Supply Chain · Resilience

Backup Supply Plans

For every critical input, document the alternate source, the qualification gap, and the switching trigger before you need it.

Time1 h
FormatTeam
StageResilience

Backup Supply Plans: what it is and why it works

A backup supply plan documents, for each critical input, what happens if the current source fails: the alternate source, the gap between that source and full qualification, the event that triggers the switch, and who is authorized to decide. Where possible, commercial terms are pre-negotiated so the switch is not delayed by contracting. The plan is reviewed yearly and after every near-miss, so it remains accurate as suppliers, specifications and people change.

The method works because the slowest part of switching suppliers is rarely finding a name; it is qualification, approvals, tooling, contracts and internal decision-making. Writing those steps down in advance shows the real switching time and lets the team close part of the gap while it is cheap to do so, for example by running a first-article inspection or a trial batch. It is lighter than full Dual Sourcing, which keeps two active sources, and suits inputs where splitting volume is uneconomic. Priorities come from the Supply Risk Map, and Stress Scenarios check whether the triggers and decision rights work under pressure.

What you need

The list of critical inputs from the risk map, with current sources
Known or candidate alternate suppliers and their capabilities
Qualification requirements: specifications, approvals, testing, customer or regulatory sign-off
Current contract terms and any existing frame agreements
Decision authority rules for sourcing changes

What you get

A backup plan per critical input with alternate source and qualification gap
Defined switching triggers and named decision makers
Pre-negotiated terms or frame agreements where feasible
An estimated switching time for each input
A review schedule and near-miss update rule

When to use it

When everyone knows a plan B exists and nobody knows what it actually is.

How to do it, step by step

For each critical input, document the current source and its dependency.
Identify the alternate source and the qualification gap.
Set a switching trigger: what event starts the switch, and who decides.
Pre-negotiate terms where possible.
Review plans yearly and after every near-miss.

Worked example: Documenting plan B for castings at an aerospace machining supplier

Illustrative scenario — figures are realistic but not from a real company.

A machining supplier producing actuator housings for aerospace customers buys aluminum castings from one foundry. Everyone assumed a second foundry could step in. When the primary foundry had a furnace failure that lasted two weeks, the team discovered the alternate had never produced the part and had no approved process.

The purchasing manager listed 18 critical castings and forgings and, for each, recorded the current source, the proposed alternate and what qualification would require: tooling, first article inspection and customer approval of the source change.
The qualification gap was estimated in weeks for each item; for the housing it was about 26 weeks without preparation.
The team defined triggers: any primary supplier outage expected to exceed three weeks, or two consecutive late deliveries on a critical part, would prompt a decision by the operations director within 48 hours.
For the five items with the longest gaps, they funded pattern tooling at the alternate foundry and completed first article inspection in advance, with a small annual order to keep the process warm.

Result. For those five parts, switching time dropped from about half a year to roughly six weeks. The cost was the tooling plus a modest price premium on the annual order. The lesson: the plan B existed in people's heads but not in approvals, and approvals were the long pole.

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Common pitfalls and how to avoid them

Listing an alternate supplier without checking qualification requirements.Document what approvals, testing and customer sign-off the switch needs, and estimate the time for each.
Vague triggers such as 'if the supplier has problems'.Define measurable triggers and name the person who decides, with a time limit for the decision.
Assuming the alternate will have capacity when you need it.Pre-negotiate capacity or terms where possible, and keep a small active relationship.
Writing the plan once and filing it.Review yearly and after every near-miss; update contacts, specifications and status.

Frequently asked questions

What should a supplier contingency plan include?

For each critical input: the current source and its risks, the alternate source, the qualification steps and time needed, the triggers that start a switch, the decision owner, any pre-negotiated terms, and interim measures such as stock or allocation. Contact details and a review date keep it usable.

What is the difference between a backup supplier and dual sourcing?

Dual sourcing splits active volume between two qualified suppliers at all times. A backup supplier is prepared to take over when triggered, but normally receives little or no volume. Backup plans cost less day to day; dual sourcing switches faster because the second source is already running.

How long does it take to qualify a new supplier?

It ranges from days for commodity items to many months for engineered or regulated parts that need tooling, process validation, first article inspection or customer approval. The backup plan should estimate this time per item, because it determines how much stock or preparation is needed to bridge the gap.

Origin

Business continuity planning — ISO 22301; contingency sourcing practice.

Used in these playbooks

Supplier crisis room 90 min

A supplier just failed: map the exposure, pick the alternates, assign actions — in 90 minutes.

Resilience audit 2 days

Two days to know your real exposure: risk map, supplier scores, stress scenarios, buffers and backup plans on paper.

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