Pilotage

Being more interested in the mechanical parts of aviation than in avionics, only once in a while does a black box capture my imagination. First was VHF communication/omnirange navigation (the nav/com), which was a leap above scratchy, low-frequency talk and the four-course range that I studied as a teen. Next came distance measuring equipment, which — added to VOR — gave you position and groundspeed at a glance. It came alongside airborne weather radar, providing great aid and comfort in the convective season. By 1970, the transponder (along with extensive air traffic control radar deployment) had made the magic words "radar contact" the norm, eliminating most of the whiz-wheeling drudgery of position reporting on IFR flights. All of the above — when I had use of it — made my flying easier, safer, and more fun.

Loran sneaked up on me. We had it in our DC-7Cs in the 1960s. A 200-pound console stashed in the navigator's station, it produced dial readouts that had to be plotted on huge dedicated charts to achieve a position fix, and subsequent plots were needed for groundspeed and drift. It was strictly an adjunct to celestial navigation and was used only on overwater flights. Flying domestic trips, I paid it little mind.

Of course, electronic miniaturization, along with enormous progress in computer hard- and software, have, over the past 20 years, transformed the loran turkey into the loran eagle. The latest loran receivers, with their encyclopedic, easily accessible, menu-driven databases, are fine tools for VFR and some IFR work, and they are very reasonably priced.

So why don't I have one?

Well, while signal coverage in the United States in now complete, it is — on a global scale — quite spotty and likely to remain so. Loran use would be limited should I ever actually make the international flights that I plan from time to time. And while I'll admit to a less than perfect sense of direction (I still get lost in courtesy cars), for the past 25 years there has not been a time while flying when I haven't known my position and which way to head. Also, my mostly VFR flights are (when airspace restrictions permit) made direct, by dead reckoning and pilotage, skills that I enjoy maintaining.

Loran has missed me. I'll go for the big, spoon-fed database but opt for a superior sensor:

The Global Positioning System is a Pentagon product designed to guide troops and ordinance with pinpoint, three-dimensional accuracy, anywhere on earth, at any time, in any weather. As the last of the system goes into orbit in the next few months, we're only beginning to glimpse the implications of this powerful system.

GPS accuracy varies, due mostly to its U.S. Air Force operators sometimes purposely degrading the signal for civilians, but even with the sullied signal, you can find your way over thousands of miles to within 300 feet of a selected spot in any weather.

To serve a terminal area, an inexpensive ground component called "Differential GPS," which is essentially a broadcasting benchmark, may be added to the system, tightening accuracy to about 3 feet. That's good enough to do some remarkable things, like allow for computer- generated precision approaches to every runway of a low-use airport, helping to promote economic growth in remote towns. Or how about (I'm speculating now) a portable system to guide water-bombers through smoke to the core of a forest fire?

Another idea would be to run GPS position data to an emergency locator transmitter, where it would be stored momentarily on a microchip and updated every few seconds. In the event of a crash, the aircraft's position could be transmitted to existing satellites, ground stations, and rescue craft, directly, without time-consuming triangulation. (This feature already is available with loran C.)

It's hard for most airmen to adopt and trust a new device without a reasonable understanding of its technology. With GPS, for the first time, I'm having to take quite a bit on faith, not knowing an algorithm from a fox trot. The basics of GPS are simple, however.

Twenty-four satellites circle in 12-hour, 12,500-mile-high orbits. Four each are deployed in six planes, each about 60 degrees apart. This provides a "constellation" where at least four satellites are "in view" at all times, anywhere on earth. Using synchronized atomic clocks aboard each moonlet, their positions — at any given time — are precisely known. Calculating a position fix on earth requires only simple trigonometry, but with all elements in motion, what really makes it work is a tiny computer of great power in the receiver, fed by mind-bending software. Looking beyond the basic layout makes my brain itch.

The speculation (not wholly my own) continues.

GPS could replace traffic alert and collision avoidance systems (TCASs) at perhaps one tenth the cost. To the basic receiver, one would add a low-power transponder and an equally low-power transponder interrogator. Upon interrogation, the transponder would reply with the aircraft's position. The low power would limit the range of interrogations and replies to, say, 25 miles. Then the receiver's software would erect a "safety bubble" around the aircraft, adjustable in size for enroute or terminal navigation. Only converging or nearby transponder replies within the bubble would be depicted for the pilot.

With traffic and navigation information of this quality, one could fly on instruments the way that we now fly visually, that is, providing our own traffic separation and deciding our own route of flight. The concept of "see and be seen" would be expanded to become "detect and be detected." The "C" word could be removed from the title: air traffic control specialist. They could watch their screens and macro-manage traffic flow while pilots micro-managed traffic separation. That would remove the ambiguity of aircraft command that has existed for decades and create a team with the potential for far greater efficiency. Oshkosh is the VFR analogy: The specialist directs traffic, and the pilots separate themselves.

GPS will soon be able to locate and navigate anything that moves. Its profound effect upon our lives will likely rival that of the magnetic compass — which GPS, of course, makes obsolete.