Posted by Bruce Kahl on December 10, 1999
In Reply to: "Push the envelope" posted by Arthur Smith on December 10, 1999
: : I will accept the premise that "push the envelope"
: : originated with airline pilots, but I would like to
: : know in exactly what context: the actual practical
: : mechanics of flying as in the use of the controls
: : relative to a certain aspect of aircraft performance,
: : the theory of flight as in aerodynamics or the
: : efficiency with which the aircraft performs relative
: : to outside forces, or some other practical
: : explanation?
This expression comes out of the US Air Force test pilot program
of the late 1940's.
The envelope refers to a plane's performance capabilities. The limits of the planes ability to fly at speeds and altitudes and under certain stresses define what is known as its performance envelope. It's an "envelope" in the sense that it contains the ranges of the plane's abilities.
"Pushing the envelope" is a good example of how jargon -- the specialized or technical vocabulary of a group or profession -- gradually enters general usage. "Pushing the envelope" comes from the jargon of test pilots, and has actually been around since the end of the Second World War. The "envelope" involved is a sort of visual metaphor for the technical limits of a high-performance aircraft. A graph of such an aircraft's performance would appear as a rising slope as the craft approaches its limits of speed and stress, then fall off rapidly (putting it mildly) when the plane exceeds its capacity and the pilot loses control. Safety, relatively speaking, lies within these limits, or "inside the envelope." A pilot who "pushes the envelope" and tries to exceed the known capabilities of the aircraft risks what engineers delicately term "catastrophic system failure," otherwise known as a crash.
Because "pushing the envelope" had such a esoteric origin, it took a best-selling book -- Tom Wolfe's "The Right Stuff" in 1979 -- and later the popular movie "Top Gun" to introduce it to the general public. Since then it has begun to crop up in increasingly non-technical contexts, to the point where it is now a currently trendy metaphor for simply "pushing it," or testing the limits of what is permissible in a given situation.