Chicago o hare. SID climb

[Picasso787]

Hi Folks,

I'm really curious about the calculation of the possible climb gradient on departure. This question came up the other day when we departed from Chicago o'Hare Airport. In the departure plate it says the o'hare departure needs you to be in 5NM at 3000ft and in 8NM at 5000ft. How can you calculate if you are able to do it if you fly an e.g. B 777 or 787 etc. I check the AFM but no answer ...

Thanks

[767__FO]

I'm really curious about the calculation of the possible climb gradient on departure. This question came up the other day when we departed from Chicago o'Hare Airport. In the departure plate it says the o'hare departure needs you to be in 5NM at 3000ft and in 8NM at 5000ft. How can you calculate if you are able to do it if you fly an e.g. B 777 or 787 etc. I check the AFM but no answer ...

Since I fly 767/757 we never worry about this stuff because we know they have A321s doing the same thing. Sorry couldn't resist :-)

SIMPLIFIED:

Let's just say you are climbing out at 150 knots, that's 2.5 miles per min, you will reach 5NM in 2 minutes so you need 1500 FPM.

If I recall in the Airbus, if you put the constraints in the FMS, and you cannot make that constraint, the Airbus will call you a retard, OK kidding again, but it will turn amber or red, a circle around that fix.

[Picasso787]

that sounds good enough but my worry is about if fully loaded and bad weather how could be sure to make make it.......

[DDDOF]

We just tell CD unable speed and alt restrictions on a heavy weight 777 dep. even if we might make them.
They don't seem to care. I guess they make some sort of adjustment in separation or vectors??

[767__FO]

Also, at SFO in the A321, we would leave the flaps out longer and climb out slower. Don't know if that's allowed at ORD depending on SID.

Like previous poster said, just tell them if you are gonna be close.

[MarkerInbound]

I have no idea on the 787 but I hear the 777 box is about the same as the 744. On the fix page, can you enter ORD/5 and then get a 5 mile circle around ORD? Then enter 3000 on R6 and it shows you where along your path you'll reach 3000?

Most of the time leaving there I'll do a close in NADP. And in the summertime I'll just tell clearance we'll be unable the restrictions.

[flyboyike]

I hear a lot of heavies call in with "unable climb restriction". I have a feeling for at least some of them it's more of a just-in-case thing.

[glendalegoon]

please remember that you are almost at 700' to start, so subtract field elevation from those numbers before doing the 767FO's calculation. I remember even before there were super gadgets inplanes that the 767FO (person on pprune) method worked fine.

[JammedStab]

Originally Posted by flyboyike

I hear a lot of heavies call in with "unable climb restriction". I have a feeling for at least some of them it's more of a just-in-case thing.

A lot can depend on the takeoff direction versus enroute direction. Using 14's for departure with a destination to the northwest shouldn't be too much of a problem, especially with NADP1.

[flyboyike]

You're flying out of ORD now, JammedStab?

[The Dominican]

I hear a lot of heavy Airbus call in with "unable climb restriction". I have a feeling for at least some of them it's more of a just-in-case thing.

There....! I fixed it for ya!

[JammedStab]

Originally Posted by MarkerInbound

I have no idea on the 787 but I hear the 777 box is about the same as the 744. On the fix page, can you enter ORD/5 and then get a 5 mile circle around ORD. Then enter 3000 on R6 and it shows you where along your path you'll reach 3000.

That would be the predicted altitude function. But....does it take into consideration, NADP procedure and climb thrust setting. Also, it would be for a no wind situation and straight out departure I would think. We had no problem today as we took off 120 degrees opposite to climb direction.