AIM Text
- Bird strike risk increases because of bird migration during the months of March through April, and August through November.
- The altitudes of migrating birds vary with winds aloft, weather fronts, terrain elevations, cloud conditions, and other environmental variables. While over 90 percent of the reported bird strikes occur at or below 3,000 feet AGL, strikes at higher altitudes are common during migration. Ducks and geese are frequently observed up to 7,000 feet AGL and pilots are cautioned to minimize en route flying at lower altitudes during migration.
- Considered the greatest potential hazard to aircraft because of their size, abundance, or habit of flying in dense flocks are gulls, waterfowl, vultures, hawks, owls, egrets, blackbirds, and starlings. Four major migratory flyways exist in the U.S. The Atlantic flyway parallels the Atlantic Coast. The Mississippi Flyway stretches from Canada through the Great Lakes and follows the Mississippi River. The Central Flyway represents a broad area east of the Rockies, stretching from Canada through Central America. The Pacific Flyway follows the west coast and overflies major parts of Washington, Oregon, and California. There are also numerous smaller flyways which cross these major north‐south migratory routes.
Source: FAA Aeronautical Information Manual · current edition · paragraph 7-5-1.
The short answer
This AIM section is FAA advisory guidance describing when and where bird strike risk peaks. Migration during March–April and August–November raises risk; over 90 percent of reported strikes occur at or below 3,000 feet AGL, though ducks and geese reach 7,000 feet AGL. It identifies hazardous species and the four major U.S. flyways.
Research Notes
Common Questions
At what altitude do most bird strikes happen?
The AIM states over 90 percent of reported bird strikes occur at or below 3,000 feet AGL, though strikes at higher altitudes are common during migration, and ducks and geese are frequently observed up to 7,000 feet AGL.
When is bird migration season for strike risk?
According to this advisory section, bird strike risk increases because of bird migration during the months of March through April and August through November, and pilots are cautioned to minimize en route flying at lower altitudes during migration.
What are the four major migratory flyways in the U.S.?
The AIM lists the Atlantic Flyway (paralleling the Atlantic Coast), the Mississippi Flyway (Canada through the Great Lakes along the Mississippi River), the Central Flyway (a broad area east of the Rockies), and the Pacific Flyway (following the west coast over Washington, Oregon, and California).