The USAF’s last overseas-based A-10 squadron

As with all US Air Force fighter squadrons based in the Republic of Korea, the A-10C-equipped 25th FS is based at Osan Air Base to defend the Republic of Korea if the Korean Armistice Agreement signed by representatives of North Korea, the United Nations Command, the United States and China on July 27, 1953, is broken.

The 25th Fighter Squadron is the only A-10C unit within the Pacific Air Forces command. It is one of two component units of the 51st Operations Group based at Osan which is south of the city of Suwon in the northwest of the country. Its sister squadron is the 36th Fighter Squadron ‘Fiends’ equipped with Block 40 F-16Cs.

According to the 25th Fighter Squadron’s official history the unit was activated as the 25th Pursuit Squadron at Hamilton Field, California, on January 15, 1941. By March 1941, the 25th was assigned to the 51st Pursuit Group at March Field, California and in July of that year the squadron received P-40 Kittyhawk aircraft. The 25th sailed aboard the SS President Coolidge on January 11, 1942, part of the first deployment of US forces to leave the United States mainland after the declaration of war. By late March, the 25th Pursuit Squadron had arrived in Karachi, India, and set up wartime operations, flying its first aerial combat mission over ‘the Hump’ – the name given to the eastern end of the Himalayas - on September 25, 1942. After the squadron moved to Dinjan in Assam, India, combat activity increased, and it was there that the 25th Pursuit Squadron picked up the name ‘Assam Draggins’. The term Draggin refers to the long difficult missions flown over the hump and back, described by squadron pilots as “Our Ass am Dragging.”

Today, the 25th Fighter Squadron’s mission set is standard to any A-10 squadron - close air support, combat search and rescue, and forward air controller airborne - but also includes a specialised mission called x-attack, another name for strike coordination and reconnaissance. According to the US Air Force Doctrine Publication about Counterland Operations, the X prefix denotes a scheduled mission with the objective of providing flexible or continuous airborne presence. The x-attack role involves an A-10 pilot looking for specific targets on the ground, be that artillery or tactical ballistic missiles or any weapon system that could threaten the Republic of Korea, and trying to strike them before they can fire.

Exercises

The standard wing-level exercise at Osan is called Beverly Herd and it is staged to demonstrate that personnel assigned to the 51st Fighter Wing can navigate conventional and unconventional attack scenarios while launching and recovering aircraft during 24-hour flying operations to test the base’s readiness and response against any adversary. Beyond wing-level training, the 25th FS participates in other exercises that are led by the US 7th Air Force, and those staged by United States Forces Korea.

Discussing squadron operations during its time deployed to Eielson Air Force Base its commander, Lieutenant Colonel Justin Davis said: “A recent exercise staged by US Forces Korea involved pretty much all types of aircraft operated by the Republic of Korea Air Force and the US Air Force based in Korea. We did a live fly exercise with RoKAF forces. The exercise got a lot of response from the North Koreans because we were practising interoperability between RoK and US forces and training for the types of missions we would expect to conduct if deterrence were to fail.

“We train to be able to survive and operate under the use of the weapons that North Korea has such as chemical weapons. During exercises, we operate in the CBRN [Chemical, Biological, Radiological and Nuclear] environment which is one of our biggest desired learning objectives for personnel that are constantly rotating through the squadron. This involves wearing protective equipment including a mask, overgarments, and gloves, practising and taking shelter, so we’re ready and can continue to operate even when those weapons are being hurled at us.”

All fighter squadrons within Pacific Air Forces deploy on a standard one-month temporary assignment, typically to Alaska and sponsored by Pacific Air Forces.

Explaining the 25th’s deployments, Lt Col Davis said: “We fly to other bases in Korea to practice the concept of Agile Combat Employment [ACE] to give our pilots and maintainers an opportunity to arrive at a bare bone location, figure out where they’re going to get fuel, food, and water from, and how to operate from the location. It also gives the pilots and maintainers the skill sets for future assignments.”

In August 2022, airmen from Osan were deployed to the RoKAF’s Gwangju Air Base to test their ability to rapidly deploy assets on the Korean peninsula. Airmen involved conducted tasks outside of their career fields in an unfamiliar environment in accordance with the US Air Force’s Agile Combat Employment concept of operations. The objective of the ACE concept is to is to remove dependency on main operation bases and instead project air power from smaller dispersed forward operating locations.

Daily ops at Osan

Like all US Air Force fighter squadrons, the 25th FS conducts its daily flight operations based on the training plan that the squadron’s weapons officers have built to maintain currency in all the mission sets the squadron is tasked to do. Explaining how weekly flight schedules change, Lt Col Davis said: “One week we’ll fly close air support, and the next week we might fly combat search and rescue, so our flight operations rotate through the different missions. We try to take a building block approach to be proficient at close air support and must be proficient at basic weapons employment, so we conduct a mission called basic surface attack [BSA] so we start our training with a couple of weeks of BSA, then move into a surface-to-air training phase when we conduct more than just basic weapons delivery and practice the geometry of the tactics and weapons employment. For example, we’ll depart a tactical hold, follow our tactics for ingress to the target, attack the target and return to base. It’s just part task training for executing the tactics, and entirely divorced from any kind of scenario.

“Once the surface-to-air training phase is complete, we train for close air support working with JTACs, and if there are no JTACs available, the instructor pilot flying in the two-ship of four-ship formation pretends to be a JTAC on the radio, they’ll create a scenario and conduct close air support as fully missionized and as real as possible.

“We run a pretty standard schedule with a first go [mission] and a second go. For each go, a set of pilots will plan, fly, and debrief followed by a second set of pilots who repeat for the second go. Sometimes we use hot-pit refuelling. This involves one set of pilots flying a first and second go. After flying the first go, they land, remain in the aircraft, refuel in the hot-pit with the engines running, then take-off for a second go, either returning to the same area or to different airspace for a different mission, and then they return to Osan, land and shut down. The maintainers then service the jets during a longer period between flights ensuring the aircraft are ready for a third go that day. That’s the typical daily flow and we fly five times a week, and on weekends during exercises. We also stage dedicated night phases in accordance with our training plan. This might involve one week of daytime ops followed by one week of night-time ops. The weekend in between provides an opportunity for our airmen to shift their circadian rhythm from daytime to night-time.”

North Korea

Training undertaken by the 25th Fighter Squadron is designed to specifically facilitate and counter North Korean weapon systems as per the latest appraisals held by RoK and US intelligence agencies.

This combined with the proximity of Osan to North Korea drive the tactics used and makes the 25th’s training a little different to what an A-10 squadron based in the US would undertake. Within the US Air Force, the 25th and the 36th Fighter Squadrons are the two permanently based deployed fighter squadrons located closest to an adversary’s border.

Commenting, Lt Col Davis said: “It takes about 25 minutes to fly from Osan to North Korea, so very, very close. Because of that, we focus specifically on North Korea and the threats we know that it holds, and we must remain ready to fight tonight. By doing that we maintain a credible deterrence so that hopefully, we can maintain the armistice and not ever have to launch such missions.

“By comparison, US-based A-10 squadrons, for example, assigned to Moody, Davis Monthan, the Air National Guard, and the Reserve must be more broadly trained for a wide variety of threats. Those squadrons never know when the nation will call upon them to deploy to say, the Middle East or the Pacific or the European theatre. US-based squadrons must therefore be more broadly trained to a wide variety of threats whereas we solely focus on the threats in North Korea and being able to counter them: that’s the difference.”

When flying A-10s close to the Demilitarized Zone (DMZ), 25th FS pilots are aware of being tracked by North Korean systems and must use tactics that keep their systems passive so that North Korean operators do not capture useful intelligence. Addressing this aspect of flight operations, Lt Col Davis said: “We are fully aware that they, just like any adversary, try to monitor their enemy and understand their tactics. We are aware they try to do that with us, just as we do with them. Because of that, when we fly close to the border, there are certain restrictions that we place on ourselves to prevent certain tactics and transmissions from being given away.”

Flying close to the DMZ is restricted and requires meticulous planning.

Aviation regulation 95-3 document titled Korean Tactical Zone (RK) P518 flight procedures issued by the United Nations Command, Combined Forces Command, and US Forces Korea provides details of the flight procedures and training requirements for RoK and US aviation operations during armistice. It includes corridors, the No-Fly Line (NFL) and No-Fly Areas (NFAs). The intent of UNC/CFC/USFK regulation 95-3 is to allow coordination between the corresponding agencies and to permit efficient air traffic and airspace management.

The DMZ is an area two-and-a-half miles in width extending approximately 150 miles across Korea from the Han River Estuary (HRE) to the Eastern Sea. The general trace of the southern boundary of the DMZ is approximately 1.2 miles south of the Military Demarcation Line (MDL). The northern boundary is 1.2 miles north of the MDL.

The Han River Estuary (HRE) is the body of water extending 45 miles west from the west end of the DMZ to the Yellow Sea. The HRE is also demilitarized. The southern boundary is the western and northern shoreline of Kyodong Island extending to the Imjin River’s confluence.

The Military Demarcation Line (MDL) is a line that crosses the Korean Peninsula and tells apart UN army jurisdiction from North Korean jurisdiction.

The Korean Tactical Zone (RK) P518 (KTZ) is the area bounded on the north by the MDL and on south by a line connecting various grid references across the peninsula. The KTZ is divided into six alphabetic sectors and the No-Fly Area (NFA) is divided into six numeric sectors. The intention of the KTZ is to control aviation operations in armistice, simplify identification of air-infiltration by North Korea and to prevent inadvertent overflight of non-friendly borders. (RK) P518 Korean Tactical Zones East and West are wholly separate geographic areas from the KTZ and are referenced as (RK) P518 East or West.

The No-Fly Area (NFA) is an area bordered by the MDL on the north and extending south approximately 5.7 miles to and including the NFL. The intention of the NFA is to prevent unnecessary military discord in the border area of non-friendly nations. All aircraft conducting flights in this area must obtain clearance prior to flight and abide by the appropriate procedures while flying.

The No-Fly Line (NFL) is a line selected along visible geographic features that are located 6.7 miles to the north of MDL. This line was set across the Korean Peninsula from west to east. The purpose of the NFL is prevention of inadvertent over flight of non-friendly borders.

The (RK) P518 Tactical Zone Exemption Area is an area selected for RoK and US Helicopters’ intensive training and the operation of unmanned aircraft.

(RK) P518 E is an area from the surface of the earth to unlimited altitude that connects grid references northward along the eastern coastline. Similarly, (RK) P518 W is an area that connects grid references east along NFL from surface to unlimited altitude.

Discussing regular missions flown close to the DMZ, Lt Col Davis said: “The area is broken-up into different sectors of airspace and we regularly fly there to train close air support. Because if we went to war, and North Korea rolled south past the DMZ, those would be the areas that they would be occupying pretty much right away. So, it gives us an advantage to essentially train for combat in the areas where fighting would occur if deterrence failed. That is highly valuable training. It is more challenging to get that airspace scheduled just because it’s so close to the DMZ and as you can imagine, which military aircraft can go in there is tightly controlled, it must be scheduled. Civilian aircraft aren’t allowed to fly in there.”

Red Flag Alaska

The 25th FS was one of two 7th Air Force squadrons that deployed to Eielson Air Force Base, Alaska to participate in Exercises Distant Frontier and Red Flag-Alaska 23-2.

The A-10 squadron commander explained that the limitations in airspace and range facilities in the Republic of Korea (a country the size of Portugal or the state of Virginia ) limit the squadron’s ability to train to all its requirements, not least dropping inert and live munitions. “That’s the main reason we come to Alaska to use the extensive airspace and air-to-ground ranges. We bring our annual allocation of live munitions and drop them on the JPARC ranges during Distant Frontier. In Red Flag, we are practicing integration with other assets not least tankers. We don’t have nearly as many tankers in the RoK as we do here, which provides us more realistic mission duration thanks to multiple aerial refuellings, something we can’t do often when flying from Osan.”

The big mission staged for Red Flag-Alaska 23-2 was a Joint Forcible Entry involving transport aircraft flying US Army troops into an operational area, dropping the troops off, and taking-off to return to base. Lt Col Davis’ aircraft provided escort to the transport aircraft while inbound to the airfield and maintained overwatch and engaging threats as they arose. “Once the US Army troops or special ops troops were on the ground, we switched to our typical close air support role, in direct communications with the JTAC on the ground and attacking whatever targets came up to enable their freedom of manoeuvre on the ground,” he said.

A new way: Fighter Generation Squadrons

In August 2022, the 51st Fighter Wing activated the 25th and 36th Fighter Generation Squadrons (FGS) to support and maintain A-10C Thunderbolt II and F-16 Fighting Falcon aircraft. Consequently, the 51st Aircraft Maintenance Squadron was deactivated.

Fighter Generation Squadrons are being activated throughout Combat Air Force wings as part of the US Air Force’s evolution to Combat Oriented Maintenance Organizations (COMO). Large maintenance units such as the 51st Aircraft Maintenance Squadron are transitioning to smaller fighter generation squadrons to improve synchronisation between maintenance and operations.

COMO seeks to provide squadrons with increased control of their assets to match their mission and manning needs and to grant commanders the opportunity to set their squadron’s priorities in alignment with their airmen. As part of the shift, the US Air Force has redirected its focus towards a more tactical combat environment in which fighter squadrons are tasked to generate high sortie rates. 

Operating with the RoKAF

US Forces Korea has two formal training agreements with the RoK armed forces, one is called the buddy squadron programme, which Lt Col Davis explained: “Every year the US 7th Air Force and the RoKAF Operations Command, the equivalent to the 7th Air Force determine which squadrons will exchange with each other under the buddy squadron programme. Squadron exchanges usually take place twice a year. So, the 25th FS will host a RoKAF unit at Osan. They fly to Osan, park their aircraft next to ours, their pilots come into our building, we brief, fly, and debrief together, conducting operations for about a week. Later in the year, we flip flop and go to a RoKAF base, maybe to the same squadron that visited us, maybe a different squadron. We fly to that base, park our aircraft next to theirs and train with them, again for about a week. That’s a very good opportunity for us to work through things like language barriers and understand each other’s tactics and how RoKAF pilots might see a problem, which may differ to the way we see a problem. It’s also a chance for us to talk about the same problem and come to a consensus on the right way to tackle the problem.”  Formerly known as the buddy wing programme, the buddy squadron programme is used as an opportunity to build trust, introduce new tactics, and exchange ideas for pilots, maintenance technicians and support personnel from both bilateral partners. In March 2023, the 25th FS hosted the RoKAF’s F-15K Slam Eagle-equipped 102nd Fighter Squadron from Daegu Air Base. The programmes have been in existence for more than 20 years.

The second formalised training event is called Combined Forces Training (CFT) which involves joint flight operations with both the 25th FS and the RoKAF squadron involved launching from their respective base and operating in the same airspace.

Lt Col Davis said: “We try to debrief with them over the phone as best as we can because that’s a very important part of the training process. You can mission plan and fly, but if you can’t capture the lessons learned from that flight or the mission planning, that’s kind of useless training. We also look for informal ways to interact with our Korean partners as well. Such interactions are more personality based. For example, I graduated from the school of advanced military studies at Fort Leavenworth, Kansas with the US Army. Two of my classmates recently took command, they are both battalion commanders in the RoK Army, so we’re looking to do some exchange work so we can show them the A-10 aircraft and talk about our mission, and then train with them. Because the fact of the matter is, if we’re looking at a combat situation, US Air Force and Republic of Korea forces must fit, fight, and work together seamlessly.”

Much emphasis is placed on joint operations, and they are an ongoing requirement for all US and RoKAF fighter squadrons, which is a challenge for the US 7th Air Force. Its young pilots arrive and serve for one or two years, get hyper-focused on this threat and the tactics, and then move on to another A-10 assignment or transition to the F-35. Giving further explanation, Lt Col Davis said: “Either way, they’re leaving Korea, and they’ll have to train to different tactics and different threats. So, it’s a recurring thing that we must do, and we must be diligent about it for each batch of pilots that arrive each year. RoKAF pilots live and serve on their squadron, they might change squadrons, but either way they’re staying in the Republic of Korea and they’re training to the same threat and the same tactics every day, just as we do, but without any significant change.”

Operating with the RoKAF is a straightforward process but does present a challenge in respect of the language difference. Lt Col Davis provided insight: “In a typical RoKAF fighter squadron, there maybe two to five pilots that speak English well. For example, one of the RoKAF KF-16 pilots deployed here for Red Flag-Alaska went to the United States Air Force Academy for four years. He’s quite fluent in English and a mission commander. Most of the other pilots on a RoKAF fighter squadron have a basic to intermediate understanding of English. They understand what we’re saying, but are less comfortable speaking back to us, so they always bring a translator whose sole job is to follow them around and interpret. That can be a challenge in mission planning and briefing with about half the time to cover the brief because of the need for back-and-forth translation.

“When flying, RoKAF pilots say all their tactical phrases and communication with air traffic control in English. When you’re having to explain something, they usually have someone in the formation that is well versed in English but it’s another thing we plan for. We agree on single words that when used in flight mean something expansive, and we mission plan to that. That makes it much easier for them to understand what we’re saying in flight.”

The A-10 is a unique aircraft, but its close air support mission is conducted by many air arms including the RoKAF which uses the propeller-driven, two-seat KA-1 light attack aircraft for the role. Lt Col Davis said the 25th FS does buddy squadron exchanges with KA-1 or KF-16 squadrons which conduct close air support.

As the US Air Force continues to divest the A-10, the 25th FS is making a concerted effort to not only train for the Korean theatre but is also training to increase the integration with other assets as much as possible, so its inexperienced pilots are well prepared for success when they transfer to another platform. Lt Col Davis explained more: “We’re also trying to train our young pilots to be able to take the attack mindset to the community they’re going to in order to retain a solid value for the integration between the air domain and the ground domain in their next community.”