Warren Buffett is investing big-time on an industry that he once called a death trap.

The billionaire investor’s company, Berkshire Hathaway has upped its investment into Delta Airlines and American Airlines while also purchasing a significant amount of shares of Southwest.

According to Yahoo, “Buffett purchased $2.2 billion in shares of Southwest. He also owns about $2 billion of American, United Airlines, and Delta“.

The article mentions how just over a few years back Warren Buffet called the airline industry a “deathtrap for investors” at Berkshire Hathaway’s annual meeting.

So why the change of heart?

Due to the price of oil, US airlines have shown “profits of unprecedented levels“. All four airlines that Berkshire Hathaway has invested in have shown record profits over the past couple of years.

The big four US airlines have also been upgrading by investing “in next-generation aircraft, interiors, and technology“. AA, Delta and United have also been increasing the quality of their premium cabins, going after business travelers.

All of these factors along with many more sound like the airlines could be a good bet to invest in. While I’m no expert on this kind of thing, if you follow the lead of Warren Buffett, it’s probably a worthy investment.

Find out more from Yahoo here.