Thanks for the reply. It is not only when near the stall speed or the runway threshold, but also around 200-250 knots. The drift is more prominent as you get close to the stall speed i.e. close to the runaway, I think this is what you are referring as ground effect. It seems the drift is effected by the landing gear. In my mission, when I am 15nm from the runway (at heading 324), if I do not lower the landing gear there is no drift, I can just leave the flight stick, and it stays at current heading, but when the gear is lowered the f16 starts to drift and needs +/- correction in roll constantly. I am not using any trim, just flying the plane. I did not see people correcting the drift on Youtube tutorials for landing, so I thought maybe I am doing something wrong. Anyway thanks for the detailed reply, I will keep at it, until I get better.