Full FAA Chronology at this link.
19390418: The minimum age requirement for a private pilot’s license was increased from 16 to 18 years. The rule change resulted from a protracted campaign by the father of Edward Mallinckrodt. In 1932, the 16-year-old Mallinckrodt took a friend on a flight that ended in an accident costing both their lives. The young man’s parents had been unaware that their son possessed a pilot’s license, since parental consent was not then required for pilot applicants (see December 7, 1933). The elder Mallinckrodt failed to convince the Department of Commerce that the age requirement should be raised to 18. Eventually, however, he enlisted the support of CAA board member Oswald Ryan, who pushed the reform through the Authority.