Airport layout

Why does an airport make you walk past shops to reach your gate?

You clear security, and instead of a corridor to your gate you are delivered into a perfume hall. The route bends through it. There is no way around, and the signage for gates is legible but unhurried.

The obvious complaint is that this is inconvenient design. But it is inconvenient in the same way at Amsterdam, Dubai, Singapore and Manchester — terminals built decades apart by different architects for different airlines. When an irritating feature converges independently across an industry, the useful question is not who was careless. It is: whose problem does this solve?

Start with what an airport actually sells. The intuitive answer is landing slots and passenger charges — money from airlines. Airlines, however, are ferocious buyers: they operate on thin margins, they compare airports, and in many jurisdictions those charges are regulated precisely because a hub is close to a local monopoly. So the airline-facing side of the business is squeezed on both sides.

Now look at the other customer. Ask what a passenger past security has that a shopper on a high street does not. She has time she cannot spend anywhere else. She arrived early, because missing the flight is catastrophic and arriving early is merely dull. She has cleared the one irreversible barrier in the building. She cannot leave and come back. She is, in the retail sense, captive — and she is in an unusual mood: mildly relieved, slightly bored, often travelling, and in international terminals holding a duty allowance.

How much is that worth? Enough that commercial income — retail concessions, food, car parking, property — has for years run at roughly two-fifths of airport revenue worldwide on industry figures, which puts it in the same order as everything the airlines pay. And here is the part that closes the loop: under the single till approach used by several regulators, that commercial income is counted when the regulator sets the charges airlines may be levied. Shop takings reduce what the airline is billed. The walk past the perfume is, quite literally, cross-subsidising the aircraft.

So the layout follows the money. Retail goes after security, not before, because that is where the captive time is. It is placed on the path rather than beside it, because a passenger anxious about her gate will not detour. And departure lounges are often kept modest while the concourse is generous, because a seat at the gate is a seat that has stopped spending.

But now notice the constraint that makes this delicate. What destroys the whole scheme? Uncertainty. A passenger who does not know whether screening will take eight minutes or fifty walks straight to her gate and sits there. Airports therefore invest heavily in making the queue not just short but predictable — staffing to forecast, publishing waiting times, opening extra lanes early — because it is the variance, more than the average, that converts a shopper into someone hoarding a safety margin. The commercial interest and the passenger's interest genuinely coincide at that one point.

Three refinements keep this from becoming a conspiracy story.

First, not every long walk is retail. Aircraft need stands, stands need frontage, and frontage means long piers — so gates end up far from the centre for reasons of geometry that predate any shop. Consolidating several checkpoints into one hall also lengthens the average journey, and it was done for screening cost and security consistency. The honest claim is narrower than "airports make you walk to sell you things": it is that given a walk exists, its route is drawn through the concessions, and the commercial floor is put on the far side of the barrier rather than the near side.

Second, the pull is real but not unlimited. Airports also lose money when passengers miss flights, when the concourse jams, and when connecting passengers with tight transfers cannot find their way. So wayfinding is deliberately maintained even where it works against dwell — the tension is managed, not resolved in retail's favour every time.

Third, the money is not straightforwardly the airport's own. Concessions are usually let to operators on turnover-linked rents, and where the single till applies, part of what the shops generate is handed back to airlines through lower charges. Whether that is a benign subsidy for air fares or a distortion that overbuilds terminals is genuinely argued among regulators, and the dual-till alternative exists because the answer is not settled.

• Why duty-free allowances persist between countries that have otherwise abolished tariffs.
• How single-till and dual-till regulation change what a privatised airport chooses to build.

Every term the collection defines is gathered in the glossary.