Before every flight, pilots need to make sure their aircraft is loaded correctly and can be operated safely. This involves checking two important factors: weight and balance.
An aircraft that is too heavy or incorrectly balanced may have reduced performance, handling difficulties and, in some circumstances, become unsafe to fly.
But how do pilots calculate weight and balance, and who is responsible for doing these calculations?
The process varies depending on the type of aircraft and operation. A student pilot flying a small training aircraft will generally perform the calculations themselves, while a large airline operation will typically have a dedicated load-control system and personnel preparing the aircraft’s loading documentation.
What Is Aircraft Weight and Balance?
Weight refers to the total weight of the aircraft, including its occupants, baggage, fuel and other items being carried.
Balance refers to how that weight is distributed throughout the aircraft. Pilots need to ensure that the aircraft’s centre of gravity (CG) remains within the limits specified by the manufacturer.
Both are essential.
An overloaded aircraft may require a longer take-off distance, climb less effectively and place excessive loads on its structure.
An aircraft with its centre of gravity too far forward or too far aft can also have handling problems. For example, an excessively aft centre of gravity can reduce longitudinal stability and make recovery from certain situations more difficult.
How Do Pilots Calculate Weight and Balance?
The basic principles are the same whether you are flying a small training aircraft or a large passenger jet.
Pilots or other authorised personnel need to establish the aircraft’s basic weight, then account for the items being carried.
These generally include:
- The aircraft’s basic or empty weight
- The pilot and other crew members
- Passengers
- Baggage and cargo
- Fuel
The total is then checked against the aircraft’s approved weight limits.
The distribution of the load is also assessed to establish whether the centre of gravity falls within the permitted range.
Depending on the aircraft, these calculations may use a paper worksheet, tables and graphs in the aircraft flight manual, or an approved electronic system.
How Does a Student Pilot Do It?
When learning to fly a small single-engine aircraft, a student pilot will normally learn to calculate weight and balance as part of their flight training.
For example, imagine preparing a small training aircraft for a flight with an instructor and a student, some baggage and a full or partial fuel load.
The pilot uses the aircraft’s weight-and-balance information to calculate the total loaded weight and the resulting centre of gravity.
A typical calculation considers:
- The aircraft’s basic weight and centre of gravity.
- The weight of the pilot, instructor or passengers.
- The weight of baggage and equipment.
- The weight of the fuel being carried.
- The effect of each item’s position on the aircraft’s balance.
Each item’s weight is multiplied by its distance from a specified reference point, known as its arm, to calculate its moment.
The moments are added together and divided by the total weight to determine the loaded centre of gravity.
The pilot then checks that both the total weight and centre of gravity are within the aircraft’s approved limits.
Student pilots learn this process because understanding the calculations helps them appreciate how loading affects aircraft performance and handling.
How Is It Different for an Airline?
On a large commercial aircraft, the process is more complex because there may be hundreds of passengers, large amounts of baggage and cargo, and specific loading requirements for different compartments.
Airlines generally use a formal load-control system.
Depending on the airline’s procedures, trained load-control personnel or ground-handling staff prepare the load sheet or equivalent electronic documentation. This takes account of the aircraft’s operating weight, passenger and cargo loads, fuel and load distribution.
The documentation establishes whether the aircraft is within its permitted weight and centre-of-gravity limits for the planned flight.
The loading process must also ensure that baggage and cargo are placed in the correct locations and properly secured.
Last-minute changes, such as additional passengers, baggage or fuel changes, may require the loading information to be updated.
Is the Captain Still Responsible?
Yes. The captain cannot simply ignore weight-and-balance information because someone else has prepared it.
In an airline operation, responsibilities are shared between the operator, load-control personnel, ground staff and flight crew, according to the applicable regulations and company procedures.
The captain must have the required weight-and-balance information and ensure that the aircraft’s loading is acceptable for the flight. Under Australian rules, the pilot in command must have the prescribed weight-and-balance information before the flight begins. CASA — Pilot in Command responsibilities
This does not necessarily mean the captain personally performs every calculation. Instead, the captain must follow the operator’s approved procedures, review and accept the required documentation as applicable, and ensure that the actual loading is consistent with the information used to prepare it.
If there is a discrepancy or a concern about the loading, it must be resolved before departure.
Why Is Weight and Balance So Important?
Weight and balance calculations are not just an administrative exercise. They directly affect flight safety.
Correct loading helps ensure that the aircraft can:
- Take off within the required distance
- Climb and perform as expected
- Remain controllable and stable
- Operate within structural limitations
- Land within its approved weight limits
The calculations also need to account for the planned flight. Fuel is consumed during flight, so the aircraft’s weight and centre of gravity can change as the journey progresses.
Pilots must therefore use the appropriate loading and performance information for the aircraft and operation.
Learning Weight and Balance During Pilot Training
For student pilots, weight and balance is one of the fundamental subjects in aviation theory and practical flight preparation.
It teaches students to think beyond simply controlling the aircraft and to consider the factors that determine whether a flight can be conducted safely.
As pilots progress into more complex aircraft and commercial operations, the systems may become more sophisticated, but the underlying principles remain the same.
Whether flying a small training aircraft or a large passenger jet, the aircraft must be within its approved weight and balance limits before it takes off.
At Moorabbin Aviation Services, students develop the practical flying skills and aviation knowledge required to progress towards a professional pilot career. Understanding aircraft weight and balance is one of the many important foundations of that training.