OK, you probably saw the subject line of this post and I’m lucky you’re even reading this far, right? Air traffic control? Really? Yes, really. As much as I love airframes and engines, ATC is a vital part of our modern air transportation system. A chronically underfunded and outdated part, but vital nonetheless.
This video was posted by Airbus, as an A320 was used in this test, but it is really bigger than any one company. Most people don’t realize it, but today’s air transportation system hasn’t changed much from what we had decades ago. It was designed around radar surveillance, simple aircraft transponders, ground-based radio beacons, fixed airways, and verbal instructions to pilots. All of that is outdated, we have the technology to do a much better job.
Satellite navigation provides global coverage with more accuracy than radar or radio beacons. An intelligent broadcast system called ADS-B (Automatic Dependent Surveillance – Broadcast) provides more accurate information to air traffic control (called ADS-B Out) than the old transponders, and receives on aircraft (ADS-B In) can provide automated separation and sequencing. Airlines already use datagram communications with their own control centers, but ATC is still using voice. Datagrams provide more information, clearly, without misunderstanding. Computerized systems can maintain flight paths and timing far more accurately than human pilots can.
Combine all of these and you get numerous benefits. Today airliners don’t fly from point A to point B. They fly specific air corridors from point to point, beacon to beacon. Basically ‘highways in the sky’. This concentrates aircraft into limited airspace, which creates capacity issues – especially when bad weather disrupts these routes. Exacerbating this, aircraft need to be kept separated both horizontally and vertically – and due to the inaccuracies in today’s system these distances are inefficiently large.
Updated systems would allow aircraft to fly more directly from point A to point B. This saves fuel by flying shorter distances, which is better for the environment and cuts airline expenses – fuel is often their biggest expense. This can help keep ticket prices down, good for you. And the more direct routing means shorter flights, also good for you. Furthermore, modern systems can fly direct approaches to landing from cruise. Instead of a ‘staggered letdown’ with the aircraft descends in steps, using power at each step to level off and remain there, they can remain at their more efficient cruise altitude longer and then make a smooth, continuous idle-power descent to landing.
That saves more fuel from operating higher, longer (jet engines are more efficient at higher altitudes), and from the idle descent. And it saves more time by operating at cruise speed longer and having a more direct approach. It also reduces nose around the airport as the aircraft stay higher longer, and descend at idle power – meaning little engine noise.
The list goes on and on, not the least of which is increased safety. But there’s a lot of work required to get there. Today’s ATC systems need to be overhauled, or just replaced, with these newer systems, and that takes years. In the US the FAA’s efforts in this area are called NextGen, in Europe it is SESAR (Single European Sky ATM Research). They’re very similar. Some of the technologies involved are already in limited use, such as ADS-B, and RNP (Required Navigational Performance) approaches to some airports. This video focuses on a flight test of I-4D (initial four-dimensional), which is basically what is also called RNP/RNAV (Area Navigation).
The fourth dimension is time. The aircraft is given routing information with 4D checkpoints – be at this point at this time – and the FMS (Flight Management System) maintains the aircraft’s speed and course with inhuman precision, hitting these targets within seconds. This precision allows the ATC to closely schedule departures and arrivals, providing more capacity at airports. It can also replace the old ILS (Instrument Landing System) while providing more accurate approaches and new approach paths – like curves – not possible with ILS.
While it may not seem like an exciting area I think it is actually one of the more interesting and exciting areas in aerospace when it comes to the potential global impact of these technologies. But first we need to get them properly funded and adopted. Even in the best case we’re looking at 2020-2025 for widespread use. Not only do all the ground systems need to be in place, all of the aircraft need to have the proper avionics to utilize the new systems.