KG - I should have been clearer with my question.
When you put the eng anti ice on (and therefore reduce the drift down altitude) does the FMC reduce the drift down altitude displayed.
Just trying to prove empirically the theory that the FMC is able to assess the aircraft's actual bleed configuration.
Does it matter...does to me. Like I say just lost my job ..got an interview coming up and this is one of the tech questions that gets asked.
Pint of beer for anyone willling to explore the system.