Excess CO2 emissions due to network flight inefficiency

When comparing the gate-to-gate actual trajectories of all European flights in 2017 against their unimpeded trajectories12, there is an additional 5.8% gate-to-gate CO2 emissions at European level. Figure 4.1 illustrates the average excess CO2 emissions per flight broken down into the different flight phases. The average excess CO2 emissions has remained stable over the last 6 years, even though traffic has increased.

It should be noted, however, that there are a number of reasons why the actual trajectory flown can vary from the unimpeded trajectory, and therefore 100% efficiency is not achievable (e.g. due to adverse weather, avoidance of ‘Danger Areas’, need to maintain minimum separation, lack of capacity leading to diversions, avoidance of relatively high route charges). Some inefficiency is unrecoverable due to necessary operational constraints and interdependencies [59].

The 2018 European ATM Master Plan [60] ambition is to continue reducing the additional gate-to-gate flight time and additional gate-to-gate CO2 emissions to reach 3.2% and 2.3% respectively by 2035.


12 Unimpeded trajectories are characterised by: zero additional taxi-out time, no level-off during climb (full fuel CCO), no sub-optimal cruise level, en route actual distance equal to great circle distance, no level-off during descent (full fuel CDO), no additional time in the Arrival Sequencing and Metering Area (ASMA), zero additional taxi-in time.