Bird strike is a source of distress for military airports. A bird might seem to have a little impact on a combat plane, but should not be taken lightly. For instance, if a mallard weighing 900 grams crashes into a fighter flying 370 kilometers per hour, the impact is equivalent to 4.8 tons. If the bird is sucked into the engine, the plane can crash and claim the lives of pilots. Because of this, driving birds out of an airfield is a prerequisite for air training. In one exercise, more than 10 F-16 fighters took off and birds were being driven out whenever a fighter took off.