Why Aren't Nets Used to Prevent Bird Strikes on Aircraft Engines?

Since bird strikes are quite common during take-off and landing, why isn't there a net or something over the engine that would allow air to flow through but block large objects such as birds? This question explores the feasibility and challenges of implementing such a solution in the field of aviation.

Technical Challenges and Design Considerations

The use of a mesh or net-like structure over the engine would present several challenges. Firstly, a mesh would reduce the efficiency of the engine. The fan blades would intersect the vortices created by the mesh, leading to increased noise. Additionally, there is a risk that the mesh itself could be damaged or sucked into the engine due to ice build-up, which can exacerbate icing issues and block airflow, causing a loss of power or even shutting down the engine completely.

The Nature of Bird Strikes and Their Impact

Bird strikes at high speeds can severely damage engine blades, made of strong metal. A metal cage would merely shatter, leading to metal fragments as well as the bird entering the engine. This option is therefore not viable. Even if a net were designed to be movable to open up at high altitudes, the speed at which birds strike the aircraft makes it difficult to stop them with a stationary net. Either the bird would punch a hole in the net, or it would be chopped into pieces that could still fly through the holes, reducing airflow and efficiency further.

Rare Occurrence of Bird Strikes and Associated Costs

Bird strikes are, in fact, not particularly common. According to statistics, a very low percentage of flights experience significant bird strikes that require a flight to divert—only about 1 in 4 million passenger flights. This rarity means that the costs associated with implementing a bird-catching mesh, such as disruption to airflow and reduced engine performance, are not justified. Airlines typically consider the cost of occasional bird strikes an acceptable operating cost.

Public Perception vs. Reality

It is also important to note that the high media coverage of mass bird strikes involving large birds can give the false impression that such events occur more frequently than they do. Reality indicates that multiple bird strikes occurring on a multi-engine aircraft at once are incredibly rare. Therefore, the risk of such incidents is relatively low, making the added costs and potential risks of implementing a net unattractive to most airlines.

Other Safety Measures and Trade-offs

Protection against debris is more critical for certain aircraft types that operate in high-risk environments. For instance, military transport planes and most helicopters are designed with debris protection systems to minimize the risk of ingesting foreign objects. However, for commercial passenger aircraft, the trade-off between added safety measures and operational costs typically results in a preference for higher power, lower fuel consumption, and lighter weight, which contribute positively to overall safety.

Conclusion

In conclusion, while the idea of using nets to prevent bird strikes on aircraft engines seems promising, the technical challenges, costs, and infrequent nature of the problem make it an impractical solution for most commercial airlines. Instead, airlines focus on other, more cost-effective safety measures to protect against such occurrences.