WASHINGTON — New airplanes are grounded, investigations of fatal air and car crashes are going undone and scientific studies dependent on government funding have ground to a halt because of the partial government shutdown now in its second week, the Senate Commerce Committee was told Friday.

The economic impact will only intensify as the shutdown continues, affecting everything from the aviation industry to Alaska crab fishermen who may see their lucrative, one-month harvest delayed, witnesses told the panel.

Marion Blakey, CEO of the Aerospace Industries Association, said the shutdown already has virtually stopped certification of new aircraft, equipment and training simulators because the Federal Aviation Administration has furloughed more than 90 percent of its employees who work on those issues. Blakey is a former FAA administrator.

New planes aren’t being delivered to buyers because routine government approvals “essential for our manufacturers to compete and for our industry to grow” aren’t taking place, Blakey said.

But Boeing Co. said this week said the FAA certification staffers for its new South Carolina-made 787 were back on the job.

Deborah Hersman, who chairs the government’s National Transportation Safety Board, said furloughs have stopped her agency from sending investigators to most air and motor vehicle accident sites, including those with fatalities. Already, she said, the agency has ignored a fatal bus crash that killed six people in Tennessee, an oil spill site in North Dakota and a small airplane crash in Arizona that killed four people.

The NTSB has said it will send investigators to accidents where it believes there are safety concerns that pose a threat to lives or property. The board recently kept investigators on a train collision in Chicago after the shutdown for that reason.

But the agency has suspended as many as 1,500 active accident investigations because of the shutdown, Hersman said. The agency has also stayed out of the investigation of a battery fire in a Tesla Model S car. Battery fires are a key safety issue the agency has been focused on.

Routine NTSB help for the State Department and civil aviation authorities in other countries also has stopped, Hersman said.

Alan Leshner, CEO of the American Association for the Advancement of Science, said the shutdown was “a serious blow to an already beleaguered American scientific enterprise” and could disrupt or halt many studies because grants aren’t being renewed. Even the accuracy of studies could come into question, he said.

Keith Colburn, a crab fisherman featured on the Discovery Channel’s “Deadliest Catch,” said a lucrative, one-month crab season harvest scheduled to begin Oct. 15 is endangered because the National Oceanic and Atmospheric Administration is not assigning quotas to boats and permits during the shutdown.

“Collectively, the fleet already has (spent) millions of dollars out of pocket just gearing up for the season,” Colburn said. “Each day tied to the docks will cost these boats thousands more. Many fishermen and coastal communities are already facing tough times. This unnecessary shutdown may be the tipping point if the situation isn’t resolved soon.”