WIRE COMMUNICATION AIDS TO AIR TRANSPORTATION 465 



Teletypewriter service offers the advantages of simultaneous com- 

 munication with any desired number of stations, the communications 

 being automatically recorded on machines at each point. A message 

 using code or abbreviations, if desired, can be sent instantly without 

 the necessity of calling in or checking with the receiving stations; thus 

 the immediate attention of only the sending operator is required. 

 Automatic recording reduces the possibility of human error and per- 

 mits the most efficient use of operating personnel with resulting savings 

 in labor. Furthermore, as contrasted with radio, this system, utilizing 

 wire transmission, is not so subject to variations in meteorological 

 conditions; it is thus more dependable, and has the advantage that it 

 can be readily extended to handle large volumes of business. This 

 system also is well adapted for carrying on administrative and other 

 work as well as for weather reporting and plane dispatching. 



Transmission of Weather Reports 



Material progress has been made in reducing the effect of weather 

 hazards to air transportation, through the service rendered by the 

 Department of Commerce and United States Weather Bureau in the 

 collection and dissemination of weather reports supplemented by other 

 reports collected by individual transport companies from planes in 

 flight. For this service a s^^stem of practically continuous reporting 

 and forecasting for areas along air routes has been developed and 

 weather observations have been extended to include data of particular 

 benefit to air navigation. 



The teletypewriter networks furnished the Department of Commerce 

 are devoted largely to this purpose and in conjunction with its radio 

 telephone broadcasting service are the means for providing to pilots 

 information relating to existing conditions and forecasts for both 

 general and local areas. 



Twelve selected Weather Bureau airport stations located at strategic 

 points in the country's airway network prepare summaries of weather 

 conditions in their own areas and make area forecasts every three hours 

 based on data collected over the Department of Commerce circuits 

 from connected airway stations and over commercial telegraph lines 

 from other reporting points. These summaries and forecasts are then 

 transmitted over the teletypewriter circuits and made available to all 

 airway stations. 



While the forecasts include predictions as to storm developments 

 or movements, conditions in specific localities are often likely to change 

 rapidly and it has been necessary to provide additional reports along 

 the air routes on an hourly basis in order to keep pilots continuously 



