AI traffic behaves strange...

Dear friends,Recently I intended to make my AI traffic more realistic so I started downloading many realistic AI traffic plans from Avsim. Together with FSPainter and AI Aardvark aircraft they really make a difference however I'm facing some weird things:I noticed that almost none of my AI's were actually landing; they simply appeared at the gate a short time before they have to start their next leg.Changing the airspeed in the aircraft.txt files of the fp's, from the original cruise speed, to 200 knots solved this, but I still don't know why that is... (does anyone?)btw, all flight plans use exact arrival times (the @ symbol in the flightplans.txt) Now AI planes are landing around scheduled time, but why do some of my AI's crash into the ground or land too early (and then taxi to the runway, which looks very silly) when they are in the vicinity of their destination airport and can this be helped?Thanks very much,gts Bastiaan