The User (PAF) submits its operational requirements to the Combat Aircraft Prime Contractor (CAC). The CAC submits technical specifications to the Radar Subsystem Manufacturer (CETC). The radar manufacturer submits its product according to these specifications and provides standard technical interfaces. The CAC generates weapon interface standard information based on these standard interfaces and other relevant technical information. The weapon manufacturer produces and supplies weapons according to this weapon interface standard information.
After obtaining the weapon interface standard information for the JF-17B3, Pakistan can independently develop weapon payloads. When these weapon payloads are mounted on the JF-17B3 fighter jet, they can be recognized by the fighter's mission computer and integrated into the combat mission system.
This is a standard operating procedure within the system.
Weapon interface standard information is divided into different levels. For general aerial bombs, only L1/L2 level is required. For ground-attack missiles and precision-guided bombs, the requirements need to rise to L3 level. For BVR missiles, it can operate normally at L3.5 level, but higher technical requirements necessitate L4 level.
The interface details of missile weapons and launch platforms vary from country to country. Especially when cross-border cooperation is involved, these capabilities are severely limited. If L4-level cooperation between missiles outside the system and fighter jets is required, all three parties (missiles, fighter mission computers, and radar) must re-coordinate and adapt. This is extremely difficult.
Turkey's F-16 fighter jets use an "external load" mode when using domestically developed weapon payloads. Turkey has developed its own Aircraft Independent Firing System (UBAS), which bypasses the F-16's native fire control system. This allows these F-16s to "normally use" Turkish-developed weapon payloads. If we observe them closely, we will find that these pilots are carrying tablets.
China's Su-35 fighter jets cannot directly use Chinese missiles. Similarly, Chinese engineers have adopted a similar "external load" method for the Su-35 to enable it to "normally use" Chinese missiles.
Of course, the external load mode comes at a cost. They can only reach a maximum of L3.5.
Turkey is currently developing its own AESA radar, mission computer, and other avionics systems. If they could completely replace the avionics systems inside these F-16 fighter jets with domestically produced components, they could achieve native Level 4 weapon application. Otherwise, their pilots would have to carry tablets indefinitely.
The source code for radar, mission computers, and other components is a core secret of each manufacturer. They will not disclose it to anyone. If weapon adaptation requirements exceed the technical specifications, the original manufacturer needs to re-adapt the source code and submit new technical specifications.
==================
For high-tech weapon payloads, the "external payload mode" can also be used "normally," but with some differences:
1. Data updates during the missile's mid-flight phase are limited. Mid-flight communication refresh rates are low, and time synchronization errors are large.
2. Multi-target management capabilities are limited. The mission computer cannot uniformly allocate targets.
3. The missile's anti-jamming capabilities are limited. Radar waveforms/jamming strategies cannot be deeply integrated with the missile.
4. Pilot involvement is increased. Pilots need to spend more time and effort manually selecting targets, inputting parameters, and adjusting mid-flight updates, etc.
Unless we are having translation problems - The assertion that access to “source code” is a prerequisite for full weapon integration (Level 4 capability) is technically flawed and reflects a misunderstanding of modern avionics architectures.
You do not need the source code of a radar or mission computer to integrate a weapon. You need the Interface Control Document (ICD) and compliant drivers. In modern avionics, the Mission Computer (MC) and Radar are “black boxes” that communicate via standardized buses (MIL-STD-1553B, ARINC 429) using defined protocols. As long as the Prime Contractor (CAC) provides the Weapon Interface Standard (which is effectively an ICD), the integrator writes a software “driver” that translates the missile’s data into the format the MC expects.
The assertion that “source code” is required for full weapon integration (what you call “Level 4”) is incorrect and is equating proprietary vendor locks with software architecture.
Btw - just so we are all clear -
There is no “Level 1-4” standard in global military aviation.
If the JF-17 uses an Open Architecture as claimed then it is specifically designed to decouple the weapon from the flight software. Since Pakistan has the Weapon Interface Standards (ICDs) now from CAC and access to the Store Management System (SMS), they can write native drivers for any weapon. The radar simply outputs track data to the bus; it doesn’t know or care what missile receives it. No radar source code is required. The WMMC (Weapon Mission Management Computer) was specifically designed to be “open” to allow Pakistan to integrate Western weapons (like the Ra’ad ALCM) and avionics (like Aselsan targeting pods) without asking CAC to create a “driver” every time.
Turkey uses tablets on Block 40/50 F-16s because Lockheed Martin digitally signs the Mission Computer software. Turkey cannot install new missile drivers because they lack the Crypto Keys, not because they lack the radar’s source code. This is a misunderstanding and a misnomer you are repeating.
This might have been true in the 1970s with the AWG-9 to Phoenix combo on the F-14 physically generated the guidance signal and sent it directly to the missile. If you didn’t have the radar’s schematics, you couldn’t fire the missile.Your suspicion that the radar could have a “firmware whitelist” or “lock” that prevents it from tracking targets for non-Chinese weapons is applying 1970s hardware logic (like the F-14’s AWG-9) to a 2000s bus-based architecture.
Today the radar is just a sensor on a network. It broadcasts “Target at X, Y, Z” to the Mission Computer (WMMC) via the bus. The Mission Computer then reads that data and sends a separate command to the missile station via the Store Management System (SMS).The weapon never “talks” directly to the radar. It talks to the SMS. Since the PAF controls the SMS software and the 1553 bus messaging, they can integrate any weapon that speaks the bus language, regardless of what the radar “wants” to do.
You dont need the radar’s source code to tell the missile where the target is.You only need the Message Format (e.g., “Target Azimuth” is bits 1-16 on Word 3 of the 1553B bus). As long as the Prime Contractor (CAC) provides the Weapon Interface Standard (the ICD), the integrator writes a “driver” or “wrapper” that translates missile data into the format the MC expects.
There is no physical wire between the KLJ-7 radar and the missile pylon. They are on separate “addresses” on the data bus. The radar sends data to the Mission Computer; the Mission Computer re-packages it and sends it to the missile.For a “lock” to work, Chengdu would have to program the radar to stop tracking targets entirely if it somehow sensed a foreign missile was on the wing. But since the radar isn’t connected to the Store Management System, it has no way of knowing what’s on the wing.
Turkey uses UBAS and tablets on legacy F-16s because those specific jets have closed, proprietary architectures (legacy Block 40/50) where the OEM (Lockheed Martin) refuses to update the OFP. Lockheed Martin effectively “locks the bootloader” on legacy F-16s. The tablet is a workaround for a legal/administrative block, not a technical need for source code.
Furthermore, even with this restriction, Turkey successfully integrated the SOM-J and other munitions using UBAS. The “limitations” you listed (mid-course updates, anti-jamming) are functions of the Datalink implementation, not the radar source code. If the external pod can broadcast Link-16 or proprietary datalink signals, the missile receives updates just fine - NO CAPABILITY IS LOST.
For the Özgür Project (Block 30 modernization), Turkey replaced the Mission Computer entirely. By owning the computer, they gained the ability to install native drivers for Gökdoğan/Bozdoğan missiles. They achieved this without needing the Northrop radar source code and they simply read the radar’s output from the bus.
The limitations on the Su-35 (lack of mid-course updates for PL-15) exist because Russia did not provide the ICD (API access) to the fire control system, nor the Data Link Protocol.
True high-level integration (mid-course updates, DLZ calculations) is achieved via Store Description Files (SDF).
• When a new missile is integrated, engineers load a data file containing the missile’s ballistics, drag coefficients, and seeker field-of-view into the aircraft’s Store Management System (SMS).
• The SMS uses this data to calculate launch parameters. The radar software remains untouched; it simply outputs track data to the bus, which the SMS reads.
Btw - Israel did something on the F-35 which further disproves your argument - They didn’t ask for the radar source code.They installed a “Man-in-the-Middle” C4I computer on top of the F-35’s avionics. This computer translates Israeli weapon data into a format the F-35 understands.
