Most of those are the pilot crashing alone, but there have been some high-profile crashes of commercial flights that have either been confirmed or are strongly suspected to have been intentional, like EgyptAir 990, Germanwings 9525, and SilkAir 185. The mysteriously missing MH370 was also likely an intentional act.
It isn’t what I would call “common”, but it happens: Suicide by aircraft
Most of those are the pilot crashing alone, but there have been some high-profile crashes of commercial flights that have either been confirmed or are strongly suspected to have been intentional, like EgyptAir 990, Germanwings 9525, and SilkAir 185. The mysteriously missing MH370 was also likely an intentional act.