In the preamble to the final Respiratory Protection Standard, OSHA discussed extensively its rationale for requiring that employees breathe air consisting of at least 19.5 percent oxygen. The following excerpt, taken from the preamble, explains the basis for this requirement: Human beings must breathe oxygen . . . to survive, and begin to suffer adverse health effects when the oxygen level of their breathing air drops below [19.5 percent oxygen].
- The Tu-144 supersonic transport was the fastest commercial jet plane at Mach 2.35 (1,555 mph, 2,503 km/h). It went into service in 1975, but soon stopped flying. The Mach 2 Concorde aircraft entered service in 1976 and flew for 27 years..
The Lockheed SR-71 Blackbird is the fastest jet ever built, a machine so far ahead of its time even its own pilots thought it looked more like a spaceship than an airplane.It is an engineering marvel, powered by innovative engines that operated most efficiently at Mach 3.2, its typical cruising speed.lying the world's fastest plane: Behind the stick of the SR-71. By Spencer Hall ï @edsbs on Mar 7, 2014, 1:30p 86. Spencer Hall interviews former SR-71 Blackbird pilot Rick McCrary about what it's like to fly the world's fastest plane.