Abridgment of lighting of airways and airports

The Department of Commerce under the Air Commerce Act is responsible for the installation, operation, and maintenance of the national airways. The lighting facilities along the airways consist of revolving beacons at 10-mi. intervals and intermediate landing fields approximately every 30 mi. The intermediate landing fields, in addition to the revolving beacon, are provided with an illuminated wind cone, boundary, approach, and obstruction lights. The Department of Commerce is also responsible for the rating of airports, although their establishment, maintenance, and operation are matters of municipal or private concern. The rating of an airport is a measure of the facilities available. A preferred rating for lighting facilities requires the installation of an airport beacon to locate the airport from distant points, an illuminated wind direction indicator, white or yellow lights marking the boundary of the landing area, red lights on all obstructions, green range lights marking approaches, floodlighted hangars or other buildings as a measure of altitude and to illuminate identifying markings, a searchlight for measuring ceiling height, and suitable floodlighting for the landing area. In view of the regulating authority vested in the Department of Commerce, the practise in lighting airways and airports follows very closely established standards. The floodlighting of the landing area proper offers the greatest opportunity for original thought and ideas. There have developed two schools of opinion regarding the fundamentals of field floodlighting systems. One school favors the use of a single unit, or a group of units, at one location for floodlighting the field, which system is referred to as the centralized system. The opposing school, advocating two or more light sources placed at different locations about the field, is known as the distributed system. Both systems have in common the use of lighting units delivering a fan shaped beam of light only a few degrees wid- in the vertical plane and varying from 45 deg. to 180 deg. in the horizontal plane. The present lighting facilities are found very satisfactory during fair weather but the problem of aiding the flier during fog still faces the engineer and research scientist as a problem.