A bird strike happens when a bird collides with an aircraft during takeoff, landing, or low altitude flight. These events matter because even a small animal can carry enough kinetic energy to damage a windshield, dent a leading edge, or be pulled into a jet engine. Airports take bird strikes seriously because aircraft are moving fastest near the runway while pilots have little time and altitude to respond.
The greatest concern is engine ingestion, where birds enter the fan at high speed.
Key Facts
- Kinetic energy increases with the square of speed: KE = 1/2 mv^2.
- Impact force depends on how quickly the bird is stopped: Favg = Δp/Δt.
- Momentum is p = mv, so a heavier bird or faster aircraft creates a larger collision impulse.
- Jet engines are tested to survive specified bird ingestion events without causing an unsafe failure.
- Bird strikes are most common below about 3000 ft because birds and aircraft both occupy the airport environment.
- Wildlife control reduces risk using habitat management, radar, patrols, sound devices, and coordinated airport procedures.
Vocabulary
- Bird strike
- A bird strike is a collision between a bird and an aircraft, usually during takeoff, landing, or low altitude flight.
- Engine ingestion
- Engine ingestion occurs when a bird or other object is pulled into a jet engine inlet and reaches the fan or compressor.
- Kinetic energy
- Kinetic energy is the energy of motion and is calculated by KE = 1/2 mv^2.
- Impulse
- Impulse is the change in momentum caused by a force acting over a time interval.
- Wildlife hazard management
- Wildlife hazard management is the set of airport practices used to reduce animal activity near runways and flight paths.
Common Mistakes to Avoid
- Thinking only large birds are dangerous: small birds can still cause damage because impact energy rises with speed squared.
- Using mass alone to judge strike severity: speed is often the dominant factor because KE = 1/2 mv^2.
- Assuming an engine must keep producing full thrust after ingestion: certification focuses on preventing unsafe failure and maintaining controlled outcomes under specified test conditions.
- Ignoring airport habitat: standing water, food sources, grass height, and nesting areas can attract birds and increase strike risk.
Practice Questions
- 1 A 2.0 kg bird strikes an aircraft moving at 75 m/s. Calculate the bird's kinetic energy relative to the aircraft.
- 2 A 1.5 kg bird is brought to rest relative to a windshield from 80 m/s in 0.040 s. Estimate the average impact force using Favg = Δp/Δt.
- 3 Explain why airports use wildlife control methods before takeoff rather than relying only on strong aircraft materials and engine testing.