I assume we are discussing TCASII version7:
Because of a/c climb performance limitation at high alt or in some flap / gear configs an a/c installation may be configured to inhibit climb or increase climb RA under some conditions.These inhibit conditions can be provided via pin programs in the tcas connector or in real time via an input through FMS
.Also the lead time to the
Closest
Point of
Approach (CPA) called tau( i think thats a greek alfbet) is more at higher alt its 15sec at 1000' ----35sec at fl420