Tool Gate · How it works
How the Critical-Spares Stockout Watchtower gate works
How the Critical-Spares Stockout Watchtower grades each critical spare on how exposed it leaves the line and rolls up to the worst: a single-failure cascade gate escalates a critical part with zero on hand, months of lead time, and no substitute to SINGLE-FAILURE RISK.
How the gate works
This tool grades one spare's stockout risk — the gap between its replenishment lead time and the downtime you can tolerate on the asset it protects. It reads 4 risk signals and rolls them into one verdict — the worst, never the average — and then a gate that can only make it worse.
The 4 risk signals
| Signal | Verdict |
|---|---|
| Asset criticality · A (line-down / safety) | CRIT-Atop tier — a stockout stops the line |
| Lead time vs tolerable downtime | EXCEEDS182d lead vs 3d tolerable · +179d over |
| Qualified substitute | NONEno fallback part on file |
| Effective supply · on hand + on orderfix first | ZERO0 on hand, 0 on order |
The verdict bands
When all four are true at once — a criticality-A asset, nothing on hand or order, no qualified substitute, and a lead time past tolerable downtime — the base severity escalates to SINGLE-FAILURE RISK: one failure downs the line with no recovery path inside the window you can absorb. It releases the moment any single leg clears.
In the worked sample it reads SINGLE-FAILURE RISK — This spare serves a criticality-A asset and every protective leg is gone: nothing on hand, nothing on order, no qualified substitute, and a 182-day lead against just 3 days of tolerable downtime. On the factors alone it reads HIGH — but with all four legs absent at once, the cascade gate escalates it to SINGLE-FAILURE RISK. One failure downs the line with no recovery path. The one thing to fix first: Effective supply is 0 — nothing on hand or on order — so placing the order is the fastest leg to clear. The gate releases the moment supply, a qualified substitute, or a shorter lead brings any single leg back inside the tolerable window..
Common questions
Can every signal look survivable on the How the Critical-Spares Stockout Watchtower works and the company still read SINGLE-FAILURE RISK?
Yes. The roll-up takes the worst of 4 risk signals — never the average — then a worsen-only gate, the Single-failure cascade gate, escalates when trouble clusters. In the worked sample it reads SINGLE-FAILURE RISK because this spare serves a criticality-A asset and every protective leg is gone: nothing on hand, nothing on order, no qualified substitute, and a 182-day lead against just 3 days of tolerable downtime. On the factors alone it reads HIGH — but with all four legs absent at once, the cascade gate escalates it to SINGLE-FAILURE RISK. One failure downs the line with no recovery path.
What is a worsen-only gate?
A dispositive rule that can only lower a verdict, never raise it. One fatal flaw overrides an otherwise-set of survivable lines, because a single disqualifying gap shouldn't hide behind an average of the healthy ones. The tool also names the one thing to fix first — here, "Effective supply is 0 — nothing on hand or on order — so placing the order is the fastest leg to clear. The gate releases the moment supply, a qualified substitute, or a shorter lead brings any single leg back inside the tolerable window.".
Grades a spare's stockout risk, never a person or a named supplier. Deterministic and offline — your storeroom data, no benchmark. Not procurement, financial, or engineering advice.
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<p style="font:14px/1.5 system-ui,sans-serif"><a href="https://redhub.ai/visuals/tool/critical-spares-stockout-watchtower">How the Critical-Spares Stockout Watchtower gate works</a> — by <a href="https://redhub.ai">RedHub AI</a>, the AI that tells you when to doubt it.</p>Image + link — a static picture for any blog
<a href="https://redhub.ai/visuals/tool/critical-spares-stockout-watchtower"><img src="https://redhub.ai/visuals/tool/critical-spares-stockout-watchtower-share.png" alt="Diagram of the Critical-Spares Stockout Watchtower: critical spares rolled up worst-not-average, a single-failure cascade gate, and the shop reading SINGLE-FAILURE RISK on a zero-stock long-lead part." width="760" loading="lazy" style="max-width:100%;height:auto;border-radius:16px"></a>
<p style="font:14px/1.5 system-ui,sans-serif"><a href="https://redhub.ai">RedHub AI</a> — the AI that tells you when to doubt it.</p>
This is how Critical-Spares Stockout Watchtower works. More diagrams in the Visual Field Guide.