Improved Climb Performance 737NG

[Driver 170]

In my Flight Planning and Performance Manual;

737-800W CFM56-7B26
FAA
KG/°C/M CATEGORY C/N BRAKES
OPTIONS
24K Derate
22K Derate Gear Down Dispatch

It has a section for Improved Climb if climb limited, but why does it also have a Improved Climb Tire Speed Limit weight?

[Chesty Morgan]

Improved climb will increase your V speeds which could, depending on stuff, get close to or exceed max tyre speed. If the increased V speeds actually exceed max tyre speed then that will become limiting.

[Driver 170]

But aren't you deciding on what tables to use before increasing any V speeds.

The tables are;

Improved Climb Field Length Limit

And;

Improved Climb Tire Speed Limit

[Chesty Morgan]

I don't have that manual to hand so can't answer definitively. I guess you'd come up with an IC weight then adjust it for tyre speed limit.

These days I just plug stuff into the EFB.

[MarkerInbound]

You run a bunch of calculations and then try to increase the most limiting. Not much you can do about structural. If you are landing weight limited you might look at the alternate. That leaves you with TO runway limits and TO climb limits. If you are runway limited more flaps might get you off shorter but hurt the climb numbers. If you use improved climb numbers you are using some of that now excess runway to increase your speed and therefore your climb gradient.

[Driver 170]

CM i can send you the FPPM if you like? I'll send it to my dropbox...

Well thanks alot guys.

[B737900er]

You cant use improved climb if your field limited for starters.
IC uses excess runway to help clear obstacles, this is done by increasing the Vspeeds.

Speeds can be increased up to the point where the field length limit TOW and Tyre speed limit TOW becomes more limiting that the CLB limit TOW. If the resulting V1 exceeds Vmbe the improved TOW must be adjusted.

Due to higher speeds, there is an increased chance of being limited by brake energy (which limits V1) or tyre speed limitations (which limits Vlof, thus Vr). Vtyre might inadvertantly be exceeded by slow rotation.

[Driver 170]

Yeh Field length limit TOW is the lowest of the ASD limit TOW (accelerate stop distance) and TOD limit TOW (Takeoff distance)

Also thats not mentioned is the Obstacle Clearance Limit TOW to clear all obstacles with the required margin.

I think i know why my FPPM now supplys charts for;

Improved Climb Field Length Limit

And;

Improved Climb Tire Speed Limit

As any of these can be the limiting factor on the ground for the Improved climb? I stand to be corrected. If anyone would like to see the FPPM and those charts let me know. It may help my confusion..