With the first-quarter 2016 earnings season in full swing, the past week saw releases by airline heavyweights like Southwest Airlines LUV, United Continental Holdings UAL, American Airlines Group AAL, JetBlue Airways Corporation JBLU and Alaska Air Group, Inc. ALK. While weak oil helped carriers register impressive year-over-year growth, passenger revenue per available seat mile (PRASM, a measure of unit revenue)-related woes continued to hurt the top line.The earnings beat by quite a few airline players in the quarter wasn’t much of a surprise as the Zacks Consensus Estimate has been pretty conservative following the multiple downward revisions made in estimates over the past few months. Moreover, cheap oil has been benefiting the bottom line over the past few quarters and has not been so much accretive to earnings this time around. Meanwhile, the top line has been continuously grappling with issues such as PRASM and capacity, which have been bothering investors as well.The series of earnings beats have not been able to cheer investors as is evident from the 6.29% decline in the NYSE ARCA Airline index to $90.63 over the past five trading days.Read the last Airline Stock Roundup for Apr 20, 2016.Recap of the Past Week’s Most Important Stories1. American Airlines Group Inc. reported higher-than-expected earnings in the first quarter of 2016. Adjusted earnings per share of $1.25 beat the Zacks Consensus Estimate by 7 cents. Meanwhile, in order to modernize its fleet, the carrier took delivery of 15 new mainline aircraft and 13 regional ones during the reported quarter, while retiring 22 aircraft (read more:American Airlines Tops Q1 Earnings, Okays Buyback). 2. United Continental Holdings’ first-quarter 2016 earnings (on an adjusted basis) of $1.23 per share beat the Zacks Consensus Estimate by 6 cents. Earnings, however, declined 19.1% on a year-over-year basis owing to higher taxes which mitigated the positive impact of low fuel costs. Revenues were hurt by a strong dollar (read more: United Continental Q1 Earnings Top, Revenues Miss).3. Alaska Air Group, the parent company of Alaska Airlines and Horizon Air, reported first-quarter 2016 earnings per share of $1.45, which surpassed the Zacks Consensus Estimate of $1.42 and also increased 29% year over year. Quarterly revenues also improved 5% year over year to $1.35 billion, steering past the Zacks Consensus Estimate of $1.34 billion. On a year-over-year basis, Passenger revenues improved 4% (read more: Alaska Air Group Q1 Earnings, Revenues Top; Up Y/Y).4. Southwest Airlines reported first-quarter 2016 results wherein both the top and the bottom line surpassed the Zacks Consensus Estimate. The low-cost carrier reported earnings of 88 cents per share, outpacing the Zacks Consensus Estimate by 4 cents. Quarterly revenues moved up 9.3% year over year to $4,826 million, steering past the Zacks Consensus Estimate of $4,818 million. On a year-over-year basis, Passenger and Other revenues increased 5.3% and 101%, respectively, while Freight revenues dropped 4.5% (read more: Southwest Airlines Beats on Q1 Earnings & Revenues).5 Shares of the Long Island City, New York-based low-cost carrier JetBlue Airways were adversely impacted on Apr 26 despite an earnings beat in the first quarter of 2016. Declines in PRASM (8% to 11.35 cents) and operating revenue per available seat mile (RASM fell 7% to 12.41 cents) hurt the stock. JetBlue’s earnings (excluding special items) of 59 cents per share beat the Zacks Consensus Estimate of 53 cents. Earnings improved substantially from the year-ago figure, thanks to low fuel costs. Operating revenues came in at $1,616 million, below the Zacks Consensus Estimate of $1,622 million. However, revenues improved 6.1% from the year-ago figure benefiting from a 20% increase in other revenues. Passenger revenues climbed 4.9% in the first quarter of 2016.For the second quarter of 2016, the carrier expects fuel price, including fuel taxes, to be $1.33 per gallon. Capacity in the second quarter of 2016 is projected to increase in the band of 9.5% and 11.5%. For 2016, the metric is still expected to increase in the range of 8.5% to 10.5%. Consolidated operating cost per available seat mile, excluding fuel and profit sharing, is projected in the band of -0.5% to +1.5% for the second quarter of 2016. For 2016, the metric is expected to grow in the range of 0% to 1.5%.6. Another low-cost carrier, Spirit Airlines SAVE, has also beaten earnings aided by low fuel costs. The carrier’s first-quarter 2016 earnings (on an adjusted basis) came in at $1.01 per share, beating the Zacks Consensus Estimate of 97 cents. Earnings also improved 5.2% on a year-over-year basis. Spirit Airlines reported operating revenues of $538.1 million, beating the Zacks Consensus Estimate of $532 million. An increase in flight volume led to a 9.1% year-over-year rise in quarterly revenues. In the reported quarter, operating revenue per available seat mile fell 13.8% year over year while load factor (% of seats filled by passengers) dropped to 84.7% from 84.9% in the year-ago quarter. Load factor declined as traffic growth (26.2%) was outpaced by capacity expansion (26.5%) during the first quarter. Average economic fuel price per gallon declined 37.4% to $1.22.Performance The following table shows the price movement of the major airline players over the past week and during the last 6 months. CompanyPast WeekLast 6 monthsHA-12.77%25.35%UAL-16.04%-19.36%GOL-4.59%-17.91%DAL-8.44%-14.31%JBLU-4.84%-19.83%AAL-10.55%-20.53%SAVE-9.35%36.84%LUV-2.61%1.56%VA-0.24%58.87%ALK-7.60%8.22% The table above shows that all airline stocks traded in the red over the past week with shares of United Continental depreciating the most (16.04%) on the back of PRASM related worries.Over the past six months, airline stocks exhibited a mixed trend with the NYSE ARCA Airline index declining 1.46%%. Shares of Virgin America VA appreciated the most (58.87%) during the period and American Airlines emerged as the biggest laggard (20.53%).What's Next in the Airline Space?There are a few airline companies lined up for release over the next few days. The most notable one being the low-cost carrier Virgin America, which is scheduled to report first-quarter financial numbers on Apr 28. Meanwhile, a couple of April traffic updates are also awaited.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 >>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 AIR (LUV): Free Stock Analysis Report JETBLUE AIRWAYS (JBLU): Free Stock Analysis Report ALASKA AIR GRP (ALK): Free Stock Analysis Report UNITED CONT HLD (UAL): Free Stock Analysis Report SPIRIT AIRLINES (SAVE): Free Stock Analysis Report AMER AIRLINES (AAL): Free Stock Analysis Report VIRGIN AMERICA (VA): Free Stock Analysis Report To read this article on Zacks.com click here.