The initial operational capability (IOC) is the point at which an aircraft's ability to effectively employ a weapon, item of equipment or a system that is manned by a trained military unit is tested and reviewed by officials, according to Military Factory.
As the fighter jets are expected to cross the pond anytime between June 5 and June 10, weather permitting, Wing Cmdr. Scott Williams, the UK's senior national representative at South Carolina's Marine Corps Air Station Beaufort, told Defense News that his pilots are undergoing additional training and making sure their planned UK home base in Marham, England, "is able to take and operate that airplane."
"We are at a point now where we believe we can do that," he told the outlet. "And the final thing… that is really driving it all, is that it gives us more time in the UK to do that — build up to the IOC."
"We train at a very basic F-35 level that's common across the two services," Williams noted, adding that the only differences in training between American and British pilots is that they'll occasionally attend different briefings.
According to the publication, as the four F-35Bs make their way to the UK, they will be accompanied by an Airbus A330 tanker that will refuel the fighter jets during the flight.
Though it's unclear exactly what the Royal Air Force (RAF) will be looking for when it comes to the IOC test, Williams told Defense News that examinations will involve suppression of enemy air defenses, and defensive and offensive air actions.
The UK has already committed to purchasing some 48 F-35s, with another 138 fighters to be paid for at a later time.
The BBC reported that the F-35s will replace the Tornado GR4s at the RAF Marham base, which will retire from service in 2019. The Tornado GR4s are currently deployed in operations over northern Iraq and Syria.