Also found this in the FCOM 4 regarding down route ETA predictions displayed on the MCDU:--
WIND PROFILE
To obtain the best predictions, the pilot must enter the wind for various flight phases and specifically for waypoints in cruise. ON GROUND : During flight planning initialization, enter the winds for climb and cruise phases using HISTORY WIND and WIND pages. You will enter, manually or with ACARS, different wind values in climb and cruise phases. The system will compute a wind for all waypoints of the F-PLN using linear interpolation between manual/ACARS entries. This wind profile will be displayed on F-PLN B page and is called forecast wind profile. Pilot or ACARS entries are displayed in large font, system computed winds in small font. The forecast wind profile will be used to compute fuel and time predictions as well as econ speed/Mach targets.
IN FLIGHT : the system updates the predictions and the current econ speed, using the measured wind at present position. It mixes actual wind and forecast winds to compute the wind ahead of the Aircraft but this is totally transparent to the crew.
Last edited by nitpicker330; 13th September 2012 at 11:43.