Ground-air emergency code.
https://s3-us-west-1.amazonaws.com/h...e_fullsize.jpg
Previously:
https://www.homemadetools.net/forum/...160#post191735
https://www.homemadetools.net/forum/...239#post146020
https://www.homemadetools.net/forum/...igns-gif-74564
https://www.homemadetools.net/forum/...634#post170504
https://www.homemadetools.net/forum/...702#post170671
