I recently came across a striking story that perfectly captures a challenge many industries are grappling with today—how critical knowledge disappears when people retire or leave, and how rebuilding that expertise can take years. This isn’t just about factories and missiles—it’s happening right now in software engineering, and AI might be hiding the cracks until it’s too late.
When decades of know-how vanish overnight
At the 2023 Paris Air Show, Raytheon’s president shared how restarting production of the Stinger missile was a logistical nightmare. The original schematics were decades old, workers retired, and test equipment was gathering dust in warehouses. They had to bring back engineers in their 70s to teach younger workers how to build the missile by hand just like in the Carter era. Orders placed in 2022 for components wouldn’t arrive until 2026. The Pentagon hadn’t bought a new Stinger in twenty years, so the production line had essentially shut down from a lack of institutional knowledge.
This story illustrates a broader pattern. When Russia invaded Ukraine, the U.S. and Europe had to scramble to supply weapons and ammunition. But years of optimization for cost-efficiency and peace-time economies had hollowed out manufacturing capacity. France hadn’t made propellant in seventeen years. Europe’s biggest TNT producer was just one plant in Poland. Key facilities were shut down or mothballed, leaving the continent unable to deliver promised supplies on time.
Every major defense ramp-up took 3-5 years—even simple systems—and knowledge loss, not money, was the real bottleneck.
Lessons from Fogbank: Why written records aren’t enough
Perhaps the most striking example is the story of Fogbank, a classified nuclear warhead material produced from 1975 to 1989. When the government tried to recreate it in 2000, they found they simply couldn’t. Key experts who knew how to make it had retired or passed away, and official records missed an unintentional impurity critical to its function. Years and $69 million in reverse engineering later, they discovered the missing piece of “tribal knowledge” wasn’t documented anywhere.
This demonstrates a crucial insight—knowledge tied exclusively to people is fragile. No matter how digitized or documented a process might be, the tacit understanding that comes from years of hands-on experience often doesn’t survive without deliberate knowledge transfer.
What this means for software engineering and AI
I came across insights revealing that software engineering is following a similar trajectory, with worrying signs popping up. Just like defense manufacturing, building senior-level skill sets takes many years. Junior developers typically need 3-5 years to become competent mid-level engineers, and 5-8+ years to reach senior or architect roles. These timelines can’t simply be sped up by throwing money—or AI—at the problem.
Interestingly, a METR controlled trial found experienced developers using AI coding assistance actually took 19% longer to complete tasks than predicted, even though before starting they expected a 24% speed boost. Plus, AI-generated code now floods the workflow, making code review the new bottleneck, since humans still have to carefully vet what AI produces.
Hiring surveys reinforce this picture: many engineering leaders expect AI to reduce junior-level hiring, while computing programs see enrollment decline, meaning fewer fresh engineers entering the pipeline. When junior developers don’t go through the traditional process of debugging and learning from mistakes—and lean too heavily on AI—they risk developing what a DoD study calls “AI-mediated competence.” Essentially, they get good at prompting AI but not at understanding or critiquing its output.
When juniors skip formative mistakes, their tacit expertise never develops—creating a “Fogbank for code” that risks disappearing knowledge.
This means when senior engineers retire or move on, their institutional knowledge isn’t replaced, and AI tools can’t fill those gaps—they only reflect the capabilities set by the humans who trained them. We might find ourselves in a future where entire layers of critical software expertise evaporate just as suddenly as Fogbank did in defense manufacturing.
Key takeaways for developers, teams, and leaders
- Don’t mistake AI as a shortcut for deep expertise. AI is a tool, not a replacement for experience and judgment.
- Prioritize deliberate knowledge transfer. Mentorship, documentation with context, and embedding ownership in junior engineers are crucial.
- Recognize that rebuilding lost skills takes years. It’s a long game that requires sustained investment beyond flashy innovation.
The defense industry’s decades-long struggle to restart production lines and recreate lost expertise teaches us an invaluable lesson: optimizing for short-term efficiency without nurturing the human pipeline can leave us vulnerable when crises hit. In software, as AI becomes more integrated, we can’t afford to lose sight of the fundamentals of building and retaining true technical mastery.
We’re already seeing the consequences—shrinking talent pools, reduced hands-on debugging experience, and an overreliance on AI-generated code. Only by recognizing the limits of AI as a crutch and recommitting to developing seasoned engineers can we avoid the costly mistakes of the past.
And if history teaches us anything it’s this: the bill always comes due.
