Between the surface and an altitude of 29,000 feet (8,800 m), no aircraft should come closer vertically than 300 metres, unless some form of horizontal separation is provided (Note: for countries that measure altitude in feet, a 1,000 feet minimum is observed rather than the 984.252 feet found in 300 meters). Above 29,000 feet (8,800 m), no aircraft shall come closer than 600 m (or 2,000 feet), except in airspace where Reduced Vertical Separation Minima (RVSM) can be applied.