Projecting constraints in multi-tier supply chain networks: Why suppliers…

Finding bottlenecks before a production ramp-up requires information sharing that accounts for suppliers’ commercial risks.

Editor’s note: This is part 1 of a 4-part series on multi-tier supply chain networks. Part 2 in the series will publish on Tuesday, Nov. 10, with parts 3 and 4 publishing on Nov. 17 and Nov. 24

Here is a thought for supply chain directors (SCDs). What if we went looking for the bottleneck (BN) in the supply chain network (SCN) now, in calm times, before a supply stoppage ever hits—and began strengthening it?

If you have spent time in this industry, you may know the state that Boeing and others call recovery: the emergency footing a stretch of the network drops into once backlog has piled up at a supplier and a supply stoppage looms. In recovery, the original equipment manufacturer (OEM) sends its own engineers into a struggling supplier to raise output and claw the schedule back. Boeing has run a standing “supplier recovery team” for exactly this. It works—but it is, by definition, a response after the damage is done. If you have lived through the chaos of one even once, wouldn’t you rather act one step before it begins?

The risk you can control

Let me set one thing aside first. This is not disruption from disaster or accident. That kind of risk is real, but it falls across every firm more or less randomly, and at roughly equal probability. You can insure against it, site a plant away from known hazards, do what is reasonable—yet your rivals face the same exposure, and there is no end to that kind of preparation against the uncontrollable risks.

What is inexcusable, for an SCD, is leaving unaddressed the risk you can control. Picture a marching band of players of very different fitness, gradually asked to march faster. Sooner or later the least fit member falls behind. Now imagine lightening that member’s load, or giving them a boost to keep pace, before the parade ever sets off.

Planning a ramp-up is exactly that moment. As you raise the production rate across the network, the weakest process—the node with the least headroom—will, at some point, fail to keep up and begin to delay. This is controllable for two reasons: the ramp is planned, so you know it is coming; and the weak point, if you go looking in advance, may well be found. If you know today where it is, you can concentrate your investment there. Diagnosis precedes treatment; making the slowest node visible, before it bites, is that diagnosis. It may be the single most important discipline in the generation of supply chain management.

Consider why this matters competitively. If a bear is chasing you, run—and for an SCD, running is not optional but a duty. The person beside you may laugh: the bear is far faster than any human, so why bother? But I do not need to outrun the bear. I only need to be one step ahead of the person beside me. Handling your controllable risks will not prevent every disruption. But when a risk you managed well is one a rival stumbled on—when they could not ramp and left their customers waiting—you take their , and improve your own odds of survival.

When a network gets too deep to see

I have worked on supply chains from both sides of the buyer-supplier relationship, and the need for visibility was opposite at each. At Intel, the upstream network is relatively small; the people responsible knew their suppliers’ situations—and those of the equipment makers their suppliers bought from—in considerable detail. The network was shallow and narrow, and there was little role for a network-wide tool to locate a BN. At Boeing, it was the reverse. The number of suppliers behind a single aircraft is of another order entirely. In the automotive industry the count can run to thousands of firms. And beyond Tier 1, visibility grows dim; one cannot claim to see clearly up there. The breadth of the space governs how deeply one can see into it. Visibility, in other words, is not universally necessary. It becomes necessary only once a network passes a certain depth and breadth—and today’s complex products, cars and aircraft, are long past that threshold.

The hundred-page survey

Take the Rate Readiness report. At the aircraft manufacturer, we, the OEM, imposed it on our Tier 1 heavy-industry suppliers: a survey well over a hundred pages, asking how ready they were for a future rate increase, which they had to answer. Each department filled in its dozens of pages; sales pulled it together; a single round took three months. It covered capital investment and much else—a heavy burden for the supplier. And if that worked, why does supply disruption still surface the way it does? For one, the survey may not carry all the way through to the Tier 2 suppliers above Tier 1 and beyond. And by demanding that every item be answered, by every Tier 1 firm, does it not lower the quality of the whole? When you learn a language, which teacher would you rather have—the one who says to memorize the whole dictionary, or the one who narrows it to the grammar that matters? Rather than burden every firm with an exhaustive report, shouldn’t we narrow the burden to just what locating the constraint requires, and lighten the load?

Why suppliers keep the door closed

I have visited many suppliers. Ordinarily, most were reluctant to allow us access or to information. Propose that we find the BN process together and strengthen it now, in calm times before recoveries, and getting agreement was extremely hard. Almost no firm ever took us up on it. Only in a crisis—that recovery state, backlog piling up, a stoppage looming—would they grudgingly allow a visit and let us measure process capacity. One supplier, after we had grown close over a long time, let me in on what suppliers rarely say out loud: “You can tell me to hand over the internal process information. But at year’s contract renewal you’ll use it to negotiate the price down, won’t you? So how could I hand it over easily?” That is entirely reasonable. A one-sided demand for disclosure is nothing but exploitation. And there is always the risk the price leaks to one of the supplier’s rivals, who undercuts them and takes the business.

So an OEM simply demanding the information from a supplier cannot work; it is structurally impossible. Even if you asked every firm in the SCN to reveal its internal information, each would push back: why come to us? Do we even have to answer? Ask all of them equally, and one firm reckons it can stay quiet without standing out, while another braces for the reverse—that having answered honestly, it alone will be the one to lose. To get cooperation, you need one of three things: a special case with overwhelming leverage to compel it, some benefit to the firm from answering, or grounds strong enough to justify the request.

What I want to propose over this series is an information-sharing platform for exactly that. Rather than ask every firm to open its interior, it takes a single number from each, and from those alone draws out where the constraint of the whole network sits, in peacetime. Everyone comes to know who carries the weight of the whole—and no firm loses by disclosing.

As it happens, the key has been sitting in plain sight for more than half a century. It lies in two old tools that grew up separately, in project management and in production management, and have rarely been brought together. time, I want to propose that these two are in fact saying the same thing. Once that is clear, a single number from each firm may be enough to draw the BN candidates across the entire network.

Brian (Yoshiatsu) Kawabata began his career at Honda, earned an MBA at Toulouse Business School in 2008, and went on to work at Boeing and Intel. In June 2026, he completed a PhD in computer science at Tokyo University of Agriculture and Technology, with a dissertation on detecting the constraints of multi-tier supply chain networks from minimal shared information; a related paper appears in Information Technology and Management (Springer, 2026; ). He writes from both sides of the work—the factory shop floor and the theory.

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