Airway Radio Progress
Twenty Four Weather Stations and Eight Rural Beacon Stations Now Rendering
Service to Transport Lines
by Martin Codel
Department of Commerce Aeronautical Radio Stations
(click for larger image)
Work is progressing apace on the aeronautical radio system projected along
the civil airways by the Airways Division of the Department of Commerce.
Transport lines now flying the routes on regular schedules are daily taking
advantage of the vast weather reporting and radio-beacon network already in
operation, although they have recently projected a supplementary system of
their own to furnish radio services where the government cannot. Even
the itinerant pilot, if his craft is equipped with a simple radio receiver,
can now take advantage of the fast-expanding airways radio system, which the
government expects to have in full operation some time next spring.
Weather transmission schedules from the 24 stations transmitting sector weather information prepared by the Weather Bureau have been increased from half hour to 15-minute intervals. Fifteen more such stations are under construction. When they are completed, there will be hardly a square mile in the United States not covered by the radio broadcasting of weather information, according to Capt. F.C. Hingsburg, chief of the Airways Division.
There has been somewhat of a letup in the construction
of radio-beacon stations, eight of which are now in operation from Boston to
Hadley Field and thence along the Transcontinental Airways to Des Moines.
This has been partially due to great expectations from the visual beacon,
which it was hoped might render the aural beacon obsolete and makes it more
desirable to install visual beacon transmitters solely. The several
beacon stations now in operation are all of the aural type, certain
characteristic breaks in the continuous stream of long dashes telling the
pilot flying the beacon course whether or not he is straying away from it.
Department of Commerce Radio Range Beacon System
(click for larger image)
It has now virtually been decided to proceed with the construction of the remaining aural beacon stations, and about 35 of them will be completed by next April or May. The visual beacon with its reed indicator needs more experimentation, and the seven visual stations now under construction at the laboratories of the U.S. Lighthouse Service at Detroit will be installed at key points to further these experiments. They were originally destined for the New York - Atlanta route, but aural beacons will be installed instead, largely, it is understood, because of the insistence of the Pitcairn Company which flies that route with the air mail.
The two systems weather broadcasts and radio-beacon transmissions, complement each other. Both, of course, are intended to increase the safety of flight. Capt. Hingsburg is authority for the statement that the National Air Transport, which flies the mail along the Transcontinental to Chicago, claims 30 per cent increase in performance due to the aural beacon.
While airways light, now spaced 10 miles apart along the route with lighted intermediate fields at 30-mile spacings, are excellent guides under conditions of good visibility. Radio direction signals will hold the pilot to his course in the thickest fog. If he drifts off his course, he loses the signal from the ground station, hears the "dot-dash" or "dash-dot" characteristic of the beacon and pulls back to his course. Long waves, i.e., the 285-350 kilocycle band, are used for the radio range beacons.
In the same band of wave lengths, the weather reporting service operates, so that the same receiver that tunes in the beacon signals will bring in vocal descriptions of weather and landing conditions ahead at 15-minute intervals. There are, of course, more actual broadcasting stations in operation today than there are radio-beacon stations, for the development of the former began long before the beacon was perfected.
The ground stations of the beacon system do not project their signals in only one direction, but, as at Boston, mark four-way courses. At Hadley, for example, the station not only marks the directional course to Bellefonte, but also a course to Washington.
The antenna system of the radio-beacon station consists of two directional loops supported on a pole. The transmitter sends out a characteristic signal from equivalent loops alternately in a character that interlocks,, marking the radio course by interlocking dashes. There are four courses, each approximately 3 degrees in width, ranging from the radio-beacon. These can be shifted by means of the geniometer to coincide with the lighted airway. The receiver on the plane has earphones fitted in his helmet so that he can hear the signals.
Two of Transcontinental Air Transport's radio broadcasting stations, the one at Columbus (Ohio) and the one at Indianapolis (IN), will probably be taken over by the Airways Division of the Department of Commerce on 1 December and included in the general setup projected by the government.
(this article originally appeared in Aviation, November 16, 1929)
