On 3/10/2012
QUOTE
NAVAREA IV
SPACE WEATHER
1 - HF COMMUNICATIONS AND GNSS POSITIONAL INFORMATION
MAY BE DISRUPTED BY EFFECTS OF SOLAR FLARES.
2 - DURING INCIDENTS AT SEA, MARINERS SHOULD CHECK THEIR
POSITION USING ALL ALTERNATIVE MEANS AVAILABLE.
3 - CANCEL THIS MESSAGE 101200Z MAR.
UNQUOTE
http://olivier.marsan.free.fr/AMARADNEWS/NAVEREAALERTESOLAIRE.jpg
The answer is the NEW 500 kHZ NETWORK.