Bird strikes are an ever-present danger in aviation. When a plane collides with a bird or a flock of birds, it can cause serious damage to the aircraft and potentially lead to an accident. This is why pilots, air traffic controllers, and airport personnel take bird strikes very seriously and make efforts to prevent them. But what actually happens when a plane hits birds in mid-flight? Let’s take a closer look.
Immediate Effects of Bird Strike
When a plane hits a bird, the immediate effects can range from no damage at all to major structural failure, depending on the size of the bird and where on the plane it hits. Here are some of the most common effects:
Engine Damage
One of the most dangerous scenarios is when birds get sucked into jet engines. This can destroy multiple fan blades and cause the engine to lose thrust. At low altitudes, this can make it impossible for the plane to maintain lift. Even if the strike happens at cruising altitude, damage to two engines on the same side can make the plane impossible to control.
Windshield Damage
Birds striking the windshield can shatter or crack the glass. This reduces visibility for the pilots and compromises the aerodynamics and structural integrity of the cockpit. If both pilots are incapacitated, it would likely lead to a crash.
Wing and Tail Damage
Bird strikes on leading wing edges and tail surfaces can dent or bend the metal, changing the airflow and causing imbalance. This imbalance makes the plane harder to control. In severe cases, bird strikes have sheared off entire wing segments or caused the stabilizers to detach.
Landing Gear Damage
Birds sucked into wheel wells and landing gear compartments can damage hydraulic and electrical systems. Wheels and flaps may fail to deploy on landing, leading to runway belly landings. Strike damage has also locked landing gear into the up or down positions.
Cockpit Damage
Penetration of the fuselage by bird strikes has injured and even incapacitated pilots in some instances. Cockpit damage or pilot injury increases the chances of losing control and crashing.
No Damage
In minor bird strikes, the plane may escape unscathed or suffer a hardly noticeable dent. Airlines have protocols for assessing damage before continuing flight.
Factors That Determine Severity
Several factors influence the amount of damage from a bird collision:
Bird Size
Large birds like geese and swans pose the greatest danger. Strikes with smaller birds like starlings may leave only a mess on the windshield. The number of birds also matters – hitting a dense flock increases the collision forces.
Aircraft Speed
The closing speed of the collision determines impact energy. Birds seem almost stationary to fast jets, so the relative speed is the plane’s cruise velocity. For prop planes and on takeoff and landing, closing speeds are lower.
Location of Strike
The most critical locations are the engines, cockpit, leading edges of wings/tail, and wheel wells. Strikes on less critical areas like the fuselage may not affect flight.
Angle of Strike
Head-on collisions impart the most damage. Glancing blows with lower impact energy often just dent the skin. Spanwise strikes on wings can shear off sections.
Structural Strength
Parts like engine cowlings are designed to shear off on impact to protect the engine. The reinforced windshield and cockpit are also designed to withstand most bird strikes.
How Do Pilots React to Bird Strikes?
Here are the typical steps pilots take following a suspected bird strike:
– Stabilize the aircraft if it begins banking or pitching from imbalance or control surface damage.
– Inform air traffic control about the strike and request clearance to divert or return for inspection if damage is major.
– Check engine readings and reduce thrust on damaged engines. Reroute engine bleeds to maintain pressurization.
– Run checklists for electrical, hydraulic, flight control, and landing gear failures.
– Declare emergency if necessary and prepare for crash landing.
– Divert to nearest suitable airport for overweight landing if fuel is leaking or engines are out.
– Use flaps conservatively for landing since they may have suffered strike damage.
How Can Airlines Prevent Bird Strikes?
Airlines, airport authorities, and regulators collaborate to reduce the risk of bird strikes using these methods:
Airport Bird Hazard Management
Airports perform bird patrols, habitat modification, food source management, and nesting prevention to scare birds away from runways and approach corridors. Recorded bird distress calls and pyrotechnics are also used.
Engine Anti-Ingestion Designs
Jet intakes have spiral ducts to redirect birds into the bypass flow. Fan blades also have bird debris resistant designs. Proposed innovations include laser bird deterrent systems.
Avoidance Procedures
Pilots lower the landing gear early on approach to scare birds away from the runway. Takeoff and landing climb profiles may also be adjusted to avoid large flocks.
Radar Tracking
Ground-based radar detects flocks near the airport. Pilots also use weather radar to spot flocks ahead and choose alternate paths.
Reporting and Information Sharing
Pilots are required to report all bird strikes. Data collected is used to identify high risk zones on airport approach paths.
Notable Bird Strike Incidents
Here are some well-known bird strike events that illustrate the potential consequences:
US Airways Flight 1549 “Miracle on the Hudson”
Date: January 15, 2009
Aircraft: Airbus A320
Bird Species: Canada geese
Effect: Both engines failed after ingesting geese shortly after takeoff from New York’s LaGuardia Airport. Captain Chelsey Sullenberger glided the crippled jet to a safe ditching in the Hudson River. All 155 on board survived.
Ryanair Flight 4102 Emergency Landing
Date: October 12, 2018
Aircraft: Boeing 737-800
Bird Species: Heron
Effect: The left engine ingested a heron during climb after departing Rome-Fiumicino airport. The engine surged and shut down. The crew declared emergency and landed safely back at Rome.
| Date | Flight | Aircraft | Bird Species | Effects |
|---|---|---|---|---|
| January 15, 2009 | US Airways Flight 1549 | Airbus A320 | Canada geese | Both engines failed. “Miracle on the Hudson” ditching. |
| October 12, 2018 | Ryanair Flight 4102 | Boeing 737-800 | Heron | Left engine failed. Emergency landing. |
KLM Flight 867 Collision Over Tenerife
Date: June 25, 1969
Aircraft: Boeing 747-206B
Bird Species: Lesser than golden plover
Effect: Multiple bird strikes at takeoff resulted in the 747 crashing back onto the runway and catching fire. The fuselage split into two. All 248 aboard survived but 14 were injured.
Baghdad Airbus A300 Crash
Date: November 22, 2003
Aircraft: Airbus A300B4-605R
Bird Species: Unknown
Effect: After hitting a large bird during climb, the left engine caught fire and separated from the wing. Control was lost and the plane crashed near Baghdad, killing 34 people.
Key Statistics on Bird Strikes
Looking at FAA data on reported bird and wildlife strikes highlights some key statistical insights:
| Year | Total Reported Strikes | Strikes Causing Damage |
|---|---|---|
| 2018 | 16,376 | 772 |
| 2019 | 15,815 | 743 |
| 2020 | 9,813 | 467 |
– Reported US bird strikes decreased in 2020, likely due to reduced air traffic during the COVID-19 pandemic.
– Around 5% of reported bird strikes cause damage to the aircraft. 1 in 5 of those damage events affect the engine.
– Canadian geese, gulls, and raptors are the most hazardous birds due to their size and flocking behavior.
– Over 216 people have been killed worldwide due to bird strikes.
– The majority of bird strikes happen at under 500 feet altitude during takeoff and landing.
– Estimated global cost of bird strikes is over $1.2 billion annually.
Conclusion
Bird ingestions and collisions remain an ever-present safety concern for the aviation industry. While rare, they can and have caused catastrophic accidents throughout history. Engine failures, cockpit penetration, and control surface damage are among the most serious effects when planes collide with birds. Though designing better jet engines and airframe structures can improve resilience, limiting the presence of birds near airports and altering flight paths to avoid them are key to reducing the likelihood of catastrophic damage. Continued vigilance and information sharing between pilots, controllers, and airport wildlife staff is crucial to mitigating the hazards posed by birds to aviation.
