing etc.......
So a crew will input the appropriate speed mode on the climb/ cruise/ descent page as per the flight plan.

3. I'm sorry, but this question simply does not make any sense? Can you rephrase it and I will try to answer it for you? :confused: :confused:

B

Thanks Banana head, I rephrased my question:

During cruise, if forecast winds are entered & propagated and cost index is also set, which speed mode should be selected on the FMC VNAV page ?

ECON. If you manipulate the Cost Index, it will alter the ECON speed to a new scale, but it will still show ECON. We select 0 during climb, and usually 90 or leave at 0 is required. When you select 90, it shifts the speed up slightly in ECON. You can select 400 as max. It will still display ECON, but cruise speed will go up to M.865 or so. Any time you like, you can select a Manual speed in the FMS which will show as Mod Spd M.85 cruise and maintain that speed in VNav.

One of the means of adjusting default climb and descent speeds is via use of Cost Index. I'm not a fan of the procedure, but it has been used by my company in the past. I would prefer that they plan on a Mach number or a CI and tell me why, then let me adjust the speeds on th VNAV page for climb nad descent if necessary.

In general, if planned for a CI, accept the speeds that CI gives you for cruise. If a headwind bust makes an adjustment necessary, adjust the CI downward but remian in ECON. Remember that ECON with CI=0 is the most fuel efficient profile, INCLUDING WINDS. LRC does not give any wind correction.

Got your final words... LRC does not give any wind correction. Thanks