A new modified "flying radar" plane, the A-50U or called "Mainstay" by NATO, has been shipped to the Russian air force recently. Basically as I understand it, these planes provide radar coverage where the army has no radar. So when a part of the air force or navy is going somewhere they would probably like to have a powerful radar with them, capable
on spotting any enemy units that may be around or to use it more for targeting their attacks. Such planes began being used in the 1980s but in 2011 they released an upgraded version of the old plane which can conduct its functions digitally. More pictures inside, also the photos are clickable and are pretty widescreen.