Another ? for ATCers - Writing a Paper

[minitour]

I've got a paper to write about "Aviation Safety" ... pretty basic. It can be about anything I want as long as it is related to safety. So I figured I'd address the airport environment. Runway incursions, LAHSO, taxi instructions, ATC, stuff like that. So here's the first question that I can think of to ask:

We'll talk about ORD, since (I would assume) almost everyone is familiar with the stuff that goes on there. Here's the diagram if you aren't familiar.

http://download.aopa.org/iap/20041125/airport_diagrams/00166AD.PDF


Lets say we've got five aircraft at the "Cargo Area" on the lower left portion of the diagram. We've got a C152, Baron, KingAir350, CRJ, and a 747. I just kind of picked these planes out of nowhere, so it might not have any baring on the situation...just hang tight.

Current Situation:
Info T - Winds 190/08 - 10SM - CLR - 1/M1 - A2991
Arrivals:Vectors ILS 22R ILS 27L Visual 27R LAHSO 22R / 27R
Departures:22L 32R 32L at T10

Before I continue: Those of you that fly into/out of there or those of you that work ATC there...wow...major props to ya...

Moving On:
So we've got our 5 aircraft at the cargo area and one at a time, they call up metering and such...ground gives 'em a call and tells them to taxi to 22L (they're all South Departures) via K T12 T S Q...

I understand that they've been cleared to taxi across all runways and taxiways along that route except for their runway (22L) but how does that work with departures going off of 32L?

Is that something that Ground works out with Local before issuing such instructons or doesn't it even matter since the departures are going from T10 which is way the hell down the runway?

The reason I threw in the different aircraft is because I know there's some rules out there about having more than 1 aircraft on a runway at the same time....could be a landing thing though...

Anyway...any help is appreciated
Thanks!
-mini

 

[Vector4fun]

We'll talk about ORD, since (I would assume) almost everyone is familiar with the stuff that goes on there.

Mini,

Wow, major assumption on your part. ORD ATC is kinda like sausage, I'm not sure I wanna know what goes on there.

However, given the conditions you described, I would *assume* the Local and Ground have an agreement that ground can cross 32L south of T10 at will unless otherwise coordinated. That's not illegal. The problem's gonna come at the approach end of 27L.

In the "real world", and not having a clue how ORD actually assigns departures to runways, I'd probably give the 74 the full length of 32L for departure, the CRJ the full length of 22L, and the rest an intersection departure on 22L from S4. That, of course, would depend on how many other departures were staged to go from the end of 22L.

The full length of 22L does not seem like a good choice for very many departures as they would be in the 27L ILS and approach safety area for some time as they took the runway and started roll. Going from Q might help a bit, but from the diagram, it appears departures would need to hold north of 27L at M untill cleared into position, or cleared for TO. Seems like a potential for an unfamiliar crew to depart 27L instead. That might seem silly, untill you've seen pilots line up for TO and Landing on taxiways, roads, stopways, etc.

"Cessna XXX, uh, well, just fly taxiway heading..."

I actually heard that one once.

 

[Sctt@NJA]

At big airports you are likely to get taxi instructions in stages. Sometimes many stages with multiple frequency changes along the way.

If there are active runways between where you are and where you are going you will likely be issued "hold short" instructions. You can also be told to hold short of taxiway intersections.

It is true that when cleared to taxi to a runway you are cleared to cross any other runway to get there (but not the one you were cleared to if you need to cross it to get to the end). Thats why most of the time you will get taxi instructions with "hold short" locations that are critical to read back and understand!

 

[minitour]

Wow, major assumption on your part. ORD ATC is kinda like sausage, I'm not sure I wanna know what goes on there...
"Cessna XXX, uh, well, just fly taxiway heading..."

I actually heard that one once.

LOL x2

I just meant "what goes on there" as in: Busy...lots of traffic...whole bunch of **CENSORED****CENSORED****CENSORED****CENSORED** all at once...

Anywho...thanks guys...This paper's a beast....I have to figure out a way to get 10 pages out of this stuff...

Break out the Coffee

-mini

 

[Flibmeister]

There are several "real world" problems with your scenario, but to answer your basic question, no, Ground Control doesn't make any arrangement with Local Control for runway crossings-- at the approach end of 32L with departures at T-10, or anywhere else. The only time Ground Control is allowed to cross a runway at ORD without specific coordination is if that runway is closed (which may be an officially notamed closure, or an "in-house" closure, where all controllers in the tower are made aware that the runway is not to be used for takeoffs or landings).

In your scenario, Ground Control would issue "hold short of 32L" with the initial taxi instructions. Depending on how busy each controller is, the Ground controller might keep the airplanes on his frequency and verbally coordinate with Local for crossing, or he might pass the flight progress strips to the Local controller and put the airplanes on his frequency for crossing. After crossing 32L, the same will apply for the 27L crossing-- the Local controller working that runway will specifically authorize the runway crossing, either directly or indirectly.

While it may seem reasonable for such crossings to work under a precoordinated arrangement, 32L is the longest runway at ORD-- which means that arrivals that are unable to use the "normal" arrival runways will be individually coordinated (from approach control) and landed on 32L. This coordination goes direct to the two local controllers involved (the one handling the 32L T10 departures, and the one handling the 27L arrivals/22L departures). It's quite possible that Ground Control will be totally unaware that there's a 32L arrival inbound, so to keep things simple, all runway crossings must be either made by, or individually coordinated with, the Local controller involved.

In days of old, ORD ground controllers did have authority for "look and go" crossings of runways at ORD, but that ended on 2/15/79 (see link below).

http://ntsb.gov/ntsb/brief.asp?ev_id=37977&key=0

 

[minitour]

Thanks for the info and the link...any more would really help since I'm trying to gather as much info as I can for this paper..

Take care

-mini

 

[Lrjtcaptain]

I don't work ORD but can guarantee that they don't just get taxi instructions to the departure runways. Something like, "UAL54Heavy, runway 32L, hold short of 27R at tango." They'd be playing with fire if they assumed local would give them crossings when they needed them.

 

[Flibmeister]

Thanks for the info and the link...any more would really help...

-mini

The link I gave you is the official report of the accident that eliminated "look and go" crossings by Ground Control (GC) at ORD-- but, of course, it really doesn't tell the story. So, here it is:

It was an RVR day, visibility poor in fog, maybe 1/2 mile. There was a steady stream of arrivals on 9R, and there was a Delta (DL) 727 on T, facing southeastbound, short of 9R, waiting to cross the runway (note that the angle of the intersection is such that the 9R arrivals are coming at a 50 degree angle from the right rear of DL, making them difficult for the pilots, or the Chicago Center controller riding in the jumpseat, to see).

GC, looking out the tower window, was barely able to make out a DC-10 rolling out on 9R through the fog. As that aircraft passed taxiway T, GC looked at the BRITE (radar) scope and saw that the next tagged arrival was an L-1011 at the outer marker. He cleared DL to cross 9R.

Based on the "rules of engagement" in place at the time, this was actually a reasonable decision: the arrival he'd seen rolling by was a heavy jet, so the closest arrival behind should have been at least 4 miles; the outer marker is less than 5 miles from the end of the runway, so it was reasonable to assume that the L-1011 arrival he saw on the BRITE was the next arrival.

It wasn't, of course. Unbeknownst to the GC, approach control had stuffed a Flying Tiger (FT) B747 between the DC-10 and the L-1011. FT should have been issued an early go-around, due to his close proximity behind the preceding heavy jet, and the approach controller and the local controller did discuss doing so on the landline-- but decided they could "make it work". (They did, too, in that the DC-10 was clear of the runway when FT crossed the threshold....).

Unfortunately, at the time GC checked the BRITE, FT was close enough to the end of the runway that his tag had already dropped off the screen, due to his proximity to the radar antenna (which is located on the west side of 14R). However, he wasn't yet close enough to appear on the ASDE (ground radar-- very rudimentary, almost useless in those days anyway). And, of course, GC couldn't actually see the 747 out the window, due to the fog.

As DL began to cross the runway, FT landed. Approaching taxiway T, he saw DL entering the runway from the left, and took evasive action to avoid a collision by exiting the runway to the right, into the mud (the Center controller in the DL jumpseat said the left wingtip of the 747 actually passed over the cockpit of the 727, with the #1 engine passing just a few feet in front of the nose). The FT 747 shed the nose gear, right main gear, and either one or two engines prior to ending up on its belly, just short of Lake O'Hare.

The end result was multiple millions of dollars in damage to the 747, and the runway was closed for weeks, as they had to build a road in the mud, capable of carrying the weight of the nose and right side of the 747 on flatbed trucks during the extraction. But, thankfully, there were no injuries.

For awhile after that, it was decreed that all runway crossings would be made by Local Control, on their frequency. However, due to the increased frequency congestion and workload placed on Local Control by that rule, it was eventually modified to allow GC to make crossings on their frequency, after appropriate and specific coordination with Local Control.

And that, as Paul Harvey sez, is "the rest of the story"!