The flight engineer is a dying breed of
pilot whose job is to monitor an
aircraft's systems during flight and fix any minor problems that arise in the air. Generally, he or she sits on the right side of the
cockpit facing sideways at a large panel of
gauges and
blinkenlights, and can be identified by the
briefcase full of tools that they carry onto the plane.
Why is the flight engineer "dying?" Early commercial aircraft had four men in the cockpit: a captain, first officer, navigator, and flight engineer. The navigator began to disappear once air traffic control became widespread, leaving only three men in the cockpit—a major efficiency improvement for the airlines. Now that new airliners have electronic readouts to monitor vital systems, the flight engineer is slowly being cast out from the cockpit: virtually no commercial aircraft built since the 1980's require a three-man crew to operate. Some common aircraft that do require flight engineers include the Boeing 747 (100, 200, and 300), McDonnell Douglas DC-10, Lockheed Tristar, and Boeing 727. Many military aircraft still use flight engineers as well.
Flight engineers have to be certified as pilots, despite the fact that they usually do not fly the plane themselves. Most flight engineers are new pilots doing time before their promotion to first officer: many are mechanics who obtain pilot licenses and get transferred to the cockpit. Becoming a flight engineer also requires special certification in the form of a three-hour written exam, which tests knowledge of aircraft and engine components and how they work.
In the United States Air Force, a flight engineer earns around $38,000 a year: in the airline industry, flight engineers start out slightly above their Air Force counterparts, and earn more as they gain experience. It's not a bad job for techies who want to fly.*
* Disclaimer: Do not listen to me. I am not your guidance counselor, and even if I were, you still shouldn't listen to me, as I have never flown an airplane in my life.
Incidentally, these facts were taken from the Department of Labor's useful web site at www.bls.gov.