Conversation so far:
Who was involved in the car crash with Patsy Cline?
Patsy Cline and her brother Sam Hensley, Jr. were involved in an automobile accident.
When was the accident Patsy Cline was involved in?
Patsy Cline's automobile accident occurred on June 14, 1961.

Question: How did the crash happen?
Self-contained rewrite: How did the car crash Patsy Cline was in happen?