To honesty add Common Sense. You can't make rules to cover every scenario, hence the need for nouce. Sadly the desk jockies who do nothing but count the money have no such nouce. What ever rules they make these bean counters will find loop-holes. It's a game like foxing the taxman in Italy. There will be ferrets trying to find holes and round-about methods to cheat the rules.
It was well demonstrated by rosterers in 2 companies. FTL's is mathematics to them; nothing more or less. Maximise & minimise. On 2 seperate flights, in said 2 different companies, we started at point A, flew to B, a shortish flight, then back to A and finally onto C, a longish flight. The total duty time was too long for 2 crew. So, of course, we saddled up with 3 pilots and set off. Could we not leave the relief pilot sleeping at A and pick him up on the way back. Nope; not allowed, he had to be in the crew at the beginning. So now the relief pilot was as knackered as the rest of us, as of course the whole dingaling was a night flight, and with unsuitable crew rest facilities.
Common sense was AWOL. As long as this maximise/minimise attitude exists there will be no change.
I've always said that senior managemnt, rosterers, CAA inspectors and medical bods, plus a few from the Transport ministery, should be required to sit on the jump seat for a 3 day stint of mixed day/night short or long-haul. Then they might have a vague idea of what they are talking about and a bit more respect from us for the rules they make. At the moment the pilot commumity has little faith in any of them. One train crash and all hell is let lose by the politicians to prevent another. One tired pilot crash and simple 'pilot error' brushes it under the carpet. Share prices remain. Bad luck, but can't rock the profit boat too much. And please don't someone come back with "it's the profit that gives us a job." Of course it is, but there are sensible criteria and acceptable practices. It just makes me puke to hear all airlines saying 'saftey is our number 1 priority' and then operating in such opposite fashion regarding what some might say is the weakest link or the last line of defence. This includes everyone in the chain including all ground staff, engineers, ATC etc.
The next CEO who says safety will not be sacrifised for profit will grow a very long nose. It is rarely more than legal minimum.