The new JDAM GPS guided bomb is considered a major success, and there doesn't appear to be any way to screw it up. The JDAM actually carries two guidance systems; GPS and old fashioned inertial. GPS will land the bomb with 30 feet of the location specified. The inertial system will only get the bomb to within 150 feet. But the inertial system automatically acts as a backup for the GPS system. This is actually a major improvement over the older laser guided bombs. These weapons could get the bomb to within ten feet of the target, but were subject to getting lost if there was a lot of rain, fog or blowing sand around the target. In those cases, the bomb would miss by hundreds, or thousands, of feet. Moreover, the GPS has technology to defeat jamming. The anti-jamming features have not gotten a battlefield workout, and are not guaranteed to work in all circumstances. But, overall, the JDAM is the most effective bomb ever built. So effective is the JDAM that kits are being built that will fit on smaller, down to 250 pound, bombs. This way, aircraft can carry more bombs and destroy more targets. Heretofore, bombs that small were not that effective, because the laser bomb system required that each bomb have a laser designator (sort of a high powered laser flashlight) shined on the target so the bomb could home in on the reflected laser light. With JDAM, all you have to do is enter the coordinates of the target into the JDAM guidance system and drop the bomb. The JDAM kit attached to the bomb contains the GPS receiver, electrically powered fins to control movement, a computer to send adjustment commands to the fins and a battery to power it all. Once released, a JDAM bomb seeks out it's target and explodes. For a major attack against enemy installations, you can enter the coordinates of targets in several dozen 250 pound bombs before the aircraft takes off. Once the bomber gets close enough to the target, the pilot lets all the bombs go and each of them seeks out the precise location they are to hit. Spotters on the ground are getting better computer controlled, laser range finder equipped binoculars and radios that allow the spotter to scan the battlefield, press a few buttons and send target coordinates to a bomber overhead. The bomb is then released while the spotter is looking for additional targets. The ability to just enter coordinates into a JDAM and drop it makes it much more effective and flexible. That, plus the fact that it can be used in any weather, cannot effectively be jammed and is cheap has made bombers much more dangerous weapons.