Canadian biz jet operators and other high-performance aircraft owners are being urged to get their planes upgraded now for the new world of high-level air traffic control coming by the end of 2004. Nav Canada will implement the Southern Domestic Reduced Vertical Separation Minimum at the same time the U.S adopts the reduced vertical spacing and aircraft that don't have the avionics required for the system will be excluded from FL 290 to FL 410. Unlike Europe, the North American conversion will not be phased so all airplanes wanting to use those flight levels will have to be upgraded. Minimum equipment includes two independent altitude-measurement systems cross-coupled to a static system with ice protection, if required. The aircraft must also have among their electronic arsenal: air data computers and displays, a transponder, an automatic altitude-alerting system and an automatic altitude-hold system.