Mandatory Transponder Carriage Areas

Mandatory Transponder Carriage Areas

Best Practice – Mandatory Transponder Carriage Areas

To provide the most amount of airspace open to all users, airspace is designed to afford the maximum protection to commercial aircraft in the minimum space possible. This means that stepped airspace bases are a common experience around major airports. A number of incidents occur where a non-transponding aircraft is believed to be below the base, but is actually inside controlled airspace.

  • Introduce mandatory transponder areas to reduce the risk of these incidents whilst still allowing open access to the uncontrolled airspace they cover.

Cost – Consultation and regulation process.


In the Netherlands the majority of the airspace requires the mandatory carriage and use of Mode S transponders for all motorised and non-motorised flights. Whilst this means that more infringements are now seen and reported, the risk from non-transponding traffic is greatly reduced. Germany and the UK have introduced more geographically specific mandatory transponder carriage areas to provide greater protection to commercial aircraft, particularly in infringement hotspots.

Sample Material

Stansted TMZs.

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