Airline stocks have always been a volatile investment, and even airline CEOs have been gun shy about sinking their money into them. As former American Airlines CEO Robert Crandall somewhat infamously said, “I’ve never invested in any airline. (American’s) a great place to work and it’s a great company that does important work. But airlines are not an investment.” That’s not exactly a ringing endorsement.

But almost exactly one year ago, Delta Air Lines (NYSE: DAL) was added to the Growth Portfolio in Personal Finance. While it’s been something of a turbulent ride, since then the shares have gained nearly 60%, making it one of the best performing airline stocks on the market. It also continues to score highly on Chief Investment Strategist Jim Pearce’s IDEAL stock rating model with an ‘8’ rating out of a possible perfect score of ’10.’

So, why is Delta flying higher than its peers? For one thing, it makes its own jet fuel. Back in 2012, one of Delta’s subsidiaries acquired a refinery south of Philadelphia for $150 million. It then spent around another $100 million to convert the facility to maximize jet fuel production.

While a lot of folks were skeptical of Delta’s pickup – it’s tough to deny that running an oil refinery is very different from running an airline – the deal has resulted in the airline’s average fuel cost running roughly a dime lower per gallon then the industry average. That equates to an annual savings of nearly $300 million on the business’s main expense, nothing to sneeze at. Throw in the recent plunge in crude prices and you can expect to see even better cost savings.

We were, in fact, already seeing the beginnings of that last year. In 2014, Delta brought in more than$4.5 billion in pretax income, nearly $2 billion more than in 2013. That resulted in $3.7 billion in free cash flow, which was used to pay down $2.1 billion in debt while more than $1.3 billion was returned to shareholders as the company repurchased about 13 million shares and paid out $251 million in dividends.

Airlines generally are also catching a tailwind from economic improvement. While global growth is spotty, here in the U.S. the economy is still humming along. As more Americans find jobs, we can expect both personal and business travel to continue picking up as consumers feel more prosperous. That means fuller aircraft and higher returns on each flight, boosting overall profitability. In fact, margins improved by more than 4% last year alone.

In fact, after posting earnings per share of $0.78 last year, analysts are currently forecasting earnings growth of more than 500% to $4.70 in 2015. They further expect nearly 20% growth in 2016, with earnings forecast to reach $5.55. The company itself expects to lock in a significant profit increase this year thanks to lower fuel costs and improving loads, while paying down another $1 billion in debt by the end of 2016. It has also said it plans to spend at least $1.5 billion in dividends and share repurchases. It also expects to purchase 150 new planes over the next few years, modernizing its fleet and taking advantage of fuel saving technology.

That’s what I call flying high.

So while Delta appears to be commanding a pretty decent premium with shares trading 58.9 times trailing earnings, it’s at just 8.3 times forward earnings – a pretty decent bargain. That’s attracting some serious buying interest, with total shares bought over the past two years up by more than 65% among institutional owners such as hedge funds. Investors are clearly coming around to the notion that Delta is on the right track.

Another potential benefit for Delta is that it is largely a domestic player. The U.S. dollar has been in strengthening mode of late, dragging down earnings at American companies with major overseas operations. While Delta isn’t totally immune to that effect, more than 70% of its revenues are generated within North America, where it holds better than 20% market share. And while other carriers have been looking to expand internationally, most of Delta’s growth plans are domestically focused.

So with the dual tailwinds of an improving U.S. economy and low fuel prices, Delta’s shares are set to soar to 2015.