
Notes for the 1940 Airways Route system.

The Airways in the 1940s were established by four-course radio range stations, which broadcast in the LF band, the same band used by NDBs today. Each station put out a focused signal in four directions, like the spokes of a wheel, although the azimuth of each spoke was adjustable. The radio range stations broadcast two Morse code signals, the letter "A" and the letter "N." When a pilot was exactly on course of one of the four "spokes" of a station, the A and the N signals merged into a constant tone in the earphones. If the pilot drifted off course, either the A or the N Morse code signal would be heard. The loudness of the A or N indicated how far off course the pilot was, the louder the letter, the farther off course. Whether one heard the A or N dictated which side of the course the aircraft was.



Notes for the image "airway_twa.jpg."

Here is a portion of Green Airway No. 1, in the state of Washington, in NW US. Radio Range stations
in Ephrata and Spokane defined this portion. See also the main Radio Range Network Illustration. 

East-west airways were Green or Red with a number, while north-south airways were Amber or Blue with a number.

At crossing or merging points, Green had top priority, followed by Amber, Red, and Blue. GARBo was the memory aid after the famous film star of the times, Greta Garbo. The chart also shows the A and N sides for each of the four courses. 



This info is from some of my early Navigation books.

If you have questions, just post them on the forum.

Charles Wood.
17 March 2004
