Weight and Centre of Gravity
Weight and Centre of Gravity
In all The Company documents the term “Weight” is usually used instead of the term “Mass”. For operational purposes the term Weight (W) is to be considered equal to the term Mass (M).
Definitions
Manufacturer’s Empty Weight (MEW): The weight of the structure, power plant, furnishings, systems and other items of equipment that are considered an integral part of the aircraft. It is essentially a “dry” weight, including only those fluids contained in closed systems (e.g. hydraulic fluid).
Operational Empty Weight (OEW): The manufacturer’s weight empty plus the operator’s items, i.e. flight and cabin crew and their baggage, unusable fuel, engine oil, emergency equipment, toilet chemicals and fluids, galley structure, catering equipment, seats, documents, etc.
Dry Operating Weight (DOW): The total weight of the specific aircraft ready for a specific type of operation excluding all usable fuel and traffic load. It represents Operational Empty Weight plus items specific to the type of flight, i.e. catering, pantry equipment, extra crew, etc.
The DOW includes:
Maximum Zero Fuel Weight (MZFW): The maximum permissible weight of an aircraft with no usable fuel. The weight of the fuel contained in particular tanks must be included in the zero fuel weight when it is explicitly mentioned in the Aircraft Flight Manual limitations.
Zero Fuel Weight (ZFW): The weight obtained by addition of the total traffic load and the dry operating weight.
Maximum Allowed Weight for Take-Off: The maximum allowed weight for take-off for a specific flight considers:
Take-Off Weight (TOW): The weight at take-off at the departure aerodrome. It is equal to the landing weight at destination plus the trip fuel (fuel needed for the trip), or to the zero fuel weight plus the take-off fuel (fuel needed at the brake release point including reserves).
Maximum Allowed Weight for Landing: The maximum allowed weight for landing considers:
Landing Weight (LW): The weight at landing at the destination aerodrome.
Take-Off Fuel: The weight of the fuel on board at take-off.
Traffic Load (TL): The total weight of passengers, baggage and cargo including nonrevenue loads (if any).
Payload (PL): The total weight of the revenue load (passengers, cargo or mail).
Last Minute Change (LMC): A late change/amendment to the weight and balance sheet which does not require the preparation of a new weight and balance sheet if the changes/amendments to the existing weight and balance sheet do not exceed the limits specified in the OM Part B.
Maximum Approved Passenger Seating Configuration: The maximum passenger seating capacity of an individual aeroplane, excluding pilot seats or flight deck seats and cabin crew seats as applicable, used by the operator, approved by the Authority and specified in the OM Part B.
Passenger Classification:
Operational Centre of Gravity Envelope: This is the operational centre of gravity envelope which further restricts the certified centre of gravity envelope to compensate for errors such as the differences between assumed passenger weights and actual weights, use of one common moment-arm for several seat rows, deviations in the distribution of baggage/cargo/mail in the various compartments, inaccuracies in the actual weight of baggage, deviation caused by gear and/or flap positions, in flight movements of passengers, cabin crew and pantry equipment (trolleys), deviation in fuel distribution etc.
The operational centre of gravity envelope shall never be exceeded.
Methods, Procedures and Responsibilities for Preparation and Acceptance of Weight and Centre of Gravity Calculations
The Weight and Balance Document (i.e. Load and Trim sheet), manual or computerised, will establish the aircraft’s weight and centre of gravity. It must contain the weight and disposition of all loaded items, including fuel, indicating whether standard or actual weight values for passengers have been used.
The Commander shall insure that before each flight a load calculation is prepared on the correct form and complies with the aircraft weights and CG certified limitations.
The Ground Handling Staff is responsible for ensuring the correct traffic load totals and correct Load and Trim sheet calculation. The person who prepares the Load and Trim sheet must be named on it.
The person supervising the loading must confirm by signature that the load and its distribution are in accordance with Load and Trim sheet.
The correct loading of the aircraft is the legal responsibility of the Commander. He must satisfy himself that the load is distributed in a correct and safe manner and that it is properly stowed and secured. Actual weight must be used when taking freight or ballast into account.
The weight of fuel on board the aircraft is directly given by the Fuel Quantity Indication (FQI) of the aircraft. The Commander should assess this quantity by comparing this figure with the quantity on board before refuelling plus the quantity delivered by the tanker. Fuel measurement through magnetic fuel level indicators (dipsticks) should be used only in case of FQI failure (dispatch under MEL).
The Commander is personally responsible for:
Load and Trim sheet shall be issued and signed, at least, in triplicate and distributed as follows:
Standard Weight Values for Operating Crew
Standard Weight Values for Passengers and Persons other than Operating Crew
To determine the weight of passengers, normally standard (including hand baggage) weight values given in table below shall be used. However, if a significant number of passengers on any flight and/or a significant amount of checked baggage are expected to exceed the standard weights then actual weight must be used or an adequate increment to the standard weights must be added.
Standard passenger weights should normally be used for calculation. Alternate weights may be used, provided that hand baggage is accounted separately and the Commander is being informed about using those alternate weights.
When using alternate weight values for carry-on baggage, 8 kg should be used per piece.
Standard Weight Values for Baggage
Note: Domestic flight means a flight with origin and destination within the borders of one State.
Flights within the European region means flights, other than Domestic flights, whose origin and destination are within the area bounded by rhumb lines between the following points:
N7200 E04500
N4000 E04500
N3500 E03700
N3000 E03700
N3000 W00600
N2700 W00900
N2700 W03000
N6700 W03000
N7200 W01000
N7200 E04500
as depicted below:
Flights within the Asian region means flights, other than Domestic flights, whose origin and destination are within the area bounded by rhumb lines as depicted below:
Intercontinental flights, other than flights within the European or Asian region, are flights with origin and destination in different continents.
Last Minute Change (LMC) Procedures
LMC is only permitted if the changes of the load (either plus or minus) are within the limits defined in the applicable OM Part B (+/- 1000kg). The changes have to be entered into the Load and Trim sheet into the ‘LMC’ column.
In exceptional cases - if time does not permit otherwise – changes may be relayed to the Commander via radio or the ground service interphone. The Commander and Ground Handling Staff shall amend their copies accordingly. The load message sent to the destination must contain the corrected figures of passengers, cargo, baggage or mail load.
Specific Gravity of Fuel and other Fluids
When entering the weight figures for the take-off fuel and trip fuel (burn off) the correct specific gravity must be used to convert the volume into mass value. The same applies to any other fluids, such as oil. Whenever possible and practicable, the specific gravity of fuel - as obtained from the fuelling crew - must be used. If this is not possible or practicable, the following specific gravity values may be used:
The weight and balance sheet is prepared assuming a particular passenger seating distribution. If a seat allocation system is used in connection with the preparation of the Load and Trim sheet, any possible errors in the CG position will be covered by the operational CG envelope – provided the passengers are seated as allocated.
‘Free seating’ however might require a repositioning of passengers in the cabin. The Commander shall instruct the cabin crew to reseat passengers so that the actual seating distribution complies with the balance part of the Load and Trim sheet. Alternatively, the Commander shall adjust the Load and Trim sheet to reflect the actual distribution.
In all The Company documents the term “Weight” is usually used instead of the term “Mass”. For operational purposes the term Weight (W) is to be considered equal to the term Mass (M).
Definitions
Manufacturer’s Empty Weight (MEW): The weight of the structure, power plant, furnishings, systems and other items of equipment that are considered an integral part of the aircraft. It is essentially a “dry” weight, including only those fluids contained in closed systems (e.g. hydraulic fluid).
Operational Empty Weight (OEW): The manufacturer’s weight empty plus the operator’s items, i.e. flight and cabin crew and their baggage, unusable fuel, engine oil, emergency equipment, toilet chemicals and fluids, galley structure, catering equipment, seats, documents, etc.
Dry Operating Weight (DOW): The total weight of the specific aircraft ready for a specific type of operation excluding all usable fuel and traffic load. It represents Operational Empty Weight plus items specific to the type of flight, i.e. catering, pantry equipment, extra crew, etc.
The DOW includes:
- Crew and crew baggage;
- Catering and removable passenger service equipment;
- Potable water and lavatory chemicals;
- Special emergency equipment as required for the route(s);
- Cabin service equipment (newspapers, pillows, blankets, etc.).
Maximum Zero Fuel Weight (MZFW): The maximum permissible weight of an aircraft with no usable fuel. The weight of the fuel contained in particular tanks must be included in the zero fuel weight when it is explicitly mentioned in the Aircraft Flight Manual limitations.
Zero Fuel Weight (ZFW): The weight obtained by addition of the total traffic load and the dry operating weight.
Maximum Allowed Weight for Take-Off: The maximum allowed weight for take-off for a specific flight considers:
- The maximum (structural) take-off weight, and
- The maximum permitted take-off weight as limited by performance reasons and the calculated trip fuel, to assure that the maximum permitted landing weight is not exceeded.
Take-Off Weight (TOW): The weight at take-off at the departure aerodrome. It is equal to the landing weight at destination plus the trip fuel (fuel needed for the trip), or to the zero fuel weight plus the take-off fuel (fuel needed at the brake release point including reserves).
Maximum Allowed Weight for Landing: The maximum allowed weight for landing considers:
- The maximum (structural) landing weight, and
- The maximum permitted landing weight for performance reasons.
Landing Weight (LW): The weight at landing at the destination aerodrome.
Take-Off Fuel: The weight of the fuel on board at take-off.
Traffic Load (TL): The total weight of passengers, baggage and cargo including nonrevenue loads (if any).
Payload (PL): The total weight of the revenue load (passengers, cargo or mail).
Last Minute Change (LMC): A late change/amendment to the weight and balance sheet which does not require the preparation of a new weight and balance sheet if the changes/amendments to the existing weight and balance sheet do not exceed the limits specified in the OM Part B.
Maximum Approved Passenger Seating Configuration: The maximum passenger seating capacity of an individual aeroplane, excluding pilot seats or flight deck seats and cabin crew seats as applicable, used by the operator, approved by the Authority and specified in the OM Part B.
Passenger Classification:
- Adults (male and female) are defined as persons of an age of 12 years and above;
- Children are defined as persons of an age of 2 years and above, but who are less than 12 years of age;
- Infants are defined as persons who are less than 2 years of age.
Operational Centre of Gravity Envelope: This is the operational centre of gravity envelope which further restricts the certified centre of gravity envelope to compensate for errors such as the differences between assumed passenger weights and actual weights, use of one common moment-arm for several seat rows, deviations in the distribution of baggage/cargo/mail in the various compartments, inaccuracies in the actual weight of baggage, deviation caused by gear and/or flap positions, in flight movements of passengers, cabin crew and pantry equipment (trolleys), deviation in fuel distribution etc.
The operational centre of gravity envelope shall never be exceeded.
Methods, Procedures and Responsibilities for Preparation and Acceptance of Weight and Centre of Gravity Calculations
The Weight and Balance Document (i.e. Load and Trim sheet), manual or computerised, will establish the aircraft’s weight and centre of gravity. It must contain the weight and disposition of all loaded items, including fuel, indicating whether standard or actual weight values for passengers have been used.
The Commander shall insure that before each flight a load calculation is prepared on the correct form and complies with the aircraft weights and CG certified limitations.
The Ground Handling Staff is responsible for ensuring the correct traffic load totals and correct Load and Trim sheet calculation. The person who prepares the Load and Trim sheet must be named on it.
The person supervising the loading must confirm by signature that the load and its distribution are in accordance with Load and Trim sheet.
The correct loading of the aircraft is the legal responsibility of the Commander. He must satisfy himself that the load is distributed in a correct and safe manner and that it is properly stowed and secured. Actual weight must be used when taking freight or ballast into account.
The weight of fuel on board the aircraft is directly given by the Fuel Quantity Indication (FQI) of the aircraft. The Commander should assess this quantity by comparing this figure with the quantity on board before refuelling plus the quantity delivered by the tanker. Fuel measurement through magnetic fuel level indicators (dipsticks) should be used only in case of FQI failure (dispatch under MEL).
The Commander is personally responsible for:
- Checking that sufficient fuel and oil are on board and correctly loaded and distributed;
- Checking the Load and Trim calculation;
- Accepting and signing the Load and Trim sheet.
- Error on initial conditions (dry operating weight and index);
- Error on cargo loading (weight and distribution);
- Error on passenger boarding (weight and distribution);
- Error on fuel (quantity and distribution);
- Error due to graphical method;
- Landing gear, flaps and slats movements;
- Movements in the cabin.
- Load and Trim sheet calculation shall be based on kilograms;
- Date;
- Route and flight number;
- Crew configuration;
- Passenger totals do not exceed or deviate from the seating and safety equipment limitations according to the aeroplane certification;
- Actual weight will not exceed the structural and operational limits for Take-off, Landing and Zero Fuel weight;
- ZFW, ZFW MAC and T/O MAC;
- Stabiliser setting is within limits;
- Fuel figures correspond to the actual amount and distribution in the tanks;
- LMC limits.
- The aeroplane is carrying all necessary legal and operational documents;
- The aeroplane is airworthy and maintenance released;
- All traffic load is authorised, correctly distributed and secured for safe flight.
Load and Trim sheet shall be issued and signed, at least, in triplicate and distributed as follows:
- 1 Original for the Commander (for flight envelope);
- 1 Copy for CIC (for destination station);
- 1 Copy for Ground Handling Staff (for the departure station).
Standard Weight Values for Operating Crew
- The standard weight value to be used for operating flight crew is 85 kg.
- The standard weight value to be used for operating cabin crew is 75 kg.
Standard Weight Values for Passengers and Persons other than Operating Crew
To determine the weight of passengers, normally standard (including hand baggage) weight values given in table below shall be used. However, if a significant number of passengers on any flight and/or a significant amount of checked baggage are expected to exceed the standard weights then actual weight must be used or an adequate increment to the standard weights must be added.
Standard passenger weights should normally be used for calculation. Alternate weights may be used, provided that hand baggage is accounted separately and the Commander is being informed about using those alternate weights.
When using alternate weight values for carry-on baggage, 8 kg should be used per piece.
Standard Weight Values for Baggage
- Crew baggage: The standard weight value to be used for crew baggage is 15 kg per crew member.
- Passenger baggage: To determine the total weight of the passenger baggage, normally the actual weight determined by weighing shall be used.
Note: Domestic flight means a flight with origin and destination within the borders of one State.
Flights within the European region means flights, other than Domestic flights, whose origin and destination are within the area bounded by rhumb lines between the following points:
N7200 E04500
N4000 E04500
N3500 E03700
N3000 E03700
N3000 W00600
N2700 W00900
N2700 W03000
N6700 W03000
N7200 W01000
N7200 E04500
as depicted below:
Flights within the Asian region means flights, other than Domestic flights, whose origin and destination are within the area bounded by rhumb lines as depicted below:
Intercontinental flights, other than flights within the European or Asian region, are flights with origin and destination in different continents.
Last Minute Change (LMC) Procedures
LMC is only permitted if the changes of the load (either plus or minus) are within the limits defined in the applicable OM Part B (+/- 1000kg). The changes have to be entered into the Load and Trim sheet into the ‘LMC’ column.
In exceptional cases - if time does not permit otherwise – changes may be relayed to the Commander via radio or the ground service interphone. The Commander and Ground Handling Staff shall amend their copies accordingly. The load message sent to the destination must contain the corrected figures of passengers, cargo, baggage or mail load.
Specific Gravity of Fuel and other Fluids
When entering the weight figures for the take-off fuel and trip fuel (burn off) the correct specific gravity must be used to convert the volume into mass value. The same applies to any other fluids, such as oil. Whenever possible and practicable, the specific gravity of fuel - as obtained from the fuelling crew - must be used. If this is not possible or practicable, the following specific gravity values may be used:
- Jet fuel A/A1: 0.796 kg/litre;
- Jet fuel B/JP-4: 0.760 kg/litre;
- Oil: 0.880 kg/litre.
The weight and balance sheet is prepared assuming a particular passenger seating distribution. If a seat allocation system is used in connection with the preparation of the Load and Trim sheet, any possible errors in the CG position will be covered by the operational CG envelope – provided the passengers are seated as allocated.
‘Free seating’ however might require a repositioning of passengers in the cabin. The Commander shall instruct the cabin crew to reseat passengers so that the actual seating distribution complies with the balance part of the Load and Trim sheet. Alternatively, the Commander shall adjust the Load and Trim sheet to reflect the actual distribution.
Weight and Centre of Gravity
Reviewed by Aviation Lesson
on
2:30 PM
Rating:
Reviewed by Aviation Lesson
on
2:30 PM
Rating:
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