theguz wrote on Dec 31^st, 2012 at 7:56am:

In real life the pilot does not know the approach and landing runway when he is about to take off, correct?  that can change in flight due to weather and traffic, so on.  what do we do if we need to change the STAR after it is initially selected?

Normally you should not fill any arrival until you get close to the airport for those reasons. On other FMC systems (737 and airbus) you can change your STAR with no problem (perhaps a discontinuity may appear). Flying on IVAO it happen to me to change SID under ATC requirments with no problem.