Bird strikes, while not considered a big issue for light general aviation aircraft, have been responsible for some major accidents and more than 300 fatalities since the age of flight began. According to an FAA study, more than 16,000 collisions occurred during a recent seven-year period over the United States, Puerto Rico, and the U.S. Virgin Islands. Nearly 80 percent occurred less than 1,000 feet above the ground, but some high fliers have encountered flocks of birds at altitudes exceeding 20,000 feet.
Some of the physics of a bird encounter may pique your interest. An FAA flight standards district newsletter mentions that hitting a two-pound seagull - the type of bird most likely to be involved in a bird strike - at a speed of 120 mph results in an impact force of 4,800 pounds. Jets have a much bigger problem. An impact at 600 mph results in a force of more than 35 tons. Frequently, jet engines will be severely damaged or fail as the result of a strike. The U.S. Air Force suffers millions of dollars of losses each year as well as periodic fatalities caused by bird strikes involving high-speed aircraft.
The engine of a propeller-driven aircraft is seldom harmed. The danger comes from broken windshields or structural damage to wings or empennage. The danger of a bird joining you in the cockpit should not be underestimated. A firsthand account comes from a Cessna 172 pilot: "With explosive suddenness, the windshield shattered, air rushed in, and my door blew open. There was a thud against the back of my seat, and the noise rose to deafening levels. With increased drag we quickly lost airspeed and altitude."
One of the most likely places to encounter birds is the airspace around airports. Airports are occasionally located adjacent to dumps. This is considered an incompatible mix as birds are attracted in large numbers to garbage and thus pose a hazard to arriving and departing aircraft. To help, FAA has published Advisory Circular AC 150/5200-33 to provide guidance to communities and airport managers.
For pilots, the Air Force Bird Aircraft Strike Hazard Team (BASH-I'm not making this up) and FAA's Aviation News from January 1996 offer this guidance for avoiding bird strikes:
For more information on bird strikes, see the FAA's bird strike page ( www.faa.gov/ arp/pdf/strkrpt.pdf ), AOPA's bird strike pamphlet (www.birdstrike.org ), and the joint FAA/USDA Web site (www.faa.gov/ arp/pdf/manfin.pdf ). Bruce Landsberg is executive director of the AOPA Air Safety Foundation.