London ATC 131.05 and 135.575

[Liffy 1M]

Hi

Can someone explain how eastbound high-level traffic from Irish airspace on airway UL975 is separated between 131.05 and 135.575 when handed over by Shannon to London?

Is it by flight level, route of flight or according to traffic loads? From an observer's point of view, it's not clear to me what governs to which London frequency (sector?) a flight will be handed over.

Many thanks for any help on this.

[LostThePicture]

The two frequencies belong to London Sector 4 (131.05) and Sector 7 (135.57). The "Lakes" airspace, as it is known, has recently been resectorised so that the old "high" sector (S4) now extends westwards all the way to the boundary with Shannon, whereas it used to only stretch as far as Wallasey. So, at the boundary, S4 sits above S7. Traffic at FL330 and below goes to S7, traffic at FL340 and above goes to S4.

[Liffy 1M]

Many thanks for that, LostThePicture.