The collision of a small plane and a helicopter above the Hudson River Saturday took place in a zone where pilots essentially police themselves.
Saturday afternoon, a small propeller plane piloted by a Pennsylvania businessman and a helicopter hired by a group of Italian tourists crashed into each other in the crowded airspace over the Hudson River.
All nine people aboard the two aircraft are believed to have been killed. Divers have recovered five bodies from the river as of Sunday afternoon.
The area is not unsafe, pilots say. But it can be "a very tricky environment," pilot Dan Rose told the New York Daily News. "Almost every time you go down there, you come closer to other planes than you normally do."
The site of the crash is governed by visual flight rules. This means that pilots are flying below 1,000 feet and do not talk to aircraft control towers or file flight plans.
Instead, they essentially police themselves. They are encouraged to report their whereabouts frequently on a radio channel that other pilots can listen to – and to keep their heads on a swivel.