Specific jet aircraft

The category transport/plane/specific/jet contains data on the fuel consumption and CO₂ emissions of jet-engine aircraft, sourced from the EMEP/CORINAIR Emission Inventory Guidebook (2007). The CORINAIR datasheet and documentation specifies fuel consumption data for 19 representative jet-engine aircraft types and also provides recommendations for the appropriate use of this data in representing other, non-documented aircraft. Following these guidelines, AMEE contains data for calculating CO₂ emissions for a total of 117 specific jet-engine aircraft.

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The methodology

CO₂ emissions are calculated by considering the fuel consumed during the discrete in-flight phases of "cruising" and the "landing-take off (LTO) cycle". Cruise emissions are defined as those occurring above an altitude of 1000 m. The fuel consumption and CO₂ emissions associated with cruising are related to distance flown, and are therefore calculated on the basis of the flight distance specified. CORINAIR provides fuel consumption data for each aircraft type at discrete distance intervals. Following CORINAIR methodology, Discover therefore interpolates between appropriate distance intervals in order to calculate the specific fuel consumption for a given distance. For example, the fuel consumed during the cruise phase of a 486 km flight would be calculated by interpolating between the fuel consumption values provided for 250 km and 500 km, according to:

cruise fuel_{486 km} = fuel_{250 km} + ((fuel_{500 km} - fuel_{250 km})*(486-250)/(500-250))

Fuel consumption associated with the landing-take off cycle is not related to distance flown, and therefore remains constant for a particular aircraft type. LTO fuel consumption does, however, vary between the individual phases of the LTO cycle (taxiing, take off, climb out, approach). Fuel consumption within each of these phases reflects typical thrust settings required and the typical duration for which each lasts. Default durations for these phases are set within this category as:

• take off - 0.7 minutes
• climb out - 2.2 minutes
• approach - 4 minutes
• taxiing - 26 minutes

Users can override one or more of these default values if necessary. Total LTO associated fuel consumption is then evaluated as the sum of each individual phase:

LTO fuel = fuel_{take off} + fuel_{climb out} + fuel_approach + fuel_taxiing

Total CO₂ emissions are calculated by combining the fuel consumption associated with the LTO and cruising phases. This total (LTO + cruise) fuel consumption (kg) is then multiplied by a CO₂ emissions factor of 3.15 (kg CO₂ per kg) - in order to convert into a corresponding quantity of CO₂ emitted - and by the quantity of flights:

CO₂ emissions = (LTO fuel + cruise fuel) * 3.15 * number of journeys

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Using this methodology

Choosing a specific activity type

To use this category, select the aircraft type via the aircraft drill-down.

Activity data required

Users can specify the flight distance by setting one of three profile item value groups:

• distance (directly sets the distance flown)
• lat1, long1, lat2, long2 (latitude and longitude values for arrival and departure locations)
• IATACode1, IATACode 2 (IATA codes for arrival and departure airports)

If latitude/longitude or IATA code profile item values are specified, Discover calculates the flight distance as the great circle distance between the two locations, inflating by 9% to account for congestion and indirect routing. If no distance profile item value is set, Discover will return a zero value. Similarly, if a distance is specified which is beyond the range of a given aircraft type, Discover will return a zero value and a notification comment.

If appropriate, specific landing-take off phase durations can be set by using the following profile item values

• takeOffDuration
• climbOutDuration
• approachDuration
• taxiDuration

If left unspecified, these profile item values will reflect default values (see above).

The number of flights under consideration can also be set using the journeys profile item value (defaulting to 1).

Users can elect to incorporate the RFI by setting the useRFI profile item value to "true", and entering a value for RFI in the radiativeForcingIndex profile item value. If no value is entered in the radiativeForcingIndex profile item value, a default factor of 1.9 will be applied (to cruise emissions only). For more information on RFI, see the here.

Calculation and result

The returned quantities for this methodology represent CO₂, emissions associated with the aircraft and distance specified. The following amounts are returned:

• cruiseCO2: CO₂ emissions associated with cruising at altitude
• takeOffCO2: CO₂ emissions associated with the take off phase
• climbOutCO2: CO₂ emissions associated with the climb out phase
• approachCO2: CO₂ emissions associated with the approach phase
• taxiCO2: CO₂ emissions associated with taxiing
• totalCO2: All CO₂ emissions
• greatCircleDistance: calculated great circle distance in kms