It was more than a decade before SESAR that I first heard the term “free flight”, a new paradigm for separating aircraft that would replace concentrated decision making with a distributed one by giving the flight crew the responsibility for ensuring separation between their aircraft. This is the normal state of affairs for VFR flights or flights in uncontrolled airspace, but “free flight” is meant for the big league, IFR flights in what is to-day called controlled airspace. Free flight techniques were being looked into as advanced methods for increasing capacity. The abbreviation ASAS was born at about the same time and stood for Airborne Separation Assurance System, basically a more scientific sounding name for free flight.
The reaction of air traffic controllers and certain ATC experts was immediate, fierce and damning. It did not help that the idea of free flight originated from the airlines, with Lufthansa and American Airlines being its biggest proponents. The message from ATC was clear: over our dead bodies.
As a former air traffic controller myself, I could not really blame them. The idea of relinquishing control to the flight crew did feel strange after having spent half a lifetime keeping them apart… But the more we studied the idea, the more its simple beauty was revealed. Some controllers said free flight would never work, others fretted about ASAS eventually taking away their livelihood. Strangely enough, this latter group provided the first proof that free flight might in fact work. Why else would the experts closest to the fire think that they may be threatened by ASAS?
Luckily for the industry, in spite of all the noise careful steps were being taken to explore the possibilities of “free flight”. NASA, EUROCONTROL, the Dutch NLR all initiated projects that looked into this controversial subject. This was not surprising. Letting the flight crew do some of the separation tasks was the first serious paradigm change being proposed since the invention of ATC and its implications were huge. While the results of this fascinating research were coming in, the spin doctors were busy making free flight palatable to a worried industry. The name “free flight” was the first to go followed by the second A in ASAS changing from Assurance to Assistance. So ASAS was now Airborne Separation Assistance System… The overall concept was also broken up into more manageable pieces with names like airborne situational awareness, self-separation, in-trail procedures and so on.
The noise did diminish a little when the research results showed beyond a shadow of a doubt that “free flight” (or call it what you want) can be done safely and will provide benefits. It may not necessarily increase capacity as it was first thought but it does enable aircraft to fly trajectories much closer to their optimum if they are allowed to maneuver around each other without the constraints of a ground based separation assurance paradigm.
Not that the results were accepted or endorsed by everyone. Those who would have rather died than seen ASAS take off may have had second thoughts by this time about the wisdom of their standpoint but plenty of others remained who continued to fight a gallant, if pointless, rear-guard action.
I could not avoid remembering the above when the latest edition of Jane’s Airport Review hit my desk a few days ago and in it (page 32) an article about the “NATS and Nav Canada in-trail separation project that is expected to reduce fuel burn and free up schedules for aircraft over the North Atlantic.”
It is a very well written and balanced article that highlights clearly why these new separation modes bring benefits even when traffic is not under pressure from a lack of capacity over the North Atlantic. By not being prevented from climbing to a more advantageous level by another aircraft 8 minutes ahead of you, a lot of fuel and carbon emissions can be saved.
But the real punch-line of the article is this: “NATS and the air transport community already have their sights set on the ultimate prize – self-separation.”
We probably no longer need spin doctors to invent pseudo-names for a concept that will, in time, revolutionize how separation between aircraft is assured, first over the oceans and then also in busy continental airspace. It will not make controllers redundant but their tasks will change as will those of the pilots. It is called progress.
In 1866 William Ewart Gladstone, speaking on the Reform Bill, famously said: “You cannot fight against the future. Time is on our side.”
Indeed!
