A top attack weapon is designed to attack armored vehicles from above, to take advantage of the fact that the armour is usually thinnest on the top of an armoured vehicle. The device may be delivered as a smart submunition or a primary munition by an anti-tank guided missile (ATGM), mortar bomb, artillery shell, or even an emplaced munition such as a mine. Top attack munitions use either a shaped charge warhead (often now tandem warheads in order to defeat ERA), or an explosively formed penetrator (EFP) warhead fired while over the target (usually by submunition).
The top attack concept was first put into service by the Swedish Armed Forces in 1988 with the Bofors RBS 56 BILL top-attack anti-tank missile.[1]
Another method of top attack is the overfly top-attack (OTA or OFTA) where a missile with a vertically oriented shaped charge jet that fires downwards. A missile is directed to overfly the vehicle where a sensor detects the vehicle, and detonates the shape charge down into the top of the vehicle. This is system employed with the NLAW man-portable ATGM.