Two of the six Lockheed Martin F-35As deployed by the US Force Lakenheath AB last week were left behind in the UK as their squadron mates made the return trip.

An USAF pilot noticed a possible refueling issue on one F-35A and decided to hold back deploying both that aircraft and its wingman, says Lt Col George Watkins, commander of the 34th fighter squadron. Watkins called the check a routine safety precaution.

“The pilot noticed he had a fuel tank float valve that was not 100%, his fuel tank may have not been reading correctly and he wasn’t sure so the pilot made the choice not to take that jet,” Watkins says. “[He was] just making sure we could air to air refuel without any problems.”

Each of the two F-35A formations that deployed to the UK last week took three different tankers, though the tankers did not accompany the jets for the entirety of the trip, Watkins says. The F-35s refueled nine times over the deployment and the last tanker refueled the jets from RAF Mildenhall.

Earlier this year, the US Marine Corps deputy commandant for aviation criticiced the refueling model for the USMC’S F-35B.

“You look at that model how many times we had to send out tankers, way too many times,” Lt Gen Jon Davis said. “We’re redoing that model so we need a lot less refuelings than we’re doing right now.”

Watkins characterised the recent refueling en route to Lakenheath as routine and noted the F-35A carries more fuel than the USMC’s short takeoff vertical landing F-35B model.

During its Lakenheath deployment, the USAF will restrict its training operations to the UK airspace. The aircraft will also fly out and back to other NATO locations outside the UK, but a USAF spokeswoman could not reveal those locations.