Airplanes are a relatively new invention, having been around for just over 100 years. In that time, birds and planes have had to learn to coexist in the skies. But do birds intentionally avoid planes in flight? Let’s take a look at the evidence.
Quick Answers
It seems that most birds do not purposely avoid planes in flight. However, there are a few factors that influence how likely a bird is to steer clear of an oncoming plane:
- Bird species – Some birds with good eyesight like raptors can detect planes from further away.
- Plane altitude – Birds are more likely to avoid planes at lower altitudes where the planes are more noticeable.
- Plane size – Larger planes and jets are easier for birds to see and hear.
While birds don’t deliberately avoid planes, they do seem to adapt over time to the presence of aircraft and exhibit avoidance behaviors around airports and flight paths. Collisions between birds and planes are rare, but can cause damage and safety issues when they do occur.
Do Birds Detect and Avoid Planes in Flight?
Many people assume that birds have some innate ability to detect oncoming planes and get out of the way. But unlike humans, birds do not have knowledge about what airplanes are or the hazards they pose. Still, it seems that birds do manage to largely avoid colliding with planes in flight. There are a few reasons why this might be the case:
- Vision – Birds like hawks, eagles and falcons which are relied on vision while hunting have very sharp eyes that can detect fast motion from far away. This helps them see and react to oncoming planes.
- Hearing – The noise from an approaching plane’s engine and airflow gets louder before a collision would occur. Birds hear this and may alter course.
- Wind gusts – The leading edge of an airplane’s wake creates air turbulence that buffets the bird, causing it to instinctively turn away.
- Chance – With airplanes occupying a tiny fraction of overall airspace, birds may avoid planes simply by chance in most cases.
Birds have sensory capabilities that likely allow them to respond to approaching aircraft and avoid them most of the time. But it seems to be an instinctive reaction rather than an intentional, cognitive avoidance of airplanes.
Factors That Influence Bird-Plane Collisions
If birds don’t deliberately avoid planes, why don’t we see more bird strikes and collisions? There are a few key factors that make mid-air collisions a rare event:
- Airplane flight paths – Airlines avoid known bird migration paths and fly at altitudes above most bird activity when possible.
- Airport precautions – Airport authorities use cannons, sirens and other tools to scare birds away from runways.
- Aircraft speed – Planes are moving much faster than birds, giving less reaction time but also minimizing time spent in intersection.
- Low occupancy airspace – Except for migration, bird densities are low at altitudes where airplanes fly.
The aviation industry has adapted to the risk of bird strikes. Avoidance measures help reduce collisions, but can’t eliminate them entirely since birds and planes do intersect at times.
Bird Species Differences
Not all birds are equally likely to collide with aircraft. Raptors like hawks, eagles and owls have extremely sharp vision and are adept at detecting and pursuing prey in flight. This helps them see and avoid planes more easily as well. In contrast, birds like herons, waterfowl and gulls have poorer eyesight and are more frequent victims of bird strikes.
Nocturnal birds that migrate or hunt at night are also over-represented in aircraft collisions. Limited visibility in darkness makes it harder for these birds to detect and avoid oncoming planes.
Altitude Effects
The chance of bird strikes declines significantly with altitude, as most birds fly within a few thousand feet of the ground. Still, collisions do occur even at high altitudes during migratory seasons. A 1988 airplane collision with a flock of geese occurred at 29,000 feet!
Airplanes are more vulnerable during takeoff and landing when crossing paths with bird activity near airports. Over 90% of reported bird strikes happen at less than 3,000 feet altitude.
Altitude | Bird Strike Rate |
---|---|
0-1,000 ft | 4.45 per 100,000 flights |
1,001-3,000 ft | 1.75 per 100,000 flights |
3,001-10,000 ft | 0.45 per 100,000 flights |
10,001+ ft | 0.06 per 100,000 flights |
Staying above 3,000 feet when possible reduces bird strike risk significantly. But collisions can still happen, so airplanes can’t rely on altitude alone to avoid this hazard.
Plane Size Effects
Larger planes like widebody jets collide with birds at a much lower rate than smaller planes. Their greater size makes them easier for birds to see and hear as they approach.
Turboprop planes experience over twice the bird strike rate of larger jet airliners. Private planes and helicopters are also more vulnerable due to their low operating altitudes and limited bird impact protection.
Aircraft Type | Bird Strikes per 100,000 Flights |
---|---|
Turboprop | 5.66 |
Narrowbody Jet | 2.94 |
Widebody Jet | 1.93 |
Private/Helicopter | 6.12 |
The increased visibility and noise of large planes gives birds more advance warning of their approach. Engine cowling and windshield designs on bigger jets are also more effective at protecting occupants in the event of a bird impact.
Bird Strike Dangers and Severity
Collisions between birds and planes can cause different levels of damage based on factors like the bird’s size, speed of impact, and location of strike. Here are some of the potential dangers:
- Engine failure – Birds sucked into engines can destroy fan blades and cause dramatic power loss.
- Windshield cracking – Bird strikes at high speeds can shatter or penetrate windshields.
- Wing/control damage – Holes or dents in wings or tail sections can affect in-flight performance.
- Fire – Bird remains and blood in engines can cause overheating and electrical fires.
- Injuries – Blunt force trauma from bird impacts inside the plane can harm crew and passengers.
Fortunately, strict aircraft certification standards ensure planes can withstand most bird collisions intact. But the results can still be catastrophic if birds disable critical components like engines, pitot tubes or control surfaces.
Engine Failure Risk
Jet engines are vulnerable to internal damage from bird ingestion. Small birds can destroy individual fan blades, while large birds can bend or fracture the main engine shaft. Either scenario can lead to violent engine failures.
To minimize this risk, engines are tested by firing dead chickens into spinning fans at high speed. Aircraft windshields are similarly stress tested by firing bird carcasses at them via cannons.
Windshield Hazards
Bird collisions with airplane windshields can cause anything from small cracks to complete penetration and loss of cabin pressure. Modern windshields consist of multilayered glass and acrylic sheets to provide redundancy if the outer glass breaks. This prevents most bird strikes from compromising the entire windshield.
Cockpit crews also train for rapid descent procedures to bring the plane to a safe lower altitude if windshield damage leads to decompression. All passengers are required to use supplemental oxygen in the event of a breach.
Wing and Empennage Impacts
Birds colliding with wings or tail sections can tear holes, bend flaps/slats, or dent the thin skin coating. But airplane wings and bodies are designed to be damage tolerant so they don’t fail even after significant impacts.
Wings are made up of strong front and back spars that form the main load-bearing structure. The surrounding wing skins help maintain the aerodynamic shape but aren’t critical to flight. So holes from bird strikes won’t cause catastrophic failure, though they may degrade performance.
Empennage strikes can damage control surfaces like flaps and rudders. But modern aircraft have triple redundancy in these systems, so total loss of control is very rare from a bird collision alone.
Preventing Bird Strikes
Since birds don’t purposely avoid planes, collision prevention falls largely on the aviation industry. Here are some of the techniques used to minimize encounters between birds and aircraft:
- Habitat management – Reduce food, water and nesting sites attractive to birds near airports.
- Sonic deterrents – Use propane cannons, electronic noisemakers and other sounds to scare birds away from runways.
- Aircraft lighting – Strobe lights and lasers on planes can help warn birds of approaching danger.
- Radar monitoring – Track bird flocks in real time to route planes around hot spots when possible.
- Engine innovations – Develop turbofans less susceptible to damage if birds are ingested.
Even using all these precautions, bird strikes still happen. But ongoing research into bird sensory perception and flight behaviors may uncover new ways to make planes more easily detectable and avoidable in the future.
Airport Habitat Control
Airports try to reduce food and water sources that could attract flocks of birds near runways. Standing water, trash piles, and tasty insects are all discouraged through drainage, frequent waste removal, and vegetation control.
Grassy areas may be planted with unpalatable plant species instead of tasty seeds. Retention ponds can be covered with nets to prevent access. Nesting spaces are also limited by removing trees, rooftop gravel and ledges.
Sonic Bird Deterrents
Noisemakers produce sounds that scare birds away from airports. Propane cannons generate periodic explosions while electronic noise emitters play high-pitched, ultrasonic distress calls to repel birds.
Visual deterrents like reflective tapes or flashing lights are also used. Trained predatory birds can even be released to chase nuisance flocks out of the airport environment.
Aircraft Lighting Enhancements
Strobe lights, pulsating LEDs and lasers have been tested for their potential to warn birds of approaching planes more effectively. The goal is lighting that is clearly distinguishable from background lights and gets the attention of birds.
Using colors on the blue-green spectrum takes advantage of birds’ enhanced visual sensitivity in that range. Quickly pulsing the lights makes them more obvious to birds through their superior motion detection.
Bird Strike Reporting and Data Collection
To better understand bird collision risks, flight crews are required to file reports whenever strikes occur. Details like altitude, species identification, damage, and any effects on the flight are noted.
Government aviation agencies and other researchers analyze this data to spot patterns and trends. The FAA National Wildlife Strike Database for the United States contains over 140,000 reported collisions dating back to 1990.
These statistics help drive new regulations, airport wildlife management practices, and aircraft design improvements to reduce future bird strike damage and dangers.
Strike Report Data Collection Process
After a bird collision, pilots follow a standard procedure to document the event:
- Note time, altitude, speed and location of strike.
- Identify species of bird if possible.
- Assess any damage to the aircraft.
- Report impacts to flight path or aircraft control.
- Log any injuries to crew or passengers.
- File a written report after landing.
Air traffic control towers are also notified when strikes happen near airports. Remains are collected forlater species identification and impact physics research if possible.
Strike Database Analysis
Collated bird strike reports provide valuable data to aid prevention efforts. Stats like number of collisions by year, altitude, airport, species and aircraft type are tracked.
Any strikes causing substantial damage or injuries get focused study. Impact dynamics and materials engineering research helps strengthen critical components.
Long term trends reveal if mitigation methods are working. The numbers ultimately guide targeted improvements to continue driving down bird collision occurrence and risks.
Conclusion
Birds don’t purposefully avoid airplanes, but luckily don’t collide that often either. Their natural sensory capabilities allow birds to react to approaching aircraft in many cases. Airlines also take steps to minimize interactions between birds and planes around airports and across flight paths.
Reported bird strike data proves collisions still happen regularly though. Ongoing research and mitigation efforts are needed to make aircraft more detectable to birds and resistant to impacts when they occur. This improves safety for birds and planes alike as they continue coexisting in shared airspace.