You know that if a plane needs to make an emergency landing or to another landing location, it will need to dump out fuel and it dumps them at the tip of their wings.
So when a plane is about to take off, it gets enough fuel and will use up most so that when it lands, the lighter weight is more ideal for the landing. If it lands on a full tank of fuel, it is like a fat guy trying to land after jumping off the roof. It will not be a pretty splash.
