RAF pilots are considered by many defence experts to be the best in the world at flying low level missions.

And their Harrier GR7 and Tornado GR1 aircraft are ideally suited to the purpose.

To get at the Serb troops and tanks repressing the people of Kosovo, pilots could be tasked to fly as low as 75ft at speeds of 550mph.

Paul Jackson, editor of Jane's All the World's Aircraft, said: "I cannot imagine a worse scenario for a combat pilot than the one they have to do in Kosovo.

"They could be operating in heavily defended airspace where they cannot kill one civilian with a misguided bomb. It really is a very difficult scenario for them."

Pilots flying below radar height are well placed to take out tanks and armoured personnel carriers, but to do so puts them at enormous risk.

They can be shot at with conventional guns or shoulder launched missiles and they also have to contend with the difficult terrain they are flying over.

'No worse scenario'

The BBC's Defence Correspondent Mark Laity said it is that "balance of risk" that Nato's commanders and war planners must weigh up in sanctioning any low level missions.

He said: "Because of the technical capabilities of the Americans the safest way to operate is at medium to high levels which would be 15,000ft plus.

"Radar guided weapons, which the Americans are able to detect, are the main threat.

"Once you go below that level you start coming into range of shoulder-launched missiles and guns."

Harriers are well suited for low level missions

He explained that the Serbs would probably try to put a lot of anti-aircraft fire up if planes come in low. It is difficult to target a low flying plane, but if enough "lead" is put up then planes might just fly into it.

Weather is not a hugely significant factor when low levels raids are being planned, and in terms of striking mobile targets they are the best method of attack.

Group Captain Ian Travers Smith, who is in Italy with RAF Harrier crews, spelt out the dangers for the pilots.

"The low-level environment is more dangerous for lots of different reasons.

"Setting aside the threat, low-level flying is dangerous at the best of times.

"That is why we have to train so hard and so long in that skill so we do it intuitively."

The Harrier carries a range of conventional weaponry

He added: "If low-level operations are part of your bag of tricks, you have to train very hard."

The high manoeuvrability of the Harriers make the pilots among the best-qualified members of the Allied force to take out the units hiding in the country.