What to Do After Scenario Planning

After scenario planning, test the assumptions embedded in whichever scenario your strategy selects. Scenarios describe plausible futures, but they do not examine whether the conditions each future depends on will hold. State those conditions as claims and look for evidence before committing resources.

In October 2001, Swissair grounded its entire fleet. Planes sat on the tarmac at Zurich-Kloten because fuel suppliers, caterers, and ground handlers refused to work without cash payment up front. The airline once called "the flying bank" had spent its reserves on a strategy that started with a set of scenarios about European aviation and ended with empty runways.

Scenario planning builds multiple plausible futures and stress-tests strategies against each one. It does not test the assumptions those strategies depend on.

Swissair and the assumption nobody checked

In the late 1990s, Swissair's leadership adopted the Hunter Strategy. The scenarios behind it were plausible: European aviation was deregulating, consolidation was inevitable, and airlines that built hub-and-spoke networks early would control the market. The strategy team concluded that Swissair needed to acquire stakes in smaller carriers before competitors locked them up.

The acquisitions came fast. Swissair took a 49.5 per cent stake in Belgium's Sabena, minority positions in LOT Polish Airlines and Turkish Airlines, and smaller holdings in airlines across Southern Europe and Africa. Each investment followed the scenario logic: consolidation would reward early movers, the hub model would sustain premium fares, and alliance partners would commit resources to the network.

None of these assumptions were tested against evidence before capital was committed. The scenarios described a future in which consolidation happened.

They did not ask whether Sabena, already losing money, would become profitable under partial Swissair ownership. They did not ask whether a Swiss-based carrier could manage operational complexity across seven different regulatory environments. They did not ask whether the cash reserves, substantial as they were, could absorb transition losses from all investments at once.

The investments drained cash faster than any scenario had modelled. Sabena alone consumed billions in subsidies and capital injections. The smaller airlines stayed unprofitable.

The hub model that justified every acquisition assumed traffic growth that never materialised at the scale the strategy required. An analysis of the collapse identifies a governance failure at the centre of it: the board approved acquisitions based on strategic fit with the scenario narrative rather than evidence about each target airline's financial condition (Hermann & Rammal, 2010).

When demand dropped after 11 September 2001, Swissair had no reserves to absorb the shock. On 2 October 2001, the airline's fleet was grounded (BBC News, 2001). Ground handlers and fuel suppliers demanded cash on delivery because they no longer trusted Swissair's credit. The airline filed for bankruptcy days later. The scenarios had been right about consolidation. They had been silent on every assumption that determined whether Swissair could afford to participate.

The failure was not in the scenario work. The scenarios correctly identified structural trends in European aviation. The failure was in what happened between scenarios and commitment: leadership treated the outputs as sufficient grounds for allocating capital, without testing which assumptions behind the strategy had evidence and which were hope. Other documented cases show the same pattern: sound analytical work, untested assumptions, avoidable consequences. A wargame leaves the same gap, because moves played against a rival team feel like proof the strategy survives contact. The check for what to do after a wargame is the same one, applied to the game's rulings and rival brief.

Name the assumption your preferred scenario depends on most and ask whether anyone tested it before the strategy was built around it. Start the Walk →

What scenario planning gets right, and where it stops

Scenario planning is one of the better-designed strategic tools available. Unlike single-point forecasting, it acknowledges that the future is uncertain and builds multiple versions of it. Unlike risk registers, it works in narratives rather than probability tables, which means the people using it can reason about causation and sequence rather than scoring likelihood and impact in a grid. The literature on the scenario planning framework is extensive and largely sound on the construction of scenarios themselves (Bradfield et al., 2005).

The problem is not in how scenarios are built. It is in what teams do with them once they are built. The standard next step is one of two moves. Either pick the scenario judged most likely and build strategy around that single future. Or attempt a "robust" strategy that performs acceptably across all scenarios. Both approaches treat the scenario outputs as the end of the analytical work and the beginning of the strategic work.

Unlike forecasting, scenarios avoid false precision about probabilities. But the transition from scenarios to strategy reintroduces a different kind of false confidence: confidence that the strategy's preconditions will actually hold.

That transition is where assumptions go unexamined. Scenarios describe conditions under which different outcomes emerge. When a team selects a scenario and builds strategy from it, the act of selection imports a set of assumptions about which conditions will actually hold. Those assumptions, embedded in the chosen scenario's logic, rarely get stated as claims to be verified.

The Shell oil company, often credited with pioneering modern scenario planning, understood this distinction. Pierre Wack, who led Shell's scenario work in the 1970s, argued that the purpose of scenarios was not prediction but changing the mental models of decision-makers (Wack, 1985).

But even at Shell, the step between shifting a mental model and committing capital required testing the assumptions the new model depended on. Most organisations skip that step because the scenarios themselves feel like sufficient preparation. The quality of the scenario work creates a false sense that the strategic conclusions drawn from it are equally well-founded.

The checkpoint between scenarios and strategy

What sits between scenario outputs and strategy commitment is not more analysis. It is a specific kind of examination: stating the assumptions each strategic option depends on and determining which have evidence behind them.

Take the Swissair case again. Four scenarios about European aviation, each plausible. The Hunter Strategy emerges from the scenario that shows consolidation rewarding early movers. Before committing capital, the checkpoint asks: what must be true for this strategy to work?

The answer produces a list of claims. Alliance partners will commit. Each target airline will reach profitability within a defined period. Cash reserves will sustain concurrent losses across every acquisition. Hub fares will hold against low-cost entrants. Each of those claims was testable. Each had available evidence that Swissair's board chose not to examine.

This is the step the Universal Decision-Making Method calls recognising assumptions. In the five-step sequence that Roger Estall and I set out in Deciding, the third step asks the decision-maker to name the conditions they are relying on and determine which can be verified. The fourth step asks whether enough of those assumptions have been tested to justify acting, the threshold Roger Estall and I call sufficient certainty.

Scenario planning does excellent work in the first two steps of that sequence: framing the decision context and identifying the elements that could shape outcomes. Where it stops is precisely where the assumption step begins.

The checkpoint is not a rejection of scenario planning. It is the work that makes acting under uncertainty rational rather than hopeful. Without it, every strategy built from scenarios inherits the assumptions embedded in the chosen future, untested and unmarked. Unexamined assumptions are the single most consequential gap that frameworks like scenario planning leave behind.

Grant Purdy is the co-author, with Roger Estall, of Deciding (2020), and the architect of the Universal Decision-Making Method.