NAT MNPS / Flying to Azores
 

Hi.
According to NAT MNPS edition 2008, and a lot of previous editions, when flying along certain routes, e.g. "Blue Spruce" and on routings from mainland Portugal to the Azores, you are allowed to have only one LRNS installed, e.g. one FMC. But the NAT MNPS document does not mention which routes from mainland Portugal to Azores it is talking about, and I can't find any special airways out there. Can anyone enlighten me?
Kind regards
Allan