NEW YORK — The helicopter company whose doors-off flight crashed in a New York City river last year, trapping all five passengers in their harnesses, exploited a regulatory loophole to avoid stricter safety requirements, federal investigators said.

FlyNYON operated under the government’s least stringent standards “to the detriment of their customer’s safety” because it described the purpose of its flights as photography, not sightseeing, National Transportation Safety Board Chairman Robert Sumwalt said.

The company instructed employees to avoid using terms like “air tour” or “sightseeing“ so it wouldn’t lose its certification under a photography exception that allowed it to fly under the same regulations as private pilots and hobbyists, investigators said.

“This is a loophole that one could fly a helicopter or drive a truck through,” NTSB Vice Chairman Bruce Landsberg said at a Washington hearing this week on the crash.

NTSB member Jennifer Homendy called it “an egregious interpretation of current regulations.”

The Federal Aviation Administration told the board that the exemption is meant for things like newsgathering, commercial photography and film shoots — not sightseeing tours, which are subject to stringent commercial aviation standards, including FAA-approved training and maintenance programs.

Nonetheless, FlyNYON has promoted “sneaker selfies,” complete with video on its website of a passenger’s feet dangling over lower Manhattan.

The helicopter crashed into the chilly East River in March 2018 after a tether meant to keep a passenger from falling out got caught on a floor-mounted fuel shut-off switch, stopping the engine minutes into the scheduled 30-minute flight. It started to sink within seconds.

In written submissions, FlyNYON faulted the design of the Eurocopter AS350’s fuel controls and its emergency flotation system, which failed to keep the aircraft upright. Flotation system manufacturer DART Aerospace said in a submission that pilot Richard Vance likely failed to fully pull the inflation lever, leaving the devices only partially inflated.

The NTSB acknowledged those issues but put most blame for the passengers’ drowning deaths on FlyNYON and the hard-to-escape harnesses that it installed on top of federally mandated restraints.

Vance, the pilot, was wearing just a seat belt and was able to free himself, investigators said.

The passengers could have survived if not for the supplemental restraints, the board said, recommending that the FAA ban such devices until the agency can get a handle on regulating them.

Sen. Chuck Schumer said the NTSB’s findings made clear that FlyNYON should stop doors-off flights.

“FlyNYON has done just about everything they can to skirt safety, accountability and best practices within their industry,“ said Schumer, a New York Democrat. “The helicopter company has proved time and again to be reckless, brazen and a hazard high above, and even down below.”

In addition to a standard lap belt and upper body restraint, FlyNYON provided passengers with a nylon fall-protection harness — akin to something bought at Home Depot — that could be released only by cutting a tether with a provided knife or unscrewing a carabiner at their backs, investigators said.

The board also slammed the safety culture at FlyNYON, which arranged the flight, and Liberty Helicopters, the company that FlyNYON contracted with for helicopters and pilots. FlyNYON’s CEO stressed profits over safety and remarked that pilots who complained “can’t get their snowflake feelings hurt,” according to Homendy.

In a statement, FlyNYON said safety has always been its “first priority and we have made changes to our operations to help ensure an accident like this never happens again.”

FlyNYON said it now operates its own helicopters with its own pilots.

Liberty declined to comment, saying the crash remains subject to active litigation.