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Flights
Fuel Burn
Flights departing from Europe
(entire flight distance)
Figure 86: Fuel burn by duration of flight (2009)
7.2.22 Figure 86 shows that 23% of flights departing from Europe are shorter than 1 hour, and
that they account for 4% of total aviation fuel burn. Therefore, 96% of aviation emissions
originate from flights longer than one hour, for which alternative modes of transport are
very limited in practice.
7.2.23 Flights shorter than 1 hour burn a small portion of aviation fuel (4%). Of this, a relatively
small proportion could be saved by substitution to rail transport with the development of
the European high speed rail (HSR) network [Ref. 29]. The potential for reducing
aviation emissions by substitution to rail transport is therefore very limited.
29 Only departing flights are considered to avoid double-counting of flights within Europe and to allow global
consolidation of such statistics. Similar statistics would be obtained for arrival flights. Over-flights are nearly
negligible (~0.5% of flights).
11 Mt
Outside
European
Airspace
107 Mt
CO2
Within
European
Union
122 Mt
CO2
Coverage EC - ETS (229 Mt)
Pan-European
airspace
(133 Mt)
EUROCONTROL
PRR 2009 76 Chapter 7: Environment
IMPROVING AVIATION FUEL EFFICIENCY
7.2.24 It is acknowledged that the aviation industry has a responsibility to reduce its impact on
global climate and that there is scope to further improve aviation efficiency in view of the
environmental benefits to society and economic benefits to airspace users.
7.2.25 Figure 87 shows a conceptual framework for the evaluation of CO2 emissions efficiency
of aviation. The overall performance is the product of four factors: net carbon content of
fuel
CO2 emissions (kg)
Actual fuel
burn (kg)
Fuel burn (kg)
(on user preferred trajectory)
Available tonne
kilometre (ATK)
Revenue tonne
kilometre (RTK)
Aircraft fuel
efficiency
ANS fuel
efficiency
Net carbon
content
Load factor
Aviation
Airlines/ CO2 efficiency
Manufacturers
ANS
Alternative
fuels
Horizontal en-route flight path
Taxi phase
Vertical en-route profile
Airborne terminal phase
Figure 87: Framework for the evaluation of industry driven fuel efficiency
improvements
7.2.26 In this framework, the overall aviation CO2 emissions efficiency is measured in kilograms
of CO2 per Revenue Tonne Kilometre (RTK), or similar measure of commercial aviation
output. This top level indicator can be broken down in four parts, which correspond to
different accountabilities and performance improvement options.
The first part is net carbon content of fuel, defined as the ratio of net kilogram of CO2
per kilogram of fuel. For kerosene, this ratio is 3.15.
7.2.27 The net carbon content can be significantly reduced with bio-fuels, produced from biomaterials
which absorb carbon from the atmosphere before it is emitted back in the
atmosphere. This ratio could even be reduced to zero if hydrogen can be used as aviation
fuel and produced carbon-free.
7.2.28 Alternative fuels are therefore a potentially powerful way to decouple aviation emissions
from air traffic, but much research, development, investment and time are still needed
before any significant deployment.
The second part is ANS fuel efficiency, defined as the ratio of fuel burn on userpreferred
trajectory and actual fuel burn. Performance in this part is under ANS
control. The potential for improvement is developed in section 7.3.
7.2.29 The evaluation of the ANS contribution towards reducing the aviation related impact on
climate in the following sections is closely related to operational performance and hence
fuel efficiency as this is an area where ANS has an impact. There is substantial
consistency between reducing GHG emissions and airspace user requirements to
minimise fuel burn.
The third part is Aircraft fuel efficiency, defined as fuel burn on user preferred
trajectory per Available Tonne-Kilometre (ATK) or alternative measure of air
transport capacity.
PRR 2009 77 Chapter 7: Environment
7.2.30 Aircraft fuel efficiency is under airlines’ and manufacturers’ influence. It can be
improved by fleet renewal with more efficient aircraft, advances in airframe and engine
technology, and optimised use of aircraft (speed, stage length, etc).
7.2.31 Over the past years, there have been significant improvements in aircraft technology and
operational efficiency (improved engines, higher load factors, larger aircraft size)
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