Accidents occur between all human-operated vehicles, vessels and transport with enormous loss of life and personal injury. Mid-air collisions of airplanes occur between military, commercial and private aircraft, most often near heavily used airports; marine collisions occur in busy harbours between vessels of all kinds and sizes; and road collisions, which involve the most fatalities, occur between passenger cars, trucks, buses and other vehicles, and between such vehicles and pedestrians. Another type of collision occurs between transport and stationary objects and includes airplanes that have flown into mountains, bridges, buildings and electrical wires, for example; ships which have struck icebergs, jetties, wharves, port facilities, reefs, sand bars and submerged rocks or wrecks; and roadway and off-road vehicles which have struck trees, poles or other objects. In addition there are collisions with animals: aircraft collide with birds; fast moving ships and boats collide with, or are struck by, whales and other sea-creatures; and road collisions occur with large animals such as horses, deer, sheep and cattle.
Collisions also occur wherever humans are moving - whether in vehicles, on skates or using other devices for accelerating movement, or even (especially in crowded cities) between people who are merely walking. The collision-prone nature of humans is an individual physical limitation which, as a form of inattention, seems also to characterize world development as nations collide with each other, partly also as a consequence of a failure to exchange adequate signals.