A helicopter was flying around Seattle

A helicopter was flying around above Seattle yesterday when an electrical
malfunction disabled all of aircraft's electronic navigation and communication
equipment. Due to the clouds and haze the pilot could not determine his
position or course to steer to the airport.
The pilot saw a tall building, flew toward it, circled, drew a handwritted
sign and held it in the helicopter's window.
The sign said "WHERE AM I"? in large letters.
People in the tall building quickly responded to the aircraft, drew a large
sign an held it in a building window. The sign said, "YOU ARE IN A
HELICOPTER".
The pilot smiled, waved, looked at his map and determined the course to steer
to SEATAC ( Seattle/Tacoma) airport and landed safely.
After they were on the ground, the co-pilot 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".