FAA statistics show that air carrier pilots aged 60 and over have a superior safety record as compared to other pilot age groups within either Part 121 or Part 135.
[As reported in Chicago Tribune, July 11, 1999.]
That chart has been proven fallacious many times. It is based on number of pilots licensed, not number of hours flown. Accident statistics are ALWAYS presented in a per 100,000 flight hour ratio. When this standard is applied to the accident statistics, there is a sharp upward turn starting at age 55.
All of that sick time/vacation time skews the graph you presented.