LE BOURGET, France — The U.S. Air Force has begun experimenting with a handful of new sensors made by a British company that could offer clues about what caused recent cases of hypoxia reported by F-35 pilots.

The idea behind the sensors is to determine what is prompting pilots to feel unwell while plugged into the on-board oxygen system during flight. While the symptoms of hypoxia, or a form of it, can be openly observed, finding the cause resembles putting together a "mosaic of events" regarding air quality and other factors, Julian Hellebrand, president of the Cobham's mission systems sector, said in an interview here at the Paris Air Show.

Defense News reported last week that Luke Air Force Base, Arizona, extended a flight pause for F-35 flight operations after five pilots complained about hypoxia-like symptoms beginning in early May. During each of the affected flights, a backup oxygen system kicked in, leaving the pilots unharmed.

Cobham's sensor kit tests the composition of the air flowing into a pilot's mask while doing the same with exhaled air. The company's engineers believe that the data gathered at those two places can be aggregated and analyzed to pinpoint any problems.

Hellebrand said the U.S. Air Force and the U.S. Navy had shown great interest in the technology.

Officials at the U.S. Air Force School of Aerospace Medicine a week ago received three inhalation sensors, with five more planned in late August and eight more after that, according to the company.

"The delivery of this inhalation sensor block marks the first step towards creating this mosaic by capturing temperature and pressure data inside the cabin, and the flow rate and concentration of oxygen being supplied to the pilot with each inhalation breath," Cobham said in a press release.

According to Hellebrand, there is also the question of why hypoxia-related problems are being found now. "Are they only now being reported? Is there some degradation in the system?" he asked, referring to oxygen-supply systems that have been built into fighter aircraft for decades.

The onboard oxygen-generation systems in F-35 aircraft are made by Honeywell.