Well, finally i changed the decel time for the carrier, now it works greatly.
Now here something else, i don't know if anything can be done for that :
I'd like to prevent the player to move his ship in the first seconds of the mission,
It works well... after the first second, it seems that when i have my thruster not at 0 on my stick, the ship will move untill fred trat the sexp.
My actual solution is to swap player's ship with a copy with a set max speed of 0 and that works, but i would like to find a cleaner solution as fighter room's in the tables are not unlimited.