MWARA (Major World Air Routes) North Atlantic (NAT) family of frequencies. Here you will find airline, charter, military and biz aircraft (mode is USB):
(NAT - A) North Atlantic Family A: 3016.0 5598.0 8906.0 13306.0 17946.0Canarias, Gander, New York, Paramaribo, Piarco, Santa Maria, Shanwick
(NAT - B) North Atlantic Family B: 2899.0 5616.0 8864.0 13291.0 17946.0Gander, Iceland, New York, Santa Maria, Shanwick
(NAT - C) North Atlantic Family C: 2872.0 5649.0 8879.0 11336.0 13306.017946.0Gander, Iceland, Shanwick
(NAT - D) North Atlantic Family D: 2971.0 4675.0 8891.0 11279.0 13291.017946.0Arctic Radio (Baffin), Bodo, Churchill (Emerg's Only), Gander, Iceland,Shanwick
(NAT - E) North Atlantic Family E: 2962.0 6628.0 8825.0 11309.0 13354.017946.0New York, Santa Maria
(NAT - F) North Atlantic Family F: 3476.0 6622.0 8831.0 13291.0 17946.0Gander, Shanwick
The best online guide I have seen on this that will answer many questions is at: www.liveatc.net/downloads/NAT-HF-Guidance.pdf. You should download this and study it to understand completely the NAT MWARA system.
Gayle