ZJX vs ZAU

Vive la Différence

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Well, “vs” (versus) might be a little strong. It’s just that there were some differences in the two facilities that required some adjustment on my part. Recall that I had nearly three years as a full performance level, high altitude controller in ZJX before I got to ZAU. I won’t elaborate on the FPB (Funtional Package B, which was the prototype radar data processing component of NAS Stage A, Functional Package A—the flight strip processing prototype), except to illuminate the crossover in utilities I expreienced and that very few (if any) others experienced.

I got to use FPB for more than a year at ZJX. We knew all along that both FPA and FPB were prototypes of the eventual NAS automation initiative. FPA had been on line since roughly 1969, and by 1972, its replacement, which we called Model Three, was being prepared for installation in the rest of the ARTCCs. I received a class on Model Three and then served as an instructor to get the troops a leg up on features and differences between it and what we’d been shaking down.

In truth, I was teaching from the book version of Model Three, as I never got my hands on it until I got to ZAU. And, by the time I got there, it had been installed, ORDed (Operational Readiness Demonstration), and certified for operational use for some months. Because of my training, I was at least a leg up on the system. The flight data processing incorporated from the basics in the prototype (FPA) into the new version (Model Three) remained essentially unchanged for the rest of my career. There was the odd patch here and there, as well as added features, but they were small beer compared to the overall system’s function and capabilities.

The more real differences I noted were radar procedures and strip marking. I have a comprehensive essay elsewhere in this section of the site that addresses ZAU strip marking. Even though the ATP (Air Traffic Procedures manual, FAAH 7110.9 then, 7110.65 now) covers strip marking, it’s a virtual Cliff Notes survey as opposed to the multiple page, actual handbook distributed to ZAU controllers. In any event, I won’t cover it further here.

There were also some equipment differences between the facilities—primarily in the controls for the radar displays—and worthy of a separate essay which I’ll undertake at a later time. And seriously, who, except a bunch of ZAU old timers were even aware of the Tasker modification and why it may have mattered?

No, the differences were more operational. For example, the size of the shrimp boats were different. The ones at ZAU were probably 15% smaller. It made sense when one saw the difference in the amount of airplanes we were handling at any one sector. And that was another thing, at ZAU we had sectors that were nearly 250 miles long. Even Ocean in ZJX wasn’t that long, even when combined.

Also, we wrote the altitudes on the shrimp boats in ZJX, not at ZAU. I suspect that difference was accounted for in the distinct difference in the kind of traffic at each. ZJX was primarily an overflight facility. An airplane that crossed the boundary with ZDC at FL310 was likely to still be at FL310 when it crossed the boundary with ZMA. ZAU was an arrival/departure facility, and altitudes of both were in flux for the bulk of their time with us.

Another difference, and one that made absolute sense to me, is how altitudes were written. The national standard (not just in ATC) is to express (in writing) altitudes in hundreds of feet. Thus 6,000' is written as 60, even though it’s still said as 6 thousand. At ZAU, we wrote altitudes in thousands. Well, we hand wrote them that way—FPA and its later equivalent continued the hundreds-of-feet paradigm. The odd thing is, that everywhere I know of, when dealing with VFR altitudes it’s always expressed in thousands, e.g. “six point five”.

I wrote in my biography about the red/blue two ended pencil we used in ZJX. Well, that was practically the first thing to go when I got to ZAU. When I whipped mine out (pencil), the other controllers laughed and remarked they hadn’t seen one of those in years—not since the Academy. We used ball point pens. And in many cases, we didn’t use the ball points—we used the grease pencil (China marker) which were also used on the shrimp boats. Almost everyone working the coordinator position wrote the coordinated altitudes on the strip with a grease pencil.

Coordinator? Yeah, every ARTCC has overhead booms, usually four per row, equipped with headset jacks, landlines, and even transmit/receive frequency selectors. In ZJX in the infrequent cases where someone was plugged into the boom, it was by a supervisor and was more of an oversight position than an actual control position. At ZAU it was a control position, it was staffed by controllers (as well as supervisors), and they were generally staffed ten to twelve hours per day.

I don’t know what comm (landline or R/T) funcions were available in ZJX, but in ZAU, in addition to lines to other centers or approach controls, there were three or four (in house) landline circuits cleverly labeled 1 through 3 or 4. If I recall, East High, East Wing, and East Terminal were on circuit 1. West High, West Wing, and West Terminal were on circuit 2, and the North wing was on circuit 3. As I think about it some more, I realize we must have had two coordinators each in high, wing, and terminal (both East and West) sharing the line.

When an arrival was approximately 150 miles out from the coordinator (who has been overseeing the whole time) keys his headset and calls the associated low altitude coordinator and asks the associated terminal coordinator to copy. Upon response, the high coordinator identifies the target (todays “point out” to low who, upon surveying the low traffic, releases an altitude for the flight. FL200 was the usual released altitude. The high coordinator then marked 20 on the strip (reaching between the D and R controllers to do so). As the flight neared 100 miles out, the high coordinator called the terminal coordinator with the actual hand off and marked the strip with a “C” in the callsign box. The terminal controller would place the shrimp boat (prepared earlier, usually by the D side, its existance indicated by a slash across the call sign box) on the target. The release of altitudes and the handoff/point out made the C position an actual control position.

Sector boundaries. We had them on the screen in ZJX, but not at ZAU. I found it quite disconcerting. Not so much that I played fast and loose with sector boundaries, but that it seemed so unstructured. How could you tell when you’d vectored someone too far, for example, or when it was time to make a handoff to the next sector? Mercifully, when we got RDP, sector boundaries were included.

As it turns out, however, that was another annoyance. I had often hollered at adjoining center sectors who had handed flights off to me then didn’t promptly ship them. More than once I got on the line and said, “if you’re not going to ship ’em when you hand them off, don’t hand them off until you’re ready to ship them!” At ZAU, it was not uncommon for the coordinator handling the DBQ High sector to place a shrimp boat on the IOW High scope for a NW flight transiting from MSP over BDF and to points south, then handing the flight off to the BDF coordinator by placing the (prepared) shrimp boat on the radar. There I was, working BDF, for example, when someone slaps a shrimp boat on a target 100 miles away from my airspace, which I now have to track and probably work for a far longer time than I ought to have to. AND, I’m in the middle of my own arrival rush!

When I got to ZAU, they were in transition to RDP and at the stage of occasional live use. To keep perspective in this narrative, I’d had something near two years of FPB in ZJX, which was basically broadband radar with data blocks attached, much like ARTS (Automated Radar Terminal System). Then I had five months of actual ARTS, before going to the center and getting to work on RDP. I was shocked to discover that RDP was narrowband…oh, dear. I’m going to have to explain.

The radar we used in the ’60s and half of the ’70s was raw radar (much as you would see in a TRACON) which was a live video feed from the antenna system at the radar site—on the airport at towers, remote locations in the ARTCCs. The video was either cable fed (towers) or brought in by microwave to the ARTCCs. The story splits somewhat as TRACONs used the raw radar on what’s called PPI (Plan Position Indicator) scopes. The center had the same downstairs, but they essentially put a video camera in front of it and piped the signal upstairs to our RBDE (radar bright display equipment) scopes. Nevertheless, the microwave was necessary because the raw video took up a lot of RF spectrum, far more than landlines were capable of carrying, and thus the radar display was called broadband.

Well, we didn’t call it broadband until the plan to digitize (make into ones and zeroes) the radar at the sites was implemented, which reduced the bandwidth to less than voice width, and which became known as narrowband. However, much like NAS which means National Airspace System and encompasses every aspect of, well, the national airspace, morphed into a synonym for Automation, both broadband and narrowband were reframed to describe the kind of display on which one was working. And by display, I don’t mean the PVD (plan view display), I mean which mode you were displaying on it.

Ironically, broadband versus landline…the original raw radar versus the modern, ones and zeroes radar, as contrasted to today’s internet systems, in which data used to come in on the landline which couldn’t support video bandwidth, versus systems capable of transmitting video, known as high speed or, wait for it, broadband. Just the reverse, don’t you see.

Nevertheless, when I got to the floor at ZAU, RDP is what I was exposed to, and it was completely different from FPB and ARTS. It wasn’t remotely a difficult transition—in fact, I certified in all of West High in about six weeks. That was an unheard of at the time, but I’d brought lots of experience. There were, however, a couple of bumps in the “upgrade”.

For one thing—and this a mere tidbit that didn’t have much import to center controllers, although it could be useful on occasion—with narrowband we lost the capability of reduced separation (from five miles to three) within forty miles of the antenna. I must digress (again) for a moment. That was due to the fact that every square mile of the facility’s responsibility was mapped by coordinates and divided into units called “sort boxes”. Each sort box was assigned a primary radar source and a secondary radar source (not primary and secondary like skin paint versus beacon, but principal versus subordinate), and there was no way of knowing from the controller’s seat, which radar information was being presented for any given sort box, at any given time. Whew!

But, the huge, monstrous bump was in weather presentation. Historically search radar is not congruent with weather radar. They share a principle and they mostly share a presentation platform. But they operate on different frequencies, for one thing, and as a result of that and other technical differences beyond the scope of this essay (or its author), “see” things differently. Both kinds of radar will display returns from rain. Weather radar more so than search radar. In search radar, however, the two subsets (broadband and narrowband) are widely different in presentation.

Speculating, because I don’t actually know, I believe whatever algorithm was chosen to convert raw video at the site to ones and zeroes, was a compromise when it came to weak returns such as with precipitation. In fact, I was taught in ZJX, even on broadband before there ever was narrowband, to never describe to pilots what we were displaying as “weather”. It raised expectations too high when they sometimes asked for help in deviating around weather, so we always hedged (or at least I did) by referring to “precip” trying to make clear that we were unable to distinguish heavy precipitation from cells of truly violent meteorological events.

With broadband, one could interpret gradations of the returns and interpolate, reasonably accurately what might be heavier precipitaion and thus, more violent conditions. When we got to using narrowband regularly, for all its advantages, we learned that recoding to ones and zeroes had removed that possibility. We had given up a lot in the service we could provide pilots in potentially disastrous conditions. In many cases, we were proved so wrong trying to do what we’d been quite successful at with broadband radar, that with narrowband, we virtually discontinued trying.

I’ll conclude (finally) by saying there were quite a few differences between the two facilites which didn’t just relate to traffic count or staffing. Everyone who transfers to another facility has to make adjustments to accommodate local peculiarities, capabilities, and practices. It’s not necessarily difficult, it’s just something to embrace and accept. I’m trying to remember an instance of washing out a journeyman controller from another facility, and while it’s possible, I don’t remember one. Oh, wait—maybe the Miami Bomber. Those who were there will remember. Those who weren’t will probably have to remain unenlightened.




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Last updated: 21 April 2016