We propose to monitor a transient black hole binary in outburst through a series of 20 ks observations. Our goal is to map the physical conditions in the accretion disk as the source evolves through the various continuum states using the spectral diagnostics available in the Fe K fluorescence emission. Measurements of the Fe K emission will allow us to quantify the thermal, kinematic, and geometric conditions in both the disk and the surrounding material. Correlating the Fe K diagnostics with sensitive measurements of the direct and reprocessed continuum emission will allow us to map the evolving conditions and constrain models of the dynamic accretion processes in black hole binaries. We will monitor 7 targets with the RXTE. This observation will be triggered when one becomes active.