America's worst-airlines revealed - with two repeat offenders continuing to receive more complaints than their rivals

America's most abysmal airlines were revealed in a new study, and two airlines in particular scored especially poorly.

The results of an annual customer satisfaction survey showed Spirit Airlines and Frontier Airlines in the bottom two places. 

The companies had once hoped to merge together, but the discount carriers have since been dogged by negative publicity and unsavory incidents.

The study took into account a wide-range of criteria, including baggage handling, call centers, boarding process, quality of in-flight meals, and the overall cleanliness of the airplane cabins and bathrooms.

They also considered airlines' loyalty programs, overhead storage, seat comfort, mobile apps, and staff performances at the gates and ticket counters.

Spirit Airlines and Frontier Airlines were ranked the worst and second worst airline in a new study conducted by researchers 

The CFI Group of Ann Arbor, Michigan, who conducted the survey, said that despite showing some improvements, Spirit and Frontier had been unable to avoid 'sitting at the low end of the industry.'

Spirit Airline, who finished in last, has been experiencing an extended period of market turmoil. Two of their proposed mergers didn't come to fruition. 

In January, after a U.S. judge blocked Spirit Airline's planned merger with JetBlue, which represented something of a life-raft for the beleaguered carrier, their stock plummeted 17 percent. 

Spirit Airlines hasn't turned a profit since the pandemic, and they will soon be forced to contend with $1.1 billion debt, which matures next year.

But the discount carrier's troubles aren't confined to financial woes. 

Both Spirit and Frontier Airlines have experienced a spate of unfortunate incidents, ranging from unsanitary leaks on planes to violent brawls in terminals and on board.

Earlier today, passengers on a Spirit Airlines flight from Atlanta to Newark were repulsed when they saw a mysterious liquid leak from the lavatory and wend its way down the cabin.

The rankings were based on numerous criteria including baggage handling, call centers, boarding process, quality of in-flight meals, and the overall cleanliness of the airplane cabins and bathrooms. Last February, a massive brawl broke out after a Spirit Airlines flight

Frontier Airlines, who finished in second last, had a flight that was forced to divert because of a mid-flight brawl

A spokesperson for the airline attributed the leak to 'an issue with a potable water line connected to a sink in the rear lavatory.' 

Last February, Spirit Airlines agents traded blows with unruly passengers as they were boarding a flight in a wild video that was obtained exclusively by DailyMail.com.

And in December, an impatient passenger was in such a hurry to disembark his flight that he stepped over the man sitting next to him.

Before that, in May, there was more bad press for the airline when a six-months pregnant passenger attacked an employee after she was told she could not board the flight after threatening a gate agent.

During one fight in a Spirit Airline terminal, a mom made a dash towards the counter and grabbed a keyboard but was dragged away and punched in the head

Her wig was torn off before a uniformed official finally showed up and the fight ended, some two and a half minutes into the video

On a Frontier flight, one woman berated another passenger before being restrained  

Spirit Airlines isn't alone. Like Spirit, Frontier, the second-worst carrier, has seen its fair share of negative news. 

Last July, shocking footage emerged of a brutal mid-air brawl on Frontier Airlines flight, which culminated in an emergency landing.

The footage shows flight attendants attempting to restrain two female passengers as they hurl obscenities and try to lunge at other travelers on Flight 2143.

The flight from Philadelphia to Las Vegas was diverted to Denver, where 'two passengers who were traveling together' were removed from the flight and handed over to cops, the airline told DailyMail.com.

The video does not show what started the dust-up, with the footage opening on one of the belligerents in a red tank top screaming at the top of her lungs while other passengers loudly shush and scold her. 

Frontier Airlines flight attendants tried to appease the women three times, before more drastic measures were taken. 

The footage stopped the moment the women were hauled off the plane, where the tensions on board were evident as the woman in red tried to mock the other woman as she was escorted away.

After she said 'get 'em out of here', the packed plane immediately erupted, telling her to 'shut the f*** up' and loudly shushed her.