War in the Balkans: The Mission: Strike aircraft hunt in deadly pairs controlled from on high

THE TWO F-16 Fighting Falcons would have taken off from Aviano air base in northern Italy as part of a typical bombing formation of eight aircraft that work in pairs or "two ship flights". But they are just the strike element of a complicated attacking "package" that has to rendezvous in the air and be co-ordinated all the way to the target and back.

First, they would meet up with an airborne tanker to re-fuel before the mission was brought together under control of an E-3 Awacs aircraft, flying at about 30,000 feet. It carries out the role of an airborne air traffic controller, guiding the various elements together.

Other aircraft would include those jamming Serb radar and carrying Harm missiles to destroy radar defences.There would also have been fighter aircraft to protect the rest from enemy fighters. "The whole mission involves punching a hole into the enemy's air defences, completing your work and then punching your way out again," said an RAF source yesterday.

The "work" in this case involved a seek-and-destroy mission against Serb tanks, other armour and vehicles on the ground. Such sorties flown by Nato planes have often been frustrated by bad weather that has kept Serb forces hidden.

The difference between this and other missions is that the exact target will probably not be known before the aircraft take off, and no prior approval will be needed. They are looking for what are called "opportunity targets", and fly in holding patterns above the area until one presents itself.

This information might come from intelligence on the ground, from unmanned drones flying over the area or from American Jstars aircraft, which use radar to spot movements from up to 150 miles away. All this would be fed to the pilots through the Awacs, which would also be sending a picture of the whole mission to air commanders, either in Italy or flying over the area in a specially converted Hercules mobile command and control centre.

Alternatively, the pilot might just see something on the ground and launch an attack. In that case, no target approval would be necessary. This kind of attack, then, is a long way from the process of checking and approving target lists that has been much discussed over the past weeks. It relies entirely on a pilot being able to identify a military target correctly .

"At the end of the day there has to be an element of discretion, because mobile targets move," said one source.

Because of continuing fear about Yugoslav air defences, particularly from hand held surface-to-air missiles, the bombing is almost all taking place from medium altitude of about 15,000ft. From that height, three vehicles in a convoy would only appear as dots on the ground.

Rules of engagement include the strict requirement for pilots to abort a mission if they are not certain they can avoid civilian casualties, and such cancelled attacks have been reported in respect of RAF Harriers. But perhaps it was just a matter of time before this kind of pilot error led to a disaster.