An aircraft is pretty similar to a coach, both have passenger seats and room for baggage. However, unlike a coach we can’t just board an aircraft, fill it with fuel, baggage and cargo and set off. Essentially the load control process allows for the maximisation of payload, all important for generating revenue whilst ensuring that the aircraft still takes off, flies and lands safely.
Four Reasons Why Aircraft Need Loadsheets
1. An aircraft filled with passengers, baggage, cargo and fuel could be too heavy for the engines to lift it off the ground.
2. The balance of the aircraft is crucial, and the location of the passengers, baggage, cargo and fuel will affect the aircraft trim.
3. The undercarriage can only support a certain amount of weight on landing.
4. Loading too much weight into a particular part of the aircraft could cause damage to the structure. Whilst this might not be evident straight away it could over a period of time shorten the working life of the aircraft.
Five Important Aircraft Weights
It is necessary to understand that at different stages of loading an aircrafts weight will alter. The majority of these weights are fixed and do not change often i.e. the basic weight of the aircraft, although others such as passenger weights will vary. The table below shows the components that make up the five different aircraft weights. The empty aircraft weight is a starting point from which various components are added providing the load controller with a weight of the aircraft at each stage of loading.
|Basic Weight||Dry Operating Weight||Operating Weight||Zero Fuel Weight||Take-off Weight|
|Cargo & Mail||*||*|
All aircraft are individually weighed and commonly no two aircraft will have exactly the same weight. The empty weight of an aircraft is calculated to include its airframe and engines, full oil tanks and unusable fuel.
Seats, galley, toilets including furnishings and emergency equipment such as oxygen masks and bottles. Anything that is standard or fitted as an optional extra to the aircraft is part of this calculation.
A combination of the aircraft weight and all its fixed equipment provides the foundation necessary to calculate the four different stages of an aircrafts weight.
Generally commercial aircraft have a standard operating crew compliment with standard crew weights used for load sheets. As an example the Bombardier Q300 aircraft has a standard crew compliment of 2 pilots and 1 flight attendant. However, this can alter for training or checking purposes when an additional pilot is carried on the jump seat or an extra flight attendant is in the cabin. The load controller must adjust the crew compliment as it will affect the weight and trim of the aircraft.
Consisting of any food, drink, provisions or objects used for servicing passengers or crew. An example of items covered in the pantry could include tea, biscuits, coffee pots and hot water. Whilst individually these items have a negligible weight, when they are carried in bulk it will naturally add weight to the aircraft in turn affecting its trim. It would be unfeasible to weigh every item of pantry carried on board each flight therefore a standard weight is created accounting for required provisions per flight. The weight and location is recorded for trim purposes and absorbed into calculations for the operating weights of the aircraft.
This is a different figure to the block fuel uplifted on the ramp. An aircraft will burn fuel as it starts engines and moves off stand taxing to the end of the runway, and lining up for take-off. Therefore the amount of fuel the aircraft had prior to engine start will differ to the amount in tanks before take-off. Subsequently take-off fuel is calculated by deducting the taxi fuel from the block fuel. In commercial load control the taxi fuel is usually a standard figure specified by the operator. Whilst this might seem inconsequential, in situations where congestion or delays are incurred such as an aircraft operating out of London Heathrow, block fuel and take-off fuel figures could differ greatly.
The total weight of all passengers carried including their hand baggage. These can be actual weights whereby all passengers and their hand baggage are physically weighed or, standard weights where an air operator has an established and documented method and calculation in their air operator’s exposition.
The total weight of all baggage carried on board the aircraft, either actual weights calculated by physically weighing baggage or, standard weights that an air operator has established and documented in their air operator’s exposition.
Cargo & Mail
The total and actual physical weight of all cargo and mail carried on board the aircraft.
Standard Weights for Passengers, Crew and Baggage
Learn more about standard-weights-for-passengers-crew-and-baggage
Different Fuel Weights for Load Control
There are a number of different fuel calculations used on a load sheet relating to the various stages of flight. This recognises fuel as a consumable item with an aircraft on landing carrying less fuel than on take-off. Fuel is a crucial component of a load sheet with its weight and location affecting an aircrafts trim and overall weight.
All fuel uploaded onto the aircraft before it has moved anywhere.
The amount of fuel an aircraft burns getting to the runway ready for take off.
Take Off Fuel
Block fuel minus the taxi fuel.
The actual fuel required from the take off to the landing.
Maximum Aircraft Weights
Airlines have weight and balance manuals stipulating weights for their company aircraft that also include maximum aircraft weights. These indicate the maximum weight at varying stages that an aircraft can be loaded to. When operating conditions, including the weather are perfect these maximum weights are used. However, should the conditions deteriorate then these figures may be restricted. An example would be a wet runway on take-off, essentially the aircraft would become restricted on take-off with a RTOW that would be lower than the MTOW.
Maximum zero fuel weight (MZFW)
Maximum take off weight (MTOW)
Maximum landing weight (MLDW)
It is the load controller’s responsibility to determine the lowest maximum weight governing and restricting the load sheet by making the following simple calculations which ensures the aircrafts structure and airworthiness requirements are not exceeded:-
MZFW + Take-off fuel
MTOW (Includes take-off fuel)
MLDW + Trip Fuel
After the above calculations have been made the lowest maximum weight will govern and restrict the load sheet. Using either MZFW, MTOW or MLDW the operating weight is subtracted providing the payload (allowed traffic load) which indicates how much additional weight can be loaded onto the aircraft. Interestingly some aircraft have higher permitted weights for take-off than landing.
How Much Can The Aircraft Carry?
Total Traffic Load
Total weight of all passengers, baggage, cargo and mail.
Payload (Allowed Traffic Load)
How much weight could be carried.
Deducting the total traffic load from the allowed traffic load provides an underload, this indicates how much weight is still available to carry anything.
- If you have an extra passengers wishing to travel that requires a late manual change (LMC) to the load sheet, you will know if you have the weight available to accept them for carriage by looking at your underload.
Balancing The Aircraft - Indexes
Once the weights have been calculated on the loadsheet this information is then transferred to a balance chart to assess the aircrafts centre of gravity. Essentially if the load is within certain limitations it can be trimmed in flight by the horizontal stabiliser. However, frequent load control errors mean the aircraft is trimmed either too nose or too tail heavy. This can be corrected by relocating the load through changing passenger seat allocations, albeit more common in turbo prop aircraft, or reassigning the baggage, cargo, mail to different holds.
Centre of Gravity (CG)
The central balance point of an aircraft.
Basic Index (BI)
A fixed point on a numerical scale representing the central balance point of the aircraft, this includes furnishings and fixed equipment.
Dry Operating Index (DOI)
The fixed point on a numerical scale representing the balance point of the empty aircraft, this includes crew and catering.
Supporting Paperwork For The Loadsheet
Whilst the terms will vary slightly between airline operator and country, these are essentially standard and internationally accepted supporting documents to a loadsheet.
Special Load Notification To Captain (NOTOC)
A dangerous good or any other special load is not generally carried onboard a commercial aircraft unless a NOTOC has been completed, and this is usually supported by an entry shown on the load sheet identifying its location, weight and description.
Some examples of special loads are:-
Loading Instruction Report (LIR) or Load Plan (LP)
The purpose of this document is for the load controller to allocate the load, and the loader to confim where the actual load is located on the aircraft. The LIR/LP is prepared by the load controller detailing where the planned load is to be located in the holds, the loader then records where the actual load and weight is distributed in the holds. Sometimes it is necessary for the LIR/LP to be changed by the loader i.e. a hold is bulked out before it contains the entire planned load. The amended LIR/LP is communicated to the load controller enabling them to produce a loadsheet that accurately reflects the actual weights and locations of the load.