The recent notification of the establishment of a Radio Mandatory Zone (RMZ) around Southend airport has led to a lot of discussion about the implications for free fliers. Some of the opinions expressed seem to be based on an incomplete understanding of the nature and purpose of RMZs, so this is an attempt to explain how they work.
In August 2013, the CAA published a policy for RMZs. The purpose of a RMZ is to enhance safety. Only the CAA can “notify” (i.e. establish) a RMZ, which can be “sponsored” (i.e. proposed) by an airport or other interested party. The sponsor is obliged to consider the impact of a RMZ on all airspace users and make suitable allowance for non-compliant aircraft (e.g. those without an airband radio) to gain access to the RMZ where a legitimate requirement exists. The dimensions of a RMZ have to be the minimum possible to meet the controlling authority’s operational requirements. There is provision for non-radio aircraft to make “agreed tactical arrangements” with the controlling authority.
A RMZ is very different to Class D controlled airspace (which is what Southend have applied for), in that flight in a RMZ is not necessarily controlled: it simply means that air traffic controllers will be aware of all the traffic in the zone and the position and intentions of each aircraft. In Class D airspace, full control of each aircraft is mandatory. As long as the controller knows where you are and what you want to do before you enter the RMZ, you can fly through it. The controller cannot exclude you, but it is your responsibility to remain clear if you are not sure that the controller knows about you. This knowledge can either be through prior contact on the ground, or radio contact in the air. For the latter, you need a licenced airband transceiver capable of transmitting and receiving on the appropriate frequency (130.775 MHz for Southend), and a Flight Radio Telephony licence.
On 3 July the CAA confirmed that a temporary RMZ will be established around Southend airport, commencing at midnight on 18/19 July 2014. It has the same dimensions as the control area (CTA) of the Class D airspace that Southend applied for. It extends from the surface to the base of the existing overlying controlled airspace.
We are trying to get information from Southend air traffic control about what they require in terms of prior notification and “agreed tactical arrangements” to cover the case of the very infrequent need to cross the Thames in the western end of the RMZ, and will make you aware of their requirements in the near future.
17/7/14 - Although the first NOTAM in respect off this RMZ gave a telephone contact, subsequent ones appear to require radio contact only. Consequently it would appear at this time that all pilots wishing to fly within the RMZ must either make radio contact themselves or be in a flight of aircraft, the leader of which makes contact with Southend.
Ed Bewley & Steve Purdie