Mrs. Steingar wanted me to do something like that with my mother in law’s cremanes. When I learned about some of the issues involved I decided not to. Airplanes are for the living. The down side is my mother in law is still a resident of my basement. Creepy.
Happens a fair amount, sadly. I'm aware of an older one where some lingering bone fragments from the cremains got jammed in the elevator... I was able to quickly find two more on the NTSB site in addition to the one Jeff posted: