New York CNN  — 

You’re soaring 2,000 feet above Manhattan’s sparkling East River, the distant skyline glistening at dusk as your feet dangle from the side of a whirring doors-off helicopter.

“It feels like when you are on top of the world,” Judith Verweijen, of the Netherlands, said of her recent flight. “You don’t think about fear. You think about the joy … that you’re able to do that.”

That aura of invincibility shattered the evening of March 11 – one day after Verweijen’s excursion – when a helicopter booked by the same firm she flew with splashed into the East River. Five passengers drowned, unable to break free from harnesses meant to prevent them from falling out. The pilot escaped.

It was the deadliest crash involving a national doors-off helicopter tour. Experts say the industry runs with scant oversight, even as its popularity surges in step with the desire – especially among millennials – for breathtaking, unobstructed photos to post on social media.

“This accident has the potential to be a watershed event for the industry,” said Peter Goelz, a former managing director of the National Transportation Safety Board.

“There are clear questions about whether this type of operation was appropriately overseen by the FAA and others.”

In light of the fatal crash, the Federal Aviation Administration issued an order suspending “doors off” flights involving “restraints that cannot be released quickly in an emergency.”

On Monday, the National Transportation Safety Board issued an urgent safety recommendation asking the FAA to ban commercial flights using harness systems that don’t allow for easy release during emergencies.

The NTSB said the harness system on the aircraft was not installed by Liberty Helicopters but was a collection of “off-the-shelf components” provided to the passengers by FlyNYON, the tour company that hired Liberty.

“The harness system provided to the passengers on the accident flight was not evaluated by the FAA,” the NTSB said.

With its mandate, the agencies seem to have keyed in on a critical difference between doors-off flights, which strap in passengers with harnesses, and traditional helicopter tours, which use seat belts. While a harness might seem safer to untrained thrill-seekers who want to snap a “shoe selfie” to pin on Instagram or Facebook, they also can prove harder to escape in an emergency.

The order affects “several dozen” national helicopter tour companies offering doors-off flights, FAA spokesman Gregory Martin told CNN. Tours from major cities to the Grand Canyon to remote scenic locations on the Hawaiian Islands are affected. All operators must be certified by the FAA.

The agency said it also was conducting a top-to-bottom “review of its rules governing these flights to examine any potential misapplication that could create safety gaps for passengers.”

Meantime, US Sen. Chuck Schumer of New York has called on the FAA to suspend the operating certificate of Liberty Helicopters, which provided the aircraft that crashed, until the company’s safety record and the cause of the accident are fully assessed.

Martin said FlyNYON has suspended all doors-off flights.

The tour company, on its website, said it has “voluntarily chosen not to operate doors-off flights while we we review all of our procedures and ensure we are at the highest level of safety possible.” It continues to operate “doors on, windows open photo flights.”

‘No evidence of abnormalities’

The FAA conducts on-site visits as well as reviews of maintenance and safety records with a limited number of inspectors, Martin said.

“You have inspectors that also have air carriers with hundreds of flights a day carrying hundreds of people,” he said. “So there’s a risk-based approach there versus very limited and specific operations for these helicopters.”

The NTSB said it had interviewed Liberty Helicopters’ personnel, including the pilot, adding that the helicopter’s engine showed “no evidence of abnormalities.”

The crash was Liberty Helicopters’ third in the past 11 years.

Investigators are scrutinizing the harnesses. They also are inspecting the helicopter, its flotation devices, the weather and other factors, the NTSB said.

Liberty Helicopters posted a statement on its website after the crash, saying it was “focused on supporting the families affected by this tragic accident and on fully cooperating with the FAA and NTSB investigations.”

FlyNYON said it was fully cooperating with the FAA and NTSB investigation, according to a Twitter statement.

Since the crash, the companies have referred CNN’s requests for comment to federal agencies.

The FAA action comes after years of warnings by experts who have predicted that lax rules governing the commercial air tour industry could invite a deadly wreck much like the one in New York.

‘Less stringent operations’

Aviation experts have pointed to specific dangers inherent to commercial air tours.

The doomed flight was conducted under Part 91 of FAA regulations as a commercial flight for “aerial photography,” which apply to air tour operators that take off and land at the same airport and stay within 25 miles of that airport, Martin said.

Companies governed by Part 91 have “less stringent operations, maintenance, and training specifications” and are more likely to crash than other commercial air operations, according to a 2014 study for the National Institutes of Health by Navy flight surgeon Sarah-Blythe Ballard.

“The Part 91 air tour crash rate of 3.5 per 100,000 (hours) flown is similar to the reported crash rates in categories considered to be ‘high hazard’ commercial aviation,” said the study, referring to operations such as emergency medical flights and transport to off-shore drilling sites.

Part 91 tour aircraft have less stringent flight-duty-time and rest requirements as well as lower pilot qualification standards, according to another study by the same author.

Aviation experts and the NTSB have long recommended elimination of the “25-mile exception,” which allows flights without stricter FAA flight data monitoring and pilot-training required of other commercial operators to fly within 25 nautical miles of the departure airport, the study said.

But the FAA said in 2007 – the last time the regulation was amended – that many companies operating under the exception would “go out of business” if the rule were eliminated, according to an agency report on its National Air Tour Safety Standards.

“The FAA believes there are other alternatives to achieve satisfactory safety goals, minimize impact on the industry, and still increase the level of safety, rather than eliminating the 25-mile exception,” said the agency, referring to requirements for pontoons on over-water flights and briefings on emergency landings, water ditching, and the use of seat belts and life preservers.

The rules were created “at a time that didn’t comprehend that every person would have a cellphone with a panoramic feature recording device or GoPro cameras,” Martin said. They applied almost exclusively to professional photography and survey work.

“So you didn’t want to limit very specific and unique type of operations with the same level of oversight that would apply to flights carrying dozens or a hundred-plus people,” he said.

Today, those rules are being revisited.

“Certainly you’ve seen new revenue opportunities for some of these operators,” Martin said. “In the case of this flight – to take people up and have them shoot panoramic scenes with their iPhones.”

‘Nearly impossible … to escape’

The level of instruction offered to helicopter tour passengers on escaping safety harnesses has also come into question.

The FAA requires all over-water commercial air tour operations to conduct preflight safety briefings “on procedures for water ditching, use of required life preservers, and emergency exit procedures in the event of a water landing.”

There is no requirement to specifically instruct passengers on escaping harnesses during an emergency.

Verweijen, the woman who took a FlyNYON tour the day before the crash, told CNN she works in the offshore oil and gas industry and has regularly flown over water in a helicopter. She said bailing out of a sinking aircraft requires practice and expertise.

“In my opinion, it is nearly impossible for a non-trained passenger to escape,” said Verweijen, who has received helicopter underwater escape training. “You completely lose the orientation.”

A 2014 study on helicopter crashes into water, published in the journal “Aviation, Space, and Environmental Medicine,” said reports of such accidents showed “the principal cause of death was drowning from failure to escape due to disorientation.”

The reports showed that helicopters making water landings typically sink rapidly and flip over. The journal article recommended increased training emphasizing the lack of warning in accidents, underwater escape maneuvers and post-crash survival in the water.

“It is dark, cold and you cannot see anything,” Verweijen said. “The pilot could get out because he was trained.”

Passengers who took flight with FlyNYON prior to the crash said they were shown brief safety videos. One shared the video with CNN.

The three-minute video devotes about 20 seconds to how to get out of what the company calls its “proprietary 8 Point Safety Harness System” during an emergency landing.

“In the rare case of an emergency, the harness can be released by opening the quick-release clip in the back of the harness,” a voice on the video says.

A curved cutter located on the harness’ shoulder strap can also be used to cut through the strap, according to the video.

There was no mention of how to escape a sinking helicopter, or the disorientation that is common as the aircraft goes underwater rapidly and, many times, turns upside down.

After the March 11 crash, police and fire department emergency divers, in frigid waters, discovered that the safety harnesses had become death traps. The pilot escaped, but his five passengers died from accidental drowning.

‘Dangling your feet for a #shoeselfie’

FlyNYON offered its “doors off helicopter photo experience” in New York, Las Vegas, San Francisco and Los Angeles, promising to make “professional aerial photography services accessible to everyone,” according to its website.

A promotional video offered stunning views of the city, with two young women in heels and a young man in plaid shorts and sneakers with legs dangling from a helicopter dancing over the East River to music worthy of a Hollywood movie trailer.

“You’re looking down at the city that never sleeps,” the company website says of the 15-minute “New York experience” flight. “Trying to take it all in. Dangling your feet for a #shoeselfie.”

The experience isn’t cheap. FlyNYON’s 11 flight offerings in the city range from $99 to $2,000 for online bookings.

In New York alone, the helicopter tour industry contributes $50 million a year to the local economy and employs more than 200 people, according to the Helicopter Tourism and Jobs Council.

The deadly crash, though, could change that.

“I realize you get a good picture if you have a door open but the door-open rule was put in for … commercial aerial photography, not for tourists,” Goelz said.

“The NTSB is going to look very closely at this whole harnessing system and the process of approving it.”

CNN’s Eric Levenson, Rene Marsh and Paul Murphy contributed to this story.