Science: Landing Mirror

Landing airplanes on a carrier has always been tricky, and it gets trickier as airplanes get faster. Last week Britain's Royal Navy told about a new and reasonably prang-proof system for landing the fastest jets.

British carriers are to be equipped with big curved mirrors that face aft from the end of the landing runway (see diagram). The mirror is mounted like the mirror of a dressing table, so that a gyro stabilizer can keep it at the proper angle no matter how much the carrier may be pitching. On each side of it are horizontal rows of colored lights. Strong white lights shine into it from near the carrier's stern.

When an airplane makes its approach, the pilot sees a spot of white light reflected in the mirror. If it appears to be above the line of colored lights, he knows that his airplane is above the proper landing path. If it appears to be below, he is lower than he should be. He corrects his approach so that the reflected spot is in line with the colored lights. Then he knows he is right.

Since the pilot must keep his eyes on the lights ahead, he cannot watch the instrument panel to keep track of his air speed. So the Admiralty provides him with a set of colored lights that reflect in his windshield. Connected with an air speed indicator, they tell him if he is flying too fast (red), too slow (yellow), or just right (green).