Before a fighter pilot fires, one question has to be answered with certainty: is that contact a friend or a foe? On the F-16 Fighting Falcon, the box that answers it is about to change. BAE Systems announced on 29 September 2026 that its AN/APX-127(V)1 Combined Interrogator Transponder has received AIMS certification from the US Department of War for use on the F-16.
AIMS is the Pentagon programme office that certifies IFF equipment for US military aircraft. Without its approval, a transponder does not go on a combat jet. With certification in hand, BAE says production is under way and the first lot of 90 units will be delivered this year.
Datos rápidos
- Sistema: BAE Systems AN/APX-127(V)1 Combined Interrogator Transponder (CIT)
- Certified: AIMS certification for the F-16, announced 29 September 2026
- Modes: Mode 5 (encrypted military) and Mode S
- Sustituye a: AN/APX-113(V), AN/APX-125(V) and AN/APX-126(V) as a drop-in unit
- Producción: Greenlawn, New York, and Austin, Texas
- First lot: 90 units, deliveries expected in 2026
- Track record: BAE says it has delivered 1,500+ interrogators and 6,000+ CITs
What the new box does
An IFF system does two jobs. The transponder answers when someone else asks who you are. The interrogator asks the question of every other aircraft on the radar. The APX-127 combines both functions in a single unit designed for highly manoeuvrable jets, which saves weight, space and wiring in a fighter where all three are scarce.
The important part is Mode 5, the encrypted military IFF standard used by the United States and NATO. Unlike older modes, a Mode 5 reply is cryptographically protected, so an enemy cannot simply record and replay it to pose as a friendly aircraft. The APX-127 also supports Mode S, the civil mode that lets fighters work alongside airliners in crowded airspace, and BAE says it adds extra receive channels for passive acquisition of other aircraft’s signals.
For F-16 operators, the most useful feature may be the least glamorous. BAE designed the APX-127 as a drop-in replacement for three earlier units, the APX-113, APX-125 and APX-126, which means an air force can swap the box without redesigning the cockpit or rewiring the jet.
BAE builds the APX-127 at its plants in Greenlawn, New York, and Austin, Texas. The company has been making IFF equipment for more than 80 years and says it has delivered over 1,500 interrogators and 6,000 combined interrogator transponders so far.
Why identification still matters
IFF sounds like a solved problem until it fails. In April 1994, over northern Iraq, two US Air Force F-15Cs shot down two US Army UH-60 Black Hawks they had misidentified as Iraqi helicopters, killing all 26 people on board. Problems with IFF interrogation were among the many failures investigators found.
Modern air wars are far more crowded than that. Drones, cruise missiles, allied fighters, tankers and airliners can all share the same patch of sky, often within minutes of each other, and the rules of engagement increasingly depend on electronic identification rather than a pilot seeing the target with their own eyes. A secure, reliable IFF is what lets a pilot shoot quickly without shooting the wrong thing.
The F-16 is flown by more than two dozen air forces, and many of them fly with NATO. A certified, drop-in Mode 5 box gives all of them a straightforward way to keep their Vipers talking the same language as the rest of the alliance.
A clear explainer of how identification friend or foe and secondary surveillance radar work.
Sources: BAE Systems press release (29 September 2026), FlightGlobal, Defense Daily, Defence Blog
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