Earlier this year, Warren Buffett's Berkshire Hathaway loaded up on airline stocks, doubling its position in American Airlines Group Inc. (AAL), boosting its stake in United Continental Holdings, Inc. (UAL) by over 600% and increasing its holdings in Delta Air Lines, Inc. (DAL) by almost 1,500%. When Buffett makes a move, smart investors take notice. (See also: Warren Buffett Buys $5.5 Billion in Airline Stocks.)

There are several good reasons why 2017 could be the year that airline stocks really soar. First, revenue per available seat mile (RASM) is poised to increase for the first time in over a year due to an expected increase in airline fuel prices next year. Then there's the issue of capacity, which the airlines had been increasing at a fairly rapid pace in 2015 and 2016. In 2017, the major carriers are looking at capacity increases of 0% to 2%, down from 5% during the previous years, which should support increasing RASM.

If you're ready to jump into the domestic airlines' $190 billion aggregate market cap to grab a piece of the potentially high-flying profits, exchange-traded funds (ETFs) are a great way to diversify and hedge your risk. For a pure airline play, however, the market is surprisingly tight, with just one ETF focused solely on the industry. Still, you can put your money in a transportation ETF and gain some exposure to the airline industry. Here are the best ETFs in this sector for 2017. (See also: Top 3 Transportation ETFs.)

Note: Funds were chosen on the basis of performance and assets under management. Year-to-date (YTD) performance figures reflect the period of Jan. 1, 2017, through March 15, 2017. All other information was current as of March 16, 2017.

US Global Jets ETF (JETS)

Issuer: US Global Investors

Assets under management: $67.34 million

YTD performance: -1.58%

Expense ratio: 0.60%

This is the only pure-play airline ETF in the game at the moment. It's a relatively new fund with an inception date of April 30, 2015. JETS invests primarily in domestic airline companies and companies involved in the airline industry (aircraft manufacturers, terminal services companies and airports), although about 21% of its portfolio is in international companies.

JETS is heavily weighted toward large caps, with 70% of its holdings in these stocks. The rest of the stocks in its basket of 33 holdings are selected on the basis of fundamentals such as sales growth and sales yield. Liquidity is a concern at just under $1.5 million in daily volume, and its average spread of 0.17% isn't exactly stellar, but if you're looking for pure exposure to the airline industry without buying individual stocks, JETS is the only game in town. Its one-year returns were 11.01%. (See also: Berkshire Still Looms Large for Airline ETF.)

iShares Transportation Average ETF (IYT)

Issuer: BlackRock, Inc. (BLK)

Assets under management: $1.19 billion

YTD performance: 1.05%

Expense ratio: 0.44%

IYT tracks a handful of domestic transportation stocks chosen by the Dow Jones Average Committee, which are weighted by price. The unusual weighting scheme of one share for each security lends itself to overweighting the high-priced equities and underweighting the lower-priced stocks. The airline sector accounts for 23% of the fund's portfolio of 20 stocks.

The fund has good liquidity, with an average daily volume of $58 million and a relatively tight spread at 0.04%. Alaska Air Group, Inc. (ALK) lands in the top 10 holdings. IYT's one-, three- and five-year annualized returns are 20.33%, 8.15% and 13.40% respectively. (See also: Tips for Trading the Dow Jones Transportation Average.)

SPDR S&P Transportation ETF (XTN)

Issuer: SPDR

Assets under management: $244 million

YTD performance: -1.07%

Expense ratio: 0.35%

This fund is designed to track a broad-based index of equities in the US transportation industry. There are currently 44 holdings in the fund's portfolio, which is heavily weighted toward ground freight at nearly 50%. Airlines take second place at just 26%, but this is due to the fund's equal-weighting approach to the transportation industry to work around its high concentration issues.

XTN is the cheapest in its segment. It has decent liquidity ($2.5 million average daily volume), and compared with its peers, XTN has an acceptable spread of 0.12%. One-, three- and five-year annualized returns are 21.51%, 8.43% and 17.77% respectively. (See also: The Industry Handbook: The Airline Industry.)

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