Understanding Bird Strikes and Airport Operations: Why They Occur During Takeoff and Landing

Introduction

Why do bird strikes commonly occur when planes are approaching landing or departing from airports? This question often prompts skepticism, yet it is a legitimate concern for aviation safety and operational efficiency. This article delves into the reasons behind these occurrences, based on the natural behavior of birds and the specific conditions of airport operations.

Why Birds Fly at Low Altitudes

Birds are generally observed flying at low altitudes, typically 5,000 to 10,000 feet above ground level (AGL). This behavior is attributed to several factors:

Foraging Needs: Birds require food and water, which are abundant at ground level. Nesting and Roosting: Many species prefer close proximity to the ground for their nesting and roosting activities. Visual and Auditory Sensory Adaptations: Birds are adapted to visually and audibly detect threats at lower altitudes, making such areas safer for them.

Additionally, airports often sit near residential areas or bodies of water, which attract a variety of bird species. These geographical features provide open spaces that birds find conducive for their natural behaviors.

The Danger of Bird Strikes

During takeoff and landing, aircraft operate at lower altitudes where the risk of bird strikes is significantly higher. Here are some critical points:

Plane Altitude: Planes must descend to their operational altitudes, which they never maintain during takeoff and landing until they are safely in the air or on the runway. Engine Protection: Birds, particularly small birds, can enter aircraft engines and cause catastrophic damage. For instance, US Airways Flight 1549 famously resulted in a bird strike that led to an emergency landing in the Hudson River. Visual Detection: Pilots have to constantly scan for any bird activity, especially during takeoff and landing, as the visual cues are more critical due to lower altitude and limited visibility.

The need for meticulous visual and auditory scanning is why pilots often abort takeoffs in the event of bird strikes. The potential for engine failure necessitates immediate action to ensure the safety of passengers and crew.

Thermal Differentials and Bird Activity

Jet aircraft cruise at high altitudes where birds are less likely to be present in significant numbers. However, birds are more abundant at lower altitudes due to thermal activity. Thermals, which are pockets of rising air, can be observed near airports, particularly on hot days and during the early morning hours.

Large open fields, grass runways, and paved aprons all contribute to the formation of thermals, attracting birds for easy ascension. On one occasion, a near miss was observed with a large bird at approximately 1,800 feet AGL during a tow operation. This emphasizes the importance of constant vigilance on the part of pilots and ground crews.

Migratory Birds and Flight Patterns

Migratory birds often fly in large flocks, which can pose a significant danger to aircraft. These birds can be easily detected, particularly when airports are located in areas with open views. However, in urban environments, tall buildings and other obstacles may impair visual line of sight, making it more challenging for pilots to spot these flocks.

While the natural flight patterns of birds are a key factor, the operational requirements of airports also come into play. The precise choreography of takeoffs and landings is critical, with pilots constantly adjusting altitude and speed to ensure a safe and efficient operation. Understanding the natural flight behaviors of birds is an essential component of ensuring aviation safety.