The couple was in the midst of a monthslong relocation from Maryland to California when the coronavirus pandemic engulfed the United States this spring. Since then, the husband and wife have established a list of criteria for choosing what flights to book: blocked middle seats and absolutely no layovers.

"If you are on a flight without a booked middle seat, you are just asking for it. Shoulder-to-shoulder for five hours without masks? No, thank you," said Darrell Riley, who recently flew Delta Air Lines from Los Angeles to Minneapolis-St. Paul.

"It was tough enough on that flight, which was pretty full other than the middle seats," said Darrell Riley. "That was all I could tolerate."

The major airlines have been brought to their knees by the global pandemic, sharply cutting the frequency of flights, parking planes and laying off workers.

As fall approaches, normally a peak time for business travel, they are vying for a much smaller pool of committed, nonbusiness passengers. And they're trying to reach them with a different message. Perks and amenities are no longer the focus, health and safety are.

"The airlines need us, they need us more than ever before," said Jason Cochran, editor-in-chief of Frommers.com. "For the last 20 years or so the average consumer, the economy flier, has been more or less ignored by the airlines. It was an arms race of amenities, like lounges and upgrades, largely aimed at the business class. That's all meaningless now."

More than half of U.S. air travelers are uncomfortable flying because of concerns about the coronavirus, according to a Gallup poll released last week. Those who do fly are booking based on a hodgepodge of safety measures put in place by different airlines.

To lessen the virus' spread, many passengers have stayed home for the past five months, avoiding being indoors — or in an airplane — with others for extended periods of time.

Slowing the burn

The carriers, hemorrhaging billions of dollars in the early weeks of the U.S. spread, immediately focused on stabilizing distressed balance sheets by retiring hundreds of airplanes, reducing their workforce and axing flights.

These moves helped Delta Air Lines, the dominant carrier at Minneapolis-St. Paul International Airport, cut its costs by more than half, reducing its daily cash burn from $100 million in March to $27 million in June.

But it's not enough. The airlines have to find a way to break even.

As the U.S. settles into a new normal of living within the prolonged crisis, the survival of airlines depends on their ability to convince passengers that flying aboard their planes is safe — or at least safer than those of their competitors.

"Airlines are competing on cleanliness and hygiene because there are no federal standards or mandates they all need to follow, so they see [this] as a way to differentiate from one another," said Henry Harteveldt, president of Atmosphere Research Group and a travel industry analyst.

Delta may be pushing the cleanliness message hardest of all. Chief executive Ed Bastian has been on a national media blitz in recent weeks, explaining all that the Atlanta-based airline is doing to keep people safe while traveling, from sanitizing aircraft between every flight with an electrostatic sprayer to prepacked snack-and-cleaner bags given to every customer.

Delta and JetBlue are currently blocking sales of all middle seats to give passengers some social distance. Southwest Airlines, which doesn't have seat assignments, is attempting to create more space by only selling two-thirds of all seats, effectively keeping middle seats open.

But competitors American and United airlines haven't put limits on capacity, arguing that social distancing on planes isn't possible and blocking seats is futile.

In July, Delta's Bastian told investors he disagrees.

"In the face of a health crisis, that space onboard really matters," Bastian said on a recent earnings call. "This is, to us, a really important safety feature."

In a note last week to employees, Bastian said the company's ability to break even depends on these precautions. "We hear from customers every day telling us they are switching their loyalty to Delta because of the safety practices we have in place," he added.

The more that is learned about this virus, Cochran said, the less worried people are about surfaces.

"It's ultimately about the people around me and their behavior. Are they wearing a mask or not?" he said. His readers at Frommers have consistently said they trust Delta more because of the extra space created by the blocked middle seat.

While the large U.S. airlines can afford to cap the number of seats sold per flight, such a move could sink low-cost carriers like Spirit, Frontier and Sun Country.

"If we were required to leave middle seats open, that would be a pretty substantial financial burden for us, which would eventually have to be paid for by the customer," said Jude Bricker, chief executive of MSP-based Sun Country Airlines.

In the sky, passengers rule

No matter the safety measures an individual airline puts into place, there's a level of risk involved in flying that's dependent on other people's behavior.

"It's not like people are masked up on the whole flight. They could have it off for a couple hours, just sipping coffee or eating their pretzels," Riley said. "I'm just in this little cocoon with other people for hours on end. That's why people are just a little on edge when traveling."

There's a growing push among industry insiders and analysts for a federal standard of airline safety measures to combat COVID-19 and reduce travel anxiety for passengers.

"Once the plane leaves the gate, the flight attendants are really powerless," Cochran said.

The airlines can, and do, ban passengers from travel if they fail to comply with the mask mandate. But, Cochran said that doesn't help those who had to sit near the passenger during the flight.

"The U.S. government has decided to sit this one out," Harteveldt said. "Certainly the steps airlines are taking to address these concerns are very smart. But I think it would help the airlines if the government said, 'Look, here are the things you need to do to help travelers feel safe,' just as it has since the dawn of aviation in making sure air travel is safe. But they haven't even said how often they need to clean their planes."

Without government guidance or rules, it's up to airlines to sell passengers on their cleanliness and it's up to passengers to both behave well and decide whether they trust others — including the airlines — enough to fly.

"We already have this rocky relationship with the airlines after being disrespected for so many years, so it's really hard for the average consumer to believe their promises," Cochran said. "Now they are trying to claw their way back to a place of intimacy."

As for the Rileys, they aren't overly anxious when flying, but just want everyone to do their part.

On a cross-country flight in late May, Lynda Riley approached people who weren't wearing their masks. "I'd say, 'I hate this, too, but everybody has to do it,' and stare at them until they put it on," she said. "I'm that person, but I don't care."

Most of their friends wouldn't even consider stepping on a plane.

"When traveling, everyone is just thinking, 'I know this is a little bit wrong, but this is how I get from point A to point B,' " Darrell Riley said. "The worst thing you can do on a plane is cough."