It unfortunatley wasnt that uncommon for crazies to blow up planes for the insurance money back in those days.
In 1955 or so a UA
DC-6 exploded killing all on a flight from DEN
, a guy wanted to collect insurance money on his wife.
In 1962 a CO
707 was bombed on route from ORD
-KCI, for the same reason.
In 1944 my grandfather just missed a flight by a few minutes in Quebec. It was a Dc-3 and it was bombed for insurance money
1972 However is about the time terror began rearing its head. But since this was in LAS
, it probably wasnt a political terror act by middle eastern terrorists, who at that time were communists and pan arabists, not islamists