When is an air crash a planned suicide mission and when is it the result of a disastrous technical fault? On the morning of October 31, 1999, the EgyptAir Flight 990, a Boeing 767, left John F Kennedy (JFK) International Airport for Cairo. Soon after take-off, it plunged into the Atlantic Ocean, killing all 217 passengers. Nearly two decades on, the question that still has not been convincingly answered is 'why'?. The initial US investigation blamed the co-pilot and concluded the crash was "as a result of the relief first officer's flight control inputs", adding that the reason for his actions "was not determined". But today the evidence behind this conclusion looks far from convincing, as this Al Jazeera World investigation exposes. The Boeing 737 Max 8 jet crashes in Jakarta in 2018 and Addis Ababa in 2019 have resulted in investigations into this model of aircraft.