Virtually all cargo aircraft will be required to have TCAS installed by Oct. 31, 2003, under a notice of proposed rulemaking (NPRM) issued last week. Turbine airplanes of more than 33,000 lb mtow operated under Part 121, 125 or 129 would be required to be equipped with TCAS II. Turbine airplanes with mtows of up to 33,000 lb operated under Part 121, 125 or 129 would be required to be equipped with at least TCAS I. Furthermore, all piston airplanes, regardless of weight, conducting operations under Part 121 or 125 would be required to be equipped with TCAS I. Currently, TCAS is required only on Part 121 and Part 135 passenger-carrying turbine airplanes. Comments on the NPRM are due December 31.