As the GNSS world starts to appreciate the era of multiple global constellations, it’s probably worth considering the impact on aircraft navigation, GNSS airborne receivers and what these changes might soon bring to those who develop and use GNSS for airborne en-route navigation and approaches. Design and manufacture of new breeds of receivers are only the first of many steps along the road to full-fledged use of new capabilities. In aviation in particular, and in other high-precision fields to a lesser extent, many stages of study, regulation, development, test, and certification must be undertaken to eventually reach the promised land. The following capsule history of our progress to date also sheds light on what we may have to undertake in the future.