O'Hare Take-Offs

[shon7]

Was at O'Hare today and noticed an interesting thing with regards to take-offs. On runway 32L some aircraft were taxing right to the beginning of the runway, while others took off entering from an intersection. There seemed to be no logic to this -- for ex: An Alitalia 767 was asked to taxi right to the beginning, while a Lufthansa 747-400 took the intersection.

So my questions are:

1) can anyone explain how takeoffs are determined -- and if aircraft request the intersection or if it is assigned?

2) is the "take-off" data conveyed to the control tower (which would include estimated roll) for each flight?

 

[typhoonpilot]

Hi Shon:

I'll try to answer but it has been a few years since I've been to O'Hare.

1) can anyone explain how takeoffs are determined -- and if aircraft request the intersection or if it is assigned?

= Actually aircraft that need the extra length request the full length departure while others use the intersection. The problem with the full length departure is that it interferes with traffic landing on 27L so unless you really need it you wouldn't ask for it.

2) is the "take-off" data conveyed to the control tower (which would include estimated roll) for each flight?

= No, but they pretty much know that the United 747 to Hong Kong is going to use full length while a USAirways 737 will just use the intersection.

Typhoonpilot

 

[PBE]

When ORD is using 32L as a departure runway the default is to depart from intersection T10, 8800 feet available. If you need the full length you must request it from ground metering at the start of taxi, and some international flights do need it. Don't have my jepps in front of me but I think full length is around 12 or 13 thousand feet. As typhoonpilot said, it interferes with the normal flow and will result in a short delay until they build a gap for the full length departure, so using it is not done unless you really need it. One requirement for intersections is stating the available runway length, which is always on the ATIS at ORD but most controllers will state it again per the regs. The amount each flight actually needs is done through your performance calculations within your company and takes in account your weight and the wx conditions at the time. That info is what we use to set our speeds, thrust and flap settings from. (I saw you were low time from your profile so I added the last bit in. Good luck in your training and come join the ORD circus someday.)

I've been driving in/out of ORD for 20+ years, those are the best controllers in the business.