By Robert N. Rossier, EAA 472091
This piece originally ran in Robert’s Stick and Rudder column in the March 2025 issue of EAA Sport Aviation magazine.
The shroud of morning fog had just lifted as I taxied cautiously to Runway 07 at Westerly State Airport (KWST) in Rhode Island. As I traveled down Taxiway Alpha, I came upon a gaggle of geese waddling across the grass and over the taxiway, seeming nonplused by the gentle rumbling of the engines and spinning propellers. I eased on the brakes, let the geese pass, and made my way to the run-up pad.
A couple minutes later, I taxied onto the runway and lined up for takeoff. Then I stopped as another gaggle began a slow stride across the runway. I pulled ahead slowly, hoping they might take the hint and get out of my way, but no, it was I who needed to wait. The last thing I needed was to tangle with wandering waterfowl on takeoff.
Sharing the sky with our fine feathered friends is just one of the challenges we face in flying. But having an idea of where and when the potential danger is greatest can help us prepare for the challenge.
Collision Dynamics
Not all bird strikes are the same. Factors that make a bird strike more dangerous include the speed of impact and the weight (or mass) of the bird involved in the impact. The dynamic kinetic energy of a moving object, like a northbound goose or a departing airplane, can be expressed mathematically as E = 1/2 m v2, where E represents the kinetic (dynamic) energy, m represents the mass of the object, and v represents relative velocity.
In plain English, the kinetic energy of a collision is equal to half the mass times the square of the velocity. For a bird strike, doubling the bird’s mass means doubling the kinetic energy. But since the kinetic energy increases with the square of the velocity, airspeed is even more important. If we triple our speed, perhaps from 60 knots on liftoff to 180 knots in cruise, the kinetic energy in a bird strike increases by a factor of nine! There is little we can do to change the mass of a bird, but we can dramatically decrease the force of an impact by flying slower.
Perhaps the most widely known example of a high velocity bird strike is US Airways Flight 1549 flown by Capt. Chesley “Sully” Sullenberger in January 2009. For Sully, the culprits were Canada geese, like the ones I encountered sauntering across the runway. Even at low speed, these waterfowl that weigh 5 to 20 pounds and have a wingspan of 4 to 6 feet can cause serious damage on impact. For Sully, impacting a flock of Canada geese at 185 knots as his Airbus A320 was climbing through 2,800 feet took out both engines, putting him, his crew, and passengers in peril.
Tip No. 1: Slow to maneuvering speed or below when at lower altitudes and in the pattern. This allows both birds and pilots to maneuver out of the way more easily, and reduces the impact energy and damage.
I was lucky. The geese were right there where I could see them and avoid conflict. In such a situation, when birds are on the ground at the airport, the best tactic is to have airport personnel scare them off before attempting a takeoff or landing. The problem comes in the early morning or evening when no airport personnel are around. In this case, we might taxi slowly near the birds to scare them off, or select a runway that allows us to avoid the birds entirely. Unfortunately, waterfowl have their own ideas about right of way.
Tip No.2: If birds are on or near the runway, ask for assistance from ground personnel to encourage them to leave the danger zone. Or if available, pick a different runway.
Evasion Tactics
Knowing what birds might do during an encounter can help us plan our evasion maneuvers for dealing with an encounter. What we do know is that most birds on the ground will typically fly up when frightened or disturbed. That is, if they notice us. This might suggest that it is a better bet to touch down well before or after the point where birds are on or adjacent to the runway. Experts also tell us that in the air, birds are more likely to dive, since it is easier for them to spill lift than to climb.
Tip No. 3: When encountering birds near the ground, expect them to fly up to escape the perceived threat.
Tip No. 4: Turn the landing lights on, or increase the engine noise on the approach, to help alert birds to our arrival and encourage them to depart ahead of us.
Tip No. 5: For a midair encounter, climb over birds since their natural tendency is to dive away from the danger.
Favorable Environments
Bird strikes can happen just about anywhere, but the risk is greater in environments where birds live, hunt, and breed. Not all birds are the same, and the environments they favor can vary significantly.
According to experts, Canada geese favor large, flat spaces in urban areas such as golf courses, parks, and areas with manicured lawns and retention ponds. Clearly, airports might be included in that list. They generally prefer open grasslands or shallow wetlands where they have ready access to both land-based and aquatic resources. Territorial in nature, Canada geese are well known for their aggressive behavior, perhaps explaining their cavalier attitude toward approaching aircraft on the ground.
Tip No. 6: Use extra caution when flying near the environments where the birds live, hunt, and feed.
Timing is also important. Most bird strikes occur in the early mornings and near dusk when birds are actively feeding. Along the coast, some birds will align their feeding with the cycle of oceanic tides. Many shore birds will feed near low tide when shellfish are exposed and easy to find. Airports near the coast have been known to experience “air drops” of shellfish, sometimes with rocks still attached, as gulls and other species drop them on the tarmac to crack them open for easy consumption. The danger to aircraft in such circumstances is obvious.
Migration Routes
Another place to exercise caution is along migratory routes or “flyways.” Various bird species follow well-established routes along which they can find food and shelter. These routes typically follow coastlines, mountain ranges, and rivers. Peak migration seasons are in the spring (March and April) and the fall (September and October). Canada geese typically migrate during spring and fall, flying in a characteristic “V” pattern at an altitude of about 3,000 feet.
Tip No. 7: Use caution during migration season, particularly along migration routes.
Taking Action
Spring migration is upon us, and the last thing we need is to collide with birds. By understanding the dynamics of bird strikes and the nature of birds, we can perhaps lessen the risk of encountering such midair mayhem.
If we do suffer a bird strike, we should land promptly and carefully examine the aircraft for damage. Bird strikes should be reported through the FAA at Wildlife.FAA.gov/add.
Robert N. Rossier, EAA 472091, has been flying for more than 40 years and has worked as a flight instructor, commercial pilot, chief pilot, and FAA flight check airman.