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Punctuated equilibrium One of my favorite authors, Stephen Jay Gould, a paleontologist, wrote a paper in 1972 along with another paleontologist, Niles Eldridge, describing a theory of evolution he called “punctuated equilibria.” This was a new idea. The previous theory was called “phyletic gradualism” and essentially said that species change slowly over time, accreting changes at a more or less constant rate (what I would call a mechanical engineer's vision of evolution). Gould said, no! Change is non-linear (more my style, you see). What we really get is a rapid change in a short amount of time followed by long periods of no change, or very little change. For those who really like paleontology, Gould and Eldrige's theory actually accounted for the fossil record, where we find that species tend to be stable over long periods of time. Well, the same is true of aircraft instruments and avionics. We can see classes of changes that occurred to instrument panels that spread rapidly. Der Grosser Krieg The first major changes to the very sketchy instrument panel of the 1903 Wright Flyer were driven largely by the First World War. The airplane was coming into wide use as a military machine, much to the surprise of various generals and field marshals. This use required a huge number of new pilots as the heavier-than-aircraft had existed for less than two decades. The military, of course, excels at training up huge numbers of anything at all, but they do require consistency and rather more information that the Wrights had. Both the magnetic compass and the altimeter came into wide use and the control interface, if you will, were rationalized and systematized. This is also when aircraft began carrying radios. The cockpit as we understand it today was invented during the war. Even so, it was pretty sketchy and there was no such thing as instrument flying. Jimmy Doolittle, Harry Guggenheim, and the Inter-war years Following the end of the war, aviation began to carry the mail (and a very few passengers) instead of bombs and bullets. It began in the UK, Europe, and the US, spreading to Australia and South America. Mail, of course, wants to be delivered on a regular schedule, regardless of the weather. What we learned in the course of trying to do exactly that (and killing a great many young pilots in the process) is that the humans cannot fly an airplane straight and level unless they can see the horizon. No matter what you thought, no matter what your inner ear told you, or what you thought it told you, without a horizon to refer to, there was no way to guarantee that the airplane would be right side up after descending through a cloud layer. And there were a great many cloud layers. Lindbergh To illustrate my point, Charles Lindbergh, who famously crossed the Atlantic solo in 1927 (thereby winning the fabulous $25,000 Orteig Prize) had been an air mail pilot for about two years prior to his record flight and during those two years he had to bail out of his aircraft twice because there was no clear path for him through the cloud layer. There are many airmail pilots who did not bail out, and a great many of those died in crashes due to their being disoriented coming out of the clouds (or running into the ground if the cloud layer went all the way down). What Lucky Lindy knew was that descending through a cloud layer was a sucker's bet given the instrumentation they had in their WWI surplus airplanes. Nor was there anything better on the civilian market. Guggenheim Harry Guggenheim of the fabulously wealthy Guggenheim family (they made their money in mining), the same family that funded some eight magnificent art galleries around the world through their philanthropic foundation, flew Curtiss flying boats in WWI. He also knew Lindbergh—in fact, he shook Lindbergh's hand prior to the solo crossing take-off and invited him to come see him when he returned (if he returned, Guggenheim didn't think he had a chance and Guggenheim knew flying). This problem of “blind flying” became one of Harry's projects. He founded the Guggenheim Fund for the Promotion of Aeronautics to find a solution. And he succeeded with the help of a genuine aviation phenomenon, Jimmy Doolittle, the same Doolittle who led a formation of B-25s in America's first air strike against Imperial Japan in 1942. Interestingly, Doolittle bailed out in China after his airplane ran out of fuel and was helped to escape through Japanese lines by one John Birch, a Baptist missionary. Yes, the same John Birch that the conservative US political group is named after. Doolittle US Army First Lieutenant Jimmy Doolittle was, according to an aviation historian I know, the finest pilot ever to grace the air. He combined impressive flying skills (he flew the first ever outside loop) with both a masters degree and a doctorate in aeronautics from MIT. Doolittle flew a Curtiss R3C-2 seaplane to win the 1925 Schneider Trophy race, the same race that would eventually inspire the Supermarine Spitfire fighter that was the backbone of the British Royal Air Force during the Battle of Britain in 1940 (unless you take the word of those Hawker Hurricane fans, of course). Doolittle worked out the fundamentals of terrestrial radio navigation. Doolittle was the first pilot ever to take off, fly a course, and (safely) land his aircraft without being able to look outside. His first test flight using the system was done one foggy morning before the official witnesses arrived. His work was supported by the Guggenheim Fund's Full Flight Laboratory, established specifically to support Doolittle's efforts. Sperry and the artificial horizon To enable that historic flight, Doolittle needed the help of Elmer Sperry (among a great many others), whose company was making the marine gyro compasses that Sperry himself helped invent. Doolittle wanted a single integrated instrument, but Sperry suggested breaking it into two instruments, a gyro compass and an artificial horizon, for ease of manufacturing. Interestingly, it wouldn't be until the advent of computer displays on the flight deck half a century later that Doolittle's vision of a single display would be realized. The artificial horizon would be combined with the gyro compass (along with airspeed indicator and the altimeter), giving pilots all the critical information they needed to safely fly the airplane. Elmer's son, Lawrence, inventor of the autopilot for aircraft, died in in a plane crash in 1923 while working on this same problem of blind flying, Elmer following him in 1930, the year after Doolittle successful flight. The Sperry Corporation, of course, went on to become a giant in the nascent avionics industry. Kollsman Doolittle also got the help of a young German-American engineer named Paul Kollsman. The altimeter then in use wasn't very precise. At all. With Kollsman's “sensitive altimeter” Doolittle could fly the airplane all the way down to the ground and be so precise with the blind landing that if he bounced, he thought it was sloppy. This was a tremendous achievement. Kollsman-type altimeters are still in use today and the company he founded is still at the cutting edge of blind flying instruments.
Rapid change Obviously, before Doolittle, there were no artificial horizons, no four-course radio ranges, no marker beacons, nothing really that was needed for what we now call instrument flying, or flying IFR (Instrument Flight Rules). Shortly after Doolittle's remarkable flight, those instruments were being produced and installed by the hundreds and by the thousands as World War Two rolled around, only a decade later. While the four-course radio range morphed into the VOR, which morphed into the TACAN and VOR-DME, and the Instrument Landing System (ILS) acquired a glideslope, there were no fundamental changes for half a century. Punctuated equilibrium. EFIS The next big step in avionics was the Electronic Flight Instrument System (EFIS), or “glass cockpit.” First rolled out on the Boeing 757/767, immediately followed by the Airbus A310 (then Gulfstream rolled out their glass cockpit), EFIS is essentially a computer monitor that displays all the information that the pilot needs to safely fly the aircraft. It shows heading, altitude, airspeed, and a great deal more. The airplane is still navigating by VOR, still landing by ILS, still using VHF radios (and still has a small group of traditional instruments as a fail-safe back-up), but now there are computers, “data processors,” taking in the data from the various sources, processing it, and displaying it on the six or eight screens mounted on the instrument panel. Cathode ray tubes at first, same as the old televisions, but they were replaced with LCD displays that weighed less, used less power, and could be read even in direct sunlight. By itself, EFIS didn't really change anything other than the way the air and navigational data were displayed. However, EFIS made possible later changes that could not have been implemented without those crucial data processors and displays. But, until then, nothing much changed. Punctuated equilibrium. GPS In 1994, some thirteen years after EFIS entered service, the FAA approved GPS “for use as a supplemental navigation system for oceanic and remote, domestic en route, terminal, and non-precision instrument approach....” This was a huge change. Prior to GPS, air navigation was done by interpreting the radio signals from expensive ground-based transmitters that had to be built, calibrated, and maintained, even in remote areas. For large countries this is a huge expense, and for poor large countries, unsupportable. So, radio navigation in some parts of the world was a lean proposition, indeed. With the advent of GPS, a space-based system, every part of the globe was now navigable by the same system, and it didn't depend on local maintenance, just the continued indulgence of the US Department of Defense, which owns the system. I won't go into the details of how it all works (I can hear the sighs of relief all the way over here), just that it is a constellation of satellites in low earth orbit. Moreover, there are a few other satellite navigation systems that may supplement or replace GPS at some future date, including the Russian GLONASS, the Chinese Compass, and the EU Galileo systems. These form what is called a GNSS or Global Navigation Satellite System. It isn't really functional yet, but it is a great idea. There are also existing systems available to improve, or augment, the accuracy of the GPS receivers, like WAAS and differential GPS, among others. Over fifteen years ago, back when I was designing airplanes, we estimated that the navigational error of the system was smaller than the pilot's chest. Today, there are published GPS non-precision approaches at almost every airport in the world. You can even have your very own private GPS procedure created, if you like, and some operators do exactly that. Some years ago, Southwest stripped their ancient ADF receivers out of their aircraft that had GPS installed, leaving the standard VOR receivers as their mandatory redundant system, and saved quite a lot of weight. Synthetic Vision Remember those data processors I mentioned in regards to EFIS? They become even more helpful about the time that GPS is approved by the FAA.. Something called the Enhanced Ground Proximity Warning System gets a complete, worldwide terrain database that the EGPWS computer uses to determine if the crew is about to fly the airplane into the ground. Seriously, this used to be a big problem. Let me back up a minute. In the late 1960s and early 1970s, we were losing three or four airplanes a year to CFIT accidents. A CFIT is Controlled Flight Into Terrain, i.e., a perfectly good crew flew a perfectly good airplane into a mountain or a dead-flat sea level swamp like the Everglades (I'm not making that up—Eastern Flight 401, 1972). A Canadian engineer named Don Bateman invented the Ground Proximity Warning System (GPWS) that used some radio navigation aids and the onboard radar altimeter to determine if the airplane was too near the ground. It was a good system for its day, but it had some problems and the EGPWS was designed (by Don again) to fix them. He added an enormous database of terrain all around the world, and a computer to analyze the flight path of the aircraft and compare it to the terrain model loaded into storage. Too close, too fast, wrong configuration--alarm. It has been incredibly effective. Since the FAA mandated the original GPWS in 1974, not a single passenger has died as a result of a CFIT accident in US airspace. That's amazing, if you think about it. But, I digress. Synthetic vision is yet another computer (aren't you glad they don't run Windows?) onboard the aircraft that accesses the terrain database and instead of comparing that to the aircraft's predicted flight path, the computer renders the terrain on the pilot's primary EFIS display, just like you see in Microsoft Flight Simulator. This is an enormous help at night and bad weather when the pilot can't actually see the terrain. The synthetic vision really enhances the crew's situational awareness. Synthetic vision is impressive, but now companies like Garmin are shouldering aside industry giants like Honeywell and Collins, making displays that not only show the usual EFIS instruments and the terrain, but now add additional features like Highway In The Sky (HITS), a system that helps the pilot visualize where the airplane will be in the very near term future. Garmin has also layered on other kinds of information like weather data and the location of other aircraft (determined from their onboard transponders). And the prices of Garmin systems are well below the established industry standards. This is a distinct change. Enhanced vision It just keeps getting better. Gulfstream has recently certified what they call their Enhanced Vision System, which is basically an infrared camera that looks ahead of the airplane, just the way the pilot does. The image taken by the camera can be shown on a Head Up Display (HUD) or on the pilot's primary EFIS display. Guess who makes the system? Kollsman. What's next? I don't know exactly what will be next. In some respects, I feel like we are already living in the future. I have personally flown a small four place Cessna aircraft with a Garmin system in it and I was in awe. It rocks! But, we haven't yet pulled the last rabbit out of the avionics hat. The next bridge, I think, is what we call “Free Flight.” That is a computationally intensive system that would allow the crew to fly directly from one airport to the next without regard to current airways. With such a system, the crew could even perform a more efficient cruise-climb rather than staying at one altitude or step-climbing. Whatever is next—and however long it takes to get here, it will likely be based on ever more computers and it will be cool. I can't wait! Terry Drinkard is currently consulting on an aviation start-up. His interests and desire are being involved in cool developments around airplanes and in the aviation industry. Usually working as a contract heavy structures engineer, he has held positions with Boeing and Gulfstream Aerospace and has years of experience in the MRO world. Terry’s areas of specialty are aircraft design, development, manufacturing, maintenance, and modification; lean manufacturing; Six-sigma; worker-directed teams; project management; organization development and start-ups. Terry welcomes your comments, questions or feedback. You may contact him via terry.drinkard@blueskynews.aero Other recent articles by Terry Drinkard:
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