4D Contract Guidance and Control

The small/medium size focused research project 4DCo-GC (4D Contract Guidance and Control) relates to the activity 7.1.1 "Pioneering the air transport of the future" of the Work Programme 2010 Theme 7 "Transport (including aeronautics)".

The 4DCo-GC project aims at exploring the concept of "4D Contract guidance and control of the aircraft" as a step change in air transport operations by providing a more radical and environmentally efficient solution for the management of the airspace. The above mentioned object can be represented either in a form of a stationary “tube” in a 4-dimentional space-time or as a 3-dimentional volume in motion. Each aircraft is supplied with its own contract and its movement is allowable only inside this construction.

The 4DCo-GC brings together the expertise of 13 European and associated partners coming from 7 countries, for a total budget of 5.5 M€ and a total requested funding of 3.9 M€.

This 36 months duration programme of work is built on the results and orientations drafted by several past EU programmes and projects. Regarding the short/middle-term expected evolutions of the European air transport system (ATS), 4DCo-GC is fully aligned with the orientation of SESAR.

Main results expected out of 4DCo-GC project are technological components (software / hardware / architectures) and recommendations for future 4D trajectories (4DT) guidance and control systems.

With the use of the approach mentioned above following goals can be achieved:

Harmonious airspace usage (with the help of nonintersecting contracts)

• ATM automation (excluding air traffic controllers immediate participation)
• Increasing predictability of air traffic
• Minimizing delays at the airports

ATM participants and their functions:

1. Central ATM service department – issues contracts to immediate users of air space
2. Aircraft (AC) supplied with on-board navigational systems – fly according to the gained contracts

Thus, the offered concept leans on two absolutely different areas of research: formation of effective contracts (from the point of view of profitability, safety and efficiency) and an effective management of air traffic according to the issued contracts (an on-board task).

As the contract considerably defines (through some restrictions) aircraft movement, at its formation a number of parameters and factors has to be considered: aircraft characteristics, weather conditions, atmosphere parameters etc. Simultaneously the above mentioned contract has to consider air space user’s preferences and restrictions as well. This particular task is poorly formalizable and sometimes is extremely hard to resolve.

Additional complexity is made by a coordination needed between ATM and AC. During the flight there can occur a situation when an existing contract is needed to be corrected during the flight. This kind of situation can occur owing to change of a weather situation, intentions of the operator or other unforeseen circumstances. In such cases two opportunities are provided. First of all, AC can send a request to the central ATM service department to change the existing contract. Then, AC itself has the opportunity to generate the short-term self-assigned contract on the basis of the previous contract, in case both current situation in air traffic and further intentions of aircraft in hand are clear.

In the on-board part of the system a module for short-term forecasting of a trajectory of the aircraft for situations of possible violation identification of the contract is provided as well. In case the situation of such kind is encountered inquiry adjustment procedure or (if AC fails to connect to ATM department) generation of the short-term contract on-board is initiated.

Main subsystems of AC:

• FMS
• Autopilot and autothrottle
• Module of contract violation forecasting
• Module of short-term contract generation

ATM subsystems:

• Contract’s planning in an airspace
• Contract’s planning on an airport surface
• Coordination of arrivals/departures (air and surface contracts joining)

Monitor Soft participation in this project was mainly concentrated in two aspects:

• General concept development and refinement
• Development airport ground movement planner model capable of working with 4D contracts

The latter one was needed to extend the concept used to the airport and thus implement gate-to-gate approach in ATM. With help of it one managed to show that 4D contracts can be used in realistic ATM environment successfully. 

Thus, the presented concept opens wide prospects for air traffic optimization, but careful research of its applicability is demanded. Experiment of participation in this projects have shown high potential of this approach.