Global Positioning Systems The new Avionics Modernization Program (AMP) systems installed in the F-111E and EF-111A have raised their share of questions, so I have decided to continue my series of "Everything You Always Wanted To Know" handouts to you pilots, navigators, and maintenance technicians on how the cotton-picken' thing works. This informational pamphlet is an overview of the GPS system as a whole, NOT the system- specific hardware that you find in your respective aircraft. I'll cover the basic theory of operation here, and if there proves to be sufficient interest in platform-specific installation, that will be covered in a later supplement. THE