|
?:reviewBody
|
-
In the 1920s, the U.S. Post Office began experimenting with cross-country delivery of mail by air. Before the advent of radio guidance, mail pilots picked their way along from visible landmark to visible landmark, a system that somewhat served where there were recognizable geological or man-made features to be guided by, but not at all in areas such as vast stretches of empty, repetitive desert. In 1924, in recognition that its pilots needed more help finding their way, the Post Office began erecting combinations of large concrete arrows and lighted beacons along its established airmail routes: Roughly every ten miles along these paths, mail pilots would encounter 50-foot towers topped with rotating lights at whose base were 50- to 70-foot concrete foundations that from the air looked like arrows. These course lights flashed a code to identify each beacon’s number. In 1926, the Post Office Department turned management of the beacons over to the Department of Commerce. The project was finished in 1929, thereby completing a route from New York to San Francisco. When visibility wasn't impaired by weather conditions, the light from the next beacon could be seen from the one currently being flown over. Additionally, each arrow pointed to the next arrow, a feature that helped keep pilots on course when bad weather obscured the signal from the next lit beacon. The arrow-and-beacon system did not long serve the country's aviators. By the early 1930s, technological advances (radio guidance and radar) began to give those flying over featureless terrain far more reliable methods of finding their way. These days, while scant few of the towers remain (many were disassembled for scrap metal during World War II), quite a number of those painted concrete arrows still dot the American landscape.
(en)
|
![[This page as RDF]](http://data.gesis.org/claimskg/static/rdf-icon.gif){kind=icon}