Flight attendants say they're less vigorous about enforcing rules and fear being attacked

— -- In the wake of an infamous April incident that saw a bloodied passenger dragged off a plane, some flight attendants are saying that they feel passengers are being more "defiant," leading to them become less vigorous about enforcing some safety rules to avoid confrontation.

“Some passengers feel now that they can be more defiant and that has us on edge,” one flight attendant said.

Another added, "I don't want them to be afraid of me, but I also don’t want them to ... break, or cause, a security breach, because now we tell them, 'The fasten seat belt sign is on' or 'Please be seated,' now the camera phones are coming out."

“The Dao incident brought a lot of attention to us and not in a way we would like,” a third flight attendant added, referring to the now-viral video of Dr. David Dao, who was forcibly dragged off an overbooked United Airlines flight.

Dao eventually sued the airlines, and United settled for an undisclosed amount.

Now three flight attendants working for three different airlines are saying that the incident has emboldened some passengers to feel as if they can disregard flight attendant's instructions on board. The flight attendants were introduced to ABC News by their union and spoke under the condition that their names, faces, and the airlines they worked for would not be disclosed.

The first flight attendant said, "The minute something happens, I believe that it will escalate higher than it was with Dao."

"There's other times when you're trying to get someone to comply, and three rows back ... a shout, 'Careful, they're going to drag you out,'" he added. "And the cameras, or the phones ... you'll see phones, I’m not saying they're up filming, but you see them and then the whole situation makes you pause and want to step back."

The flight attendants say that the heightened tension is leading them to enforce some rules with less rigidity than they once did in order to avoid confrontation, including everything from seat belt buckling to technology use, to getting the verbal “OK” they need from passengers seated in an exit row that indicates they will assist in an emergency.

“Now if you don't acknowledge me, I just kind of shrug and go my way,” the first flight attendant said. “I want you safe, there’s not enough time to beg you.”

A second flight attendant added, "I will tell you once, maybe tell you twice. I'm not going to get into a major argument with you."

A third said that when someone does not comply with their instructions, "It’s a huge safety issue.”

The Federal Aviation Administration denied claims that recent incidents are affecting safety onboard flights, saying in a statement to ABC News that they have not witnessed crew members commitment to safety "wavering."

"Equally important, passengers have a responsibility to follow crew safety instructions," the FAA added. "Recent airline travel incidents that have gained attention on social media have been customer service-related and not safety.”

One flight attendant, however, said that she feared for her own safety while working.

“My greatest fear now is just being attacked,” the third flight attendant said. “Physically attacked.”

Airlines for America (A4A), an industry advocacy group, acknowledged the new tension, but said in a statement to ABC News, "We are currently living in the safest period in aviation history."

"It is our hope that both passengers and crew members commit to and understand the importance of listening to and working with each other in order to make every flight both a safe and positive experience," A4A added.

One of the flight attendants told ABC News that she does not foresee tensions calming down to how they were prior to the incident involving Dao.

"I don't think it's going to be as good as it was," she said.

Her colleague added that she hopes to see more respect for crew members going forward.

"Because if they don't respect us, then they won't listen to our safety commands and that's where the big issue is," she added.