It’s been close to one month since Delta Air Lines Inc. DAL kick-started the second-quarter earnings season for the airline space. Overall, the season has been mixed for the industry, with several operators missing revenue estimates. The airline companies belong to a bottom-ranked Zacks industry (bottom 8%). Lets’ delve a little deeper.Inside Earnings Delta’s second-quarter earnings (excluding 30 cents from non-recurring items) of $1.77 per share surpassed the Zacks Consensus Estimate by 5 cents. The bottom line also expanded on a year-over-year basis despite high fuel costs. Operating revenues came in at $11,775 million, outpacing the Zacks Consensus Estimate of $11,678.8 million. The top line increased more than 9% from the year-ago figure. Strong demand for air travel boosted revenues.United Continental Holdings Inc.’s UAL) earnings (excluding 75 cents from non-recurring items) of $3.23 per share surpassed the Zacks Consensus Estimate of $3.07. The bottom line also increased significantly year over year owing to higher revenues. Operating revenues came in at $10,777 million, which outpaced the Zacks Consensus Estimate of $10,702 million. Moreover, the top line was up 7.7% year over year. The company anticipates capacity to expand between 4.5% and 5.5%, while pre-tax margin (adjusted) is estimated between 8% and 10%. Passenger unit revenues are anticipated to increase 4-6% year over year.American Airlines Group Inc.’s AAL second-quarter 2018 earnings (excluding 41 cents from non-recurring items) of $1.63 per share surpassed the Zacks Consensus Estimate by 4 cents. Quarterly earnings decreased on a year-over-year basis mainly due to high fuel costs. Revenues of $11,643 million fell short of the Zacks Consensus Estimate of $11,652 million. The top line, however, improved on a year-over-year basis. Strong demand for air travel led to the year-over-year improvement in the top line.Low-cost carrier Southwest Airlines Co. LUV reported second-quarter 2018 earnings per share (excluding a penny from non-recurring items) of 1.26, beating the Zacks Consensus Estimate of $1.25. Operating revenues of $5,742 million lagged the Zacks Consensus Estimate of $5,771 million. However, the top line improved year over year.JetBlue Airways Corporation’s JBLU second-quarter 2018 earnings per share (excluding 76 cents from non-recurring items) of 38 cents surpassed the Zacks Consensus Estimate of 36 cents. However, the bottom line decreased significantly on a year-over-year basis primarily due to high fuel costs. Total operating revenues of $1,928 million fell short of the Zacks Consensus Estimate of $1,931.2 million. Nevertheless, the top line increased approximately 5% from the year-ago figure.Alaska Air Group Inc. ALK reported second-quarter 2018 earnings per share (excluding 10 cents from non-recurring items) of $1.66, which surpassed the Zacks Consensus Estimate of $1.63. Earnings declined due to high fuel costs. Revenues came in at $2,156 million, which fell short of the Zacks Consensus Estimate of $2,174.2 million. However, revenues increased year over year.ETF in Focus Since results were mixed, investors having a strong stomach for oil-related risks may go for a basket approach. This approach makes up for company-specific concentration risks as one company’s weakness compensates for another company’s strength (read: Winning and Losing Sectors ETFs Post OPEC Decision).JETS in Focus The $98 million-fund holds more than 30 stocks in its portfolio and is concentrated on a few individual securities. United Continental (13.02%), Southwest Airlines (12.74%), Delta Airlines (12.01%) and American Airlines (11.08%) take the first four positions in the fund. Alaska Air and JetBlue hold the seventh and eighth positions in the fund with a 3.88% and 3.68% weight, respectively. The product charges 60 bps in fees (see all industrials ETFs). Want key ETF info delivered straight to your inbox? Zacks’ free Fund Newsletter will brief you on top news and analysis, as well as top-performing ETFs, each week. Get it free >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Southwest Airlines Co. (LUV): Free Stock Analysis Report JetBlue Airways Corporation (JBLU): Free Stock Analysis Report Delta Air Lines, Inc. (DAL): Free Stock Analysis Report American Airlines Group Inc. (AAL): Free Stock Analysis Report Alaska Air Group, Inc. (ALK): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report