Wednesday, March 31, 1999 Published at 09:52 GMT 10:52 UK
Weather outwits 'smart' weapons
Heavy rain, smoke or fog can disrupt or obscure the laser signal
In the high-tech world of modern warfare it seems incredible that the RAF can be foiled by nothing more than a bit of fog and rain - yet that is exactly what has happened in the skies over Kosovo.
Some would say these "smart" weapons cannot be that intelligent if they can be stopped by smoke.
The Ministry of Defence is adamant that these raids are "not a failure" - so what is making the top guns hold their fire?
The Ministry of Defence says the aim, quite literally, of these missions is to precisely pick off military targets while causing a minimum amount of collateral damage.
For that they use laser-guided air-to-ground bombs such as the Paveway II and III - costing about £40,000 each. But even in this age of high-technology a pilot must still be able to see the target in order to guide the bomb home.
But heavy rain can cause the laser beam to scatter, meaning the target cannot be pinpointed and locked. Equally, if fog, smoke or flames mean the pilot who is using the laser equipment to "designate" the target cannot see what is being aimed at - even with infra-red equipment - then he cannot lock on the laser beam and will call off the attack.
Nato is working hard to bring in aircraft like the B-1 bomber that can deliver weapons whatever the weather - bombs such as the Jdam, a bomb that relies on satellite guidance.
This is the first time that modern precision-guided weapons - "smart" bombs - have been used in such an extensive operation in a European theatre of operations.
Public expectations about the effectiveness of air power are to a large extent based on the experience of the Gulf War. But Kosovo, even in spring, is not Kuwait or Iraq. Indeed it is often forgotten that the weather too played a factor in the early stages of the Gulf War air campaign.
At the UK Ministry of Defence briefing the day after a second set of Harriers returned to base fully loaded, Chief of the Defence Staff Sir Charles Guthrie underlined the goal: "What we do not want to do is to create any more collateral damage than we have to - we do not want to kill innocent civilians.
"What we really do need is to have visual contact between the pilot and the target he is going to attack."
"We behave in accordance with international law unlike Slobodan Milosevic. We are constrained by the need to be precise," he said.
But the pilots of No 1 Fighter Squadron know what their job is. As one Scottish pilot said: "In peace time if you get it wrong you get a hard time from the rest of the formation.
"The difference here is that if you get it wrong you die. For us as pilots it is a success that we all come back. Our prime aim is to survive."