The F-15E is a two-seat version of the F-15 that is optimized for ground attack introduced in 1988. It is crewed by a pilot and weapons systems officer (WSO, pronounced "wizzo"), and is fitted with equipment that extends the F-15's range and gives it all-weather ground attack abilities. It retains the earlier F-15's air-to-air capabilities, although its increased weight causes some loss of agility. Its primary role is that of a strike fighter designed to fly deep into enemy territory to bomb key assets while being able to defend itself against air threats.
It can be distinguished from air superiority models of the F-15 by its conformal fuel tanks (CFTs) under the wings along the outside edge of the intakes, and extra navigation/targeting pods attached just under the intake. It has a much darker grey paint than the air superiority F-15s, which is the source of a few of its nicknames. It is affectionately known as the Mudhen, with Mud in reference to its air to ground role and darker color scheme and hen referencing its fat CFTs. F-15C crews call the F-15E, "the dark side" and pilots that transition to the F-15E are "joining the dark side".
The F-15E was first deployed in Operation Desert Storm where it was arguably the unsung hero of the war. The F-15E was the most tasked airframe in the US Air Force during the conflict, with planes flying as many as three missions a day. Because of its advanced APG-70 radar, other planes such as the F-16 and F-18 often rely on the F-15E to direct them to targets. Because of its cost, few countries outside the US operate the F-15E. Countries that do however often operate more advanced versions of the plane; Korea operates the F-15K, which features improved engines and added anti-ship missile capability.
Although specialized for attacking ground targets, full air-to-air capabilities are available to F-15E crews. It carries the same gun, AIM-9 and AIM-120 armaments as the F-15C though it rarely carries the F-15C's full air to air loadout. The F-15E typically caries a wide variety of bombs including the GBU-15, a 2,000 lb TV or IR guided bomb and the AGM-130, a GBU-15 turned into a missile by attaching a 1,000 lb rocket. Despite being based on an effective air superiority design, the F-15E to date only has one air-to-air kill. In an unusual employment of weapons during Operation Desert Storm, an F-15E crew downed a flying Mi-8 Hip helicopter with a laser guided bomb.