Unlocking the Win–Win of MOSA

From mandates to momentum

Eric Alexander, Director of MBSE Services

For too long, the Modular Open Systems Approach (MOSA) has been viewed as a compliance exercise. A box to check in a contract response. But MOSA is about more than mandates—it’s about momentum. By enabling modularity and openness, MOSA unlocks the innovation needed to outpace fast-moving adversaries, shifting markets and emerging technologies. It is the foundation for maintaining adaptive overmatch in both military and commercial systems without compromising on resilience.

WIN #1: GREATER AGILITY AND AFFORDABILITY

Across defense and commercial markets, organizations face the same challenge: technology cycles move fast, but programs and products often move slow. MOSA helps break that cycle.

• Faster upgrades: Standardized interfaces enable plug-and-play swaps as technology matures

• Lower life cycle costs: Avoids dependence on a single supplier and allows true competition across vendors

• Operational agility: Systems can adapt to new missions, markets, or customer needs without waiting for a wholesale redesign

MOSA keeps innovation in motion—enabling platforms to evolve continuously instead of stagnating until the “next big program” or “next product generation”.

WIN #2: INDUSTRY GAINS OPPORTUNITY AND GROWTH

Some companies fear MOSA threatens traditional business models. In reality, it expands them.

• Bigger addressable markets: A sensor, software module, or subcomponent designed for one platform can scale across many

• Reusable IP: Develop once, deliver many times. This is the same value proposition that drives model-based systems engineering (MBSE) and digital engineering . Just like modular hardware, models become reusable assets that accelerate delivery and reduce cost

• Level playing field: The best technology wins, not just the incumbent

For integrators and manufacturers, MOSA and MBSE together create a powerful multiplier: MOSA ensures openness at the system level, while MBSE ensures digital assets can be reused, adapted and integrated across programs. This synergy simplifies portfolio management, strengthens competitive advantage and keeps innovation moving faster.

WIN #3: COMMERCIAL SECTORS LEARN AND CONTRIBUTE

MOSA principles are not unique to defense.

• Automotive: EV makers use modular platforms to support multiple vehicle models

• Aerospace: Airlines rely on retrofit modularity to keep fleets current without grounding operations

• Healthcare and Internet of Things (IoT): Open architectures allow new devices and software to plug in seamlessly, enabling faster patient care and consumer adoption

• Consumer Tech: Smartphone ecosystems thrive because open app standards let developers innovate at-scale

By aligning with MOSA, defense and commercial sectors stay interoperable with one another, encouraging dual-use innovation and lowering barriers for new entrants.'

THE RISK OF STANDING STILL

Here’s the hard truth: without modularity and openness, systems stagnate. Lock-in creates brittle architectures, rising sustainment costs and slow refresh cycles.

It’s like pouring concrete without rebar, it might look strong at first, but it will crack under pressure. MOSA is the rebar in the concrete: the unseen strength that makes systems resilient, adaptable and future-proof.

THE MANDATE VS. THE MINDSET

MOSA is required by law. Title 10 of the U.S. Code mandates that all major defense acquisition programs use a modular open systems approach. But here’s the problem: the mandate leaves many organizations without practical frameworks for implementing MOSA effectively. Too often, this results in rigid architectures that check the box but miss the true intent of openness and adaptability.

For our commercial readers, think of it this way: an executive memo or corporate policy can declare “you must be modular and open,” but without clear frameworks, teams struggle to comply – and end up designing systems that stifle innovation.

The law may require MOSA, but culture and practice are what make it successful.

KEEPING INNOVATION IN MOTION

MOSA is not a checkbox, it’s a culture shift:

• Customers (government or commercial) win by avoiding lock-in

• Industry wins by competing on innovation and growing markets

• End users (whether warfighters, drivers, or patients) win with faster, more capable systems in their hands

That’s a win–win–win worth building into every design.

MAKING MODULARITY DEMONSTRABLE

In our experience, MOSA gains real momentum when paired with MBSE. MBSE turns the principles of modularity into something tangible: openness isn’t just declared, it’s modeled, queried and proven. Interfaces can be mapped, traced, and visualized across the lifecycle – providing evidence of compliance while also enabling adaptability.

This is where MOSA shifts from a mandate to a mindset. It becomes less about policy, more about practice; less about constraint, more about freedom to innovate.

CLOSING THOUGHT

For too long, MOSA has been treated as a box-checking exercise. It’s time to embrace it as a design principle; one that creates lasting momentum across government, industry and commercial sectors.

The journey is ongoing. Every program is learning how to balance compliance, openness and innovation. But the opportunity is clear: when modularity becomes culture, everyone wins.

If you’d like to see how we’re putting MOSA and MBSE into practice across defense and commercial programs, you can explore more at stc.arcfield.com.

Eric Alexander serves as a senior director of MBSE services for STC, where he leads initiatives in MBSE, digital transformation and AI-enabled engineering. With a background spanning complex defense and aerospace programs, he’s passionate about empowering teams to deliver clarity, speed and innovation through integrated digital ecosystems.