Lt. Col. Tucker Hamilton, F-35 Integrated Test Flight director at Edwards AFB, California, finally became a believer in October 2017 when eight Joint Strike Fighters flew together in a complex test scenario, seamlessly passing information back and forth.
The so-called eight-ship mission was a capstone event, designed to prove the offensive counterair capability of Lockheed Martin’s controversial new fighter in a large-force exercise.
“It proved to me that the F-35 was indeed the aircraft we needed it to be. It’s come a long way,” said Hamilton, who is also the commander of the 461 Flight Test Squadron, during an April 12 media call. “I don’t know if I would’ve said that a few years ago, but the jet is really capable right now.”
The F-35 has indeed come a long way since the first flight of the F-35A, AA-1, on Dec. 15, 2006. More than 11 years later, the JSF finally completed flight testing on April 11, 2018, at Naval Air Station Patuxent River, Maryland. The final flight-test event, executed by U.S. Navy test aircraft CF-2, was a mission to collect loads data while carrying external, 2,000-lb. GBU-31 Joint Direct Attack Munitions and AIM-9X Sidewinder heat-seeking missiles.
Completing the flight test is the culmination of years of hard work and dedication from the joint government and industry team, Vice Adm. Mat Winter, F-35 program executive officer, said in a statement. Since that fateful first flight, the developmental flight team has conducted more than 9,200 sorties, accumulated 17,000 flight hours and executed more than 65,000 test points—all without a single mishap, Winter said.
Andrew Maack, chief test engineer at the F-35 Pax River ITF who has been on the program since the first flight of the X-35 on Oct. 24, 2000, recalled the deliberate, high-risk development of the aircraft’s vertical operations capability. He described the months of testing the team undertook to ensure that the 40,000-lb. thrust-class vertical propulsion system worked safely, without damaging other aircraft or the deck of the ship with the hot gas being blown out of the engine, and that the aircraft could be controlled in a hover.
“It was a great day when we finally got there. It worked, and the airplane was rock steady in the air,” Maack said, adding that the first vertical operations on the USS Wasp amphibious ship “were just fantastic and spectacularly thrilling to watch.”  
The developmental flight tests cleared the way for the JPO to deliver Block 3F capability to the warfighter this year, allowing U.S. Air Force F-35 pilots, both stateside at Hill AFB, Utah, and overseas in the Pacific, to finally employ the stealth fighter’s full suite of lethal air-to-air and air-to-ground weapons in combat.  The U.S. Marine Corps’ F-35Bs and the U.S. Navy’s F-35Cs will be able to deploy with their full 3F capability in May and June, respectively.
For Lockheed Martin test pilot Billie Flynn, the most surreal experience working on the F-35 was taking the aircraft into the climactic chamber to see how it fared in the most extreme environments.
“Freezing it down to 40 below and baking it up to 120 degrees, firing ice at it through these one-of-a kind ice-maker jet rockets, and all the while hovering an F-35 inside a hangar with the doors closed,” Flynn said, describing the climactic tests. “We have crushed all the preconceived notions about what this jet is capable of ... it is survivable and lethal above any of our expectations.”
But while completing flight tests is a significant milestone, the F-35’s $55 billion development phase, called System Development and Demonstration (SDD), won’t be over until the aircraft successfully completes its final exam, initial operational test and evaluation (IOT&E), and the Pentagon approves Lockheed to begin full-rate production.
IOT&E is scheduled to begin in September 2018.
In the meantime, there is no rest for the developmental test team at Edwards and Pax River. The pilots and engineers are now moving on to testing the early “block 4” capabilities to be included in the F-35’s follow-on development, called Continuous Capability Development and Delivery (C2D2).
C2D2 is designed “to provide timely, affordable incremental warfighting capability improvements to maintain joint air dominance against evolving threats to the United States and its allies,” a Lockheed statement said.