470 BELL SYSTEM TECHNICAL JOURNAL 



readily establish the location of the plane. The dispatchers generally 

 maintain a typewritten, chronological log of position reports from each 

 plane in the air. Bulletin boards are also used, marked with the 

 stations along the route and with spaces for filling in data such as plane 

 number and license, name of pilot, time of arrival and departure at 

 each station and final destination. 



A considerable volume of information is required to be transmitted 

 in connection with the handling of traffic on large lines. This usually 

 consists of data as to reservations, number of passengers and amount of 

 mail and express carried, connections to be made, and arrangements 

 at terminals. Supplementary instructions to pilots and many ad- 

 ministrative matters requiring prompt handling are also transmitted. 



Although the airways teletypewriter circuits furnished the Depart- 

 ment of Commerce are used mostly for handling weather reports, 

 considerable information is also transmitted over them relating to 

 departure and arrival of planes and their position in flight. Upon 

 request the Department of Commerce will send over its teletypewriter 

 system the license number of a plane, the station from which the plane 

 is departing, its time of departure, and its destination, to stations along 

 the route of the flight. Stations on the route knowing approximately 

 the time the plane will be due watch for it and record the actual time 

 the plane passes so that other stations may be informed. 



Teletypewriter Circuit Layout 

 Teletypewriter networks furnished by the Bell System for service 

 along airways are composed of some 30 separate circuits. Circuit 

 mileage of the longest is about 2,000 miles and of the shortest, 200 miles. 

 The longer circuits generally connect 15 to 20 intermediate stations. 

 Since airways naturally follow direct air lines the intermediate airway 

 stations are often located at points considerable distances from main 

 communication lines, which, generally, are constructed along routes 

 connecting the industrial and more populous centers, due regard being 

 given to topographic and other conditions. At the larger airports such 

 as Newark and Cleveland, local teletypewriter circuits are also provided 

 to connect the Department of Commerce station with the offices of the 

 various transport companies, the post office, and weather bureau. 

 Automatic transmission equipment is provided so that information 

 received on one circuit can be retransmitted over one or more other 

 circuits if desired. 



A layout diagram of a typical circuit is shown in Fig. 4. Facilities in 

 the New York-Cleveland long distance cable are used for establishing 

 the main links totaling 515 miles. Repeater stations on the cable 



