Way back in 1968 an Aer Lingus Viscount crashed into the sea on a flight from Cork to Heathrow under mysterious circumstances. There have been many contradictory theories as to the cause of the crash, some quite bizarre, and investigations have produced inconclusive results that open more questions than answers.
Conspiracy theories have abounded (given some credence by some investigators - and none by others) that even involve the serious suggestion that Irish ATC falsified their records after the event to cover up the true cause.
Irish radio has just run a half hour special on the crash and subsequent investigations. The website is
http://www.rte.ie/radio1/investigate/tuskar.html# and there is a link there to the radio show - it's at
http://www.rte.ie/radio1/investigate/rams/2008/tuskar1.smil if you just want to go straight there. Run them both, though, if you have time, as the subject is a real mystery and very intriguing.