Why Do Planes Lower Their Landing Gear Only Very Close to Landing?

When you board an airplane, you might notice that the pilots usually extend the landing gear only a short distance from the runway. This delay in lowering the landing gear is crucial for several important reasons. In this article, we'll explore why this practice is necessary, discuss the aerodynamic efficiency, and highlight the safety and mechanical reliability aspects involved.

Aerodynamic Efficiency

One of the primary reasons for keeping the landing gear retracted during flight is to reduce drag. Drag is the force that opposes the motion of the aircraft through the air and can significantly impact fuel efficiency. Lowering the landing gear early can increase this drag, leading to higher fuel consumption and reduced overall performance. Most modern airliners fly at Mach 0.75–0.85, and at these speeds, the additional drag from extended landing gear could be detrimental to fuel efficiency and overall performance during cruise.

Weight Distribution and Control

Aircraft are meticulously designed to handle specific weight distributions to ensure safe and stable flight. Extending the landing gear too early can disrupt this delicate balance, affecting both the aircraft's balance and handling characteristics during approach. Pilots need precise control over the aircraft to ensure a smooth and safe landing, and lowering the landing gear late allows for better control and handling.

Mechanical Reliability

Another crucial factor is mechanical reliability. Lowering the landing gear too early could put undue stress on the systems, increasing the risk of mechanical issues or malfunctions. Keeping the landing gear retracted until closer to landing ensures that the systems operate under optimal conditions, reducing the likelihood of in-flight failures. Additionally, there is a specific sequence of steps that must be followed for the landing gear to operate correctly, and these steps are better managed when the aircraft is in a more controlled descent.

Pilot Control and Safety Considerations

Pilots typically prefer to extend the landing gear when they are in a stable and controlled descent. This timing allows them to focus on other critical aspects of the landing process, such as maintaining the proper speed and approach angle. By extending the landing gear only a short distance from the runway, pilots can also ensure that they have the necessary time to address any gear-related issues before landing. This approach minimizes the risk of unexpected disruptions during the final approach and landing.

Specific Speeds and Optimum Performance

Each aircraft has specific speeds and limitations that must be respected to ensure safe and efficient operation. For example:

VF Design Flap Speed: The speed at which flaps should be deployed to prevent structural damage. VFE Maximum Speed with Extended Flaps: The highest speed at which the aircraft can fly with flaps deployed without causing structural damage. VLE Maximum Speed with Gear Extended: The highest speed at which the aircraft can fly with the landing gear extended without compromising safety or structural integrity. VLO Maximum Speed for Gear Operation: The maximum speed at which the landing gear can safely operate.

Flaps enable the aircraft to fly slower without stalling, after which the gear can be extended. In severe emergencies, pilots may intentionally extend the gear beyond these maximums, knowing that damage is likely to occur but prioritizing the safety of the aircraft and its occupants. This practice is a last resort and is not preferred due to the risks involved.

Conclusion

In summary, the practice of lowering the landing gear only very close to the landing is essential for several key reasons: aerodynamic efficiency, weight distribution and control, mechanical reliability, pilot control, and safety considerations. By carefully managing the timing of this critical procedure, pilots can optimize performance, maintain control, and enhance overall safety.