What Is Landing Weight? Why It Matters and How to Calculate It

Landing weight is one of the most important parameters in aviation. That weight is very critical to whether the plane can safely land, and whether it will be able to stop safely on its landing distance, brake systems and runway conditions. In fact, landing weight plays a significant role in at least the planning phase of any flight as it directly affects aircraft performance calculations such as braking distance, fuel burn and even the maximum permitted speed you can land at.

In this article, we will take a look at what landing weight is and how it affects flight safety as well as its calculation followed be its relationship to fuel burn limits relating to other important parameters such as the maximum landing weight, runway consideration etc.

Understanding Landing Weight

Landing weight is the mass of Lifting aircraft just before or during landing phase of flight while on the runways final approach. However, this mass is not constant and changes during the flight due to several different factors:

Fuel weight: an aircraft consumes fuel during the flight and its mass is decreasing continually while flying.

Loading passengers/cargo: The number of passengers and, if applicable, the amount of cargo or baggage on board also contribute to the aircraft's landing weight.

Weather conditions: However, weather has a big impact on how the aircraft handles landing but not direct factor of weight — as air density or wind direction.

The Max Landing Weight MLW is usually a figure published by the manufacturer of an aircraft. That is the maximum landing weight also known as max landing weight it able to land when aircraft is certified for. We must not land over this weight, or we may damage the aircraft or be unable to stop in the runway length available.

Landing Distance: The Effect of Landing Weight on Aircraft Performance

Landing weight is one of the most critical details affect landing distance. Higher landing weight means a longer distance to land. This is due to the fact that a heavier aircraft develops far more kinetic energy which must be dissipated by the braking systems of the aircraft.

The effect of landing weight on the landing distance is due to several factors:

Kinetic Energy — A plane that weighs a lot has more kinetic energy. During the landing phase this energy needs to be cancelled, usually by using brakes, reverse thrust and aerodynamic drag (by deploying spoilers and flaps).

Stop Now: The brakes have to do a lot more work to stop an aircraft when it's heavier. The braking systems are placed under increasing stress with a higher landing weight, although they are built to handle the weight.

Landing Weight: As the aircraft gets heavier, this relationship translates to needing more runway (up to a certain point) for a safe stop. That is also why pilots must consult landing distance charts during the flight planning process to ensure that sufficient runway exists at the destination.

Aircraft Stability

Landing weight can impact the aircraft stability especially pitch control. That higher landing weight may necessitate alternative methods to control the aircraft's center of gravity (CG). Toward heavier aircrafts and lesser responsive to the control inputs, particularly at slow speeds when approaching or touching down (flare, sensation of transition between a descent route into level flight).

Depending on weight for landing, pilots will need to manage approach speed of the aircraft. With a higher weight comes a higher approach speed, which it affects the flare and touchdown speed.

Braking Systems

The landing weight impacts also the braking systems of the aircraft (which contains in their design; wheel brakes, reverse thrust, and aerodynamic spoilers). Aircraft with more mass need stronger brakes to decelerate. This means that the braking systems also has to be designed for heavier planes.

With an increased landing weight, the forces acting on the landing gear are also greater and need to be accounted for in designing its structure and in that of the aircraft. For example, the tires must carry more load, which can affect what tire pressures and tire maintenance are used.

What Is Landing Weight and How Does It Get Calculated?

Landing weight is necessary to calculate to ensure a safe flight. It's a mix of several, and should be considered in real-world flight scenarios:

Takeoff Weight:

When the flight starts, the airframe is at its maximum take-off weight (MTOW), which is comprised of fuel in the tanks as well as all passengers and cargo along with the dead weight of the aircraft. The plane is losing weight as it burns fuel in the air. This means that landing weight is always balanced to be less than the takeoff weight, except for diversion or early landing cases where the aircraft may land with additional fuel on board.

Fuel Burn:

Given the rule we mentioned before for landing weight, namely getting rid of the fuel burn from our initial takeoff weight. The aircraft proposes fuel consumption using the on board Flight Management System (FMS) which can calculate fuel flowouts on-the-fly during an ongoing flight. This enables pilots and ground personnel to predict the aircraft landing weight according to fuel burned at descent and landing.

Let's say an aircraft has a takeoff weight of 200000kg; If in the during flight it consumes 30000Kg of fuel then its landing weight will be about 170,000 kg (not accounting other changes with cargo and passengers onboard).

Payload Changes:

A realistic portion of the total weight of passengers, baggage and cargo can change during flight (off load/freight weighted, etc.) While this may change the landing weight marginally, it is a small portion of the fuel burn. Any change in payload is typically considered in the flight plan of the aircraft, which will have taken into account before take-off.

Zero Fuel Weight (ZFW):

ZFW (Zero Fuel Weight): The weight of the aircraft at take-off subtracting the fuel mass. This weight includes everything held on airframe, cargo and so forth. ZFW + remanent fuel = landing weight

Maximum Landing Weight (MLW)

Every airplane has a Maximum Landing Weight (MLW), which is the highest weight at which the aircraft is certified to land safely. The manufacturer of the aircraft will set this limit and it depends on;

The strength of the landing gear.

How the brakes of the aircraft can stop it.

The pressure on the airframe when it comes in to land.

Surpassing the MLW places more strain on the aircraft structure than it was designed for, threatening damage or failure to critical components. That means the pilot must be constantly monitoring how much weight is in the aircraft and schedule a landing, pre-determined they are in control of the plane as best it can.

Noteworthy Aspect of Landing Weight to be Considered Operationally

In both long and ultrashort flights, landing weight is additionallyconsidered in flight planning. One of the top priorities for pilots is to ensure that an aircraft is capable of being landed (and stopped) within the available length of runway, which means that not only has landing weight and other threshold weights to be considered due to it affecting performance parameters but;

Weather: Runways that are wet or slippery may diminish the ability of the brakes to slow the airplane do its entire weight. Crosswinds and gusts, which impact braking performance as well.

Runway elevation: Longer landing distances are required due to decreased air density at higher-altitude airports.

Aircraft configuration: Flaps and spoilers and reverse thrust must be selectively utilized to maximize stopping performance.

Prior to a landing, pilots will generally reference some sort of approach distance charts and also be using the aircraft’s flight management computer to generate an appropriate approach speed and landing distance at the current gross weight. It is then calculated to ensure the aircraft can come to a halt under even the most difficult of scenarios.

Conclusion

Landing weight is an essential metric in aviation that affects nearly all spheres of aircraft performance such as landing distance, braking, stability, and overall safety amongst others. Pilots need to calculate landing weight accurately so the aircraft lands safely and can stop in the length available without overloading any of its systems such as the landing gear or braking system.

Managing landing weight is the only area where fuel burn, payload and airplane design limits come to play. When the numbers are crunched, and the math is all dialed in, pilots will safely get their aircraft onto the ground well within required parameters so that passengers and crew remain safe.