Nick Pope was posted to a division called Secretariat (Air Staff) where his duties included researching and investigating the UFO phenomenon. Although most sightings could be explained as misidentifications of known objects and phenomena, a small proportion appeared to defy any conventional explanation. These included cases where the witnesses were pilots, police officers and military personnel, cases where UFOs had been tracked on radar, and cases where there had been near-misses between UFOs and civilian aircraft.