"Free flight is a misunderstood concept," says Lars Lindberg, president of AvTech aviation technology consultants in Sweden. "Some people think it is a licence to do aerobatics. It isn't. It is more about collaborative air traffic management [ATM] than allowing aircraft to fly wherever they want to go."
The misconception stems from a belief that the realised concept of free flight will mean aircraft deciding for themselves the most direct route possible. Although that is true, says Lindberg, it misses the point. "The biggest problem we have in Europe is capacity and to improve it we need to improve the ATM system. That means flying as efficiently as possible without burning the extra fuel as aircraft sit in holding patterns."
That, he says, is what is behind the drive for free flight. But turning what are various definitions and research projects into a single free flight programme with specific goals is at the core of the European approach. In addition, and unlike the North American goals which are to use free flight as a method of calculating the most cost-efficient route, Europeans see it as a long-term solution to its ATM capacity bottleneck.
Yet even as the first practical demonstrations are being carried out, there is no definitive outline as to what free flight is. Eurocontrol's ATM 2000+ strategy defines it as where "aircraft will fly and find efficient user preferred trajectories and separate themselves from other aircraft".
Most argue that a final definition beyond this fairly broad description is unnecessary for the moment. Moreover, the consensus appears that whatever form of free flight is adopted, it will happen in stages.
Second, it will not be completely adopted for about 15 years or so and third, when operating it will probably look radically different from what is being demonstrated today.
The first stage is already partially in operation in the South Pacific where aircraft are fitted with FANS 1A communications, navigation and surveillance/air traffic management (CNS/ATM) technology. The second stage, beginning in 2004, will see more use of satellite navigation equipment, new communication technology used with digital datalink communications and the beginning of free flight Collaborative Decision Making in areas of dense traffic, without the need for formal transfer of responsibilities to the aircraft's crew. This will use International Civil Aviation Organisation CNS/ATM 1 standards. The final stage, tentatively set for around 2008, could see full free-flight capabilities switched to aircraft with enhanced communication and surveillance technology.
Peter Potocki, Airbus director for air traffic systems, says that when the developers talk of the beginning of the final stages of free flight where there is self separation in fairly empty skies, there still needs to be time for standards to be adopted and then a period of around seven years for airlines to equip their aircraft. "Any quicker than that and you are forcing a lot of people to move very quickly and taking an industrial/regulatory process out of sequence."
Off the drawing board
For now, the excitement among the developers is that industry is taking the second stage of the free flight concept off the drawing board and looking at ways of putting it into practice. Eric Hoffman , free airspace manager at Eurocontrol's research and development centre, says it was an important step forward for the free flight projects to have Airbus and Boeing take an active role because it shows that everyone, including the airlines, are serious about getting the project going. One job now is to convince carriers to have new aircraft fitted with the "hooks" of advanced free flight technology and to make sure that the experimental stages can be successfully brought through into implementation. There are signs that this is happening. Work is being done at Airbus for example which will examine how to "mass-produce" the technology and install it safely and cost-effectively on board new aircraft.
In this sense, it means the Europeans could have caught up and passed the USA in terms of developing the infrastructure needed to allow free flight to be introduced over the next 15 years. Airbus is at the forefront of this movement. So is the European Commission (EC) and Eurocontrol, motivated by the fact that Europe needs free flight more than the USA does.
Eurocontrol's Hoffman agrees with this and adds that the transfer of separation responsibilities to aircraft in the longer term is designed specifically to improve the capacity in the core European airspace area. "The second step is to move the separation into low density airspace then gradually introduce it to higher density airspace."
This does not mean that Europe is working in competition with the USA. The opposite is true - many of the myriad of acronymed projects which make up free flight are collaborative. More important, however, is that the will in Europe is stronger to get free flight started.
The EC as a driving force has proved important. Through the research and development directorate, it has begun defining the operational concept for future air traffic management in Europe through two projects, TORCH and the Validation Master Plan. These could be the basis on which all free flight projects work towards one goal and one timetable.
"This means that more and more research and development is moving away from national authorities and towards the European Commission," says Lindberg. "I think this is the right approach because these projects are too big for one country to embark on."
Others agree. "The European Com-mission has a significant input in terms of initiating the free flight projects," says Eurocontrol's Hoffman. He says this is especially true of automatic dependent surveillance broadcast system (ADS-B), the second stage technology.
With this sort of momentum building, free flight in Europe stands a chance of being realised within 15 years. The technology is almost there, says AvTech's Lindberg, but the biggest problem is changing the procedures and mentality of those affected. This includes the airlines, which will have to pay for the technology, as well as pilots, airports and air traffic controllers.
Savings potential
Convincing the airlines that the cost of installing free flight will be less than the losses they incur through delays over Europe could prove to be a hard task for developers. Airbus' Potocki says he believes the savings will be "substantial" and points to the fact that most new customers - 95% of all Airbus' orders for the last three years, or around 1,500 aircraft - have the technology installed when the aircraft are being built.
"But we have to prove from day one that all the equipment works and that all the studies show that the system is safe," adds Hoffman. "However, now that the airlines want more capacity and general aviation wants more flexibility and safety, everyone is more open than they used to be."
Nevertheless, proving to airlines, and especially to their financial officers, that it makes sense to invest in technology today to achieve savings in five years' time will be tricky. The system must be proven to work without any lingering doubts.
In February, many of these doubts were addressed when the various developers and potential beneficiaries of free flight met in Sweden and demonstrated the new system. It used what is the now fairly well tested ADS-B technology, where aircraft communicate with each other as well as the ATC centre on the ground. But this was the most advanced version of ADS-B yet and enabled the aircraft to automatically detect and resolve future possible collisions while airborne.
The new system has yet another acronym, the network update programme (NUP), and is also capable of detecting possible conflicts on the ground at the airport using a Swedish-developed global navigation satellite system (GNSS). One of the critical new elements in this updated ADS-B system is that an aircraft sends directly to other aircraft what its intentions are in terms of route.
Predicting conflicts
This lays the foundations for computers on board each aircraft to calculate where possible conflicts could occur. As an aircraft is on final approach, the ADS-B technology is able to detect the encroachment of an airport vehicle (which also has to be fitted with a transponder) on to the runway and can immediately begin a landing abort manoeuvre. Clearly, therefore, this adds an additional safety feature which could prevent another disaster such as the incident at Los Rondeos in Tenerife in 1977 when two Boeing 747s - one taking off, the other taxiing - collided in dense fog, killing 586 people.
The Swedish demonstration showed what free flight could look like. It would ultimately mean flying in an environment where aircraft fly the optimum trajectory with minimum disturbance from controllers as well as having the ability to detect possible conflicts between each other. Importantly, these detentions are made over a longer distance so adjustments in the flight paths are made a early.
"Instead of flying up to the conflict and making an abrupt turn," says AvTech's Lindberg, "the system means pilots can detect if there is a conflict ahead and perform the correct manoeuvre from a long way out."
Free flight will not spell an end to ground ATC centres, but it will mean a change of procedure. As much of the "control" element will be removed, there will probably be a shift towards flow management, particularly at airports.
"Even in free flight there will always be a ground segment," says Hoffman. "The role will be completely different as it won't be a classic radar control and more of a flow management role, making sure the local density does not exceed the capabilities of the equipment on board the aircraft so that it can solve conflicts by itself. There will also be some kind of safety function if an aircraft has a system failure and the ground back-up needs to be there."
Trial goals
But the real goal of the Swedish trial was to show that the technology worked. "This sort of demo is very important in regards to selling a concept," says Potocki. "There is still a lot to be done to show that you can get the equipment on the aircraft with the sufficient safety measurements but we also need to convince airlines chief financial officers that it is worthwhile investing in the technology for the business side of operations."
Adding up the figures for airline managers is a job that can and probably will be done successfully. "In their hearts and minds, airlines are convinced free flight will work," adds Potocki. But changing the minds of the air traffic system (ATS) providers could be a different matter.
"The biggest problem we have today is not with the technology," says AvTech's Lindberg, "it is changing the procedures and mentality of those who will have to use it. It is after all, a paradigm shift in how we do our business."
This means that many of the new possibilities free flight will bring have to be reflected in changes in the regulations that govern ATM. The reduced vertical separation minima (RVSM) over the North Atlantic, for example, enables aircraft to fly with a 330m vertical separation. Horizontally, however, aircraft have to be separated by a "distance" of about 10min, or 95km (50nm). With free flight, these horizontal separations can be reduced dramatically, producing more capacity.
Eurocontrol says there remains a lot of work to be done to satisfy the regulators what a safe reduced horizontal minima should be and that means more testing - it cannot be done by experimentation alone.
These are the future possibilities for free flight. Ultimately it will give Europe the extra capacity it needs and the USA will get, perhaps in 10 to 15 years' time, the optimal routes for which airlines are looking.
"The pressure on the organisations to push the change through is intense," concludes Lindberg. "But there is more and more a sense of collaboration between the airlines, the regulatory authorities and the ATS providers to get this through. The biggest risk therefore is a political one.
Source: Airline Business
