Funnily enough was only reading this thread the other day - I think this explains the dual controllers heard on a single frequency.
http://www.pprune.org/atc-issues/306...-director.html
Morning.
119.72 is the Intermediate Director on the Northern side; there is another on the southern side on 134.97.
The northern Intermediate director, being the busier, is deemed the Master Director and in theory he/she plans and communicates the landing order to Int South. Once the arrival delay has got to more than about 10 minutes we offload this work to a support controller; this controller takes on all the non-radar phone work and the initial calls of stack arrivals. This leaves Int N to get on with the primary task of radar direction.
Both Int N and the support controller operate on 119.72, sat imediately next to each other. It is a technique of operation that one picks up quite quickly. The support guy will instinctively know from what he can see on the radar when the radar guy is going to need the r/t. Sometimes we trip over each other but it is relatively rare. Support's primary r/t task is the laddering down of traffic in the stack and whilst this is important for maximum level availability, the radar task takes priority.
Once we get over about 15 minutes delay the support task is further enhanced (in preparation for EATs) by handing off the planning role to a supervisor. This leaves support free to concentrate on supporting his radar man (an essential task). A tardy support controller makes radar's task difficult.
Having agreed, and established the arrival order, the two radar directors, Int N & S, hand traffic off to 120.4 in the landing order for him to sequence accurately.
Hope that helps.
.4