This would still add a random penalty thta players would not be able to combat.
If mishaps and crashes were to be modelled, I agree it should be some sort of cumulative risk factor based on aircraft age, condition, and checks, staff morale and levels etc. Additional factors could also be extreme range flights, poor weather (time of year), night flights etc.
I would be happy if no single factor was required, so for example a new aircraft could have a mishap etc if staff morale and levles were poor and a check was missed. Then ther ewould be no obvious way to avoid consequences of poor management simply by having a young fleet or enough staff in isolation.
Maybe as an added protection no airline could have a crash until it had suffered at least two mishaps, so players get fair warning they are pushing their luck.