If we flew for FREE it would save about $3.88 per ticket per hour on an 80% full MD-88.
Personally, all the labor costs savings on earth will not bring a poorly managed airline out of the doldrums but we are, however, very easy and politically correct targets.
MD-88 - 142 passengers (80% load = 114 pax)
*Estimated* per hour cost of pilots, plus retirement, medical etc: $442/hr
$442 divided by 114 = $3.88 per hour per ticket.
So basically, if you're on a two hour flight from Tampa to Cincinnati, if your pilots flew for FREE, you might see a $7.75 cheaper ticket.
Instead of paying $374 from TPA to CVG (as per Travelocity.com), you'd be paying a super duper sale price of $366.25 if those rotton, evil, overpaid pilots would just fly for FREE!