Mapping Sub-Tier Dependencies in Aerospace

The challenge

An aerospace manufacturer knew its direct suppliers well but had limited sight of who supplied them. When a disruption surfaced, it often originated with a specialist casting, forging or coating provider several tiers down that was shared, unknown to anyone, by multiple tier-one suppliers.

The approach

Procurement and engineering jointly identified the components where a supply failure would stop assembly. For those parts, tier-one suppliers were asked to disclose their own critical sources, under confidentiality terms that addressed their commercial concerns, and those sources were in turn asked about theirs.

The resulting map was combined with qualification requirements, since in aerospace an alternative source cannot simply be switched on. Nodes where many parts converged on a single, hard-to-requalify provider were flagged as priorities for mitigation planning with the relevant tier-one suppliers.

What changed

The manufacturer found single points of failure three tiers down that had been invisible from its own contracts. Mitigation shifted from reacting to shortages towards targeted actions agreed in advance, such as protective stock, earlier qualification of alternatives and closer monitoring of the most exposed sub-tier suppliers.

Lessons for practitioners

Sub-tier mapping depends on trust more than on software. Focus on the critical parts first, be clear about how disclosed information will be protected, and treat the map as a living record rather than a one-off project.