Central to virtually all UFO reports is the integrity of the witness and the reliability of their evidence. In a great many cases the actual status of the witnesses is also of crucial importance. People can genuinely believe they have witnessed a UFO, when sometimes the real explanation lies in something considerably more mundane. Weather balloons and the planet Venus are much cited examples.

The fact is that regardless of what witnesses actually see, lack of expertise in say climatology or astronomical phenomena mean that the seal of official approval is often not forthcoming. There is however one category of sighting that involves two types of expert witness - one human, the other mechanical. It is the sober and hard edged world of radar!

Radar sightings of UFO's are remarkably common, and also the most authentic. The word of expertly trained operators, backed up by tangible echo returns from unidentified intruders is hard to deny. In many cases these bizarre blips that suddenly invade military and civil radar screens are seen to execute manoeuvres completely beyond the abilities of any known aircraft. Ground speeds of up six thousand m.p.h are nothing unusual, and as if to add further credence to these incidents, many of these 'radar visuals' as they are called, have been simultaneously witnessed by naked eye observers, both on the ground and in the air!

Nor it appears is there any lack of these sightings. In his book 'The Flying Saucerers' author Arthur Shuttlewood claims he once met a retired RAF wing commander who estimated he had witnessed no less than 700 cases of 'radar visual' UFO's.