Originally Posted by
skywatch
Every airframe at Delta flies this way - I doubt they would do it if it increased the operating costs.
Actually, PPAS accounts for airframe time, engine wear, etc. as well as crew costs and then balances the combined hourly cost vs the cost of fuel to determine the best cruise speed. As the cost index number goes down, fuel is saved. As C/I goes up, more fuel is wasted but all other costs are reduced.
Or, more importantly, as C/I goes down, Delta saves money. As C/I goes up, Comair saves money. Guess which one Delta tells us to do...