When I was updating the 744 tracker post earlier, I noticed that each aircraft that had a new reported total hours figure seemed to have done very close to 4,000 hours in the most recent year - often to within a couple of hundred hours of 4,000.
It made me wonder whether 4,000 hours a year is an actual target that the fleet is operated to? Or is that just the way it happens to pan out, given the way that the fleet is used?