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This is a fictional story about two pilots flying to an annual fly-in convention of the Experimental Aircraft Association in Oshkosh, Wisconsin. It was written to illustrate the benefits of a new technology called SCAN invented by the story's author. The purpose of this story is to show how the implementation of SCAN could not only replace the current air traffic control radar structure with a much less expensive, more reliable and safer system, but would immediately save many of the lives needlessly lost each year to aviation related fatalities.

The year is 2000. I am a private pilot, and my name is Ed. I am also an artist, a sculptor of some distinction who somehow strayed off course to became a part time, self-styled inventor and engineer. Why? On January 15, 1987, ten innocent people, including my close personal friend and flight instructor, died in a tragic mid-air collision. Like all other mid-air collisions, it should never have happened. What a terrible waste of human life (and two perfectly good airplanes). I can't help thinking that my obsession to change that day in the only way I know how will finally be put to rest tomorrow.

Dave and I finish loading our few final pieces of luggage through the cargo door. Anticipating the long, one-day flight, I am finding it excruciatingly difficult to concentrate as well as I should on the standard pre-flight check. Never-the-less, forcing myself to do it, I finish up, kick out the 2 x 4 chocks, hook the towbar into the front wheel and pull my white and blue Piper Comanche out into the glittering morning light. Quickly, I stow the bar, shut the lid, check the lock and retreat to my half of sliding barn door. With one giant lunge, I step back and watch as Dave's door and mine close like a huge stage curtain, except that when they meet, they collide with that familiar empty hanger "boom" punctuated by an echoed "click" of the lock closing in the hasp.

"What a useless place," I thought, "an empty hanger." But to me, an empty hanger is a perfect hanger, perfect because, when it's empty, I'm flying.

Subconsciously, I check the sky and the wind before stepping up on the wing and slipping inside. Scooting over into the left front seat and stowing my map and gadget tray, I put both hands on the yoke and mumble, "Beautiful airplane." I should have anticipated it because it always happens just before a flight a little like stage fright but never like this. A giant rush of adrenaline! Flushed, I think of the significance of this flight from U42 to Oshkosh with my good buddy, Dave. Nerves tingle in anticipation of the flight because tomorrow, we will be on stage!

"O.K. Dave. I'm ready. Climb in and lets go!"

"'Where there is no vision, the people parish'" I thought as Dave squeezed in. "May be a good line for my talk-- a direct quote from the scriptures. The Indians at Custer's last battle had a better line, like 'It's a beautiful day to die.'" Somehow, I felt slightly more akin to the Indians at the Custer battlefield. "Inappropriate for a pilot and his passenger just before a flight, though," I thought, " but not inappropriate on that cold day in 1987, when Paul and his buddy in the Mooney and all those people in the Sky West commuter died in the sky. . . right there where the nose of my airplane is now pointing."

Looking up at the altitude where they had collided, I imagined what it must have looked, felt and sounded like to all the kids and their parents coming home from school and work with airplane and human parts raining down all over their houses and yards. I remembered news reports urging everybody to keep their kids and pets locked up in their houses. Looking down at the panel I said, "Well, Dave. Here we go. Just look at this display. Isn't she a beauty?"

"The perfect navigation system," Dave responded, giving emphasis to each word.

"It took me a long time just to get the FAA and the aviation industry to take me seriously. When I tried to tell them, they weren't interested. When they finally caught the vision themselves, it seemed so simple that they just couldn't believe I had a patent. And when they discovered I did, they just got mad and ignored me. Human nature, I guess. I am grateful for the one FAA contract I got in '93 to demonstrate SCAN as a method for avoiding runway incursions. That opened the door just a crack and had some beneficial effect."

As we buckled in, I glanced at the small black buss-mounted box docked in its holder under the panel. It looked classy, but it was just a small metal box. I plugged in a hard disk cassette and a PCMCIA card. Inside the box was a small, but powerful, SCAN computer, a GPS receiver and finally, the key component in the SCAN system a duel-band data link radio transceiver. A small red transducer mouse button was permanently mounted on each yoke at the right thumb position; on the left, the trim and com radio switches. An active matrix VGA color display screen was mounted on each yoke in the center spot normally occupied by the pilot's and co-pilot's clip-boards.

"Luckily, Dave, the head-up display was just completed and mounted in time for us to test it on the trip. The GPS antennas for attitude determination have been permanently mounted at the tip of each wing and at the front and back of the fuselage. As we fly, we will switch to head-up projections and see the computer- generated world through the windscreen in true 3-D perspective; in fact, it should pretty well match up with what is out there in real life. I'm anxious to have you look at the display. Both right and left eye images are projected to converge at a pre-selected range in front of the canopy. Since depth perception is lost beyond a quarter mile, we can each adjust the inter-ocular spacing in our wind-screen to enhance 3-D perspective. With that, you will be able to detect differences in depth up to fifteen to twenty miles away. That's a real kick.'

'This software version also has all airports, NDB's, restricted airspace, etc. in its data base. See these cards. They contain geographic maps of all the terrain in North America. When a message comes up, all I have to do is switch the data cards as we go from the Rockies to the Mid-West, or to the Eastern or Appalachian Range. These have very detailed airport maps that have been re-surveyed using GPS, so the accuracy is much higher than that contained on traditional Jepp charts. You will also be thrilled to see that we do have a few uplink stations that give us full access to satellite weather maps, wind aloft charts, Doppler radar maps, DGPS, etc. As you know, we have been working on an aircraft data collection system where each aircraft constantly monitors wind direction, wind velocities, air temperature and dew point and reports the information to other aircraft, satellites or ground-based monitoring stations. That data is all shipped to a central computer which composes 3-D data banks for cockpit use. Actually, it's just a 3-D array of numbers that the software convets into a map. This continuously updated map is available over one of the dedicated data-link channels. So, once in place, we will see a complete 3-D picture of the airspace. As we turn aircraft vectors on, you will also notice an accurate portrayal of wing-tip vortices, down-drafts, micro-bursts, and so on."

"Wow! What else?"

"Well, for starters, you will notice just how much more opportunity we have to keep our eyes outside the cockpit. In fact, you will feel far more relaxed and able to enjoy the terrain. The small bar graph in the corner of the display monitors all engine functions, so if anything falls outside its pre-determined operating range, an alarm will let us know."

"Speaking of alarms, there are two general traffic alerts: one is a potential collision and the other is a proximity warning. A proximity warning is handled in such a way that you can determine the position of an aircraft strictly by sound. That is particularly important when we are on parallel approaches. Since most aircraft have been equipped with a GPS SCAN squitter, you will be able to see that on the screen, once our flight gets under way."

"So? Why don't we get under way?"

"Rrright. Master on! Set throttle, mixture, fuel pump. . . . one, two, three seconds, fuel pump off"

As I yell 'CLEAR PROP!" through the porthole, I look about for stray bodies before kicking the starter. "And thar she blows!" comes out after only one complete turn of the crankshaft wakes up the engine. "Just like the old Model A." The whirring gyro and engine noises go from rough to smooth as the oil begins to flow and I adjust the mix to begin our taxi.

"This is great," Dave declares, watching SCAN initialize and then come on-line. I immediately toggle the U42 airport symbol on. The airport display box indicates current local wind direction, wind speed, local barometric pressure setting, temperature, dew point, and notes which runway is currently in use. We watch the runway map for obstructions or other aircraft in the air, in the pattern or on the ground.

"Is this information available at every airport?"

"Only airports that are equipped with a local SCAN transmitter. But it's inexpensive enough even for private airfields a terrific aid at any uncontrolled airport or landing spot. Of course, all major airports are equipped with a more formal ATIS and full Differential GPS for instrument landing capability. You will notice that: if I switch the DGPS button on or off, the airplane is either plotted in its normal GPS position with its DOD induced Selective Availability error, or moved to its corrected location. In order to receive DGPS, a local airport has to transmit the DGPS error correction, or it must come from one of the FAA's WAAS, or Wide Area Augmentation of Differential GPS, system stations."

"So, if you can take the error out of the signal anyway, why doesn't the DOD just turn it off?"

"That idea has been suggested for over 10 years now. It's really a political/national security issue. Some say it will eventually happen; others truly believe it will take place very soon. But I wouldn't put money on it. For us, it would make life easy if they did turn SA off, because then we could all make precision landings into any spot on earth. If we didn't need to correct the signal, it would also give the computer a rest."

"How do you deal with the computation?"

Noting the wind sock as I turn right for runway 34, "Actually, its already quite simple. At each tower, or controlled airport, ground-based computers correct each aircraft or ground vehicle position. Since the GPS error is consistent between all targets assuming they are monitoring the same set of satellites the relative error between aircraft is only one meter horizontal and a one meter and a half vertical. To keep life simple, SCAN just corrects the position of the airport. Remember, correcting the GPS error is only important when you intend to interface with the ground. It would be confusing to have some craft broadcasting their corrected position, and others broadcasting raw uncorrected data. Even without Differential GPS, precision is still good enough for non- precision approaches. What is interesting: airports that were surveyed using old-fashioned land survey methods often have a much bigger error than uncorrected GPS. For example, when we mapped the Salt Lake area using GPS, we discovered that the Tooele airport, according to the Jepp charts, was nearly a full mile off. To achieve accuracy and repeatability, all airports need to be resurveyed using DGPS, or Military GPS, in order to have the necessary precision."

"Look at the SCAN screen! I can tell that that's a home-built on the ramp, a Cessna in the run-up area and, there's a Piper twin on downwind, a helicopter out about 6 miles and several commercial planes approaching Salt Lake International. In fact, that's Leonard's N number in the run-up area. Can I send him a 'Hello' over the SCAN data link?"

"Sure. Nice thing is, he's busy right now. He can ignore it and answer later if he wants. No hurry.'

'Here we are. Let's see, checklist: throttle, run- up, rpm, mixture. . . check, left mag. . . check, right mag. . . check, vacuum, oil pressure, manifold, EGT, CHT, alternator, fuel, engine gauges, check compass and adjust heading indicator; check trim, check controls. . . fuel on proper tank, fuel pump on. O.K.! Check the door lock, door seal on, strobe on, landing gear light. Double-check your seat belt. Are you ready?"


"No answer yet from Leonard, even though he's putting out a good signal." After a short wait for Leonard's "Old Yeller" to clear the runway, I toggle the com button with my left thumb:

"Salt Lake Number Two traffic, Comanche niner one zero two papa, taxiing onto active 34 for departure. . . and rolling."

"Throttle full in. . . 50, 60, slight right rudder, up, up, up and away! Flaps up. . . gear up. . . check gear light. . . and clean up. Fuel pump off. . . adjust mix. Hope you don't mind my saying all these things out loud; just works out better for me when I do, 'specially when I'm alone. Tell me if I miss anything," I say as my right hand rests on the gear handle to feel it raise and lock, and I watch the message come onto the SCAN screen reporting "GEAR RETRACTED."

"No, not at all. Doesn't bother me."

"Salt Lake Number Two traffic, Comanche niner one zero two papa on cross-wind, turning downwind for departure east." Switching to Salt Lake Approach and listening, I call, "Salt Lake Approach, Comanche niner one zero two papa departing number two for Oshkosh. Request permission to turn east."

"Comanche niner one zero two papa, SCAN location indicates 1 mile south of Salt Lake Number Two, squawk 0393 and proceed east. Maintain 5500 until east of the freeway, approved to enter Class B airspace for transition to VFR 'free flight' for Oshkosh, as per flight plan."

"What's that? You didn't even file, or open a flight plan, did you?"

"Yup. Its all automatic now for anyone with SCAN. Look! When I toggle the Utility Menu, you will see a Flight Plan button. When I toggle Flight Plan, you see a U.S. map which shows my intended route. I did all that on my computer at home last night and checked it this morning. Takes about ten minutes. See this line. All we have to do is fly the line. If we get a little off course, we can move the line if we want. But that usually isn't necessary. This morning, I uploaded all the wind aloft, significant weather maps, PIREPS, NOTAMS, etc., and updated the international flight plan form you see right here." As I toggled the Flight Plan button on the map display, the standard flight plan form was filled in in the typical fashion. "Only a few blocks need to be changed each time you make a flight. See? Even if you change the plan from the time you first filed, the change is instantaneously logged and verified through air traffic control facilities on the ground as soon as you hit the File button. Other than that, there is no need for human intervention because, that function is handled automatically. Also, it can be accessed at any time by request from any traffic control center."

"How does it do all that?"

"Well, Dave, the secret is in the data link. It's a duel-band multi-channel receiver which can perform many separate functions while it ticks away, transmitting and receiving position information just like an old Timex. In fact, hear that message beep? It's from Leonard. He has already toggled our aircraft symbol which gives him a complete list of data we are putting out. So, he already knows who we are, where we are, our current heading, ground speed, altitude, flight plan and active com frequency. You probably didn't notice, but when you sent your 'Hello, Leonard,' we got a returned verification that his SCAN had received it, even though he hadn't read it yet. As soon as you read his message, toggle the ack, or 'message acknowledged' box. O.K., now toggle his airplane symbol on, and tell me what you see?"

"He's a little over two miles away and you are closing on him. He's lower, also going to Oshkosh what a coincidence but obviously, we'll be there a long time before he arrives."

"When we get outside the Class B airspace, we'll tune in to his com frequency and talk to him. If we lose him on com, we can still talk over SCAN, at least for a while. Its just a little harder to type in data for a long message."

"If we do that, will everybody else be able to read our message?"

"That will depend upon the way we choose to send it. If we send it globally, everyone will receive it, but if we make it a discreet message to Leonard, only his SCAN system will receive and interpret it."

"This is really impressive. I can tell where he is just by the sound coming in on my headset. He must be within our proximity bubble you were telling me about. Without even looking at the display, I hear him getting closer and passing further and further below our relative flight level. How do you do that?"

"We have just filed a patent application on that particular feature, so the idea is still proprietary. Pretty slick though, isn't it. What I am really trying to do is extend the human senses beyond the cockpit. As an artist, that is just how I perceive the world and try to present it to others. Through a pilot's eyes and ears, I want him or her to be able to sense the presence of other aircraft by sight or sound, just like birds do when flying in dense flocks.

"Amazing. I can tell that the sounds coming from different aircraft could really be confusing without stereo. Hey, What's that? I can see the outline of the mountains and various other terrain features coming through the head-up display. And that's in stereo too? With the sun coming up in the east, they are faint, but they seem to line up in perfect perspective with whatever exists out there in the real world. And the horizon is properly alligned too. Its nice to have a top down view on the SCAN screen and the 3-D head-up display in the windscreen, isn't it?"

"Absolutely. Another patent in the making. If I turn, the update is a second late, but that's tolerable. Watch the horizon change like the gyro HSI when I turn. Can you see our flight path floating over there? Looks a little like a pathway in space. That really helps, especially on an approach to a runway. Then, its augmented with a series of boxes placed at one half mile increments."

As we approach the mountains in a slow steady climb, we are able to zoom back at the larger picture of the greater Salt Lake area. Since the SCAN signal is line-of-sight, Salt Lake heliports, Bountiful, Provo, Ogden, then Morgan and Heber City airports gradually pop into view as we gain altitude. Also, various aircraft enroute, taking off, landing or taxiing at these various locations or any other location within our range, become immediately obvious.

"I see that. I am amazed with how well the symbols depict each type of aircraft. How many targets can the system plot at one time?" "Well, the computer is actually more limited than the radio, but right now, the radio can handle well over 1000 separate aircraft or ground targets operating within a 40 nautical mile radius."

"What is that? I see a square box around that aircraft."

"The box means that that particular aircraft has quit putting out data. It looks like he has flown behind that peak way over there. Since we're line-of-sight, the computer will keep the data in its buffer for a full minute. As you can see, a counter on top of the box shows how many seconds old the data is. If we toggle on the aircraft symbol, the data list and vector are still active. This shows us his last known position, altitude, velocity, heading and where he should be in one minute if he is still maintaining a constant flight path. However, if something has gone wrong let's say in the event of a crash or loss of power the data will be saved in permanent memory until it is later purged. We'll see if he shows up again. He's a glider, so he'd better. However, before he disappears, his last known data is recorded in permanent memory; we can bring it up later. There, he just came back. Notice the jump when his box went away and his position updated?"

"You told me there is another important aspect to SCAN that pilots didn't have before an emergency alert and emergency location system?"

"Yes. If I toggle this Emergency Menu button, I can either conduct a test or announce an actual emergency, that is, if I have one. For example, with this quick list on the Emergency Menu, I can toggle the exact nature of the emergency, such as fire, fuel, engine, airframe, electrical, weather, illness, etc. Once toggled, that message is received by everyone within receiver distance. For example, if this aircraft on the display were in trouble, I could toggle on his symbol and know how I might help. First, I would tune in his active com frequency while I assessed the problem. In one incident, a pilot actually had a heart attack and died in the left seat, while a friend who had never flown was able to fly the aircraft to a near perfect landing."

"Really? That sounds impossible. How could he do that?"

"It was actually a 'she.' She simply had been told by the pilot, 'If anything should happen to me while we're flying, just keep flying the airplane and toggle this Emergency menu on. Then press the button on that says 'illness,' and listen to the radio.' That is exactly what she did. They were in a rather remote area somewhere back east, but as soon as the incident occurred, another pilot within range luckily saw the alert and was able to help."

"What did he do?"

"After listening to the com frequency indicated in the SCAN data block, the pilot called the woman in distress over the voice radio. She responded, but was obviously stressed out and frantic. Upon learning what had happened, the pilot in the other craft attempted to calm her nerves by saying something like this: 'Just relax and keep flying the airplane ahead straight and level and you'll be O.K. I will stay with you and help you get down. Careful, you are gaining a little altitude, so push the yoke in a little. That's it. Now, I want you to try a very slow turn to the left. See that arrow at the top of the SCAN screen? Turn until the number '092' shows up inside the arrow. That is the heading you will be flying which will bring you back to Timbucktu airport. Watch your altitude. . . Perfect. Now I'm going to teach you how to land the airplane so when you get back, you'll be ready:'"

'Fine. O.K. Now point the nose down just a little. As you pick up a little speed, pull the throttle back and trim the airplane nose down a little more. It would also help slow you down if you put in some flaps. The flaps switch in your airplane is located . . . ' and so on and on it went on until she was able to safely land the plane. By the time she reached the ground, she was even able to make a nice little flare and guide the airplane down the runway as she pulled the throttle off. She then was told how to taxi the airplane to a safe place and turn the engine off, all while the pilot was flying around in the pattern and radioing the information in to the Timbucktu airport traffic on the ground."

"That is absolutely miraculous. But with the information in each SCAN target aircraft box, I can see how it could happen."

"Beep . . . beep . . . beep . . . ."

"That's a collision warning. Military helicopter. We have a minute to go, and as the seconds count down in the warning box, I just turn a few degrees to the right and voilů, the collision warning goes away. We'll keep our eye on him. . . . There, now that he has penetrated our proximity bubble, can you hear him? Can you see him yet? five miles, still a little far, but yup, there he is right over there against the foothills."

Oh! Yeah, there he is, I see him too. Sure does help to know where to look and what you are looking for."

As the hours drone by, the talk turns to other subjects and some of the reasons for my talk tomorrow.

"It is a miracle that you ever got the system approved and implemented," says Dave. How was it to work with the FAA?"

"For the most part, especially during the early years, it was awful. Other than one small contract, I was totally on my own. I mortgaged everything I owned just to keep the project going. And from the FAA, as the old expression goes, 'I got little respect.' They weren't good at answering letters or returning phone calls. Eventually, they just proceeded with their own version of my technology just as if I didn't exist. Because of their attitude, it was difficult to get funding from others in the industry."


"I don't know, but I have some pretty good suspicions. Unless you are part of the good old boys' network, you are dead. The FAA is a slow cumbersome bureaucracy. They talked about getting new technology on board quickly, but just didn't know how to change their old habits. The old timers protected the status quo. At the time I first started advocating SCAN, the TCAS system had just been created and mandated. TCAS was it. I went to the FAA as early as 1991 to tell them that TCAS would never work as predicted. That's why I created SCAN. I knew TCAS would eventually need to be replaced. Even though the SCAN concept was far superior and less expensive, they simply ignored me. They continued on with TCAS, even though it was costing airline companies a quarter of a million dollars per aircraft. They then finally admitted that TCAS was an interim solution. They predicted any long term solution would take 15 to 20 years.'

'Several years later, when the FAA finally came to the same conclusion I had come to earlier, they proceeded to invent what they called the 'Mode S Squitter.' The Mode S Squitter is the same technology as mine, except for the data link. Where I chose to design a completely new radio around SCAN's specific function--you know the old artistic expression, 'form follows function,' --the FAA preferred modifying the transponder, as they said, "to keep the system TCAS compatible." It really didn't. In the beginning, they would never have tolerated my doing do the same. But in a way, it was an admission that TCAS didn't work and that my technology was really the best solution. It was obvious to me that they were simply attempting to save TCAS by adding yet another expensive layer on top of an already over-taxed radar system. The solution was limited mainly because the transponder used old outdated AM radio technology. In fact, that choice ultimately proved to be a serious mistake. Already, the FAA had bungled a number of other projects including the Micro-wave Landing System, the Airport Surface Detection radar System and the highly computerized Air Traffic Management System. These had cost hundreds of millions of dollars, even billions, had run overtime and over budget, and were limited to site-specific applications. GPS changed all that. The problem was not an airport problem, but a problem in dynamics. Loran, and then GPS, were successful because they put the control back in the cockpit where it belongs. And that solved the dynamics problem."

"So, how did you get past all that?"

"Eventually, the mandate didn't come from the FAA. It came directly from the Congress. The only reason it ended up being my system instead of the FAA's or someone else's is that my system was completed and ready to go, and I had a lock on the technology. I also had established a unique position on the radio spectrum which, it turned out, was a tremendous benefit to the FAA and ICAO, the International Civil Aviation Organization. Cost was an important factor. If the FAA had really been interested in the best technology, they would have realized how much easier and quicker the compatibility issue could be resolved by putting a SCAN squitter on all commercial airlines, rather than the other way around. When we produced a system nearly as good as the one we are flying today for as little as $4,000 to $6,000 pilots went crazy to have it. Since we could put a $1,500 Beacon squitter on non- electrical craft, insurance underwriters and traffic controllers immediately jumped on our bandwagon. Remember when we flew past Heber and there were a couple of gliders in the sky? We saw them but they didn't see us. I could tell by their signature that they didn't have the ability to detect other SCAN equipped craft. The nice thing is: every system is upgradeable to the next higher model. With a small power supply, even gliders can be equipped to see all other craft, and at a very reasonable cost. The same is true of other non-electrical craft, balloonists, hang gliders, etc."

"Amazing! And look how many aircraft are already equipped. We have seen a lot already."

"That's why I'm anxious to get to Oshkosh. Then we'll really know. Of course, sales are telling us, but this trip is a reality check. And remember, if anybody disappears from the screen away from a landing field, not only will you know it instantly, but others will too, and help can be dispatched to the location within minutes or seconds."

. . . . . "Who would you contact?"

"As you have noticed, I still use Flight Following. But if you're not on the radio, toggle the Utilities Com button and you'll get a list of frequencies in the area. You could call 121.5 or toggle on a nearby airport, or call another aircraft. Lots of choices."

"How would you know if it were a crash or just an aircraft landing?"

"If it were a helicopter flying close to the ground, you might not know immediately, that is, unless you were purposely tracking that aircraft. However, if a glider or normal airplane went down in an area not equipped with a landing field, you would know it instantly. In the past, it typically took the Civil Air Patrol 4 to 6 hours to reach a crash site. Many people who survived forced landings generally died from exposure, starvation, shock, trauma, or bled to death. Now, help can arrive in minutes. The FAA is noticing a rather profound improvement in air fatality statistics already."

"Do we still need an ELT?"

"Most aircraft still have them, but since the new mandate has been in place, aircraft with SCAN have always been located using SCAN instead of the ELT. When all aircraft have SCAN, I suppose ELT's will either be phased out or left in place just for redundancy.'

'Speaking of redundancy, have you noticed how I am constantly following a course in True, rather than Magnetic North? The compass is now the redundant navigation instrument; GPS has become the primary navigation tool. In fact, the gyro compass is even less accurate than GPS.

"Is it wise, or even possible, to use Loran, or the Russian GLONASS system which has also recently been declared fully operational?"

"The answer is 'yes.' It is indeed wise and possible. We sometimes forget that a single source of information might be perilous if something were to go wrong. So, I have both a Loran and a GLONASS backup. However, as a user, we must be aware of error discrepancies. The software deals with that. When using a different set of satellites, or any alternative positioning device, the relative error between targets must be known. A large error, of say, up to a half mile or more, might exist between an aircraft using Loran and one using GPS. GPS uses dilution of precision and figure of merit values to compute a potential error in its signal. The dilution of precision is a larger issue when two targets are monitoring different groups of satellites. These errors are part of the algorithm structure within the SCAN system which draw a kind of invisible precision bubble around the airplane. As the aircraft flies, it computes and reports its own figure of merit to other users. This, along with knowing the assigned numbers of the satellites being monitored, generally gives the user at the other end, very reliable precision numbers to work with, particularly among aircraft using standard GPS service."

"Now you tell me, Dave. You are building another home-built. How important would SCAN be to you?"

"First, I have been told that my insurance premium will be less if I have a SCAN system installed and operating. Secondly, it will be easy to install. It will, by far, be the most important single piece of avionics equipment I can put on my airplane. As a pilot, it amazes me that this single piece of equipment can solve all major issues that relate to navigation, surveillance and communications. In fact, in my case, it eliminates the need for an ADF, extra VOR and second com radio. That alone will pay for the system. Of course, I do have my portable com . . ."

"And, you might want a portable SCAN for backup. If you're ever forced down and have to walk out of some place, that's when you will really appreciate it. You can even use it when you go fishing or hiking, you know. And, as long as you pack enough batteries, you won't even need a compass. Since the normal SCAN system also saves all the flight data, it makes a terrific way to practice your flight at home on your PC, or review data from previous flights."

"Great for the FAA to write citations, too. I'll bet?"

"I hope not. They should view this as an opportunity to bring people into the office for help and instruction, or to head off an incident before it happens, rather than as a tool to punish pilots. Congress is working on that one as we speak. Actually, it makes the airspace pretty much self-policing. Pilots can help pilots in a way they have never been able to do so before while controllers can concentrate on areas of greatest need."

"You know, Ed, my last flight instructor sent me out on a cross-country flight not too long ago. He didn't allow me to use his onboard SCAN receiver during that flight, so my data going out was flagged for broadcast only to other aircraft. However, his receiver was still working. He simply turned off the display and alarms and recorded and played the data back when I got home. I was a bit embarrassed by a couple of overshoots on approach and some abrupt altitude changes over the mountains and inside the Class B airspace. But all in all, it pointed out my weaknesses. In hindsight, I am a better pilot because of it."

"Let's get a weather update on the SCAN screen. Mmm. Select weather, Satellite Map, Western USA, Winds Aloft Local, Winds Aloft Destination And Points In Between, Doppler Radar, Weather Advisories including PIREPS, SIGMETS, etc. Only a few seconds and 'shazam,' and thar she is again."

"Impressive! Displayed right over our moving map, with other airplanes still plotted and everything. Can get a little busy though, huh?"

"Yes, but we can dim down or turn off whatever we don't need. Let's keep life simple and dim it.'

'And look, if we needed to make an emergency pit stop, all I have to do is toggle on a nearby airport. See this! Cheyenne, Wyoming, CYS. The block shows distance, wind direction, wind speed, barometric pressure, temperature, dew point and runways in use. However, if I toggle CYS on the Flight Plan map, I can change my waypoint instantly and page through all the data normally available in the GPS Jeppeson data- base. See? Time, distance, frequencies, TPA, MSA, runway lengths. . . ."

"Denver Center calling Comanche niner one zero two papa, come in please!"

"Go ahead, Denver, zero two pop."

"We notice you are enroute from U42 to Oshkosh and will soon be approaching Sioux City, South Dakota. We have a suspected downed aircraft approximately 20 miles just north of your current flight path. We would like to ask a favor."

"Sure, what are friends for, zero two pop."

"Its a Cessna, N number 596 November Charlie, en route from Casper to Oshkosh. We think he went down just a few minutes ago. Last known SCAN coordinates at 18:02 Zulu show North Latitude forty one degrees, 59 point 7237 minutes, West Longitude 97 degrees, 26 point 8342 minutes and altitude 1287 feet. Looks like he may have gone down in the foothills. Can you deviate and check it out? This frequency should hold, but if we lose you, can you send us a message on SCAN?"

"Roger. We'll check it out and report right back. Zero two papa, out."

"Watch this, Dave. I simply select the flight plan map and insert a waypoint between Casper and Sioux Falls. Since the number is so precise, I'll enter it by keypad instead of dragging the rubber band like flight path line. There we go. On this map, since the coordinates are lat-lon, you still see our flight path indicated. You also see a dot for the destination point and the inserted waypoint on the waypoint list. As we go back to the moving map display, the flight line we are following goes right to the exact spot they just gave us. On the head-up display, an arrow points to the exact location of the next waypoint, so we just fly straight at it. We'd better trim down now, gotta loose 8,000 feet in exactly 16.3 miles. Whew! That ought to do it. Look at those mole hills, all trees and granite."

"Why don't you enhance the perspective in the head-up?"

"O.K. How's that?"

"Down, down, closer and closer, 2.3, 2.2, 2.1 miles, altitude 3,500 feet."

"Look! I see them straight ahead, right next to the arrow on the head-up display. Not more than a few hundred yards off. Looks like they're on a dirt road. Yup, by darn. Look, Ed. They are jumping up and down and waving. You can sure see that yellow jacket from up here. Plane doesn't appear too bad. Let's take a closer look."

"Yeah, Dave, and look at the screen. They have a portable hand-held SCAN and we have a message."

"Emergency landing, 5 aboard + dog, no injuries. No food or water. Please send help."

"Type this in Dave, 'Help coming immediately. Please remain at present location. Good Luck!"

"Denver Center, Comanche niner one zero two papa, do you read?"

"scratchety scratch. . . " adjust squelch and listen to noisy silence. "Tshhhhhhhhhhhhhh. . . ."

"A little more altitude and we'll try again. . . . Denver Center, do you read? Comanche niner one zero two papa, calling Denver Center."

"Go ahead Comanche zero two papa, Denver Center."

The report was made with assurances that Sioux City had already been notified and was standing by. Help was being dispatched immediately and would arrive at the scene in approximately 10 minutes. "Can you forward the outcome to us Denver Center, zero two pop."

"Affirmative Comanche zero two pop, thanks and good day."

"No sweat, zero two pop."

"Wow! That sure gives a pilot an added sense of security, doesn't it? Beats the ELT."

"Sure does, Dave. And imagine how you would feel crossing the ocean or the Great Lakes, knowing that ships are using the same set of frequencies. It also gives them the same sense of securit. . . Oops! Switch to inboard tank, right side. Reset timer. That reminds me, my wife says sculptors, brain surgeons and pilots should never say 'oops!'"

Twenty minutes later, SCAN beeped an incoming message, "Denver Center reports from Sioux City Municipal, everyone onboard Cessna 596 November Charlie safe, including dog. Oshkosh trip on hold for a couple of days. They are anxious to look you up. Understand you invented SCAN. They, and we, are grateful. Thanks a bunch!!!"

"Send them this, Dave: Quote, 'Aw, shucks,' end quote."

"Do they need your ID?"

"Nope. With SCAN, our ID is automatically appended to the message. In fact, when I changed our route, I toggled the file button so our flight plan was also automatically appended. Arrival times have been re-computed, and as you can now see, will be landing at Oshkosh at exactly 2:32 CDT."

"Newest weather update! Hmm. Light showers, and I'm VFR. Typical afternoon buildups, I suppose. Hope we'll be O.K."

"What do we do when we get there?"

"Not much. It used to be tough. Without SCAN, the FAA had a complicated procedure, and that still exists for unequipped aircraft. But for the rest of us, when they tell us to follow a specific aircraft, we simply toggle him on. That way we see his N number, know what type craft he is, see his heading and airspeed and use our vector for spacing. It's much better than radar, and doesn't have the delay. Radar takes about twelve seconds to update, so its harder to judge. We could come in too close. SCAN is one second late, but with the GPS time stamp, we have the information presented in real time. When our leader slows down, we can avoid running over him. Simple."

"Hmm. Here we are in the long sequencing pattern. We'll look at Oshkosh ATIS and toggle approach. This lets them know who I am, what I am, where I am, and lets them know my intentions. See what happened. Look at the message:"

"Comanche niner one zero two papa, squawk 1239, fly route 3 to runway 36, follow Experimental 999XF, maintain 140 knots with normal separation. Cleared to land."

"Comanche zero two pop following Experimental 999XF at 140 knots with 1.5 miles separation, descending through 2500 and cleared to land."

Route 3 comes with a set of ASCII instructions and a graphic map to follow.

"See, I told ya so; simple. Just stay on the line just like we did getting here. Turn on vectors. As you notice, with approach toggled, you can now see the rectangular windows we fly through. Our glide path is determined by our own computer and will take us right down to the turf, flare and all. Toggle Experimental 999XF so we can follow him down the tunnel. There, his vector is flashing, and ours is following. Watch his airspeed and altitude, and watch ours. The vector is a minute long, so when we slow to 90, that's a perfect 1.5 miles, the required minimum. We'll give him just a tad more in case he doesn't get off the runway in time; he's got a long taxi. And look at that: they appended our approach map to guide us to the exact tie-down spot. Yup, simple. Told ya so."

"Yyyup. Sure did," says Dave with a big grin. "What a great sight. Wow! See what I see? A great big city of airplanes, thousands of them, lined up everywhere. And look at your screen. SCAN sees airplanes of all types and sizes, taxiing, parking, flying. Some look like they are landing in the water over there about 10 miles away. And look at the runway vehicles. Think we can spot Poberezny's little Red convertible VW?'

'Great approach. Nice landing. Just like you said, right down the tube, or tunnel, or whatever. Didn't even hear 'em squeak. Boy, look at this crowd already. Are you ready for this? Are you ready for tomorrow?"

"Thanks to you for the rehearsal, I think I'm ready. Let's get in our place and then find the FAA pavilion so we can unload and get set up as soon as possible."

"How much work will that take?"

"Mmm. Not too much. Simple for us, but if were the old days, I could guarantee, there would be someone assigned to try to make things as difficult as could be. Luckily, not too many of that type around anymore. After they slowed the world down so they could climb off, things started picking up again. I'm really looking forward to seeing the crew sent to help us set up in the FAA pavilion this year."

"The nice thing is, pilots, controllers, aircraft owners, insurance underwriters, passengers, aircraft manufacturers and major airline executives are all extremely happy."

"So is the FAA. And don't forget, Dave. Because of SCAN, more people are alive today. Just think how happy they and their families would be if they only knew. I only wish it had happened 8 years sooner. It could have."

Proof-of-concept testing of SCAN took place in 1990. In 1994, a test was conducted for the FAA; design and construction of a beta test system is over 90% complete. With the right kind of support, the SCAN system can be available in the marketplace within one year.

Copyright, 1995, TERRASTARR, all rights reserved

For more information, write or phone:
Edward J. Fraughton, President
10353 South 1300 West
South Jordan, UT 84095
Phone: 801 254-3303
Fax: 801 254-6606

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