Fedora radars

Last weekend the Baneasa Bucharest airport (BBU) hosted the yearly edition of the big air show of Bucharest. Aircraft and helicopters offered a spectacle in the air and thousands of people admired them. In addition to that, a nearby hangar was organized for an exhibition with booths and early in the morning, before the show in the sky to start, I gave a tour of the exhibition floor when a complex device in a middle of the Linux boot process caught my attention: I quickly reached my camera to capture an image of the standard init, when the guy at the booth (for the air traffic systems, radars and such) told me to wait a bit for the system to start and get a better picture. I replied I was interested to see it booting Linux and we chatted a bit, apparently in the last year they migrated all the infrastructure to Linux, coming from Unix. In the meantime it reached the desktop and I saw for a fraction of a second it was Fedora Core 6 (complete with the DNA wallpaper) and when wondered why a 5 years old system is used, I was explained such an old system has all the bugs fixed.
When talking, a second display showed its desktop for a few seconds and it had the Fedora 15 stripes. I wondered about the combination of an old and a newer system and was advised to wait more and talk with an engineer. Couldn't wait, the things outside started to warm-up, but in the working radar system picture the legend is: on the left a Fedora Core 6 system, on the center and top Windows 7 systems and on the right a Fedora 15 system. I am not a specialist, so can't say what every of them is doing.