Take-off for the 4D trajectory
The 4D trajectory concept requires that airspace users are able to agree directly with the air navigation service providers on the detailed trajectory for the flight in four dimensions (three spatial dimensions, plus time). Before and throughout the flight, the aircraft’s trajectory information containing current and predicted positions will be exchanged with all concerned Air Navigation Service Providers, and possible time constraints will be agreed at specific waypoints in the vicinity of congested areas. Air Traffic Management (ATM) operations will be automated to a greater extent than they are today, with data exchanged directly between the airborne and ground systems. More precise information about the current and future positions of every aircraft at any given moment will improve safety as well as flight predictability. This system will allow a significantly more efficient resource planning which will in turn enable airports and the European sky.to cater for more flights than they can today.
"Initial 4D" is the first step towards "full 4D" operations which are planned in the SESAR target concept. Initial 4D operations work by defining a time constraint for each aircraft at certain crossroads in the sky, in order to sequence the traffic. Typical crossroads for these time constraints could be in the vicinity of congested airports. Initial 4D requires only a light avionics upgrade and could be in operation from 2015 on all current generation aircraft. The objective of Project 9.1 is to progress on the airborne part of the technical definition and the system design of the initial 4D function, so that a cost effective and robust industrial development of aircraft systems can be launched. The project is led by Airbus with support from SESAR members, Thales, Honeywell, Alenia Aeronautica and Eurocontrol.
Scope & approach
The first part of the project deals with the functional definition of the airborne segment and will provide information on the capabilities to be implemented onboard, independently of the aircraft architecture. The second part of the activities addresses the Verification and Validation (V&V) of the airborne system. For that purpose, airborne system mock-ups and prototypes will be built for mainline and regional aircraft. Initial V&V will be conducted using mock-ups in a simulated aircraft environment, possibly coupled with a simulated ATM environment. Final V&V will be carried out using prototypes fitted in a flight test aircraft (real architecture and real interfaces) flying in real ATM environments provided in the framework of SESAR Work Packages (WP) 4 – En-Route Operations and 5 – Terminal Operations.
As the trajectory of each aircraft is defined in detail in advance, with local conditions and other airspace users taken into account, the overall predictability and efficiency of the air traffic will be enhanced. The 4D trajectory will also improve safety as it decreases the work load for pilots and air traffic controllers who will have more time for monitoring safety aspects. Knowing the exact trajectory and timing for each flight means that aircraft can optimise their routing and fuel usage which will lower costs but also reduce the CO2 emissions per flight. In addition, 4D trajectories can take into account local needs in terms of noise and other pollution and avoid unnecessary over-flights.