Tony Webber the ex Qantas economist said that pilot costs were 1-2% of the operation. IATA also make mention of this. Even the 30% pay cut on the 787 flying long haul makes 0.3% difference
Grumpy pilots load more fuel than satisfied happy pilots while almost hoping a management pilot queries them on it.
fuel is 40% plus of the cost
Grumpy pilots make less effort to investigate and obtain more efficient flight levels.
fuel is 40% plus of the cost
Grumpy tired pilots configure earlier on approach than satisfied happy pilots.
fuel is 40% plus of the cost
Grumpy tired pilots utilise less single engine taxi.
fuel is 40% plus of the cost
Grumpy pilots don’t wait at the aircraft for the ground staff to hook up ground power before giving up and leaving the aircraft with the APU running as happy satisfied pilots.
fuel is 40% plus of the cost
Grumpy pilots are less likely to extend duties.
Grumpy pilots ‘self manage’ their rosters with sick days more often than happy satisfied pilots.
The above statements might not reflect well on the professionalism of pilots, but they are the realities of human nature. Human nature won’t/can’t be bent by rules or ideology, (see communism) it just is. There will be exceptions to the rule but overall it is the case.
So with pilot costs being substantially lower than fuel costs, it is cost effective to ensure the grumpy/happy ratio is maintained at an economically viable level.