The T-45C Goshawk is a single engine, two-seat, carrier-capable jet trainer aircraft. The aircraft is used by the U.S. Navy and Marine Corps for intermediate and advanced jet training.
T-45C pilots raised concerns over "physiological episodes" in the cockpit, apparently caused by contamination of the aircraft's Onboard Oxygen Generation System, the Navy said.
Since then, Navy officials have implemented a modified mask tested successfully by the Naval Air Systems Command that circumvents the aircraft;s On Board Oxygen Generator System.
"After briefings and discussions with our aircrew, their training wing leadership, the engineers, and aeromedical experts, we have identified a way forward to resume flight operations safely by limiting the maximum cabin altitude to below 10,000 feet in order be able to operate without using the OBOGS system," Vice Adm. Mike Shoemaker, Commander, Naval Air Forces (CNAF), said in a statement.
Instructor pilots will be first to resume using the aircraft as they begin warm-up flights. Then, students and pilots will be briefed on modified equipment.
All instructor pilots will eventually complete their warm-up flights, and then student pilots will begin warm up and training flights, the Navy said.
Shoemaker said finding the root cause of the issue on the sophisticated aircraft will be a challenge.
"We will be able to complete 75 percent of the syllabus flights with the modified masks while we continue the important engineering testing and analysis at PAX River [Naval Air Station Patuxent River, Maryland] to identify the root cause of the problem. This will remain our top safety priority until we fully understand all causal factors and have identified a solution that will further reduce the risks to our aircrew," Shoemaker said.
Navy officials say they are using "unconstrained resources" to tackle the problem. The investigation is ongoing.