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.  The pilot saw a tall building, flew toward it, circled, and held up a handwritten sign that 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 he had done it. 

"I knew it had to be the Microsoft Building, because they gave me a technically correct but completely useless answer."