WASHINGTON — A rash of technical and safety problems has left the U.S. Navy’s fleet short by about 90 fighter pilots. Fixing the issue is an uphill battle, a top aviator said last week.

The Navy has seen a slew of issues, including problems with the oxygen flow to the pilots causing negative and unsafe physiological responses in pilots and trainees, as well as readiness and engine trouble with aircraft. All of this has extended the time it takes to create a fighter pilot from three to four years, and the issues have created a gap in the number of pilots in the fleet, naval air training chief Rear Adm. Robert Westendorff said at a virtual Tailhook symposium on Saturday.

“We can’t just snap our fingers and produce those immediately. The time to train of a strike fighter pilot is about three years; due to the bottlenecks we’ve had, its getting closer to four years,” Westendorff said. “We’re doing everything we can to get that back down to the three-year mark. But the recovery plan is a three-year plan. And if we stay on track, it should take us about three years.”

An issue with the T-45′s engines “dramatically reduced” the availability of the aircraft this year, but the program is getting back on track, Westendorff said.

Additionally, the general shortfall of F/A-18 Super Hornets throughout the fleet has impacted training, but Naval Aviation has been focused on bringing those numbers back up in recent years by fixing jets unable to fly for mechanical reasons.

Naval air training has been beset in recent years with controversy over the so-called physiological episodes, the cause of which has been very hard to pin down.

The Navy now believes it’s a complex issue involving air flow and air pressure related to the breathing apparatus, and measures have been put in place to mitigate it, USNI News reported in June.