After what came to be known in New Zealand as the "Kaikoura lights", I always figured that you cannot deny the existence of UFOs. During the months of December 1978 and January 1979, UFOs were repeatedly sighted from the Wellington-Christchurch cargo flight, then operated by Safe Air.
Not only were these "objects" observed by the flight crew, but were also detected by both the aircaft's onboard radar, as well as that at Wellington Airport's Air Traffic Control Centre. Furthermore, on the night of the 30th December, these objects were also filmed by an Australian TV crew who were aboard the aircraft.
When these objects were observed by up to five different people while at the same time being detected by two different sets of radar - AND recorded on movie film - it is very hard to deny their existence! (People can perhaps suffer from hallucinations, but radars and movie cameras?). Of course, UFOs don't necessarily mean aliens.