I just added ADS-B Out to my airplane. I’ve been looking forward to this moment for a very long time—48 years to be exact.
It was 48 years ago that my very first aviation article was published. Its title was “The Role of Computers in Air Traffic Control.” I was 26 years old at the time, not long out of college, and starting a career in computer software at the dawn of the computer age. I’d only been a pilot for five years and an aircraft owner for two.
I timidly submitted the 3,000-word manuscript to Leighton Collins (1903-1995), the dean of general aviation journalists (and Richard Collins’ dad). Leighton founded his magazine Air Facts in 1938, the first GA magazine to focus primarily on safety. In the ‘50s and ‘60s, Leighton became a pioneer in using GA airplanes to fly IFR, something that was considered risky business at the time. In 1970, I was a newly-minted CFII and Skylane owner, and Leighton was my hero and Air Facts my bible.
Leighton loved my article, and published it in the May 1970 issue of Air Facts. I was thrilled. I was also hooked and went on to write more than 500 published aviation articles between then and now.
How big is the sky?
I’d been instrument-rated for about four years when I wrote that article, and had thought quite a bit about the differences between VFR and IFR flying:
A pilot flying VFR in clear weather is unlikely to see more than a few other aircraft on a typical flight; to him the sky seems to be a rather empty place. Yet to the pilot stuck in an IFR hold with an estimated-further-clearance time forty-five minutes away, the sky seems to be an order of magnitude more crowded. Why? Clearly there is no shortage of airspace; every VFR pilot knows that. The aircraft flying under IFR have the best equipment and the most proficient pilots aboard. Where does the congestion come from?
My conclusion was that the fundamental difference between VFR and IFR lies in who is separating aircraft. VFR pilots are responsible for their own separation, while IFR pilots rely on air traffic controllers to keep them separated from other traffic. Thus, I reasoned, the comparatively low capacity of the IFR system must be attributable to some failing on the part of controllers. Yet as someone who has spent many hours visiting ATC facilities and observing controllers at work while plugged in beside them, I can testify that these folks are amazingly sharp, skilled, and well-trained professionals who do their jobs exceptionally well.
So why can’t these hotshot controllers separate IFR aircraft nearly as efficiently as VFR pilots are able to separate themselves? My conclusion was that the very nature of the separation task is fundamentally different:
A pilot is concerned solely with the one aircraft that he’s flying, but a controller must keep track of several aircraft at once. Give a person several things to do at once—even simple things like head-patting and tummy-rubbing—and his performance in each task drops sharply. Keeping track of a high-speed airplane is considerably harder than either head-patting or tummy rubbing. Keeping track of a dozen such airplanes travelling in random directions at random altitudes is simply beyond the capabilities of any human.
Our IFR system is designed to simplify the controller’s job to the point that it is within the realm of human capability. It does this primarily by eliminating the amount of randomness the controller must deal with. It strings airplanes along a few well-defined airways/SIDs/STARs, confines them to a few standard altitudes, and sometimes slows them down to a few standard speeds. Doing these things makes the airplanes much easier for the controller to keep track of and keep separated, but it also wastes most of the available airspace and reduces the capacity of the system.
Do we really need ATC?
It seemed to me that the capacity of the IFR system could be vastly increased if we could just stop relying on controllers to separate airplanes and enable pilots to self-separate, much as they do when flying VFR. In 1970 when I wrote the article, we were right on the cusp of two major technological breakthroughs that I believed had the potential to make that possible.
One of them was the promise of accurate satellite navigation. The Naval Research Laboratory had launched its Timation satellites in 1967 and 1969, the first ones to contain accurate atomic clocks suitable for navigation. Meantime, the Air Force’s Space and Missile System Organization was testing its more advanced system (codenamed Project 621B) for aircraft positioning between 1968 and 1971. These were the progenitors of today’s GPS system—something I could see coming in 1970, although a seriously underestimated how long it would take to become operational. The first constellation of 10 “Block-I” GPS satellites wasn’t in orbit until 1985, and the system’s full operational capability wasn’t announced until 1995.
The second breakthrough was large-scale integration (LSI)—the creation of integrated circuits containing tens of thousands of transistors on a single silicon chip—and the emergence of the microprocessor. Microprocessors weren’t yet invented in 1970 when I wrote the article, but as a computer scientist (my day job at the time) I could see them coming, too. As it turned out, Intel introduced its 4004 microprocessor in 1971, its 8008 in 1972, and the 8080 (which really put microprocessors on the map) in 1974. This watershed development made it feasible to equip even small GA airplanes with serious computing power.
The ATC system of tomorrow
In my 1970 Air Facts article, I painted a picture of the kind of ATC system these new technologies—GPS and microcomputers—would make possible. I postulated a system in which all IFR aircraft and most VFR aircraft were equipped with a miniaturized GPS receiver that continually calculated the aircraft’s precise position and a transmitter that broadcast the aircraft’s coordinates once per second. A network of ground stations would receive these digital position reports, pass them to ATC, and rebroadcast them to all aircraft in the vicinity. A microcomputer aboard each aircraft would receive these digital position reports, compare their coordinates with the position of the host aircraft, evaluate which aircraft are potential threats, and display the position, altitude and track of those threat aircraft on a cockpit display.
Such a cockpit display would enable IFR pilots separate themselves from other aircraft, much as VFR pilots have always done. It would permit them to fly whatever random routes, altitudes and speeds they choose, giving them access to the same “big sky” that VFR pilots have always enjoyed.
I theorized that pilots are highly incentivized to self-separate and would do a much better job of it than what ground-based air traffic controllers can do. (Just imagine what driving your car would be like if you weren’t allowed to self-separate from other vehicles, and instead had to obtain clearances and follow instructions from some centralized traffic manager.)
What took so long?
When I re-read that 1970 article today, it’s truly eerie just how closely the “ATC system of the future” I postulated then resembles the FAA’s “Next Generation Air Transportation System” (NextGen) that the FAA started working on in 2007 and plans to have fully operational in 2025. Key elements of NextGen include GPS navigation and ADS-B—almost precisely as I envisioned them in 1970.
I was wildly overoptimistic in my prediction that such a system could be developed in as little as five years. If the FAA does succeed in getting NextGen fully operational by 2025, it will be the 55th anniversary of my Air Facts article.
NextGen also includes improved pilot/controller communication (both textual and VOIP) and various improvements designed to allow use of more airspace and random routes. Sadly, it stops well short of transferring responsibility for separating IFR aircraft from ATC to pilots as I proposed in 1970—although our aircraft will have the necessary equipment to do that if the FAA would just let us. Maybe that’ll have to wait another five decades until NextNextGen is deployed (and there’s an autonomous self-piloting octocopter in every garage).