Biases in Bird Strike Statistics Based on Pilot Reports

Abstract

Collisions between birds and aircraft are a concern because they threaten human safety and result in costly repairs. Most data on bird strikes have been provided by pilots and may be incomplete or biased. To assess whether bird strike statistics derived from pilot reports are biased, we compared the number of pilot-reported bird strikes at a Hawaiian airport during 1990-94 to the number of bird strikes obtained from regular runway searches for dead birds. We documented 526 bird strikes, of which only 25% were reported by pilots. Pilot reporting rates (percentage of all strikes reported by pilots) varied by species involved, number of birds struck, season, time of day, location on the runway during the landing phase, and the bird's mass. Reporting rates were not, however, correlated to size of the bird. Pilot reporting rates were independent of wind speed, wind direction, and percent cloud cover, and reporting rates were similar during landings and takeoffs. We found that bird strike statistics derived from pilot reports were biased. A sole reliance on such data can lead to incorrect conclusions and may cause airports to select inappropriate measures and times to reduce bird strikes.