The Earth
The Solar System & Time
Using Aeronautical Charts
Basics of Navigation
Distance, Speed & Time
Vertical Navigation
Fuel Planning
Practical Navigation Techniques
Radio Navigation
Practice Exam

Danger, Restricted and Prohibited Areas

Danger, restricted, and prohibited areas are shown on the chart as an area with a red line outline and red hatching across the area. The outline is:

Solid red when the area is active permanently or only during scheduled times
Dashed red when the area is activated by NOTAM

Every danger, restricted, and prohibited area is given a unique number. This is written next to the area on the chart, along with the vertical limits of the area. For example:

D139/1.5 is Danger Area 139, located to the north of Southend. The “1.5” denotes that it extends up to 1500ft AMSL and “OCNL/2.0” denotes that it occasionally extends up to 2000ft AMSL. A NOTAM is published when the higher limit applies.
R217/2.0 is Restricted Area 217, located around the Sizewell power station on the Suffolk coast. The “2.0” denotes that it extends from the surface to 2,000ft AMSL.

A list of these areas and associated information (and usually a contact phone number for coordination) is found in the AIP ENR 5.1. Click here to view the UK AIP.

Other Danger, Restricted & Prohibited Area Symbols

UNL means unlimited – the area extends upwards indefinitely.
This ‘double S’ symbol denotes that a Danger Area Activity Information Service (DAAIS) is available. The frequency to contact while airborne is in the chart legend.
The asterisk symbol denotes airspace which is subject to byelaws that prohibit entry during periods of activity

This cross indicates that a Danger Area Crossing Service (DACS) is available