Thanks for your answer.
I forget to mention that the C-130 was under grey faction aka civil aircraft.
In my scenario, a MiG-21 is supposed to intercept a pakistani C-130 and force him to land at Gardez or whatever airport in afghanistan.
I just try to make it works and it seems to be possible to land only on an airtrip which has the same faction than the aircraft.
If this is correct it would be nice to allow neutral faction to land everywhere...
EDIT!!
I tried with neutral faction for the C-130 and the Airfield...didn't worked...change the coalition of all the itms i put near the airfield to neutral...and at least it worked...
Everytime i'm working on something with his mission edior i learn something...still true even after 5 years...
Cheers