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ORD Approach



Click here to download sector ZAU1 (ORD Approach)

Instructions: Download this ZIP file to somewhere you will remember, such as your desktop, then unzip the contents to your ATCC folder. Answer "yes" if asked to overwrite all. This sector requires ATCC, of course, and assumes you have already downloaded sector 4. If not, a sector 4 button will appear on the panel, but just ignore it.

This ORD sector is just for fun and experimentation. ATCC was designed to accurately simulate the Center environment, not an approach control, so there are a number of "unreal" aspects to simulating Chicago Approach using ATCC. Still, it's fairly close, and is a good taste of the duties of a "final" controller.

Working Chicago Approach Sector ZAU 1

These are quick instructions to get you going---print out this page, for reference. One significant change is that if you are using the CD-ROM version of ATCC (V1.1), you only need three miles of separation (instead of 5), and the radar will update every 6 seconds, instead of 12, like real Approach radar.


The map is simple. Chicago (ORD) is in the middle of your screen. Runways 27 Left (the east to west one) and 22 Right (northeast to southwest) are active, and are drawn to scale in solid lines. Runway centerlines (dashed lines) extend out 20 miles from the beginning of the runway--- use these as guidelines to line up aircraft for approach.


You have two jobs at the same time, working as "final controller" for runway 22R and for 27L. During busy periods, these would be split so one controller would just work each runway. But, due to short staffing, you have to do both!

As in real life, there are four arrival streams coming toward ORD-- one from the northwest, northeast, southeast and southwest. The Northwest and Northeast arrivals have been told by the previous controller to expect runway 22R, and the Southeast and Southwest arrivals have been told to expect 27L. The spacing is set up so there should be enough room to fit everybody in the expected runways. However, it is possible to move an aircraft to the other runway if one side just gets too busy (more on that later).

NORTHEAST ARRIVALS: The Northeast arrivals enter your sector at 8,000, and 250 knots, and are already lined up for a straight-in approach to runway 22. Just descend these to 3,000 pretty much as soon as you see them.

NORTHWEST ARRIVALS enter at 9,000 and 250 knots, on a 090 heading, expecting runway 22R. You need to turn these arrivals to fill in the "gaps" between the Northeast arrivals, usually by turning them to "base leg" (about 130 heading) when around due north of ORD, then clear them for approach to runway 22 with ..W (dot-dot W, for "cleared runway two-tWo right approach.") When you clear them "direct W" with ..W, they'll turn toward and line up with runway 22R. They must also be descended to 3,000.

SOUTHEAST ARRIVALS enter the sector at 8,000 feet, 250 knots, and are direct ORD, expecting runway 27L. You should turn these to "base" (360 heading), then to "final" with ..S (for "cleared runway two-Seven left approach") and they'll line up with 27L. These must also be descended to 3,000.

SOUTHWEST ARRIVALS enter the sector at 9,000, 250 knots, on a 090 heading. They must be turned to base (360 heading), then to final (..S) and descended to 3,000. They must, of course, be merged together with the Southeast arrivals.

DEPARTURES: No departures! Another controller handles those. You will see a few departures on your scope headed to the west, bound for sector 75. Other departures aren't implemented in this test version...they'd normally climb well above your arrivals, anyway, so you wouldn't really see them if they were there.

OVERFLIGHTS: No overflights! The real O'Hare approach doesn't allow overflights through their airspace. Or VFR aircraft for that matter... you'll just see a big black void, so you can concentrate on the arrivals.

SWITCHING RUNWAYS: Normally, the Northwest and Northeast arrivals have been told to expect runway 22R, and likewise the Southeast and Southwest arrivals are expecting 27L. To switch them to the other runway, you have to say "..WWWWW..ORD" to tell a south aircraft to now go to the north runway, and "..SSSSS..ORD" to tell one of the north aircraft to switch to the south runway. They will acknowledge you, and turn direct to the other runway, at which point you should turn them out (fly heading 090, for example) to steer them around to the other side. Once you have turned them in place for the new runway, clear them for approach as before, with ..W or ..S. It is awkward to do all of this, and normally you shouldn't have to, but it is possible.

HANDOFFS: Things happen so fast, that you don't take handoffs, and aircraft don't check on to your frequency. The datablocks just appear, and you have to work them whether you want to or not. The aircraft are all on your frequency as soon as you see them, and don't check in (they're told to "monitor 125.0" by the previous controller).

You must, however, make a handoff to SECTOR 11 (the tower). Do not hand off to sector 11 until the aircraft is either lined up for the runway, or is just about to the Outer Marker (where the dashed runway centerlines begin, about 5 miles from the airport). Once the tower has a handoff on an aircraft, the aircraft will automatically switch over to the tower frequency by itself, after passing the Outer Marker.

FREQUENCIES: There are no frequencies to memorize-- handing the datablock off to the tower is akin to telling the aircraft in real life: "contact tower 126.9 at the outer." The aircraft will remain on your frequency, until it is about 5 miles from the airport, then will automatically go over. (If it doesn't, for some reason, ORD tower is 126.9).


Remember, this is an EXPERIMENTAL/TEST version, and we aren't attempting to fully and accurately simulate an approach control. It is not intended to become one of your 6 main sectors, though technically you can certify on it (ATCC will replace the most recent sector you certified on with this sector, if you already have 6 sectors under your belt). There are some bugs we do know about, such as aircraft suddenly hovering in mid-air, or speeding off at 1,000 knots. If you get one of these, hand them off to the tower, then remove them from your scope.

Several loopholes were used to make ATCC act more like an Approach control. One of these loopholes is the use of ..W to clear an aircraft for approach to runway 22, and ..S for runway 27. The aircraft will readback "cleared direct runway 22 right" (or 27 left). What they would really say is "cleared approach runway 22 right" or readback the ILS instructions. But, it's close enough.

Also, aircraft still think they're in the "Center" environment, so they're a little slower to respond (as opposed to the real-life ORD, where everybody's at ultimate alertness and makes QUICK readbacks). And, they may keep bugging you for lower. Just ignore all of them and keep things moving!

Quick Hints

-- The ATCC computer controller never expected to work an approach control sector, and is absolutely awful at it. Plug in right away, and don't use ATCC to "warm up" the sector before plugging in, because you'll be left with a huge mess. Also, it's best to always run the sector in "train" mode, because you'll get unfair deals if you try to "work" it. Leave the traffic level permanently at 100 for a realistic depiction of real-life ORD traffic.

-- At the 250 knot speeds in the sector, each aircraft moves basically a half mile per update. If you want to see what 3 miles looks like, click up the histories to 5, and it is one and a half times beyond that. Or, if you have vector lengths in "minutes," (CD-ROM version only), it's about 3/4ths of a vector length of 1. Real-life ARTS radar equipment, though, doesn't show histories per se, so set histories at 1 if you want a more realistic display. Generally, traffic flows come into the sector 10 miles in trail, so just aim for the middle-point in the gaps, and you'll still have a little extra room to spare.

-- In real life, aircraft slow down considerably (to 160 knots or less) as they get close to landing (starting at 5-10 miles away). To alleviate "compression," where following aircraft start to catch up with front aircraft, approach controllers start slowing everybody down to 210 knots or so when about 20-30 miles away, then to 180 knots when they're on final. The faster the aircraft move when on final, the more aircraft you can work, and in ATCC everybody will gladly remain at 250 knots until just about ready to land. So, you can just leave everybody at normal speed (250 knots), and things will run a little faster than in real life, but that somewhat compensates for some of the limitations in the sector.

-- Utilize the ability to use a period for a comma, so you can stay on the keypad as much as possible. In fact, either ..W or .W works the same (or ..S or .S), so you can type 350..W entirely from the keypad (except for the W) to clear AAL350 for the approach to 22R. Also, altitudes below 10,000 only need 2 digits, so 3,000 is 30, and 8,000 is 80, for example. As in: 123<down arrow>30. If you're busy, don't bother with temp altitudes, because approach control doesn't use them.

-- Though ..W or ..S is a little awkward to type, it is a lot easier than what the real-life ORD controller would have to say (for an ILS approach): "AAL350, you're 8 from WILTT, cross WILTT at or above 3,000, cleared ILS 27R approach, maintain 180 knots to WILTT, tower at WILTT 26.9" or something similar, for every aircraft.

-- Once you have made the handoff to the tower (sector 11), and the aircraft is about 5 miles from the airport, remember that it will switch over automatically (no * command needed), and you can safely remove the datablock. The ATCC tower controllers were never programmed to get arrivals from a human controller, though, and they occasionally get overwhelmed, panic, and switch aircraft over to the other runway right at the last second. Thus, you'll see aircraft near the airport suddenly dart out to the east to go to the other runway...just ignore it. Also, once the tower has the handoff, be sure not to steer any of your aircraft within about 5 miles of the airport (like when going over to the other runway), or the tower will "grab" them and tell them to land, figuring the computer was working Approach control and somehow messed things up.

-- You might try descending the arrivals from the northwest and southwest to 5,000 (to prevent them from asking for lower), and the southeast arrivals to 6,000. The northeast arrivals should be descended to 3,000 around the time they reach the dashed centerline for runway 22R. Once you've merged the various streams together, descend them the rest of the way to 3,000. Remember to use positive separation, though... if two aircraft are headed toward each other, or you aren't sure if you'll be able to "fill the hole" with an aircraft, make sure you have altitude separation until you are positive you will have, or already have, the proper spacing. Then, and only then, descend them the rest of the way.

-- Once aircraft are on Base (90 degrees from the runway heading), turn them to Final (..S or ..W) when they're about 2 to 3 miles from the centerline, and they should roll out right on target. If they spill over, though, they will correct by themselves, but it looks sloppy. You want a nice, neat string of pearls!

-- Unless you assign them a heading, the Northwest arrivals will automatically turn onto final for runway 22. If you want them to fly past the runway 22 centerline, tell them to "FPH" (fly present heading), or otherwise turn them to a new heading (like 5 or 10 left). If there is no gap to fit them into right away, you can turn them "downwind" to a 40 heading, then later onto Base with a 130 heading and then final with ..W. It's awkward to turn them straight from their 90 heading to final (about a 120 degree turn), so you should turn them to a 130 heading first, when they're about 5 miles (or more) from the centerline.

-- You will work many more aircraft than with the normal Center sector, so watch out for similar callsigns. Try to use the full callsign number (like 257 for UAL257, instead of 57), to avoid the wrong aircraft (like DAL157) taking the instruction. If you notice an aircraft descending on its own, that's probably what happened.

-- Timing is everything... If an aircraft on downwind (like the arrivals from the southwest, or from the northwest if you turn them to a 40 heading) is 5 or so miles parallel to Final, turn him onto Base when he is about two miles from being "nose to nose" with the one he's following (already on final). Then when he's about 2 or 3 miles from the centerline, turn him onto final with ..W or ..S. If you're late with a turn, you'll mess everything up, so you need to be at maximum alertness! The tower will still take them less than 3 miles apart, though, so just leave one at 3,000 and one at 4,000 if you don't have the right spacing, and hand off to tower as usual. In real-life, though, there's no room for error... if you don't get the proper spacing, turn one of them back onto downwind, or maybe re-assign them to the other runway, if you see a "hole" over there. You will eventually develop a "feel" for how long it takes aircraft to turn, and when the right moments are to start their turns.

-- The J-rings (<F7>J) are still 5 miles wide, though if you have the CD-ROM version (V1.1) you will only need three miles of separation with this sector. Real approach radars don't have J-rings, though, so you shouldn't use them.

--Revision 3, posted November 19, 1997



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