Abstract: An overhead transport vehicle is described for association with an Automated Material Handling System (AMHS). The overhead transport vehicle provides features to the AMHS by which the AMHS is able to reduce a number of manual urgent lot rescues by the fab operator when a logistic algorithm controlling traffic in the AMHS is unable to transport the front opening unified pods (FOUP) from one tool to the subsequent tool in the sequence of the process steps within the q-time due to unexpected problems. An indicator on the overhead transport vehicle which helps the fab operator with spotting a lot in trouble is described. A backup power source on the overhead transport vehicle used in case of a main power failure is also described.