In order to divide the environmental burden from air traffic including passengers and cargo during a specific flight there is a need to allocate emissions in a relevant way. In principle the preferred methodology should be based on the delimiting factor for a specific mode of transport i.e. defining the total environmental performance. In air transport weight is an essential and delimiting factor defining total environmental performance. Hence the basis for allocation should be weight.

The weights used in the formula above are the total actual physical weight of everything loaded onto the plane. The weight of containers, pallets and other cargo handling and securing devices must be included in the calculation.

Volumetric weight is used in air cargo transport. If the volumetric (or dimensional) weight is used for allocation, care must be taken not to use this number in the emission calculation outlined above. The allocation is in this case done using which ever the highest: the actual physical weight or the calculated volumetric weight. The industry conversion factor for air freight is 167 kg/m3 which may vary somewhat between companies. In general the actual transported weight is the chargeable weight. Additional there are extra charges for special handlings (live goods, valuable goods).

There are 2 different way of defining the weight of passengers for a given flight:

• A default weight for all pass of 87 kg including hand luggage. The average checked in luggage varies from 10-15 kg / passenger depending on market. The average is 100 kg / passenger. Lufthansa group calculates with 98kg per person on continental flights and 102kg on intercontinental flights, including the weight of the passenger as well as hand luggage and luggage.
• Individual male, female and child weights. This method is more typical in the charter market where the number of female and children typically is relatively higher than ordinary scheduled flights. It may lead to slightly lower passenger loads.

A principle discussion also revolves around total (full) or marginal (incremental) allocation of weight. In a passenger flight where one extra kilo of cargo shipment is added as belly freight will not affect the fuel consumption and the marginal emission for this shipment could be considered as neglect able. Reverse, one could argue that a specific air transport service is based on cargo flows and additional passenger’s environmental impact is only marginal i.e. neglect able. In the long run market forces should adapt to the basis of operation by operating aircrafts according to demand i.e. the long term most correct allocation should be total weight allocation.

We recommend a total allocation based on the mass weight of passengers and cargo. The overall mass is constituted by the mass of payload (passengers, luggage included and cargo, pallets and containers included) to which is added the mass of the specific equipments (equipped mass) necessary for the transportation.

The Equipped passenger mass amounts to the mass of seats, racks, galleys, food trolleys, food, to which cabin staff is added.

The equipped cargo mass corresponds to mass of all the equipment in the cargo bulks used for the transportation of cargo.

The aircraft’s structure, the weight of the flight crew and the cockpit equipment are not taken into account in the equipped masses, as they are necessary in order to transport both passengers and the cargo load, hence divides equally. The two equipped mass and freight and passenger weights are calculated in order to divide energy used and emissions based on respective total weight