Airlines can be as unpredictable as M. Night Shyamalan plot twists. Even Bob Crandall, during his tenure as president of American Airlines (NYSE:AMR), famously advised against them as investments. Warren Buffett himself has a pretty memorable quote about airlines. 

During its relatively brief history, the airline industry has been influenced by cutthroat competition, government intervention, unionized labor, and erratic fuel costs. For its most recent quarter, Delta Air Lines (NYSE:DAL) carried on in that tradition.

Analysts schmanalysts
Three months ago, analysts predicted the airline would report an earnings loss of $0.29 per share. Over the last several weeks, their outlook improved, and the Street was calling for Delta to break even. Their expectations for the Atlanta-based airline were overly optimistic.

An 54% increase in fuel-related expenses, compared to the same quarter last year, thwarted that outcome, and despite 9% revenue growth, the company's losses totaled $50 million, or $0.13 per share.

Da bulls say
For bulls, the future for Delta seems bright, and for those with enough risk tolerance to stomach investing in airline stocks, it may turn into a great turnaround story.

The upcoming merger with Northwest Airlines (NYSE:NWA) is on track to close by year's end. That consolidation should increase market share and improve Delta's chances of enduring prolonged adverse economic conditions. Management has already exhibited its ability to increase efficiency.

Da bears say
Nevertheless, as promising as its prospects seem, the challenges facing the airline remain daunting.

Delta has $3.1 billion in cash and short-term investments, but it also operates at a working capital deficit, which means it may have difficulty paying its short-term obligations without raising additional money. The current economic climate could hinder this task.

Additionally, although the airline has successfully contained costs through its practice of fuel hedging, and oil prices have plummeted recently, the uncertainty surrounding the future availability of affordable oil contributes to significant long-term risk.

The Foolish takeaway
Remember, soaring oil prices hurt Delta's bottom line this time around, and now we're seeing a reversal of that trend. The addition of Northwest's business will expand the airline's reach into more international destinations, and barring a dramatic decrease in demand for business travel, the airline should return to profitability.

Investors with long time horizons and healthy appetites for risk should take a closer look. Delta shows signs of being unbreakable in the long run, and this Fool's sixth sense tells him that good things could happen for the airline.

Chris Jones does not own shares of any companies mentioned. The Motley Fool's disclosure policy does not see anything out on the wing.