(Photo courtesy of Lockheed Martin Corporation)

Marines use the F-35B model of the F-35 Lightning II.

F-35 fighter jets have been grounded in Arizona for the second time this month.

One day after F-35s resumed flights at Luke Air Force Base in Glendale, they were canceled at the Marine Corps Air Station in Yuma.

The Air Force and Marines fly different F-35 models, both made by Lockheed Martin.

Flights temporarily stopped at Luke after pilots reported symptoms related to oxygen deprivation.

The Marine Corps grounded the jets in Yuma so crews can repair a software update to a ground-based system that military officials call the IT backbone of the F-35.

The Marine Corps said the jet is safe, but the software has to be fixed before flights can resume. Engineers are working around the clock to find a solution.