Flying the System It was late in 1981 or maybe early in 1982, because that's the only time in the history of O'Hare that the

Flying the System

It was late in 1981 or maybe early in 1982, because that's the only time in the history of O'Hare that the draconian departure restrictions in this tale were used. To understand how those departure restrictions fit into our story, you need to know a little about how IFR departures work at the world's busiest airport.

Everybody gets the same instrument departure procedure (currently the O'Hare One), which routes them over one of more than a dozen standard departure fixes, depending on requested altitude and direction of flight. If you're eastbound at high altitude, you can file whatever you want but you'll get the O'Hare One over either Keeler (ELX) or Gipper (GIJ). These fixes coincide with a letter of agreement between Chicago TRACON and Chicago Center, specifying that the TRACON ensures all high-altitude, eastbound departures are handed off to Center in two single-file lines, one destined to pass over each fix. Similar agreements cover high-altitude routes in other directions. The radar separation minimum for most Center operations is five miles, but in order to allow for margin of error (and these days, to keep the computer "snitch" quiet), the actual in-trail spacing on these routes is closer to seven.

Ideal vs. Reality

Chicago O'Hare (KORD) Airport Diagram (click here for larger version)

On ideal days, tower controllers launch departures with only three miles in-trail separation between airplanes going over the same fix. Departure controllers increase that spacing to at least five miles. Doing so isn't difficult: The speed differential between a departure three miles off the airport and one just breaking ground is substantial, so spacing naturally increases. More space can be obtained via speed control and/or vectoring if necessary.

On less-than-ideal days, when thunderstorm activity requires that the Center allow pilots leeway to make course deviations, or when controllers must provide radar vectoring to avoid big, black clouds, more spacing is required for all the zigging and zagging. The call goes out to Chicago TRACON, and to O'Hare Tower, with a restriction that will put fewer airplanes into the affected airspace. Such restrictions can involve more in-trail spacing, the combining of multiple routes into one, or a combination of both. A restriction such as, "Treat Iowa City (IOW) and Dubuque (DBQ) as one fix, 20 miles in trail," is common during thunderstorm season. The result is two airplanes in the airspace where, previously, there were eight or nine.

Since even the best departure controllers have a hard time making 20 miles out of the normal three, it's up to the folks in the tower to make up the difference, via the oldest method of separating airplanes ever devised: holding takeoff clearance until the in-trail will exist. If there's only one way to access the runway, the delay affects not only the aircraft in question, but every aircraft in the line behind it. Consequently, ground controllers at O'Hare put a lot of effort into providing a split -- separating like-fix departures from airplanes going in a different directions -- to avoid such delays.

Hurry Up and Wait

Now go back to 1981 and the months and years immediately after the PATCO strike. The five-mile minimum all but disappeared. Center controllers were stretched thin; many were working multiple sectors simultaneously, and they needed more than five miles. Twenty-, 30- and 60-mile restrictions became standard. The slightest problem with weather, of course, would exacerbate things. The result was an airliner traffic jam on the airport, pretty much all day, every day, for months after the strike.

On this particular day, I was working south Local (Tower controller), with 50 or 75 jetliners lined up for my three departure runways: 22L, 27L, and 32L from the T-10 taxiway. The line for 22L stretched over a mile down the cargo taxiway and the 27L parallel taxiway was solid with nose-to-tail jets. The 32L departures stretched out from the departure intersection at T-10 up into the terminal area. Fortunately, arrivals were being vectored for landings on the north side of the airport, where a different local controller dealt with them. My only job was to roll departures, and comply with the in-trail restrictions between airplanes cleared over the initial same departure fix. It was sometimes a slow process.

Enter the FLIB

I received a landline call from an Approach controller in the radar room 20 floors below me who knew my reputation for being "FLIB friendly." (FLIB is an unofficial controller acronym for ... um ... "Friendly Little Itty Bittys.") He wanted to get a Cherokee out of his hair, and off his frequency, just a little sooner.

The Cherokee was southeast of O'Hare, IFR to Schaumburg airport, located nine miles to the west. The problem was that while Schaumburg was VFR, the Cherokee was in IMC at minimum vectoring altitude and Schaumburg had no instrument approach. The pilot needed to make an instrument approach somewhere to get out of the clouds.

This wasn't unusual, and the normal procedure was vectors to Dupage airport (eight miles southwest of Schaumburg) where the pilot could make an instrument approach, break out, cancel IFR and then proceed VFR to his original destination. The question for me from the Approach controller was this: "Howzabout, rather than vectoring this guy all the way out to Dupage, we put him on the ILS to 32L at O'Hare? When he breaks out, give him a clearance to exit the O'Hare airspace, VFR to the west."

"Sounds good to me," I said, and a few minutes later I spotted the radar target of the Cherokee inching down the 32L final approach course.

As I perused the flight strips representing the jets at my departure runways, it became apparent that, despite everyone's best efforts, the in-trail restrictions were about to take their toll. When the Cherokee was about a seven-mile final, I ran out of rollable airplanes. The next aircraft in line at each of the three departure runways was subject to a delay and, with the traffic jam, there was no way to get any non-restricted aircraft to a runway. I made my brief, and somewhat routine, explanation on the frequency of why departures were stopped and for how long, and then sat back and waited for the Cherokee pilot to call.

The Cherokee driver was not enthusiastic about his O'Hare adventure. He nervously announced JOCKY inbound on the ILS. I asked him to report canceling IFR. He did a minute later and requested a VFR departure to the west.

With two-and-a-half miles of empty runway in front of him, and me with no one to use it for the next few minutes, I couldn't resist: "Unable. Cleared for touch-and-go on three two left, then your westbound VFR departure is approved."

You Gotta Be Kidding!

Better make it a greaser. Half of O’Hare airport has nothing better to do than watch.

Silence, at first. Then, a stammering explanation of how all he really wanted to do was go to Schaumburg and that it hadn't been his idea to make an approach to O'Hare in the first place. Clearly, he thought he was in the wrong place at the wrong time and that the touch-and-go clearance was some sort of controller code relating to his penance.

"No problem," I replied. "Cleared for the option -- low approach, touch-and-go, whatever you like. At midfield, you can turn westbound." I didn't want him going westbound from where he was. That would put him in conflict with the 22L and 27L departures that I planned to start rolling shortly. I needed him to come to the runway first, and then start the turn to the west.

He finally grasped that he was being offered a rather unusual opportunity. "Oh! OK, I'm cleared for a touch-and-go! I won't start my turn until midfield! Wow, thanks!" Creeping down final he spotted all the jets lined up for takeoff and asked, "Uh, Tower, all those airliners aren't waiting for me, are they?"

Before I could answer, someone said, "Nah, we just heard there was a Cherokee coming in here to do a touch-and-go, so we all came out to watch." The bewildered Cherokee pilot touched down softly, then lifted off and began a turn to the west.

After that, each pilot seemed in a particularly good mood. Many offered some wry comment. "Thanks for the half-time show," said one. Another observed that the Cherokee pilot would have a logbook the rest of them didn't -- their O'Hare landings were always to a full stop. He sounded a little envious.

The pilot of the Cherokee was effusive in his thanks as he departed the O'Hare airspace. I assured him that it was all part of the day's work, and not to worry, he hadn't delayed any airliners. As I approved his request for a frequency change to UNICOM, he acknowledged, then made the comment that has stuck with me all these years: "Man, the guys back in Columbus aren't going to believe this!"

They probably didn't. I hope that now they do.

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