There's still no certainty. For an airline, your prices have to be competitive. If you've locked in an oil price, and it turns out to be a high one, then your fares will be more expensive than your competitors (assuming that they didn't hedge in the same way). So the only certainty there is failure.

In all situations, hedging and non hedging, the oil price will determine whether you win or lose. There is no magical combination of derivatives that will ensure success. In fact, for every financial product you buy, you're paying a cost due to the margin that the bank/market charged you.

Hedging might make sense for some accounting/tax situations, but that's another issue entirely.