Helicopter Flight Into Seattle
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 so as to fly safely to the airport.
The pilot saw a tall building, flew toward it, circled it, 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 circling the building, 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, and determined the correct course to set to fly into the Seattle 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.