The Gander and Shanwick OCC are each responsible for half of the north Atlantic HLA airspace (border is at 30W°).
Both OCAs have been divided into various sectors to optimise traffic management and controller workload.
|Gander Oceanic clearance
||128.450 / 135.450
|Gander FSS (southern tracks)
||122.370 (12237.0 kHz)
|Gander FSS (northern tracks)
||126.900 (12690.0 kHz)
|Gander FSS (west airspace)
||127.100 (12710.0 kHz)
|Shanwick Oceanic clearance
||127.650 / 123.950
|Shanwick FSS (southern tracks)
||124.175 (12417.5 kHz)
|Shanwick FSS (northern tracks)
||120.350 (12035.0 kHz)
|Shanwick/Gander FSS (general position)
||127.900 (12790.0 kHz)
The first position to be opened is always Shanwick/Gander FSS (EGGX_SG_CTR), followed by Shanwick FSS (EGGX_S_CTR) or Gander FSS (CZQX_S_CTR).
Agree with EGGX_SG_CTR which position SG prefers. Prior permission required for Gander FSS (CZQX_W_CTR) by EGGX-Staff.
A diagram of the North Atlantic Airspace can be found here