I've starting to use my CS B767. I've yet to use the FMC. I'm now reading all the how-to's and think I've got a handle on it, but my questions is do you use the FS-ATC or radar contact when using the FMC?

If I'm right, once you start your takeoff roll, the FMC can fly the plane from that point on, so wouldn't having ATC direct you to a new heading  screw up the works?

If I'm way off base here please let me know.

Bruce

Hey Bruce welcome

Personally, I rarely use IFR ATC, I use Radar Contact (VFR) ATC if I'm using a fixed route on the FMC with waypoints, SIDs and STARs and all, but sometimes I'll use IFR vectors without messing up my original flight plan, so I open (in-flight) the ATC menu, then click open or create flight plan option and make a quick DIRECT IFR route. For this, I know from the beginning of the flight I'll be approaching and landing the airport using ATC vectors so I delete all the waypoints, VORs, etc close to me destination so I have a direct route more or less 100nm from the airport and get the IFR vectors from ATC.
The new IFR route you load in the FS Flight Planner in-flight is only for communications, this means you don't have to reload anything in your FMC, you continue with your original FMC flight plan.