WASHINGTON ― When Sen. Joni Ernst first heard instructors at the U.S. Navy’s flight school in Meridian, Mississippi, were refusing to fly T-45 training jets over issues with the plane’s oxygen system, she was skeptical. “I thought: ‘Well, shame on them,’ ” she told reporters in a meeting Tuesday.

But the issue became very real for Ernst over the weekend during a congressional delegation trip to the Navy’s bases in Hampton Roads, Virginia. As part of the trip, the Navy put Ernst put into an oxygen-breathing device and dialed back the oxygen to her mask.

“It was a terrifying experience for me, I'll be honest about that,” Ernst said. “They walked us through what symptoms we might have as the oxygen was reduced, and it was just like textbook.

“My face got hot and flush; my fingers started tingling, then got numb; my legs started tingling; it was hard to concentrate ― very hard to concentrate.”

Now Ernst has personally taken on the issue, introducing an amendment in this year’s National Defense Authorization Act that requires the Navy to give quarterly reports to Congress on its hunt for a solution to a problem that has bedeviled the service for years now.

Pilots in the T-45s, the F/A-18 Super Hornet and even the brand-new F-35 have reported physiological episodes as a result of oxygen deprivation.

In June, Luke Air Force Base grounded all F-35 flights after five pilots reported hypoxia symptoms. Flights resumed 12 days later with some restrictions, and in July the program office announced changes to the on-board oxygen generation system, which has been the main suspect in all the physiological episodes across multiple jets.

“It's a very real issue and I think something that the Senate needs to have oversight of,” Ernst said. “Which is why my NDAA amendment is very important, so the Navy knows that we are going to stay on top of this until we find a fix.”

The Navy has introduced a number of mitigating measures seeking to cut down on the incidents and is still searching for more permanent fixes to the hypoxia issue.