Guidance concerning Air Navigation in and above the NAT MNPSA
During the westbound OTS times, Controllers at Shanwick shall not clear westbound aircraft which landfall at PRAWN or north of, at FL340, except for random flights which cross 61N at or east of 20W and route ay or north of 63N030W.
The availability of RVSM levels, between 0100 and 0800 (at 30W), is summarised in the following diagrams.
Diagram 1 below illustrates the use of the Night Datum line (coloured red) in a situation when there are no Gander eastbound NAT Tracks in the vicinity.
Diagram 2 illustrates the situation when there are Gander eastbound NAT Tracks in the vicinity.
NAT Doc 007