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The planning hierarchy
Strategic, tactical and operational plans, how far ahead each looks, and how decisions hand down from one level to the next.
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Supply chain decisions come in layers. The further ahead a decision looks, the less detail it needs and the harder it is to undo.
| Level | Horizon | Typical decisions | Detail |
|---|---|---|---|
| Strategic | Years | Where plants and warehouses go, how much capacity to build, which suppliers to partner with | Product families, regions |
| Tactical | Months to a year | S&OP, aggregate production and inventory plans, contracts, workforce levels | Families or key items, monthly |
| Operational | Weeks to hours | Master production schedule, MRP, scheduling, dispatching, daily replenishment | Item, line, shift |
Each level sets the limits for the one below. Strategy fixes the capacity that S&OP can plan with. S&OP sets the volumes the master schedule must deliver. The master schedule drives MRP’s component orders and the hour-by-hour line schedule. Feedback flows back up: when the line can’t hit the schedule, the master schedule changes, and persistent gaps become an S&OP or a capacity investment topic.
Take a shampoo company. The strategic plan decides to add a line in Baddi by next year. The monthly S&OP agrees to make 1 lakh units in December and build stock ahead of the festive season. The master schedule spreads that across weeks and pack sizes. MRP orders bottles, caps and labels in time, and the shift supervisor sequences the line by fragrance to keep cleaning time down.
Words to use
- Aggregate planning
- Monthly volume, workforce and inventory plans for product families.
- Planning horizon
- How far ahead a plan looks; it must exceed the lead time of the decisions it drives.
- Time fence
- A cut-off inside which the plan is frozen or only changed with approval.
What each level hands to the next
| Level | Typical cycle | Input from above | Output to below |
|---|---|---|---|
| Strategic plan | Yearly | Business strategy | Capacity, network and supplier decisions |
| S&OP | Monthly | Available capacity | Agreed volumes by family and month, inventory targets |
| Master production schedule | Weekly | S&OP volumes | Quantities per finished item and week |
| MRP | Daily or weekly run | MPS and bills of materials | Planned purchase and production orders |
| Scheduling | Daily, hourly | Released production orders | Job sequence per line and shift |
Disaggregation: from families to items
Each step down splits a total into more detail. If S&OP agrees 1 lakh units of shampoo for December, the master schedule might split it by the recent mix: 40,000 of the 200 ml pack, 35,000 of the 650 ml pack and 25,000 sachets, then spread each across the weeks of December. The check runs the other way too: the items in the MPS must add back up to the family volume S&OP signed off. When they don’t, either the mix assumption or the plan is wrong.
Planning buckets and horizons
Higher levels use bigger time buckets and longer horizons: S&OP looks 18 months or more ahead in months, the MPS a few months in weeks, and scheduling a few days in hours or minutes. Each level must look at least as far ahead as the lead time of the decisions it controls: a plan that releases supplier orders needs a horizon longer than the supplier’s lead time.
Time fences
Plans near today are expensive to change, because materials are bought and lines are booked. Most companies divide the horizon into zones:
- Frozen: the next one or two weeks. Changes need management approval.
- Slushy: a few weeks further out. Changes are allowed within limits, for example swapping items but not changing the total.
- Liquid: further out. The plan is free to change.
Why plan in layers at all
Hax and Meal’s work on hierarchical production planning in the 1970s set out the logic: solving everything in one giant detailed model was impossible, and also unwise, because detailed forecasts far ahead are mostly noise. Aggregate decisions (capacity, workforce, seasonal stock) are made on aggregate data, where forecasts are more accurate, and detail is added only when it is needed and more reliable.
Where layering breaks
- Mix problems hidden in totals: the family plan fits total capacity, but one SKU runs only on one line, which is overloaded. Aggregate plans need checks on the critical resources for each item group.
- Inconsistency: if the levels use different numbers (finance’s plan, sales’ plan, the factory’s plan), layering amplifies the confusion instead of controlling it.
- Nervousness: a small change at the top cascades into many changes below, especially when lot sizes and lead-time offsets amplify it.
- Slow feedback: if problems on the shop floor take a month to reach S&OP, the higher levels keep committing to plans that can’t be executed.
Concurrent planning in modern tools
Advanced planning systems can solve several levels together: a constrained master plan that already respects material availability and key capacities, instead of the classic sequence where MRP assumes infinite capacity and problems are found later. This shortens the loop, but it needs accurate capacity and lead-time data, and planners still need the layered view to understand the result.
Demand-driven alternatives
Some companies decouple the operational layers with strategic buffers instead of planning every component from a forecast: demand-driven MRP (DDMRP) places stock buffers at chosen points and replenishes them from actual consumption. The tactical layer (S&OP) stays; the operational layer becomes more pull-based.
Interview kit
Practise it out loud
Answer each question yourself before opening the model answer.
Planning works in a hierarchy. Strategic decisions over years cover network and capacity; tactical plans over months, mainly S&OP and aggregate planning, set volumes, inventory and workforce; and operational plans over weeks and days, the MPS, MRP and scheduling, execute them. Each level constrains the next one down, detail increases as the horizon shortens, and feedback from execution flows back up.
Where does S&OP sit in the hierarchy, and what does it hand down?
It’s the tactical bridge between strategy and execution. Monthly, at product-family level, it balances demand with supply and finance, and hands down agreed volumes and inventory targets that the master production schedule turns into item-level plans.
Why not plan everything at item level and by the hour?
Detailed long-range forecasts are very inaccurate and changing them constantly creates noise. Aggregate long-range plans are more reliable and quicker to agree; the detail is added only when it’s close enough to act on.
Connected stops
Where this idea feeds in, or gets its inputs from.
Sources and further reading
- Chopra, S. & Meindl, P. Supply Chain Management: Strategy, Planning, and Operation. Pearson. Chapters on decision phases and aggregate planning.
- Silver, E. A., Pyke, D. F. & Thomas, D. J. (2017). Inventory and Production Management in Supply Chains (4th ed.). CRC Press.
- Hax, A. C., & Meal, H. C. (1975). Hierarchical integration of production planning and scheduling. In M. A. Geisler (Ed.), Studies in the Management Sciences, Vol. 1: Logistics. North-Holland.
- Vollmann, T. E., Berry, W. L., Whybark, D. C., & Jacobs, F. R. (2005). Manufacturing Planning and Control for Supply Chain Management (5th ed.). McGraw-Hill.