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.
The plane can go as far as 7,500 km (or around 4,600 miles) and can track up to five hundred different targets both in the sky and on the ground, up to 650 km away. It sends the commands to fighter jets so that they can destroy the targets this big plane has detected.
There are a total of 17 such planes enlisted in the Russian air force now, but only three of them have already been digitally upgraded.