| 摘要 |
A vertical lift aircraft, such as a helicopter, can land in an area with impaired visibility such as fog. Around the landing area is a plurality of laser beam emitters. The emitters project a pattern of laser beams skyward. The helicopter finds the general area by spot-lights pointing up through the fog, or by navigation. As the helicopter approaches, it sends a radio signal, which is detected on the ground. The spot-lights are switched off and the laser emitters are switched on. The helicopter is positioned within the pattern so that the laser beams reflect off of a portion of the aircraft, such as the rotor blades. This forms a visual cue, which the pilot uses to maintain the position of the helicopter relative to the landing area and descends thereto.
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