Since the dawn of aviation, aviators have been sharing the skies with birds. Knowing that there are far more of them than us in the sky, it’s likely that pilots could encounter a collision with one or more of them. Not only do birds present a safety risk to those aboard the aircraft, but the resulting damage that a bird strike can inflict could be significant and expensive to repair.

The threat and its impact

Industry research indicates that more than one bird strike occurs every day worldwide. In 2015, the FAA received more than 13,000 bird strike reports from aviators ranging from students to air transport pilots, equating to more than 35 bird strikes a day just in the United States alone. However, these numbers may be conservative, as findings from an industry study conducted by a former chairman of Bird Strike Committee Europe estimate that only 20 percent of bird strikes are reported. As many as 140 strikes per day may take place, making birds a clear threat to aviation in terms of safety and economic risk.

Looking at the busiest airports in the United States, an average of 19 bird strikes per 100,000 flight operations occur, with most bird strikes taking place at airports near wetlands and along major bird migration flyways. In fact, a major airport located in the northeast corridor reported an annual average of 80 bird strikes, roughly one bird strike every four to five days!

More than 70 percent of bird strikes happen between ground level and 500 feet above ground level—during the beginning and ending phases of flight. This makes bird strikes especially dangerous, as they regularly result in aborted takeoffs, emergency landings, fuel jettisoning, and overweight landings—which can result in increased risk to aircraft, crews, passengers, and cargo, as well as additional maintenance costs.

Research shows that the greatest danger from a bird strike results from the bird(s) being ingested into the engine(s). While this only occurs at a rate of 0.70 per 10,000 operations in the United States, globally the rate is more than triple at 2.52 ingestions per 10,000 operations.

Following a 2015 bird ingestion, the repairs to overhaul a damaged B-757 engine’s fan blades and cowling were estimated at $5 million plus $450,000 in other associated costs. The aircraft was out of service for 11 days. In the same year, it was projected that bird strikes would cause approximately 70,000 hours of aircraft downtime and more than $200 million in losses, with related costs much higher.

The costs associated with a bird strike are compounded throughout all aspects of airline operations, including the indirect costs of personal injury to crew and passengers, rerouting or rebooking passengers, rescue/ferry flights, flight and cabin crew schedule changes, and the company’s image due to possible negative publicity. The relationship of direct and indirect costs is much like an iceberg: the direct costs are above the waterline, whereas the indirect costs encompass a larger area beneath the water. One bird strike could cost an airline more than $6 million.

What’s being done?

Understanding the potential safety hazards and high economic risk to aircraft, researchers have been developing systems to effectively mitigate bird activity, particularly near airports. Good land use planning that keeps bird food sources—both grass and small animal—to a minimum has also been effective. Land maintenance plans that keep grass to a certain height and that promote covering small bodies of water are also useful in helping to prevent birds from using these areas as shelter.

Even outside of an airport’s grounds, land can become a gathering spot for birds. Recently, the construction of a municipal waste-transfer station was proposed near one of the runways of New York’s LaGuardia Airport. An ALPA airport safety liaison identified the risks posed by the birds that would flock to the site, and ALPA successfully lobbied for a full-time biologist to track the wildlife patterns in the area.

Birds are most active in the early morning and late evening, especially during peak migration periods. Flight crews should be alert for any observed activity and report any sightings to air traffic controllers so that they can share the information with other pilots.

More widely used mitigation techniques include using loud percussive cannons or other noise generators that sound at random intervals to startle birds and encourage them to find new nesting grounds. Using other animals, like trained birds of prey or dogs, to track down and disrupt smaller birds has also produced good results.

Unfortunately, some of these methods have proven to be somewhat ineffective and can, with increased use, result in birds anticipating them and becoming accustomed to their use. Even avian radar is ineffective, as it identifies the hazard but doesn’t mitigate it.

However, technology is now available that can identify, disperse, and continuously mitigate bird activity in the airport environment, including taxi, takeoff, and landing areas. A new bird collision- avoidance system uses an acoustic signal startle reflex that evokes a reaction in the bird’s hindbrain that’s neither fear- nor stress-based. The system doesn’t rely on airport surveillance radar so birds don’t become accustomed to its use, and their stress levels remain unaffected even after repeated exposure. The system doesn’t impair or harass birds.

Using panoramic infrared cameras, with a day and night detection capability that’s functional in all weather conditions, the system initiates a unique short-duration soundwave pattern that effectively signals the acoustic startle reflex to birds in the area. Designed to detect arriving, taxiing, and/or departing aircraft (including drones), as well as any bird activity, the system will self-activate to dissipate any birds if it senses a possible imminent collision. Although installation is dependent on the specific airport layout, the equipment is generally installed in the safe areas alongside runways and taxiways.

When birds and pilots are in flight, they’ll always share the skies and the associated risk of a bird strike. Data confirms that the risk is real and the results are costly. Like birds of a feather, the aviation community is embracing the opportunity to mitigate this risk. New technologies, and old-school planning, preparations, and techniques are all working hand-in-hand to help keep the number of bird strikes down and aircraft, crews, and passengers safe.

Editor’s note: Capt. Tom Kreamer retired after 34 years with US Airways. He held various ALPA safety positions and was awarded the Association’s Air Safety Award in 1994. He was also the North Atlantic regional vice president of the International Federation of Air Line Pilots’ Associations. Allison Markey is a commercial pilot and graduated from Embry–Riddle Aeronautical University. She’s been working with international and domestic aviation operators to improve safety programs, including safety management systems and emergency response.