I'm using afcad for gates and to designate runways for take off and landings, but how do I get airplanes to use both paralell runways for landings and take offs. Is there a way to override FS need for the longest runway.

There are a couple of ways to get multiple-runways to work. The first is simply to use one for takeoffs and the other for landings, by using AFCAD to close them for either landings or takeoffs. Make sure if you do this that the landing runways have ILS.The other way is to use "Overlays." What you do here is essentially create a second airport. The original airport (say KLAX in Los Angeles) would use one runway, while the new airport (typically 2LAX) uses another. The details of how to do this are contained in AFCAD. You will also need to move some of the traffic from the original airport to the overlay. This can be done manually by editing the flightplans.txt file, or you can use a tool like AITM to do it for you.You can even combine the two techniques if the airport allows it. KLAX, for example, has 4 runways. I set it up as two overlays (KLAX and 2LAX) but each overlay uses 1 runway for landing and the other for takeoff, so it's using all 4 runways for traffic.Overlays generally work well with parallel runways, but not so well with crossing runways. When a plane lands, it doesn't necessarily contact the overlay it's assigned to. Instead, it contacts the one whose 'airport reference point' is closest. (AFCAD shows the airport reference point with a small red cross, which you can move with the mouse to make it appropriate for each overlay.)