> I've heard of planes getting hijacked and going to Cuba but nothing in the way of mass murders on airplanes.
Now you have:
http://en.wikipedia.org/wiki/Pacific_Air_Lines_Flight_773
http://en.wikipedia.org/wiki/Pacific_Southwest_Airlines_Flig...
Now you have:
http://en.wikipedia.org/wiki/Pacific_Air_Lines_Flight_773
http://en.wikipedia.org/wiki/Pacific_Southwest_Airlines_Flig...
More people have been killed by lunatics while going to church without churches imposing a security theatre on attendees.
It appears that you incorrectly interpreted it as a complete list, as you concluded that only two incidents have occurred. http://listverse.com/2014/03/26/10-people-who-committed-murd... gives other examples of people who have committed mass murder on an airplane, including http://en.wikipedia.org/wiki/Continental_Airlines_Flight_11 (as a consequence of a suicide-by-bomb insurance fraud).
Also, the context was "mass murders on airplanes." Mass murder means typically 4 or more deaths. I have found many murders which took place at churches in the US [1] and ending up with one or two death. However, I haven't haven't found much in the way of mass murders of the sort that is supposed to be identified by security theater measures.
[1] If we go outside of the US then there are certainly metal detectors at some synagogues, bomb detectors at Mecca’s Holy Mosque, etc.