Commerce is a dangerous activity in Oceanyka. Bandits and highwaymen are common all around. Fortunately, oil and airplanes are also relatively cheap. This created a particular mode of commerce, later studied by "airspace trade theory", which dictates commerce can be efficiently practiced up above under certain circumstances. This is true, and goods transported by aircraft are significantly safer. However, a new class of lowlife was born from this development: air pirates. These people shoot down valuable cargo to retrieve it with paratroopers, or outright board a target plane. Air convoys are usually escorted by fighters or bomber aircraft which have been retrofit with an enormous quantity of guns.