Originally Posted by
Rusty1
Because it does not work in the Southern Hemisphere nor South of the equator.
The ICAO weather deviation procedure is for all worldwide oceanic airspace not just NAT HLA.
No, it does not indeed but we are all very much aware that this -like many others- is just a mnemonic rule of thumb which could, by the way, become unusable tomorrow morning if procedures change even in the Northern Hemisphere. No need to get excited, people still look at their contingencies for different airspaces before thinking about acronyms.