From the Fokker AOM: "Engine anti-icing must be on during all ground- and flight operations when icing conditions exist or are anticipated." With regard to wing and tail anti-ice: "The wing and tail systems must be selected on when icing conditions exist or when icing is observed."
You can read that to say, engine anti-ice on before you enter icing conditions, and wing and tail anti-ice on after you enter the same.
Fokker just come out Friday, recommending operating with the engine anti-ice on at all times when the TAT is below +6 to -25 degrees C, regardless.
With regards to Austrian Airlines, does replacing the F70 "engine ice protection system" refer to going back to the orginial design of the ice impact trays?