IRImplementing rule
SUBJECT 031 – FLIGHT PERFORMANCE AND PLANNING: MASS AND BALANCE – AEROPLANES/HELICOPTERS
Note that the term ‘mass’ is used to describe a quantity of matter, and ‘weight’ when describing the force. However, the term ‘weight’ is normally used in aviation to colloquially describe mass. The professional pilot should always note the units to determine whether the term ‘weight’ is being used to describe a force (e.g. unit newton) or quantity of matter (e.g. unit kilogram).
(1)DEFINITIONS OF MASSES, LOADS AND INDEXES Allowed take-off mass The mass taking into consideration all possible limitations for take-off including restrictions caused by regulated take-off mass and regulated landing mass.
Area load or floor load The load (or mass) distributed over a defined area. Example units: SI: N/m2, kg/m2; Non-SI: psi, lb/ft2.
Basic empty mass (BEM) The mass of an aircraft plus standard items such as: unusable fuel; full operating fluids; fire extinguishers; emergency oxygen equipment. (The lowest mass that is used in FCL exams.)
Dry operating mass (DOM) The total mass of an aircraft ready for a specific type of operation excluding all usable fuel and traffic load. This mass includes items such as: crew and crew baggage; catering and removable passenger service equipment (food, beverages, potable water, lavatory chemicals, etc.); special operational equipment (e.g. stretchers, rescue hoist, cargo sling).
Dry operating index (DOI) The aircraft index at dry operating mass.
Index An index is a moment reduced in a numerical value by an index formula.
In-flight mass/gross mass The mass of an aircraft in flight at a specified time.
Landing mass The mass of an aircraft at landing.
Maximum structural in-flight mass with external loads (applicable to helicopters only) The maximum permissible total mass of the helicopter with external loads.
Maximum structural landing mass The maximum permissible total mass of an aircraft at landing under normal circumstances.
Maximum structural mass The maximum permissible total mass of an aircraft at any time. It will be given only if there is no difference between maximum structural taxi mass, maximum structural take-off mass and maximum structural landing mass.
Maximum structural take-off mass The maximum permissible total mass of an aircraft at commencement of take-off.
Maximum (structural) taxi mass or maximum (structural) ramp mass The maximum permissible total mass of an aircraft at commencement of taxiing.
Maximum zero fuel mass The maximum permissible mass of an aircraft with no usable fuel.
Minimum mass (applicable to helicopters only) The minimum permissible total mass for specific helicopter operations.
Operating mass The dry operating mass plus take-off fuel.
Payload The total mass of passengers, baggage and cargo but excluding any non-revenue load.
Performance-limited landing mass The mass subject to the destination airfield limitations.
Performance-limited take-off mass The take-off mass subject to departure airfield limitations.
Ramp mass See ‘taxi mass’.
Regulated landing mass The lower of performance-limited landing mass and maximum structural landing mass.
Regulated take-off mass The lower of performance-limited take-off mass and maximum structural take-off mass.
Running (or linear) load The load (or mass) distributed over a defined length of a cargo compartment irrespective of load width. Example units: SI: N/m, kg/m; Non-SI: lb/in, lb/ft.
Take-off fuel The total amount of usable fuel at take-off.
Take-off mass The mass of an aircraft including everything and everyone carried at the commencement of the take-off for helicopters and take-off run for aeroplanes.
Taxi mass or ramp mass The mass of an aircraft at the commencement of taxiing.
Traffic load The total mass of passengers, baggage and cargo, including any non-revenue load.
Zero fuel mass The dry operating mass plus traffic load.
| Syllabus reference | BK | Syllabus details and associated Learning Objectives | Aeroplane | Helicopter | IR | CB-IR(A) | BIR Exam | BIR BK | Remarks | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ATPL | CPL | ATPL/IR | ATPL | CPL | ||||||||
| 030 00 00 00 | FLIGHT PERFORMANCE AND PLANNING | |||||||||||
| 031 00 00 00 | MASS AND BALANCE — AEROPLANES/HELICOPTERS | |||||||||||
| 031 01 00 00 | PURPOSE OF MASS-AND-BALANCE CONSIDERATIONS | |||||||||||
| 031 01 01 00 | Mass limitations | |||||||||||
| 031 01 01 01 | Importance with regard to structural limitations | |||||||||||
| (01) | X | Describe the relationship between aircraft mass and structural stress. Remark: See also Subject 021 01 01 00. | X | X | X | X | X | |||||
| (02) | X | Describe why mass must be limited to ensure adequate margins of strength. | X | X | X | X | X | |||||
| 031 01 01 02 | Importance with regard to performance Remark: See also Subjects 032/034 and 081/082. | |||||||||||
| (01) | Describe the relationship between aircraft mass and aircraft performance. | X | X | X | X | X | ||||||
| (02) | X | Describe why aircraft mass must be limited to ensure adequate aircraft performance. | X | X | X | X | X | |||||
| 031 01 02 00 | Centre-of-gravity (CG) limitations | |||||||||||
| 031 01 02 01 | Importance with regard to stability and controllability Remark: See also Subjects 081/082. | |||||||||||
| (01) | X | Describe the relationship between CG position and stability/controllability of the aircraft. | X | X | X | X | X | |||||
| (02) | Describe the consequences if CG is in front of the forward limit. | X | X | X | X | X | ||||||
| (03) | Describe the consequences if CG is behind the aft limit. | X | X | X | X | X | ||||||
| 031 01 02 02 | Importance with regard to performance Remark: See also Subjects 032/034 and 081/082. | |||||||||||
| (01) | X | Describe the relationship between CG position and aircraft performance. | X | X | X | X | X | |||||
| (02) | Describe the effects of CG position on performance parameters (speeds, altitude, endurance and range). | X | X | X | X | X | ||||||
| 031 02 00 00 | LOADING | |||||||||||
| 031 02 01 00 | Terminology | |||||||||||
| 031 02 01 01 | Mass terms | |||||||||||
| (01) | X | Define the following mass terms: basic empty mass; dry operating mass; operating mass; take-off mass; landing mass; ramp/taxi mass; in-flight mass (gross mass); zero fuel mass. | X | X | X | X | X | |||||
| 031 02 01 02 | Load terms (including fuel terms) Remark: See also Subject 033. | |||||||||||
| (01) | X | Define the following load terms: payload/traffic load; block fuel; taxi fuel; take-off fuel; trip fuel; reserve fuel (contingency, alternate, final reserve and additional fuel); extra fuel. | X | X | X | X | X | |||||
| (02) | Explain the relationship between the various load-and-mass components listed in 031 02 01 01 and 031 02 01 02. | X | X | X | X | X | ||||||
| (03) | Calculate the mass of particular components from other given components. | X | X | X | X | X | ||||||
| (04) | Convert fuel mass, fuel volume and fuel density given in different units used in aviation. | X | X | X | X | X | ||||||
| 031 02 02 00 | Mass limits | |||||||||||
| 031 02 02 01 | Structural limitations | |||||||||||
| (01) | X | Define the maximum zero fuel mass. | X | X | ||||||||
| (02) | X | Define the maximum ramp/taxi mass. | X | |||||||||
| (03) | X | Define the maximum take-off mass. | X | X | X | X | X | |||||
| (04) | X | Define the maximum in-flight (gross) mass with external load. | X | X | X | |||||||
| (05) | X | Define the maximum landing mass. | X | X | X | X | X | |||||
| 031 02 02 02 | Performance and regulated limitations | |||||||||||
| (01) | Describe the following performance and regulated mass limitations: performance-limited take-off mass; performance-limited landing mass; regulated take-off mass; regulated landing mass. | X | X | X | X | X | ||||||
| 031 02 02 03 | Cargo compartment limitations | |||||||||||
| (01) | X | Describe the maximum floor load (maximum load per unit of area). | X | X | X | X | X | |||||
| (02) | X | Describe the maximum running load (maximum load per unit of fuselage length). | X | X | X | X | X | |||||
| 031 02 03 00 | Mass calculations | |||||||||||
| 031 02 03 01 | Maximum masses for take-off and landing | |||||||||||
| (01) | Calculate the maximum mass for take-off (regulated take-off mass) given mass-and-load components and structural/ performance limits. | X | X | X | X | X | ||||||
| (02) | Calculate the maximum mass for landing (regulated landing mass) given mass-and-load components and structural/ performance limits. | X | X | X | X | X | ||||||
| (03) | Calculate the allowed mass for take-off. | X | X | X | X | X | ||||||
| 031 02 03 02 | Allowed traffic load and fuel load | |||||||||||
| (01) | Calculate the maximum allowed traffic load and fuel load in order not to exceed the given allowed takeoff mass. | X | X | X | X | X | ||||||
| (02) | Calculate ‘under load’/‘over load’ given the allowed mass for take-off, operating mass and actual traffic load. | X | X | X | X | X | ||||||
| 031 02 03 03 | Use of standard masses for passengers, baggage and crew | |||||||||||
| (01) | X | Extract the appropriate standard masses for passengers, baggage and crew from relevant documents or operator requirements. | X | X | X | X | X | |||||
| (02) | Calculate the traffic load by using standard masses. | X | X | X | X | X | ||||||
| 031 03 00 00 | INTENTIONALLY LEFT BLANK | |||||||||||
| 031 04 00 00 | MASS-AND-BALANCE DETAILS OF AIRCRAFT | |||||||||||
| 031 04 01 00 | Contents of mass-and-balance documentation | |||||||||||
| 031 04 01 01 | Datum, moment arm | |||||||||||
| (01) | X | State where the datum and moment arms for aircraft can be found. | X | X | X | X | X | |||||
| (02) | X | Extract the appropriate data from given documents. | X | X | X | X | X | |||||
| (03) | X | Define ‘datum’ (reference point), ‘moment arm’ and ‘moment’. | X | X | X | X | X | |||||
| 031 04 01 02 | CG position as distance from datum | |||||||||||
| (01) | X | State where the CG position for an aircraft at basic empty mass can be found. | X | X | X | X | X | |||||
| (02) | X | State where the CG limits for an aircraft can be found. | X | X | X | X | X | |||||
| (03) | Describe the different forms in presenting CG position as distance from datum or other references. | X | X | X | X | X | ||||||
| (04) | Explain the meaning of centre of gravity (CG). | X | X | X | X | X | ||||||
| 031 04 01 03 | CG position as percentage of mean aerodynamic chord (% MAC) Remark: Knowledge of the definition of MAC is covered under Subject 081 01 01 05. | |||||||||||
| (01) | Extract MAC information from aircraft documents. | X | X | |||||||||
| (02) | Explain the principle of using % MAC for the description of the CG position. | X | X | |||||||||
| (03) | Calculate the CG position as % MAC. | X | X | |||||||||
| 031 04 01 04 | Longitudinal CG limits | |||||||||||
| (01) | Extract the appropriate data from given sample documents. | X | X | X | X | X | ||||||
| 031 04 01 05 | Lateral CG limits | |||||||||||
| (01) | Extract the appropriate data from given sample documents. | X | X | X | ||||||||
| 031 04 01 06 | Details of passenger and cargo compartments | |||||||||||
| (01) | Extract the appropriate data (e.g. seating schemes, compartment dimensions and limitations) from given sample documents. | X | X | X | X | X | ||||||
| 031 04 01 07 | Details of fuel system relevant to mass-and-balance considerations | |||||||||||
| (01) | X | Extract the appropriate data (e.g. fuel-tank capacities and fuel-tank positions) from given sample documents. | X | X | X | X | X | |||||
| (02) | Explain aircraft CG movement as flight progresses given location of fuel tank (inner wing, outer wing, central, additional aft central, horizontal stabiliser) and mass of fuel consumed from that tank and aeroplane’s previous CG. | X | ||||||||||
| (03) | Explain advantages and risks associated with fuel tanks in the aeroplane’s fin or horizontal stabiliser. | X | ||||||||||
| 031 04 02 00 | Determination of aircraft empty mass and CG position by weighing | |||||||||||
| 031 04 02 01 | Weighing of aircraft (general aspects) | |||||||||||
| (01) | Describe the general procedure and regulations relating to when an aircraft should be weighed, reweighed or data recalculated. Remark: See the applicable operational requirements. | X | X | X | X | X | ||||||
| (02) | X | Extract and interpret entries from/in ‘mass (weight) report’ of an aircraft. | X | X | X | X | X | |||||
| 031 04 02 02 | Calculation of mass and CG position of an aircraft using weighing data | |||||||||||
| (01) | Calculate the mass and CG position of an aircraft from given reaction forces on jacking points. | X | X | X | X | X | ||||||
| 031 04 03 00 | Extraction of basic empty mass (BEM) and CG data from aircraft documentation | |||||||||||
| 031 04 03 01 | BEM or dry operating mass (DOM) | |||||||||||
| (01) | X | Extract values for BEM or DOM from given documents. | X | X | X | X | X | |||||
| 031 04 03 02 | CG position or moment at BEM/DOM | |||||||||||
| (01) | Extract values for CG position and moment at BEM or DOM from given documents. | X | X | X | X | X | ||||||
| 031 04 03 03 | Deviations from standard configuration | |||||||||||
| (01) | Extract values from given documents for deviation from standard configuration as a result of varying crew, optional equipment, optional fuel tanks, etc. | X | X | X | X | X | ||||||
| 031 05 00 00 | DETERMINATION OF CG POSITION | |||||||||||
| 031 05 01 00 | Methods | |||||||||||
| 031 05 01 01 | Arithmetic method | |||||||||||
| (01) | Calculate the CG position of an aircraft by using the formula: CG position = sum of moments / total mass. | X | X | X | X | X | ||||||
| 031 05 01 02 | Graphic method | |||||||||||
| (01) | Determine the CG position of an aircraft by using the loading graphs given in sample documents. | X | X | X | X | X | ||||||
| 031 05 01 03 | Index method | |||||||||||
| (01) | X | Explain the principle of the index method. | X | X | X | X | X | |||||
| (02) | Define the terms ‘index’ and ‘dry operating index’ (DOI), and calculate the DOI given the relevant formula and data. | X | X | X | X | X | ||||||
| (03) | Explain the advantage(s) of the index method. | X | X | X | X | X | ||||||
| 031 05 02 00 | Load and trim sheet | |||||||||||
| 031 05 02 01 | General considerations | |||||||||||
| (01) | X | Explain the principle and the purpose of load sheets. | X | X | ||||||||
| (02) | X | Explain the principle and the purpose of trim sheets. | X | |||||||||
| 031 05 02 02 | Load sheet/balance schedule and CG envelope for light aeroplanes and for helicopters | |||||||||||
| (01) | Add loading data and calculate masses in a sample load sheet/balance schedule. | X | X | X | X | X | ||||||
| (02) | Calculate moments and CG positions. | X | X | X | X | X | ||||||
| (03) | Check CG position at zero fuel mass and take-off mass to be within the CG envelope including lastminute changes, if applicable. | X | X | X | X | X | ||||||
| 031 05 02 03 | Load sheet for large aeroplanes | |||||||||||
| (01) | Complete a sample load sheet to determine the ‘allowed mass for take-off’, ‘allowed traffic load’ and ‘under load’. | X | ||||||||||
| (02) | Explain the purpose of each load sheet section. | X | ||||||||||
| (03) | Explain that the purpose of boxed maximum figures in load sheet sections is to cross-check the actual and limiting mass values. | X | ||||||||||
| (04) | Complete and cross-check a sample load sheet. | X | ||||||||||
| 031 05 02 04 | Trim sheet for large aeroplanes | |||||||||||
| (01) | Explain the purpose of the trim sheet and the methods to determine the CG position. | X | ||||||||||
| (02) | Check if the zero fuel mass CG or index is within the limits. | X | ||||||||||
| (03) | Determine the fuel index by using the ‘fuel index correction table’ and determine the CG position as % MAC. | X | ||||||||||
| (04) | Check that the take-off mass CG or index are within the limits. | X | ||||||||||
| (05) | Determine ‘stabiliser trim units’ for take-off. | X | ||||||||||
| (06) | Explain the difference between certified and operational CG limits. | X | ||||||||||
| (07) | Determine the zero fuel mass CG or index. | X | ||||||||||
| (08) | Explain the relationship between pitch control and CG position and the operational significance. | X | ||||||||||
| 031 05 02 05 | Intentionally left blank | |||||||||||
| 031 05 02 06 | Other methods to present load and trim information | |||||||||||
| (01) | X | Describe information from other methods of presenting load and balance information, e.g. aircraft communications addressing and reporting system (ACARS), electronic flight bags (EFBs), and the ‘less paper in the cockpit’ (LPC) software. | X | |||||||||
| 031 05 03 00 | Repositioning of CG | |||||||||||
| 031 05 03 01 | Repositioning of CG by shifting the load | |||||||||||
| (01) | Calculate the mass to be moved over a given distance, or to/from given compartments, to establish a defined CG position. | X | X | X | X | X | ||||||
| (02) | Calculate the distance to move a given mass to establish a defined CG position. | X | X | X | X | X | ||||||
| (03) | X | Describe the methods to check that cargo has been loaded in correct position in relation to the loading manifest, including identifying hazard of cargo loaded in reverse order (visual inspection of one or more unit load devices (ULDs). | X | X | ||||||||
| (04) | Determine whether CG remains within limits if cargo has been loaded in incorrect order or at incorrect location. | X | X | |||||||||
| 031 05 03 02 | Repositioning of CG by additional load or ballast or by load or ballast removal | |||||||||||
| (01) | Calculate the amount of additional load or ballast to be loaded at or removed from a given position or compartment to establish a defined CG position. | X | X | X | X | X | ||||||
| (02) | Calculate the loading position or compartment for a given amount of additional load or ballast to establish a defined CG position. | X | X | X | X | X | ||||||
| 031 06 00 00 | CARGO HANDLING | |||||||||||
| 031 06 01 00 | Types of cargo | |||||||||||
| 031 06 01 01 | Types of cargo (general aspects) | |||||||||||
| (01) | Describe the typical types of cargo, e.g. containerised cargo, palletised cargo, bulk cargo, and the advantages of containerised and palletised cargo. | X | X | X | X | X | ||||||
| 031 06 02 00 | Floor-area load and running-load limitations | |||||||||||
| 031 06 02 01 | Floor-area load and running-load limitations in cargo compartments | |||||||||||
| (01) | Calculate the required floor-contact area for a given load to avoid exceeding the maximum permissible floor load of a cargo compartment. | X | X | X | X | X | ||||||
| (02) | Calculate the maximum mass of a container with given floor-contact area to avoid exceeding the maximum permissible floor load of a cargo compartment. | X | X | X | X | X | ||||||
| (03) | Calculate the linear load distribution of a container to avoid exceeding the maximum permissible running load. | X | X | X | X | X | ||||||
| 031 06 03 00 | Securement of load | |||||||||||
| 031 06 03 01 | Securement of load (reasons and methods) | |||||||||||
| (01) | Explain the reasons to restrain or secure cargo and baggage. | X | X | X | X | X | ||||||
| (02) | Describe the basic methods to restrain or secure loads (unit load devices secured by latches on roller tracks or to tie down points by straps; bulk cargo restrained by restraining nets attached to attachment points and tie-down points). | X | X | X | X | X | ||||||
IR — Regulation (EU) No 1178/2011 · ED Decision 2020/018/R · Aircrew Easy Access Rules · EAR revision 25 Nov 2025