Said otherwise : the income statement gives you an idea on how healthy your operations are, while the cash-flow statement helps you checking you're not bleeding money, or to know what is your financing capacity.
When you're paying back big loans, your cash-flow can be dangerously in the red, even if your operations are positive. That kind of things mean you are in short-term danger, but if you survive, you should be healty.
When you bought your planes, you can have the reverse situation : a positive cash flow, but real losses, counting the airplane depreciation. It's a long term problem, because you don't make enough money to prepare the replacement of your planes when they'll get old.
Said still another way : the cash-flow statement tells you what are your short-term options/problems. The income statement tells you if your long-term management is sound.