Lessons Learned

Technical Related Lessons

Turbine engine inlet ingestion of large numbers of birds can cause substantial, and in some cases catastrophic, loss of thrust or power. Safety of flight must include both a robust engine run capability following bird ingestion as well as operational strategies aimed at avoiding the bird hazard. (Threat Category: Bird Hazards)

  • Due to the threat of multiple engines being adversely affected by small bird ingestion, turbine engines must have an adequate "continue to run" capability following a severe encounter with a flock of small birds. This accident was the result of the ingestion of a large number of small birds (starlings), the failure of one engine, and temporary thrust losses on two other engines. The adverse engine reactions resulted in a loss of airplane control and the accident.

Common Theme Related Lessons

Introduction of new configurations, technologies, or operations has the potential of exposing new vulnerabilities. Conversely, existing configurations may be operating safely only because these threats are being inherently protected from exposure without deliberate design intent. (Common Theme: Flawed Assumptions)

  • Prior to this accident, operational experience of large transport airplane engines with respect to bird encounters and bird ingestion had been favorable. Birds were not considered to be a major threat relative to their ingestion effects. With the development of the Electra L-188, the Allison 501-D13 turbo propeller engine, and other turbine-powered airplanes of the era, it was expected that this favorable powerplant experience would continue, and that engines would be sufficiently robust to withstand whatever bird threats may exist. This accident, and subsequent accidents and incidents, underscored the need for specific standards to reduce the threats posed to turbine engine inlet systems and turbine powered airplanes. 
Photo of a Lockheed Constellation in flight
Lockheed Constellation in flight  – reciprocating engines with inlets shielded by large propellers had a favorable bird ingestion history
Photo copyright Christian Waser – used with permission

Back to top