Two U.S. Coast Guard response boats search George Inlet on May 14, after a collision between two float planes near Ketchikan, Alaska. (Dustin Safranek/Ketchikan Daily News/AP)

When tourists climb onto a sightseeing plane to fly over Alaskan glaciers, or hop on a helicopter to tour the Grand Canyon, they have no reason to wonder whether the aircraft is held to different safety standards than the commercial plane they took to reach their vacation destination.

The National Transportation Safety Board says that perhaps they should.

Such tourist jaunts, some small airline commuter flights, virtually all helicopter travel and “on-demand” flights, such as those taken by the rich and famous who have a plane at their beck and call, are governed by different — and what some say are less stringent — Federal Aviation Administration regulations than commercial aircraft.

“Basically, if you’re paying money for an airplane seat, there should be an equivalent level of safety,” NTSB Chairman Robert Sumwalt said.

The NTSB cited the recent collision between two float planes ferrying cruise ship passengers off Alaska, another Alaskan float plane crash a week later, and the April 29 crash of a tour helicopter in Hawaii. In all, 11 people were killed and 10 were injured in the incidents.

NTSB investigators have not determined the probable causes of the crashes, but late last month, the agency pointed to its long-standing recommendation that such aircraft be held to standards closer to those required for commercial aviation.

“I’m not saying that we have to have the exact same regulations, but we do want an equivalent level of safety so that once somebody pays money to fly on an airplane, that they have confidence that there’s a high level of safety,” Sumwalt said. “And we’ve found from accident investigations that there’s really three things that are lacking for Part 135,” he said, referring to the category of classification for such aircraft.

The NTSB — which makes recommendations but has no role in setting federal policy — wants the FAA to mandate that Part 135 carriers develop safety management systems to govern their assessment of risks and safety procedures. They also want the aircraft to carry flight data recorders similar to those used by major airlines and for pilots to undergo additional training so they know what to do if they fly into trouble.

There are three gradations of people who can call themselves aviation pilots. Some fly general aviation aircraft — either small planes or, in some instances, helicopters. Pilots who fly Part 135 flights, generally speaking, work for commercial companies that are either very small (think two or three planes), ferry tourists or do “on-demand” flights. Finally come pilots on regularly scheduled flights, whom the FAA requires to have logged a minimum of 1,500 hours in flight.

Sumwalt said there are some “very, very good” Part 135 “operators that are doing the things that we’ve called for and basically following airline standards.”

But there are other businesses that he says are “running on a shoestring” and feel the need to cut corners. When that happens, he said, the public is in the dark.

“There’s an airplane that’s all pretty and painted up, and it looks impressive, but when you peel back the layers there, you find out that there were a lot of things that that organization didn’t do,” Sumwalt said, pointing to a 2015 incident in Akron, Ohio, in which the cockpit crew and seven passengers were killed when their Part 135 plane crashed into an apartment building.

The NTSB concluded the flight crew mismanaged its approach to the Akron landing. It also said the company had a “casual attitude toward compliance with standards” and cited “its inadequate hiring, training, and operational oversight of the flight crew” and “the company’s lack of a formal safety program.”

The Air Charter Safety Foundation, a nonprofit aviation safety organization that promotes and supports charter operations, draws a parallel to the commercial airline market as it strives to achieve the NTSB’s goals. The group’s president, Bryan Burns, said that until the airlines began code-sharing more than 20 years ago, many established their own safety standards. With code-sharing, they adopted more uniform standards.

“We measure everything we do based on looking at what the [commercial] airline safety record has been and applying it to the charter world,” Burns said. “The [charter] industry needs to take it upon themselves to self-regulate.”

Burns urged people to do their research when looking to hire a plane or book a sightseeing tour.

“It’s all about due diligence before you purchase your flight,” he said. “Ask some questions.”

Among them, he said: Does the outfit have an FAA air-carrier certificate? What is its previous crash and incident history? Does it have a safety management system in place? What standards of maintenance does it adhere to?

“You think that you’re getting the luxurious, glorified flight that has the nice, fancy pictures on the website, but in reality, do you really know who your charter is?” Burns said. “There is a wide range of operators out there who are doing minimal standards versus those who are exceeding not only FAA standards but the industry standards.”

With aircraft such as medical transports — either planes or, more commonly, helicopters — the regulations become even more nuanced.

“The first thing we’ve had to determine is whether it had a patient on board,” said FAA spokesman Lynn Lunsford, “then it was probably Part 135. But if it was just flying home with only the air ambulance staff, it’s typically operated under” the general aviation rules.

The FAA was created by Congress in 1958 after a collision between two planes above the Grand Canyon that killed 128 people. While the FAA has authority over everything nonmilitary that flies — regulating general aviation, Part 135, and commercial airlines — Congress and the White House continue to have oversight — meaning every proposed rule needs approval from the White House Office of Management and Budget.

Lunsford said that more than 20 years ago, there was a greater distinction between pilots who flew Part 135 flights and those who did regularly scheduled airline flights. That gap has closed, he said, and “now the NTSB is picking around the fringes” to encourage other improvements.

In a 2017 exchange of letters between Sumwalt and then-FAA Administrator Michael P. Huerta, Huerta said specific concerns raised by the NTSB “could be applied to Part 135 certificate holders at some point in the future.”

Sumwalt responded that “a key focus of your review will be achieving a favorable cost-benefit ratio for any new or revised federal regulation.”

Lunsford said recently that risk-benefit calculation enters into rulemaking efforts. But it’s made not by the FAA but by the Office of Management and Budget.

“They ultimately get to decide whether a regulation is going to make it or if it’s going to die,” Lunsford said. “And I’m being blunt here, but many times in the history of aviation, when that calculation was run through the process, the answer came out that, essentially, not enough people have died yet.”