Look - down / shoot - down Look - down / shoot - down is a capability a radar system is said to possess if it is able to detect , track and guide a weapon to an air target moving below the horizon as seen by the radar . Problem and naming . Airborne intercept radar relying exclusively on time domain radar techniques is effectively blind any time the radar ' s antenna is aimed near the Earth ' s surface . That is because pointing the radar at the ground produces a large reflection . That reflection and the ensuing " cluttered " display overwhelms human operators and computing systems . The only way to prevent that problem for these kinds of radar is to not point the radar at the ground . This creates a zone of weakness near and below the horizon that is used to hide from the radar . Frequency domain signal processing combined with time domain signal processing , as in Pulse - Doppler radar , is a way to eliminate that vulnerability . Look down . Militaries require performance of airborne intercept radar under all aspects , including downwards . By using techniques to effectively remove clutter , human operators and computers can focus on targets of interest . This allows the radar system to " look down " , and that eliminates the zone of weakness . Military air combat vehicles that lack this capability are blind to attack from below and along the line of the horizon . Shoot down . Once the radar can " look down " , it is subsequently desirable to " shoot down " . Various weapons systems ( including guns and missiles ) are then employed against designated radar targets , either relying on the aircraft ' s radar employing the " look down " capability or the weapon ' s own radar to resolve the indicated target ( as in semi - active radar homing ) . Concept . The technical challenge encountered by airborne radar is discerning relatively small radar returns ( e . g . other aircraft , targets ) in the presence of large radar returns ( e . g . terrain ) when the radar is pointed at the ground , " looking down " . The ground strongly reflects the radar energy while the target relatively weakly reflects the radar energy , creating confusing clutter on the radar screen . It is difficult or impossible to separate the radar image of low - flying aircraft from the surrounding ground clutter . Look - down / shoot - down radars have been enhanced with electronic programs that process the radar image and search for moving objects , which are detected by looking for Doppler shift s in the radar return . See moving target indication . The radar removes all non - moving objects ( e . g . the ground and buildings ) from the display and shows only moving objects . Since the radar is linked to the aircraft ' s fire control system , it can provide targeting information to weapons once it has detected a moving object . Look - down / shoot - down radars provide combat aircraft with the ability to engage targets flying below them . This is highly desirable , as it allows an aircraft to detect and attack targets whilst maintaining the tactically advantageous position conferred by superior altitude . History . When speaking of coalition air operations during the 1991 Gulf War , General Charles Horner described the F - 15 ' s look down / shoot down radar like this , " During the first three days of the war , when control of the air was greatly contested , what it basically amounted to was the Iraqi aircraft would take off , pull up their landing gear , and blow up . " Practical pulse - Doppler signal processing requires high - power light - weight solid state computing that became available in the early 1970s . The first aircraft to rely completely on its own radar system is the F - 4 Phantom .