One that I will never forget was the Hollywood Park (circa August/September 1982) accident that would ultimately claim the life of Sheldon “Shelly” Goudreau.
Shelly was catch driving pacer Regan's Lad, when it appeared that one of the lines snapped, and
“he lost control and then his balance,” Steve Schuelein, Hollywood Park Spokesman, said;
“he tried to jump clear but he only managed to half jump and half fall as he bailed out.” Shelly suffered fatal head injuries that the wholly inadequate helmets drivers wore in those days did little to prevent; some say it contributed to the severity of his injury.
I cannot say I know for sure, but I seem to recall that Shelly’s tragic death was at least part of the impetus for the development of the new-and-improved helmets drivers wear today.
Here's a link to the 1981 Hollywood Park American Pacing Classic; RIP, Shelly.
https://www.youtube.com/watch?v=GepLOZuA_tk
