A plane sometimes can't land with full fuel because its maximum landing weight is significantly less than its maximum takeoff weight.
Here's a more detailed explanation:
Weight Restrictions: Takeoff vs. Landing
Aircraft have different maximum weights for takeoff and landing, primarily for safety reasons. This difference is due to the structural stress placed on the aircraft during landing.
- Maximum Takeoff Weight (MTOW): The maximum weight at which the aircraft is certified to take off. This weight includes the aircraft's empty weight, passengers, cargo, and fuel.
- Maximum Landing Weight (MLW): The maximum weight at which the aircraft is certified to land. This weight is always less than the MTOW.
According to Boeing, certain planes are designed to be significantly lighter when landing than when taking off -- in some cases more than 200,000 pounds lighter.
Why the Difference in Weight Limits?
The landing gear and wing structure are designed to withstand the impact forces of landing at a specific weight. If the plane is too heavy, it could damage the landing gear, the wing, or even the fuselage.
| Feature | Maximum Takeoff Weight (MTOW) | Maximum Landing Weight (MLW) |
|---|---|---|
| Weight Limit | Higher | Lower |
| Primary Concern | Engine Power & Climb Rate | Structural Stress on Landing |
| Key Design Factor | Thrust | Landing Gear Strength |
What Happens if a Plane Needs to Land with Excess Fuel?
If a plane encounters a situation requiring an immediate landing, and it exceeds its maximum landing weight due to excess fuel, the pilots have a few options:
- Fuel Dumping: Many larger aircraft are equipped with fuel dumping systems. This allows the pilots to release fuel into the atmosphere, reducing the aircraft's weight to within the allowable landing limits.
- Burning Off Fuel: If fuel dumping is not an option or is not preferred, pilots may circle in a safe area to burn off fuel.
- Landing Overweight (Emergency Procedure): In dire emergencies where immediate landing is crucial, pilots may choose to land the aircraft overweight. This is a last resort, as it may result in structural damage to the aircraft. After an overweight landing, the aircraft must undergo a thorough inspection before its next flight.
