Looks like I am still missing something! The shaded red area on the proposed map is still both north and south of the Thames and I would have expected planes to use both routes in the interests of efficient arrivals.

"Aircraft may, at times, route anywhere within the coloured areas for reasons of safety or efficiency. However, the black lines denote the swathe in which most aircraft would be expected to be contained during normal operations.

The red line depicts the ?centre-line? for the departure route; on the proposed map the dotted centre-line shows the non-PRNAV route, whereas the solid red line shows the P-RNAV route. The proposed P-RNAV and non P-RNAV routes for easterly departures from London City follow the same alignment as one another, therefore only one red line is shown in the maps for these routes.

The colour coding shows a worst case for aircraft heights (the lowest expected); the actual height most aircraft achieve will be above this.

See part D of the TCN consultation document for a full description of how to read these maps.

Aircraft Navigation for Arrivals: P-RNAV
4.10 There are currently no set flight paths from the hold to the runway during normal operations. Air traffic controllers position aircraft across a wide swathe of airspace to ensure safety and land aircraft as quickly and efficiently as possible.
4.11 P-RNAV design of the airspace (see Part D of the TCN consultation document for an overview of P-RNAV) will provide a set route from the holds to the runway[b] which means the swathe of airspace in which aircraft are regularly seen will reduce in some places, [b]i.e. aircraft flight paths will be more concentrated along the centre of the route. However, it must be noted that even with P-RNAV, air traffic controllers will still take aircraft off the routes when necessary, to maintain safety, to land aircraft more efficiently or to provide a direct flight path reducing fuel burn and emissions when possible.