◆ PARALLAX

I work ATC. I have for eight years. I control radar and ground frequency at a medium-field tower in the midwest -- nothing classified, just busy enough to matter.

The UFO conversation on this board would be more useful if people understood what a radar actually shows and what a controller is willing to report and what he does not report, and why. I will start with the simple stuff and answer what I can.

First: what you see on a scope is not what is in the air. A radar return is a bounce. It bounces off the metal fuselage of an airplane, it bounces off weather cells, it bounces off birds, it bounces off birds a LOT, and it bounces off the air itself when the air is doing something with water in it. Every person on the internet who has looked at a radar picture and said "there is a solid object there" is partly right and partly committing to a conclusion the raw return does not support.

Second: we see uncorrelated targets all the time. Targets that do not match a filed flight plan. Most are birds, about a third of the ones that turn up in our airspace that look like aircraft. Weather ghosts, we call them anomalous propagation, the radar bounce folding back through the air in a way that creates a fake return that is not in the sky. Chaff. Sometimes another radar painting through us from a city over. And yes, sometimes there is simply an airplane flying without a transponder and no flight plan, which is illegal in controlled airspace but happens, and we vector around it.

Third: what gets logged. Every blip that matters for air traffic does. Every blip that is a real airplane with a transponder showing does. Uncorrelated targets that resolve as aircraft after a few sweeps, those get noted. Targets that do not resolve, that hang there for two sweeps and vanish, weather anomalies, birds that show up huge and vanish, the clutter from the mountain ten miles west, none of that gets logged in a way anyone would ever see it. It is radar noise. It is not safe to cram the log with radar noise or the next controller will miss the note that matters.

Fourth: why we do not report UFOs. You have two hours of traffic, a hundred-and-eighty frequencies open to crew and ground, your supervisor asking if that target is yours, and a radio chatter that is almost a living thing. A target comes up. You look at it. You ask the crew of the nearest airplane if they see it. You wait one sweep. You wait two sweeps. You ask ground if there is anything in that airspace. You look at the target and it is still there but now there are three radar sets echoing it and one of them is not and you can already hear the answer: weather, anomalous return, that sort of thing. You release it.

Now you go home and tell someone you saw a UFO on radar and their first question is always the same. Did you report it. And the answer is: it was radar clutter. It was not something I could sit down and write down. The minute I have to explain that it might have been a radar ghost, the person asking has stopped believing me, and also I have just told a story about doing my job wrong.

So. Most controllers do not report the uncorrelated targets because they are not reportable. And most controllers who have had a target that was strange, genuinely strange, do not report it because the career risk is larger than the duty to report it is. That is the honest answer. Not that we do not see them. That we see them all day and there is no mechanism to report what you saw that you could not confirm, and if there were such a mechanism the person listening would be swimming in radar ghosts from controllers who did not understand what they were looking at.

But I had one. Eight months ago, something on the scope that I could not account for. I will tell that story if someone asks, because I still do not know what it was, and I have already thought about it more than is useful.

Ron is talking about the radar side, and he is right on the systems. I work the equipment end -- I maintain and calibrate the big rotating sets. I can add to the sensors half of what he said.

The civilian radars are not magic. WSR-88D, the Doppler sets, they will show you precipitation down to small rain, they will show you hail, they will show you a bird if the bird is big enough and the setting is right. But the weather radars are not watching for aircraft. The primary radar, the air-traffic radar that shows everything in the sky, it is a little dumber and a lot more honest about it. It bounces a pulse and if something bounces back, it paints a dot. That dot is real. But what is making the bounce? Metal, mostly. But also rain. Also hail. Also a flock of geese the size of a small airplane.

And the thing no one talks about: ground returns. The radar bounce from the earth below is so massive that we have to blank it out with software. The software does not know about every building, every antenna, every power line that will return a bounce. Sometimes it paints a ghost. You get a target ten miles out that is not in the air, it is a bounce off a silo or a grain elevator or a broadcasting tower that the filter did not account for. When Ron says anomalous propagation, some of that is the radar painting the ground in a place the ground-clutter filter does not reach.

I can confirm what he said: uncorrelated targets are not rare. They are not even uncommon. On a medium-traffic day, a controller will see a dozen targets that do not correlate with anything they can identify. Most are gone in three sweeps. Most are noise. And yes, Ron, the job pressure is real and the career risk is real and there is no form to fill out for "I saw something I cannot explain."

Thank you both for this. I have been curious about the false-target rate because almost every UFO report with radar involvement seems to skip the part where someone asks "what percentage of radar returns are just noise?" If the noise rate is high enough, an interesting target can look like a ghost.

Questions: Can you say what fraction of a typical radar sweep is uncorrelated targets? And of those uncorrelated targets, how long do they typically stay on the scope before resolving or vanishing? If a target hangs for four or five sweeps before disappearing, is that unusual?

Occams: on a medium-busy day, maybe five to ten percent of the blips in my airspace are uncorrelated at any given moment. On a stormy day, it climbs. Most of those resolve within two or three sweeps, either the flight plan data catches up to a transponder signal or the target just vanishes. Targets that hang for more than five or six sweeps without correlating to anything almost always resolve as weather when I push the weather radar overlay. The weird ones, the ones that do not show on weather and are not in my flight plan database, are very rare.

I can count on one hand the times I have had something sit there for more than ten sweeps and not resolve. And those times, I have always eventually figured out what made the return: the crew of a nearby airplane confirmed they saw something that looked like a balloon or a light, or ground gave me word there was construction activity or a helicopter that was not filed, or I realized I was looking at the same target painting twice because of multipath or ground bounce. Always something, in the end.

Except one. August of last year. I will not say which tower or which date, because I want to keep my job and I do not need the phone calls. But I had a target that was solid for about sixteen sweeps, maybe four or five minutes of real time, moving east to west through my sector at a steady speed of about 240 knots. I asked the crew of the nearest airplane if they had anything visual. They did. One pilot said "unidentified object, looks like a metallic finish, not moving relative to us now, we are slowing to try and get a better look." I logged that I had asked them to look, and they reported a visual. Did not log what they saw, because what they saw was UFO-shaped and I would look like an idiot, and then I looked at the next sweep and it was gone. Radar and visual, both gone. No transponder signal ever. No crash report. No second call. I do not know what it was. I have thought about it, I have tried to fit it into everything Reg and I have told you about radar ghosts and propagation and birds, and it does not fit well. Maybe it fits and I am just not smart enough to see how. But I thought about it and I have no answer to give you. That is what I saw and that is what I do not know.

Ron, thank you for that. That is actually more useful than you might think -- not because it proves anything, but because it is a working person saying "I did my job and I do not know what I saw." That is rare. I work as an investigator for MUFON and I can tell you that the question I run into constantly is "did the controller report this?" and the answer that comes back is almost always "no, and they would not put it on record."

My question: how hard would it be, if a pilot or controller had actually, genuinely seen something that seemed important, to get on record about it? What would the process be? What would keep him from doing it?

Gail: the answer is, it is nearly impossible, and that is not a conspiracy. It is just how the system works.

The official channel is to file an ASRS report -- that is the Aviation Safety Reporting System, a voluntary safety reporting system run by NASA. It is anonymous by design. You fill out a form that says what happened, what was unsafe about it, what you did to fix it. The form was designed to get people to report safety problems without fear of retaliation. That is a good form for reporting a near-miss or a procedure problem. It is a terrible form for reporting that you saw something on radar you could not identify.

If you use ASRS and you say you saw an uncorrelated target on radar and it had a visual component and you could not identify it, you have now told NASA and the FAA that you saw a UFO on the job. That report is supposed to be confidential, and it usually is. But if a pilot or controller becomes known as the person who reports UFOs, the reputation follows, and rightly or wrongly, it makes other things harder. So nobody does it. The culture is: file ASRS for safety problems. Do not file ASRS to say you saw something unexplained. Somebody will read that form and think you are not careful.

Could you call an investigator like Gail? Yes. But then you are on the record with an investigator outside the official system, and that is riskier, not safer. If the FAA finds out, the very fact that you went outside the system makes it look like you knew what you saw was important enough to hide from the FAA. So you do not do that either.

The result is that the most interesting sightings never get reported anywhere, because the system that would reward reporting them to the FAA makes reporting them look suspicious, and the system that would let you talk to an investigator is outside the official chain and therefore more dangerous. Catch-22. So the good targets, the ones that are strange enough to matter, never get written down anywhere official, and they never come out, and they vanish into the log of things controllers thought about and never told anyone. I am telling you now because it is the internet and I am anonymous and I have nothing to lose, and also because I do not know what I saw, which makes it easier to talk about. If I actually did know what I saw, I would not say a word.

Ron and Reg: this is more useful than a hundred blurry photographs. I am a skeptic, and I mean that genuinely -- I want to know what things are. And what you have just done is explain why the radar evidence we have access to is not a representative sample. It is the leftover stuff. The boring residue that did not matter enough to hide or report. That changes how I read a radar report.

You have also done something else: you have made "I saw something and I still do not know what it was" sound like actual data instead of a conversation-ender. Thank you for that.

I do not know if the target Ron saw was anything exotic, but I know now why he would not report it and why no controller in his position would report a target like that, and I know now what that silence means. That is worth a lot.

I am not qualified to talk about radar, but I was curious about one thing Ron said. He said the pilot asked the crew of the nearest airplane if they had anything visual, and they said they did see something, looked metallic. Did the pilot try to steer closer to it? Or did they just look and wait for it to disappear? I am trying to understand what a crew would do in that situation.