Stator Vane,
The Brake Cooling Schedule is one of the few remaining graphs in our pilot’s performance manual. The JAA are trying to get all pilot data into tables instead of graphs to reduce the scope for errors or “fudging”. If you have ever tried to use this graph in a dark simulator (or worse for real) then you will know how easily misread it is. The joke here is that by the time you have both gone through the graph and agreed between you on a correct answer, then enough time will have elapsed to safely attempt another take-off!
Anyway, the advantage of having a graph is that you can see at a glance which way the corrections work. For all of our 737-3/4/500’s with various combinations of 18.5, 20, 22 and 23.5K engines, the corrections all work in the sense that you would expect, ie the way that Mutt described. I suspect that if you are using tables then the error is in the way that they were constructed because there are no such aberrations in the original Boeing graphs.
I have uploaded a copy of the graph for the 737-300 20K to:
www.b737.org.uk/perf_brakecooling.gif
for your info.
Regards
S & L