> For the complete documentation index, see [llms.txt](https://docs.os.uk/os-downloads/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.os.uk/os-downloads/products/land-and-terrain-portfolio/os-mastermap-sites-layer/os-mastermap-sites-layer-technical-specification/theme-definitions/air-transport.md).
# Air transport
This theme includes sites associated with movement of passengers and goods by air, or where aircraft take off and land.
OS MasterMap Sites Layer (yellow polygon) Air transport theme – airport
| Functional site | Description |
| -------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Airfield | An area of ground where aircraft take off and land. It may have some permanent buildings, but it is smaller than an airport and may be for private use only. |
| Airport | A feature where aircraft land and take off and which provides facilities for handling passengers, air freight and servicing aircraft. |
| Helicopter station\* | A feature from where bodies such as the police or ambulance service operate helicopter operations. |
| Heliport\* | An airport specifically designed for use by helicopters. |
{% hint style="info" %}
*Only clearly defined helicopter stations and heliports outside of airfields and airports are to be captured.*
{% endhint %}
All active air transport features (including military sites) will be captured as indicated below unless they fall out of scope (for example, a private property) or are described as disused sites.
The following features are included in the captured extent:
* Buildings for the handling of air passengers and goods.
* Buildings for the storage and maintenance of aircraft.
* Aircraft landing and taxiing surfaces (man-made or natural).
* Site access roads and paths.
* Structures associated with the operation of the site.
* Car parks for air passengers.
* Areas of man-made and natural surface totally surrounded by included areas.
* Areas of man-made and natural surface abutting included areas along a non-obstructing edge.
The following features are **not** included in the captured extent:
* Aircraft-related services outside of perimeter fence (for example, warehouses or catering).
* Public through-roads and pavements.
* Hotels adjacent to site and their car parks.
---
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