From the earliest days of flying, gusts have been a problem for aircraft. In the very early flights aircraft were flown only when it was nearly dead calm and few gusts were met. Later on and, in fact, almost up to the Second World War, flying was greatly restricted by the ground and air conditions at the aerodrome. This meant that there had to be fairly good visibility and that the grass aerodrome must not be unduly softened by water. Since the war, aircraft have been flown with much greater regularity.