Calvin Jones played his college football at Iowa and is currently one of only two players to have his number retired by the Hawkeyes.  While playing for Iowa, Jones won the Outland Trophy in 1955 as the best interior lineman in college football.  Jones was the first African-American to win the trophy.  Jones joined the Winnipeg Blue Bombers in 1956 and was selected to play in the CFL (Shrine) All-Star game in Vancouver.  On the way home from the game, Jones, along with four players from Saskatchewan (Gord Sturtridge, Mel Becket, Mario DeMarco and Roy Syrnyk) was killed in a plane crash on December 9, 1956.

Wikipedia article on Calvin Jones

Article on the 1956 Plane Crash

1956 Plane Crash Engraved on a Nation