It is nearly two decades ago that the idea of Free Flight first surfaced in discussions about the future of air traffic management. To put it simply, free flight means an environment in which air traffic control transfers responsibility for separation to the pilots. It may sound outlandish but simulation after simulation has shown that it not only safe and works but that it also brings previously unheard of efficiency to operations, particularly if combined with trajectory based operations.
Predictably the reaction of the ATC unions was hostile. They saw in this a backdoor attack by the airlines on their very profession and not the paradigm change the concept of free flight actually is. Luckily, research institutes and the more enlightened controller population recognized the potential of the new approach and work continued on exploring the details and possible pitfalls.
The very name free flight gave rise to heated debates and new designations were invented on an almost weekly basis. ASAS was the first version, which was supposed to mean Airborne Separation Assurance System. Controllers protested… so it was changed to Airborne Separation Assistance System…
In the course of ASAS work, several modes of operation were defined, each relating to specific separation assurance activities by the flight crew. It was felt, correctly, that taking smaller, incremental steps towards all-out free flight would be more realistic than aiming for the top prize immediately.
There was a huge fight during the SESAR definition phase whether or not the free flight concept should be included in the concept of operation. At one point a young guy from the French ATC organization went so far in a meeting as actually put up his hand and then shout at me: Steve, what you are saying is completely stupid. His boss later apologized and poor chap was removed from the team…
Anyway, ASAS was included in the SESAR Conops and now Airbus has come with a trial to have three Air France shuttle flights perform their approach into Toulouse under the guidance of a fully automated separation assurance system enabling them to maintain in-trail separation designed to maximize approach efficiency and increase capacity.
Previously considered mainly the domain of en-route operations, in-trail separation assurance for approach is a bold, novel step that can potentially revolutionize TMA operations.
In SESAR parlance, the system is dubbed ASPA which stands for ASAS Spacing and is meant to deliver consistent runway throughput via delegating certain separation tasks to the cockpit. The separation tasks are then carried out by the automation built into the aircraft.
The current trials are meant to show the technical and operational feasibility of the idea. In 2013 further tests will be conducted, probably in Rome. Obviously, the test of the pudding will come when the system is finally called upon to handle traffic at densities and complexity typical of a modern TMA and airport environment.
All current information seems to point in one direction: it will work.
If you are interested in some of the ground-breaking research work behind free-flight, go here.
To see an NLR demo of ho and airborne separation assurance system can resolve a “nightmare” conflict situation by small heading adjustments and no level changes, click here. As they say, do not try this in your control centre… yet.