Hygiene Zoning in Inflight Catering Facilities: Zones, Airlocks and What Follows for the Layout

Hygiene zoning is often treated as a compliance topic that comes after the layout is drawn. It is the opposite. Zoning decides where walls go, where people enter, how far a trolley travels and how many airlocks a building needs. A layout drawn before the zoning is settled will either fail an audit or cost more to operate for the rest of its life.

This article sets out how zoning is derived, what the zones are, and which design decisions follow from them. Absolute values for temperature, air pressure and cleaning intervals are not listed here, because they follow the rule set applicable at the location and the standards of the airline being served. What does not change is the logic.

Zoning is a layout decision, not a cleaning schedule

Zoning separates areas by risk and defines what may pass between them. Walls, doors, airlocks, routing and floor area follow from that. Those are structural quantities and not questions of the cleaning schedule.

Anyone who looks at zoning only after the layout has to either redesign or compensate organisationally. Organisational compensation is the most expensive answer in continuous operation, because it ties up staff every day and has to be explained again at every change of personnel.

The four functional zones of an airline catering facility

The zones begin landside and end airside. This direction cannot be reversed, because every backward movement opens a higher risk zone into a lower risk one.

Warewash

Return, dekit, tunnel washer, trolley washer and clean store. The dirtiest area of the facility and at the same time the one that has to deliver the cleanest output. The risk is remixing of soiled returns with cleaned equipment. The interface to the neighbouring zone is the clean store that feeds tray set.

Production

Ingredient store, hot kitchen, blast chilling, cold store and portioning. The risk sits in open food and in temperature transitions between the steps. The interface to the neighbouring zone is the handover of portioned components into tray set, kept apart from the ingredient route.

Tray set

Belt assembly, trolley loading, quality control and sealing. The risk is the meeting of cleaned equipment and finished components at one point with a high density of people. The interface to the neighbouring zone is the sealed trolley.

Outbound

Trolley buffer, flight consolidation, staging lanes and hi loader docking. The risk sits in waiting time under unfavourable conditions and in congestion pushing back into tray set. The interface is the handover to the vehicle.

Airlocks: what they separate and why there are usually three

Airlocks sit between the zones. With four zones in a fixed sequence there are three transitions and therefore three airlocks. Their number follows from the number of transitions and not from the budget.

An airlock has to deliver four things:

›Separation of people, so that the way into the cleaner zone stays controlled
›Separation of material, so that packaging and outer packaging do not travel along
›Hand hygiene at a point where it actually sits in the sequence
›A change of clothing where it is required

A question of its own is whether material and personnel may use the same airlock. Where that is permitted, a capacity topic appears at peak. Where it is not permitted, the floor area at the transition doubles. The concrete design depends on the rule set of the location and on the standard of the customer.

Three flows that must not cross

Material flow

The product route runs landside to airside through the airlocks. It is directional and has no return path.

Trolley return and AGV routing

Clean trolleys run from the clean store into tray set, kept apart from the product route and apart from soiled returns.

Personnel corridor

The personnel route is separate from both and reaches the zones through its own entries with changing rooms and hand hygiene.

If two of these flows cross, the result is either a hygiene risk or congestion. Usually both. How the routes are calculated in detail is covered in our article on material flow optimisation.

What zoning decides before a single wall is drawn

1The number and position of the airlocks
2Whether warewash and tray set may sit next to each other
3Where the staff changing rooms sit and how many of them there are
4Whether the AGV route is structurally possible or becomes a bottleneck later
5How deep the outbound buffer area has to be so that peaks do not push back into production
6Which areas can be extended later and which cannot

Common mistakes we see in existing facilities

›The airlock is used as storage space and loses its separating function.
›The personnel route runs through production as a shortcut, because the dedicated corridor is too long.
›Clean trolleys are returned through the goods receiving area.
›Outbound is dimensioned too tightly, so peaks arrive as congestion in tray set.
›The extension is planned on the building side where the zone sequence would have to be broken up for it.

Frequently asked questions

How many hygiene zones does an inflight catering facility need?

Four functional zones are the usual setup, namely warewash, production, tray set and outbound. The number of airlocks follows from the number of transitions between them.

Does hygiene zoning apply to an existing facility or only to new builds?

Both. In an existing facility the question is which separations can still be built and which have to be compensated organisationally.

Who defines the applicable standards?

The rule set of the location and the standards of the airline being served. Both have to be available before the layout planning, because they determine the areas.

Can zoning be added after the layout is finished?

Technically yes, economically it rarely makes sense. Separations added later cost floor area and create travel distance.

Does DSC-Consult supply the equipment?

No. DSC-Consult plans and advises independently of equipment manufacturers and supports tendering, acceptance and commissioning.

Who you would be working with

"DSC-Consult demonstrated solid expertise in the inflight catering industry, particularly in areas such as facility layout optimisation, spatial planning, hygiene zoning, and process flow design."

Kog Haja VajidSenior Manager, Regional OperationsSATS Food Solutions, Singapore