The theory behind optimal trajectories in a perfect world is well known but the challenge is to integrate these trajectories in an operational environment, where there are other aircraft in the vicinity, perhaps bad weather and even the need to arrive on time. Here things become more complex and very often aircraft do not fly as efficiently as can be theoretically expected to.
The University of Malta, QuAero Ltd and Malta Air Traffic Services, funded by the Malta Council for Science and Technology under its R&I Programme, have been addressing this problem by focussing on specific phases of flight that can offer significant opportunity for a reduction of emissions. Currently, the climb and descent phases offer the greatest opportunity for environmental gains, but these phases invariably occur relatively close to airports (within 250 km). These zones tend to be very busy, as aircraft approach airfields and others fly out of them.
This poses constraints on air traffic control as they focus on keeping aircraft safely distant from each other. As a result, aircraft during climb and descent are stringently directed and very often does this not allow aircraft to fly as efficiently as they otherwise could when there is no traffic around them. Around Malta alone, it is estimated that around 1,200 tons of carbon dioxide emissions could be avoided every year if aircraft could be allowed to fly more efficiently as they come in to land and depart from the country’s international airport.
The consortium developed, under the Clean Flight 2 project, a software tool that optimises flight trajectories for air traffic controllers so that they can plan and allow aircraft to climb and descend more efficiently whilst ensuring they maintain safe separation from other aircraft at all times.
Building on this experience, the Clean Flight 2 consortium set out to develop the software tool and a new concept of operations (referred to as CONOPS) that allows air traffic controllers to carry out the optimisation calculations whilst coordinating with pilots, thus ensuring the aircraft and airline needs are met. The CONOPS and software tool are targeted to operate in airfields that handle up to about 15 to 20 flights per hour and possibly even more, depending on the complexity of the airfield and its approaches. The consortium consider that this is where the best gains in terms of reduction of emissions can practically be met with current state-of-the-art technology.
The software tool and CONOPS developed by the three organisations in the consortium have been tested in a simulation environment using Simliner’s facilities in Malta, which include a A320 Full Flight simulator. Air traffic controllers were set up in a simulated air traffic control room with all the necessary equipment to allow them to provide the service they normally offer in real flight operations. Professional airline pilots were also used to fly the simulator.
The controllers participating in the trials found the software tool useful and of value, and the concept of operations can be readily integrated into their current procedures. This provided the consortium with confidence to continue refining the technology with the aim of introducing it into operation, thus contributing to the reduction of carbon emissions into the environment.
Project Clean flight 2 was financed by the Malta Council for Science & Technology, for and on behalf of the Foundation for Science and Technology, through the FUSION: R&I Technology Development Programme.