Statistical Analysis of Aircraft–Bird Strikes Resulting in Engine Failure

Abstract

Engine failure caused by bird strikes can be particularly perilous for today's typical twin-engine aircraft. Although large-bird populations have increased substantially since the 1970s, modern-day turbofan engines are not tested for large birds. Instead, it is acceptable for contemporary turbofan engines to lose all power because of large-bird ingestion. With the increasing use of turbofan engines and air traffic, not only are more bird strikes expected in the near future, but also more bird strikes are anticipated to result in engine failure. This study identified the factors that were statistically associated with the probability of engine failure in the event of a bird strike. A large sample of more than 42,000 U.S. bird strikes was used. The missing data in the sample were multiply imputed by using an approximate Bayesian bootstrap method. With the multiply imputed data, 15 factors were statistically analyzed. Six of those factors were found to be significantly associated with the probability of engine failure in the event of a bird strike: altitude above ground level, bird size, number of birds struck, flight phase, daylight conditions, and sky conditions. A logistic regression model was developed, and a detailed probabilistic interpretation of the model is given for practitioners. By using the findings, aviation authorities can improve bird strike hazard mitigation strategies, flight crews can reduce the potential of bird strikes resulting in engine failure, and researchers can better understand the nature of bird strikes and develop a scientific approach to minimize the likelihood of engine failure in the event of a bird strike.