While midair collisions are always newsworthy events they are fortunately quite rare. The following information comes from the1997 Nall Report, an annual review that ASF compiles from preliminary NTSB reports, which describes annual fixed-wing general aviation accident trends and statistics.
In 1996 there were 18 midair collisions involving 31 aircraft 5 accidents were fatal involving 18 fatalities. This is slightly over one percent of the annual total accidents in GA. It is not one of the major causes. That is a slight increase from 1995 when there were 15 midairs.
Airports and the airspace surrounding them are naturally where airplanes tend to congregate and are therefore the location of most mid air collisions. A recent ASF study found that 49% of midair collisions occur in airport traffic patterns or during the approach and departure phases of flight. Roughly 25% of midairs occur during enroute climb, cruise, or descent. The remainder involve formation flying and other hazardous activities.
Some midairs involve fatalities but there are almost never collateral injuries or deaths on the ground. In 1996 there was only one accident, an attempted emergency landing on a highway, that resulted in fatalities to occupants of a car.
The 1997 Nall report is available by sending an address label and $2.00 to cover shipping and handling to AOPA Air Safety Foundation, attn: Nall Report -- WEB, 421 Aviation Way, Frederick, MD 21701.