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Christmas Giveaway 2023: Question 10 - Radio Mandatory Zones (RMZ)


Aeronautical charts contain vast amounts of information! As well as identifying the locations of airfields and airports, charts also show us airspace and potential hazards, allowing us to ensure our flights are safe and legal. What does the following symbol from an aeronautical chart depict?

CAA 1:500,000 Chart Symbol
  1. Areas of Intense Aerial Activity
  2. Radio Mandatory Zone (RMZ)
  3. Transponder Mandatory Zone (TMZ)
  4. Prohibited Area


A Radio Mandatory Zone (RMZ) is a designated area of airspace within which all aircraft must establish two-way communication over, or monitor, (as determined for the individual RMZ) the relevant radio communication frequency. An RMZ is generally created to enhance the visibility of aircraft operating within or near sections of busy airspace or an airport area, improving the safety for all airspace operators. They allow Air Traffic Control (ATC) to gain as much information as possible about an aircraft within an RMZ without adding excessive controlled airspace.

An RMZ is annotated on a chart with a border of blue semicircles. Details of the zones can be found in the UK AIP both in the AIP General Section and, in the case of the Hawarden and Land’s End RMZ, the Aerodrome Section.
CAA 1:500,000 Chart Symbol

You should freecall the relevant frequency in good time to establish contact, passing the following information:

  1. the designation of the station being called
  2. callsign
  3. type of aircraft
  4. route (from - to)
  5. position (using a reference point a controller can identify)
  6. altitude, height or level and altimeter setting
  7. the intentions of the flight, routing, additional information etc

Once this information has been passed to and acknowledged by ATC, a pilot may enter the RMZ. However, if a pilot is requested to ‘stand by’ before the required information is passed, they must remain outside of the RMZ. RMZ Controlling Authorities must resume communications with pilots as soon as possible after having instructed them to ‘stand by’.

Aeronautical charts contain vast amounts of information regarding airspace features and hazards. We strongly suggest that you spend some time getting familiar with your aviation chart, as well as exploring the CAA Skyway Code, which provides an excellent overview of common airspace features and their operating rules. Here's a summary of some of the key airspace symbols, some of which were alternative answers in this question:

CAA Chart Symbols for Common Airspace Features and Hazards

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