I did a little bit of research and found this page: http://www.atchistory.org/History/Maps/Maps.htm There are examples of several different types of charts used in the 1930s. Most only showed the 4 course radio beacon routes, but there is some information about the lighted airway beacons also. Some of these charts include compass headings, and some do not. Interestingly, one of them shows the airway going directly from the arrow at exit 77 (I think) to the Lakepoint beacon. That is undoubtedly why the arrow points in that direction and bypasses the site southeast. Here is a link to that chart: http://www.atchistory.org/History/Maps/SanFrancisco-SaltLakeCity-Omaha_Airwa... It may be that the other waypoint was used to avoid overwater flights - over the Great Salt Lake. I know when an airplane is over water the engine always runs rough.