Airman 1st Class Chris O’Toole was not prepared for just how cold and thin the air at the 388th Fighter Wing on Hill Air Force Base, Utah, would get. The base spreads across a valley wedged between the mountains that send constant cold gusts right down the flight line. As an F-16 Falcon crew chief, that’s where O’Toole spent most of his time."It’s super dry, like nose-bleed dry, thin, thin air,” O’Toole said. "Being a Florida boy, I never acclimated the entire time I was there."When O’Toole’s four-year active duty enlistment ended, so did his time at Hill AFB. He returned home to the Sunshine State where he discovered the 125th Fighter Wing in Jacksonville. He immediately signed up with only a single hiccup: he had to move on from his beloved F-16 and learn to crew chief the F-15 Eagle. It’s been eight years since then, and just like O’Toole, the 388th FW at Hill AFB has also moved on from the F-16. They, along with the Air Force Reserve 419th FW, are now home to the F-35A Lightning II – the most advanced multi-role fighter jet in the world. The U.S. Air Force declared the F-35 at Hill AFB "combat ready” in August 2016. Five months later, they tested that declaration in exercise Red Flag at Nellis Air Force Base, Nevada, from Jan. 23 to Feb. 10. “Our Airmen are excited to bring the F-35 to a full-spectrum combat exercise,” said Col. David Lyons, 388th Fighter Wing commander. “This battle space is going to be a great place to leverage our stealth and interoperability. It’s a lethal platform and I’m confident we will prove to be an invaluable asset to the commander.”Red Flag is the Air Force's premier air-to-air combat training exercise. Maj. Jeffrey Falanga, 414th Combat Training Squadron director of operations, said “Red Flag is vitally important because it provides a realistic training environment for the air, ground, space and cyber domains to be able to practice interoperability both with U.S., joint and coalition forces.”Falanga said the significance of this Red Flag is that it will be the first Red Flag with USAF F-35 participation. He said the addition of the unique capabilities the F-35 provides, from a scenario generation perspective, meant the planning team had to increase the threat they provide the training audience, both in capabilities and numbers."What the F-35 offers our training audience is the unique capabilities of the platform enable it to take down threats that would not be as survivable for some of the other platforms,” Falanga said. "By removing some of those threats, by having a more survivable platform against some of the threats that we will present our training audience, it increases the effectiveness and survivability of our 4th Gen fighter assets."The unique capabilities the 5th generation fighters, such as the F-22 Raptor and the F-35, bring to combat include stealth and the ability to destroy a target beyond visual range, among others. This dramatically increases the lethality of the attack package, which required the 414th CTS to modify the scenario to rival these advantages. Pilots and maintainers from the 125th FW deployed for three weeks to Nellis AFB to train in the multi-domain, multi-national Red Flag. While there, they trained with multiple fighter and bomber units against a robust air-to-air and surface-to-air threat. The threat continuously increased in complexity over the course of the exercise, simulating high-end, major combat operations.“This exercise was an outstanding opportunity to hone our combat skills,” said Lt. Col. George Downs, 159th Fighter Squadron commander. “The ability to train with multiple coalition assets, against a high-end threat, is something that we cannot replicate in our daily training in Jacksonville.” This training is even more critical as the 159th Fighter Squadron prepares for its upcoming European deployment in the summer of 2017.Lt. Col. Mansour Elhihi, 125th Maintenance Squadron commander and F-15C pilot, said one of the typical missions they train for is an offensive counter air mission where they escort assets in to collect information or drop bombs. In this scenario, the F-35s would play the role of striker, and the F-15Cs would escort them to their targets."We would go in initially and sanitize the airspace,” Elhihi said. "We would ensure that before additional U.S. assets were brought into a certain arena there are no air threats."While the F-15C lacks the technological upgrades of 5th Generation aircraft, it remains one of the deadliest aircraft ever created with 104 confirmed kills and zero deaths. Plus, the 45-year-old aircraft now fly retrofitted with the state-of-the-art Advanced Electronically Scanned Array (AESA) Radar, an all-weather, multimode radar system in the same family as the 5th Generation aircraft. Elhihi said both generations complement each other, and by utilizing the diverse strengths, they can fight a more successful, full-spectrum war.Along that same line, coalition forces from the U.K. and Australia joined U.S. forces at Red Flag. With more than 4,000 participants and nearly 100 aircraft, this is one the largest Red Flags in history. Elhihi said working together in a Large Force Exercise (LFE) such as this not only lets coalition members learn how to work together effectively, it also builds lifelong relationships between the participating countries and service members. "By the end, it really truly builds this great bond between our allies,” Elhihi said, "so that when we do have time to answer our nation’s call, we’re ready to fight together."The Red Flag exercise has a history going back to the 1970s. During the Vietnam War, leadership observed that pilots who survived seven to 10 missions had a much higher survivability overall than pilots without the same level of battle involvement. So, in order to get pilots the experience they needed to survive in war, Gen. Robert J. Dixon established the first Red Flag training exercise in 1975.Today, Red Flag serves the same purpose: to prepare deploying pilots and maintainers for the rigors of war. Elhihi said units are required to complete an LFE like Red Flag before deploying for a real-world mission. The principle is that by simulating real-world conditions, training becomes engrained in memory, creating a seamless transition from the training environment to a combat zone."The intent of Red Flag is take an Airman and put them into a realistic combat-like training scenario so when they deploy it does not feel like the first time,” Elhihi said.Eight years after he left the 388th FW, now Tech Sgt. O’Toole once again shared a flight line with his old unit. This time he was working as a crew chief on the F-15, and they were on the F-35, but the goal was the same. At Red Flag, just like in any real-world event, everyone must work together to overcome enemy forces and accomplish the mission. O’Toole said he has nothing but positive things to say about his old squadron and the aircraft they’re working on now, but being back home in Florida and working for the 125th FW has given him the life he’s always wanted."Being able to do what I love to do and serve and be with my family is just…I couldn’t ask for anything better,” O’Toole said.