FRMS
Firstly, every airline has an obligation to its employee's called 'duty of care'.
If ,lets say, Engineer's are working shifts such as double's ,or as airsupport pointed out shifts of 24 hours in duration, then the airline leaves itself open to a huge lawsuit if there is an injury or death. That is only one issue of many.
Secondly, ICAO is ramping up an emphasis on the the Fatigue Risk Management side of industry, and this has gained momentum since the Colgan Air accident and changes are on their way. Whether an employee likes the overtime $$ or not, long overdue changes in this are of risk management are coming.
Thirdly, with the introduction of SMS into the aviation industry,I think it will be very interesting to see the changes that will have to be made in relation to rosters, tasking,fatigue etc. Plasticmerc hit the nail on the head, it is not just flight crews who suffer from fatigue.
If Senior Airline Management still delude themselves into believing that only the Drivers up front are ' the only risk within a diverse and complex operation' then they had better pull their heads out of their asses and grasp an understanding of SMS and the differnce between responsibility and accountability. Accoutability rests upon the head of the CEO, and it will be his/her ass that ends up in jail.