Planning or Scheduling?

On a recent customer engagement the project team experienced issues getting acceptance from manufacturing teams for the proposed new planning processes. The reason: “The plan should be done in the factory”; “we have full visibility of current inventories, orders, production output” and so on. This however was primarily a language issue: Are we talking planning or scheduling? Once we explained the difference both teams calmed and agreement was reached. So, what’s the difference, you ask?

One way to differentiate is looking at an example. The daughter of a friend in Europe and her friend graduated from high school and were planning a multi-month USA road trip. She did her planning extensively:

It started months before. Determine which cities to visit, what to see, where to stay and how much money to bring. All this is planning. We were asked to be a small part of the trip — they would stay with us in early April. As a supplier of accommodation we were given the forecast: approximate dates, number of days and number of people. The closer she got to the flight to the US, the more refined her plan became.

Then the trip started, we saw updates from New York, Atlanta and Miami. On the 5th we got the call: Hi, we will be arriving the 7th and we will be 3. She was now preparing the Houston schedule. She was in her airbnb in New Orleans and working out the accommodation schedule for the next few days. We confirmed the availability of our guest room and 2 days later we received a text: we are 20 minutes away.

That evening they were doing more scheduling: what does our activity schedule for tomorrow look like. Most information was already available: Their plan (a composition notebook with selected events, museums and attractions by city by week) was the primary source. Scheduling now meant: what do we do Wednesday, Thursday. Do we go horseback riding first and then drive up to NASA or do we want a ride at dusk? When are horses available during our stay? The schedule triggered making reservations where needed (local stable).

As you can see planning was different from scheduling. The three characteristics for planning best explain this:

Planning Scheduling
(how far out do you plan/schedule)
Months/Weeks Days/Hours
(how often do you replan/reschedule)
Weekly Daily
(what level of detail do your plan/schedule)
What we would like to do What we can and will actually do

Notice that she was using different windows for accommodation (days) and things to do (hours) due to lead-time constraints of affordable accommodation. Things to do was considered not constrained the same way.

In the supply chain area of expertise we have done ourselves a big disfavor. We managed to confuse ourselves on the meaning of planning and scheduling. A great example is MPS. MPS = Master Production Schedule. Even though we call it a schedule it is in fact a plan. All the literature in my book case talks about the weeks or months of the MPS. Most companies do not schedule that far out: they plan. The scheduling covers shifts, sequencing, factory scheduling constraints, workstations, people, timeslots. Not forecasted demand in weekly buckets.

Scheduling is considered part of the execution process: Assigning orders to workstations, operators or a place on the production line. Scheduling incorporates constraints that are not important for planning purposes: plant or factory layout, handling constraints and so on.

Planning are the activities associated with preparing the system for the activities that need to take place. In order to do so planning processes provide projections of what needs to be done to achieve the plan, goals, budget, whichever word you use to describe the revenue expectations for the (current and) upcoming periods.

In short: Plan > Schedule > Execute