Project Management · 2026-05-09
Known Unknowns vs Unknown Unknowns: How PMs Navigate Project Uncertainty
Known unknowns are risks you can plan for. Unknown unknowns are the surprises that define a PM's real skill. Learn how to manage both — with a real-world example from a financial center closure project.
"The oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown." — H.P. Lovecraft
PMs deal with uncertainty every day. It is embedded in every single project we take on. How well we navigate through it often determines how successful we will be at the finish line.
If there is one thing we, as project managers, must be particularly good at — it is putting structure in place. A structure that shapes chaos and grey areas into something logical, which the people around us are able to process.
This article is about how to put structure around uncertainty itself.
The Two Types of Unknowns
There are two types of uncertainty that can make or break our projects: known unknowns and unknown unknowns. This famous distinction comes from former US Secretary of Defense Donald Rumsfeld, who in 2002 explained:
"There are known unknowns; that is to say, there are things that we know we don't know. But there are also unknown unknowns — the ones we don't know we don't know."
Known Unknowns — Examples and Definition
Known unknowns are problems we can see coming. We know we don't have all the information, but we are aware of the gap.
Example: When building a new residential building, the construction team knows they might find rocks when digging the foundation. They don't know exactly how many rocks or how big they'll be — but they know this might happen. So they prepare by adding extra time and budget for potential rock removal. The gap is visible. The response can be planned.
Unknown Unknowns — Examples and Definition
Unknown unknowns are complete surprises — problems we couldn't predict because we didn't even know they existed.
Example: After starting construction, the team discovers that the neighboring piece of land has been bought by a development company. This other construction project will block most access points to their site. No one planned for this scenario. Now they need to completely redesign their technical plans and logistics. The gap was invisible until it arrived.
My Take on Managing These Unknowns
The success of a project very often depends on how we handle these two types of unknowns. And they connect directly to our two core activities — how we plan the project, and then how we manage it.
When I see a project get seriously damaged by known unknowns — risks we could have anticipated — I honestly think that is on me. That is poor planning. I should have seen it coming and prepared better.
But when a truly unexpected event hits and my project cannot recover? That hurts even more. It means my reaction was not good enough. I should have built a project resilient enough to bounce back from surprises. That is about management — and often about leadership.
A Real-Life Lesson: The Financial Center Closure
Let me share a challenging project I managed when our company needed to close one of our three financial processing centers.
Our company operated across three locations — our main office in France and two support centers in Central and Eastern Europe. The work was split between these offices: some financial tasks happened only in one location, others in another, and some were performed at all three. This system worked well until business changes forced us to close one support center.
My job was to transfer knowledge from the closing center to another location before staff left. If we failed, our company's financial operations would collapse.
Our known unknown was the tough job market at the new location. We expected trouble finding qualified people and prepared for delays — focused recruitment, adjusted schedules. This challenge did appear, but we managed it. Finally, we had the first team members on board.
Then came the unknown unknown: several new hires announced they were quitting during their third week. This was not on our risk list.
Now the situation was serious. We had burned through a significant portion of our time and buffer just getting people on board.
The Response: Two Key Actions
We reorganized quickly and focused on two things:
a) Seek alternatives: We analyzed the scope in more detail. Some financial processes existed only in the closing center — these were the highest risk. We put maximum priority on transferring knowledge for those first, working with the small team we had. The other processes were already performed at other locations, so we could absorb those volumes without a full knowledge transfer. Not perfect — but the worst case was a delay, not a total inability to serve customers.
b) Root-cause analysis: We immediately investigated why people were leaving. Exit interviews revealed the problem: the way interviews had been conducted created mismatched expectations. Candidates thought they were signing up for one type of job but found themselves doing something very different. With HR's help, we addressed this with the team leader and ensured all subsequent interviews included an HR representative.
We brought the project back on track, minimizing damage to the business. What could have been a crisis ended up as an inconvenience for a few extra weeks.
The Moment of Truth
Unknown unknown situations create those stressful moments when the project suddenly hangs in the balance. This is the moment of truth — when project managers must use every skill and resource available to push the project forward.
These moments show what project management is really about: staying calm during chaos, solving problems when no solution seems clear, and motivating the team when energy is low. Re-planning. Re-organizing. Re-charging the team with confidence.
Practical Tips for Managing Unknowns
For Known Unknowns:
1. Write down expected risks with clear plans to handle them. Discuss them with the project team and key stakeholders. Prepare mitigation and contingency actions. Follow risk management best practices — they exist for a reason.
2. Learn the true boundaries of your project. The real boundaries are usually not in the project plan — they are in the sponsor's head. Have informal conversations about "what if" scenarios. Gauge how much they'd be willing to invest extra if things go wrong. This also helps you react faster when unknown unknowns appear.
For Unknown Unknowns:
1. Stay one step ahead: Check progress regularly to catch new issues in their infancy — before they become big problems. Don't underestimate small delays. If they happen, make sure you understand why.
2. Keep communication open with everyone involved. Someone might know something you don't. Promote discussions that help the team and stakeholders capture early warning signs before an unknown unknown fully enters the project's path.
3. Build a ready-for-battle team: Help your team accept that some things will go wrong and be ready to learn and adjust quickly. Resilience is not about avoiding surprises — it is about recovering from them faster than anyone expects.
Nice knowing you, known and unknown unknowns. Till we meet again.