“This is the new flying etiquette,” JetBlue’s president said.

As demand for air travel reaches historic lows amid the COVID-19 pandemic, passenger Erin Strine was shocked to board a nearly full American Airlines flight from New York to Charlotte on Saturday.

Strine observed many passengers were sitting side by side and not wearing masks. She posted a video to Twitter, which as of Monday evening, has been viewed almost two million times – -strengthening union calls for more protection and more aggressive policies on social distancing.

“It was the first time that I felt truly unsafe,” Strine said. She was traveling to see her family following the passing of her grandmother. “I wanted to come home to be here for my parents, and my dad especially, you know it wasn’t a decision I made lightly.”

Strine’s flight was about 85 percent full, according to a spokesperson for American Airlines.

Last week there was a slight uptick in the number of travelers at U.S. airports for the first time since the novel Coronavirus began to severely impact demand for air travel in the U.S., according to screening numbers from the Transportation Security Administration (TSA). The agency screened around 85,000 more people nationwide last week compared to the week before.

“I got a report from a flight attendant last night who went back to work after being in mandatory quarantine,” Sara Nelson, both a current flight attendant and president of the Association of Flight Attendants-CWA, AFL-CIO told ABC News. “And her first flight back to work, was a completely jam packed four hour flight.”

In response to recommended social distancing guidelines, American Airlines says it is leaving about half of its middle seats empty in standard economy. Delta Airlines is blocking all middle seats in standard economy. United Airlines says although it can not “guarantee that adjacent seats will always go unoccupied” the airline believes it will be able to implement its proposed policy this week that no passenger will be forced to sit directly next to another passenger unless it is requested.

Nelson, who leads the largest flight attendant union in the U.S., called on the Department of Transportation and Department of Health and Human Services last week to mandate that that all passengers and crew wear a face covering.

“From the airport door to the airplane door, on the airplane, and then back out through the airport, we want people wearing face coverings in all those areas,” Nelson said. “That is what is recommended by the CDC to the general public when they are out in public, and that is exactly what should be happening in our airports and on our airplanes to help contain the spread of the virus.”

Since then, major U.S. airlines including Delta, American, and United announced that their frontline employees like flight attendants will be required to wear face coverings or masks.

JetBlue, which says they implemented their face covering for crew policy in mid-April, became the first major U.S. airline on Monday to announce it will require passengers wear a face covering during travel.

Passengers flying JetBlue must wear a face covering over their nose and mouth throughout their journey, the airline says, including during check-in, boarding, while in flight and deplaning.

“Wearing a face covering isn’t about protecting yourself it’s about protecting those around you,” JetBlue President and Chief Operating Officer Joanna Geraghty said. “This is the new flying etiquette.”

JetBlue’s policy takes effect on May 4.

“All airlines should follow JetBlue’s lead, Nelson tweeted late Monday. “Including its efforts to fully communicate the change before it becomes effective next week so that flight attendants are not put in the position of being enforcers without information and backing from the airline.”

This report was featured in the Tuesday, April 28, 2020, episode of “Start Here,” ABC News’ daily news podcast.

“Start Here” offers a straightforward look at the day’s top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.