Airline stocks have been in the pink of health over the past few years, mainly on the back of solid passenger revenues owing to robust air-travel demand. However, with the advent of coronavirus in the first quarter of 2020, things deteriorated for the entire aviation space as travel demand plummeted with people being confined to their homes in the fear of the contagion.What is worse is that the health peril is still very much around even though more than seven months have elapsed since the disease was declared a pandemic by the World Health Organization. Consequently, airlines continue to bear the brunt of this global adversity. As an evidence, airlines fared dismally for the third successive quarter this year with losses mounting due to crippled passenger revenues.Against this bleak backdrop, let’s recapitulate the results of a few key airline stocks for the September quarter.Delta Air Lines DAL kicked off the third-quarter 2020 earnings season for the aviation industry on Oct 13. This Atlanta-GA based company incurred a loss (excluding $5.17 from non-recurring items) of $3.30 per share in the September quarter, wider than the Zacks Consensus Estimate of a loss of $3.14. Also, passenger revenues plunged 83% year over year in the September quarter. In fact, due to low demand, this key metric declined 68% in the first nine months of 2020.Akin to Delta, Chicago-based United Airlines UAL suffered a loss in the third successive quarter of 2020. The carrier reported a loss (excluding $1.83 from non-recurring items) of $8.16 per share in the September quarter, comparing unfavorably with the Zacks Consensus Estimate of a loss of $7.63. Passenger revenues plunged 84.3% and 68.4% in the third quarter and during the first nine months of 2020, respectively.American Airlines AAL posted a loss (excluding 83 cents from non-recurring items) of $5.54 per share for third-quarter 2020, narrower than the Zacks Consensus Estimate of a loss of $5.62. Passenger revenues plunged 76.9% and 64.2% in the third quarter and during the first nine months of 2020, respectively.Dallas-based low-cost carrier Southwest Airlines LUV fared no better and announced a loss for the third consecutive quarter like its fellow airline players mentioned above. The carrier, carrying a Zacks Rank #3 (Hold) currently, incurred a loss of $1.99 per share (excluding 3 cents from non-recurring items) in the reported quarter, narrower than the Zacks Consensus Estimate of a loss of $2.44. Moreover, passenger revenues plunged 71.2% and 61.2% in the third quarter and during the first nine months of 2020, respectively.You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.Apart from the above-mentioned carriers, the likes of Alaska Air Group ALK, JetBlue Airways Corporation JBLU and Spirit Airlines SAVE continued to suffer a setback in the September quarter’s financial report, repeating the negative momentum faced in the June and March quarters.Any Respite Ahead?With airlines having performed disappointingly in the third quarter, echoing the first two quarters’ trend, the million-dollar question is whether things will look up for the stocks from hereon. Unfortunately, the answer is a big no at least for the near term. Notably, Delta's president Glen Hauenstein warned that “it may be two years or more” for the revenue stream to normalize.Even though air-travel demand showed signs of marginal recovery, particularly, on the leisure front, the spike in the coronavirus cases all across Europe (resulting in renewed lockdowns in many countries) and the same in some parts of the United States induce fears that the surge in cases might offset the improvement in travel frequency. Notably, European carrier Ryanair Holdings RYAAY forecasts losses to worsen in the second half of fiscal 2021 (ending Mar 31, 2021) from the first.Additionally, the expiry of the CARES Act on Sep 30 forced carriers like American Airlines and United Airlines to shrink their respective workforces in the face of dwindling air-travel demand. Despite some positive developments, a second round of financial aid from the government has not materialized yet, thereby making the job cuts necessary.However, on a brighter note we expect focus to shift to a second round of federal stimulus once Biden is officially declared as the next US president. The positive vibes on the package, which came from various quarters prior to the elections, might see a further impetus leading to the much-anticipated sop eventually seeing the light of the day.In the event of a further federal stimulus, the bruised and the battered U.S. airline stocks would surely get some relief as the pandemic grant will protect jobs in the near term and keep hopes afloat amid the existing unprecedented crisis.Breakout Biotech Stocks with Triple-Digit Profit PotentialThe biotech sector is projected to surge beyond $775 billion by 2024 as scientists develop treatments for thousands of diseases. They’re also finding ways to edit the human genome to literally erase our vulnerability to these diseases.Zacks has just released Century of Biology: 7 Biotech Stocks to Buy Right Now to help investors profit from 7 stocks poised for outperformance. Our recent biotech recommendations have produced gains of +50%, +83% and +164% in as little as 2 months. The stocks in this report could perform even better.See these 7 breakthrough stocks now>> 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 Ryanair Holdings PLC (RYAAY): Free Stock Analysis Report Delta Air Lines, Inc. (DAL): Free Stock Analysis Report United Airlines Holdings Inc (UAL): Free Stock Analysis Report American Airlines Group Inc. (AAL): Free Stock Analysis Report Alaska Air Group, Inc. (ALK): Free Stock Analysis Report Spirit Airlines, Inc. (SAVE): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research