Wednesday, May 21, 2014

Durban TMA and Special Rules - airspaces and routes explained

The Durban TMA or Terminal Control Area is controlled airspace around the Durban Metropolitan area and which is broken down into several zones, each with their own height restrictions. Similar TMA's have been designated over major airports in South Africa including Cape Town, Port Elizabeth, East London, George, Overberg TMA, Bloemfontein, Kimberly, Kruger Mpumalanga, Hoedspruit, and Johannesburg. This ensures that aircraft intending to fly over areas of high traffic taking off and landing at major centres are separated from each other and are controlled by airtraffic controllers at these centres. Generally the closer you get to a major centre you move from a further circle of control eg TMA E area which allows other traffic to fly higher, to a D, C, B or A area, the latter controlling all aircraft from the ground upwards.

Within and underneath TMA areas you also get CTR and ATZs - control areas, and aerodrome traffic zones which is a further control based at the airfield concerned in the control tower. Therefore as you get closer to Durban you pass either under or through TMA zones and then get handed over to the control tower at the airport or airfield you intend to land at. Most small aircraft or general aviation traffic are not allowed to fly in TMA controlled space and must fly lower and under the heights specified so as not to conflict with the commerical and airline traffic flying the busy routes to and from our major centres. 

Outside the TMA where air traffic is less busy you enter uncontrolled airspace and here the limitations are relaxed.

Radio Frequencies

Different radio frequencies are used for the different airspaces and control zones to avoid the airwaves being cluttered by pilots all talking at the same time. Each pilot therefore needs to know when to change frequency and what height restrictions apply for each part of his journey through the country. This can get quite compicated when one is flying cross-country through several TMA areas.


The blue circles with lines represent airfields on the map - there are about 450 airfields in South Africa. The orange lines represent routes aircraft must follow in controlled airspace. The pink triangles are reporting points at which pilots need to announce their position. GFAs are General Flying Areas where pilots from the various flight school may train.

This is the same TMA map shown above but with the terrain depicted. Here you can see the Drakensberg mountains to the west of Durban and the lighter coloured lower terrain adjacent to the sea.

Durban Special Rules depicted on an EasyPlan map

Special Rules set out Routes to be followed 

The routes to and from our controlled airports around major centres are further controlled in "Special Rules" that regulate the routes aircraft need to follow to avoid accidents. Usually one route and height is allowed for traffic going to the airport or airfield and a different route and height is used for aircraft coming from those airports or airfields.

The boundary of the Durban Special Rules area coincides with the TMA outer boundary, and the Special Rules are essentially a set of rules published by the SA Civil Aviation Authority setting out routes that need to be followed by VFR (Visual Flight Rules, as opposed to IFR Instrument Flight Rules) pilots operating within the area.

By requiring general uncontrolled aircraft to follow certain routes within these busy centres of South Africa conflicting traffic can be avoided and our skies made safer for all. Commercial airliners and other IFR air traffic can be assured that random airplanes will not wander into their path. For instance if you are flying VFR to Pietermaritzburg from Virginia Airport in Durban, the Special Rules require the following:

Virginia to Pietermaritzburg

All VFR traffic is to route via the Durban CBD, then west of the Pinetown CBD, then south of the N3, to the right of the Alverstone Mast, then via the Nagle Dam. Cross the Durban CBD at or below 1500FT AMSL, but above 1000FT AMSL, cross the N2 at or below 1500FT AMSL to pass west abeam the Pinetown CBD at, or below, 3000FT AMSL, to the right of the Alvertone Mast at or below 5000FT. Remain clear of the Durban TMA.

A full copy of the Durban Special Rules can be downloaded off my skydrive if you click on this link.

Read more about my African aviation adventures on my blog here.

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