A helicopter was flying around above Seattle when an electrical
malfunction disabled all of the aircraft's electronic navigation
and communications equipment. Due to the clouds and haze, the
pilot could not determine the helicopter's position and course
to steer to the airport.
The pilot saw a tall building, flew toward it, circled, drew a
handwritten sign, and held it in the helicopter's window. The
pilot's sign said "WHERE AM I?" in large letters.
People in the tall building quickly responded to the aircraft,
drew a large sign, and held it in a building window. Their
sign said "YOU ARE IN A HELICOPTER."
The pilot smiled, waved, looked at his map, determined the course
to steer to SEATAC airport, and landed safely.
After they were on the ground, the copilot asked the pilot how
the "YOU ARE IN A HELICOPTER" sign helped determine their position.
The pilot responded "I knew that had to be the MICROSOFT building
because they gave me a technically correct, but completely useless answer."