The issue is far-far more complex, and no, in many cases the airline would not make its dough. The issue evolves around overnight flights with a sector length of 4-4.5 hours, and is linked to night curfews, daily aircraft utilization and crew requirements per aircraft.
I hear what you are saying andrasz but I disagree. It is only complex at the level you have described.At a level where accountants are trying to eek out a sustainable business model within the regulations. At an Airline management level. Fatigue as it relates to Airline safety needs to be dealt with at a regulatory level and you will find that it reduces the complexity
of the decision making process at the Airline level.
For example, if the rule I proposed existed, the return sector wouldn't be on the table as an option, and all the eeking would be focused elsewhere.
But this means that the ownership cost of the aircraft needs to be spread over fewer revenue flights, pushing their cost up. In many cases, without the night flightpair to spread costs (and the 8 hours flight time is a lot), the whole daytime operation may become unprofitable.
Again, wrong level.
The demise of airlines/ bases who existence relies on the viability of such 'night flightpairs' is a small price to pay and 'the Airlines' will still make their dough....just not those ones.
This is big picture stuff and market forces will naturally resolve the complexities you talk of.
If the situation is viewed in 100 year chunks of time it becomes simpler to understand.
Thanks for you opinion by the way, interesting to see the mindset.
Cheers,
Framer