It is important to note two characteristics of GPS-guided weapons. The first is that GPS coordinates have three dimensions: elevation, latitude and longitude –
One explanation for the miss is that the SPICE 2000 bombs were incorrectly programmed to fly precisely into GPS points that were, say, 33 metres above their intended targets (the buildings on top of the ridge line). They performed as programmed and then continued on their trajectories until they struck the valley beneath.
This is a common targeting problem going all the way back to when I was on the F-111 -- before GPS.
'Vark's Weapons Systems Officers (WSO) routinely practiced these low angle approaches. The aircrew must coordinate their actions. The pilot calls out possible ingress angles and the WSO calculate the release times and altitudes. The F's Pave Tack greatly reduces targeting errors because the reflected laser beams provides the (guided) bomb real time target location. With the Pave Tack, targeting errors rests pretty much on the aircrew instead of intelligence prior to the mission. That does not mean pre-mission area intelligence is not needed. It does -- very much. Pre-mission area intelligence allows the Pave Tack equipped crew even greater flexibility in target selection because the desired target(s) may relocate while the attackers are on
en route or destroyed.
GPS co-ords are essentially high quality
GUESSES. That may not sit well with some, but that is exactly what it is -- a guess.
If you were actually at the structure and made the x-y-z measurements yourself, those figures are not guesses to you. But to the bomb -- they are guesses. If you give the bomb wrong figures, even by hundredths off, the bomb have no choice but to follow your figures. The bomb/missile did not missed. It went exactly where
YOU instructed/programmed it to go. This is where 'terminal guidance' comes in. Terminal guidance is where the weapon have its own way of verifying final target information against what was programmed. Terminal guidance reduced or even eliminate that 'guessing' factor.
Pre-mission target intelligence is not easy, even in the desert where people thinks the geoscape is relatively flat, so the targets must be clearly visible. Flatness offers little contrast in both visible and radar freq spectrum. Satellite imagery prefers slightly off angle view in order to exploit shadows and if the structure is complex, like an aircraft or an artillery piece, those shadows reveals actual physical dimensions that can be mathematically deduced.
Here an excellent example of such off angle target intelligence...
Variable terrain does offers backgrounds that can produce contrasts, but structures can be covered with anything that can spoil its true physical features, in other words, camouflage.
For what happened here, it looks like pre-mission target intelligence failed. Not the bombs.