Complex sentence: Ludington was not on the plane because neither he nor the Dineens had the money to fund his travel expenses; it was the only World Championships between 1957 and the end of the century which he did not attend as either a competitor or a coach.
Split into simpler sentences: Ludington was not on the plane because neither he nor the Dineens had the money to fund his travel expenses. It was the only World Championships from 1957 to the end of the century which he did not attend as either a competitor or a coach.