Boeing 747 and HF Radio

[Orlaam]

Anyone here know anything about the HF transmissions used for NAT routes? I've been listening to an online HF NAT stream and have listened in the past on my Kenwood HT (it has HF w/ SSB). What exactly do they relay on these comms? They don't ever seem to say anything that makes any sense. Also, what are the dual tones that broadcast on there so much?PMDG, any chance we could have a 75 meters sound wave with it's storm crashes and noise (no talking) that would come on when we tested the radio on HF? Kinda like DF and Flight 1 do on a few of their planes.Thanks

[Guest Ross]

HF radio on the NAT is used to send Position reports and other requests to either Gander, Shanwick, Santa Maria or New York oceanic control centres. This is necessary as there is no radar coverage over most of the North Atlantic. As far as I know, the dual tones you hear on there are Selcal activation tones (not 100% sure about this so don't take it as gospel). Selcal is an alerting system whereby each individual aircraft has a unique code, this code is advised on the flightplan. The system is in place so that Flight crews don't have to listen to the static on HF radio for prolonged periods. If the oceanic controller wishes to speak to a particular aircraft, he sends its selcal code and an alert bell/light is activated on the flightdeck of the aircraft in question.Hope this has been of some help.

[Guest Paragon]

You are right about the SELCAL (Selective Calling), plus it always has to be in the form of lower to higher tone.

[Guest shaheedan]

Hi all,just share my experience during monitoring HF aviation band in my country, offcourse i have a valid Ham's licence to do that. As i know, normally pilot use a HF frequency as a primary when the next reporting station more that 250nm distance since VHF AM limit on certain distance. i always tuned on 8.942Mhz USB for manila and singapore radar primary and 113.96 Mhz Vhf secondary.more instresting since i have a real ATC communicate next of my PC. Hope PMDG and FS9 will include this options in future.Regards,Shaheedan Bin Abdul WahabOil Town,Malaysia

[Guest EIDUB]

"I've been listening to an online HF NAT stream"Can you post the link for that stream?Thanks,Stephen

[Guest Paragon]

You can hear atlantic ATC on this:http://audio-master.liveatc.net:8012/atlanticedit...i included a page where it lists some live atc feeds.http://liveatc.net/feedindex.php

[Orlaam]

Thanks for the answers. Pretty neat info abou the Selcal and all. I'm an amateur radio licensee as well, however, I'm all but out of the hobby. Just own a couple HTs and a scanner. My Kenwood TH6A receives HF, but I have no where to string a wire, LOL.Not sure which frequency they're using on that web site you posted, which is the one I'm listening to, but being in radio, I'd say it's around 3 MHz. 75/80 meters is a real noisy band. 40 meters gets a little better, but it's more used in the day and 75/80 is used at night due to propagation. If you click on that link for the NAT frequencies, you'll see they span the whole HF spectrum.

[Guest rcritz]

It's actually above 40m slightly .. normally 8612 kHz or somewhere like that. I'm too lazy to pull out my NAT chart tonight ;-)

[Guest dobova]

Hi all, following is a complete list of ICAO NAT, PACIFIC, AFRICA frequency. From Europe, depending on propagation and during night time, you con listen to a lot of this freq. In particular Santa Maria station on 8906khz. Happy listening ICAO HF Aero FrequenciesFreq. Regional Coverage Freq. Regional Coverage-------------------------------------------------------------------4666 Central Western Pacific 8825 North Atlantic 4669 Central USSR, SW S. America 8843 Central E. Pacific4675 North Atlantic and Arctic 8846 W. Caribbean5493 South/Southwest Africa 8855 S. America, S. Atlantic5520 Western Caribbean 8861 NW Africa, S. Atlantic5526 Central/Northern S. America 8864 North Atlantic5547 Central Eastern Pacific 8867 South Pacific5555 Eastern Caribbean 8879 Indian Ocean, N. Atlantic5565 South Atlantic 8891 North Atlantic, Arctic5574 Central Eastern Pacific 8894 N. Central Africa5598 North Atlantic 8897 Far East5601 Middle East 8903 S. Central Africa, W. Pac.5616 North Atlantic 8918 Caribbean, Middle East5628 North Pacific 8942 Southeast Asia5634 Indian Ocean 8951 S. Central USSR5643 South Pacific 10018 South Asia5649 North Atlantic 10024 South America5652 North Central Africa 10025 Eastern USSR5655 Southeast Asia 10042 Far East5658 Northeast Africa, Middle East10048 North Pacific5661 Central Europe, Mediterranean10066 Southeast Asia5664 Eastern USSR 10084 Central Europe, Med.5667 Middle East 10096 South America, N. USSR6532 Central Western Pacific 11195 South America6533 North Central USSR 11279 North Atlantic6535 Northwest Africa, S. Atlantic11282 Central E. Pacific6556 Southeast Asia 11291 South Atlantic6562 Central Western Pacific 11300 NE Africa6571 Far East 11330 North Pacific6577 Caribbean 11360 SW S. America.6586 W. Caribbean, Gulf of Mexico 11375 S. Central USSR6589 Eastern USSR 11384 Central W. Pacific6598 Central Europe, Mediterranean11387 Caribbean6603 North Central USSR 11396 Caribbean, SE Asia6631 South Central USSR 13273 N. Central Africa, S. Pac.6649 Southwestern South America 13288 NE Africa, Middle East6673 Northwest Africa 13291 North Atlantic, ArcticICAO HF Aero page 213294 Africa, N. Pacific13297 S. America, Carib., Far East13300 Western and South Pacific13306 Indian Ocean, N. Atlantic13309 Southeast Asia13312 Middle East13315 South Atlantic13318 Southeast Asia13336 Central E. Pacific13354 Pacific Ocean13357 NW Africa, S. Atlantic17904 Pacific Ocean17907 SE Asia, N. USSR, S. Am., Car.17925 Central S. America17946 North Atlantic, Arctic17955 NW Africa, S. Atlantic17961 Africa, Indian Ocean Long Distance Operations ControlFreq. Location Freq. Location Freq. Location------------------------------------------------------------------------4654 Berne 10003 Amman, Jordan 13235 Dresden 4745.5 Berlin, GDR 10026 USA 13247 CW Havana, Moscow5529 Houston,Madrid 10018 Frankfurt 13248 Belgrade Santo Domingo 10021 Madrid 13285 Canada5532 Prague,Jo'burg 10025 CW Havana, Moscow 13285 Berne5535 London,Bermuda Prague 13307 Jeddah5538 Bahrain 10027 Europe, Canada 13324 CW Dusseldorf, GDR 5540 Stockholm 10030 USSR, Caribbean 13327 Madrid5589 Stockholm 10033 W. Afr., Mexico 13330 USA5691 Wunsdorf, FRG 10065 Frankfurt 13333 London5703 USA 10069 Berne 13342 Stockholm6526 Berne 10072 London, Bombay 13348 Santo Domingo6637 Paris, Frankf. 10075 USA 13351 Paris6640 USA 10078 Eur., Australia 6643 Berne 11182 Madrid 15024 CW Havana, Moscow6646 Worldwide 11184 Lisbon 15046 Berlin, Berne6715 USA 11193 CW Moscow 17916 Stockholm6745 CW Moscow 11215 Lima 17922 London6753 Berlin, GDR 11222 Stockholm 17925 Berlin, USA8842 CW Havana, Moscow 11237.5 Berlin, GDR 17940 USA8862 Dakar 11256 USA 17975 Berlin8910 Iceland 11311 Ottawa 17983 Jeddah8921 London,Bermuda 11312 CW Havana, Moscow 18023 Berne Frankfurt 11342 USA 21925 Amsterdam8924 S. America 11345 Worldwide 21940 Paris8930 Stockholm 11354 Middle East 21946 London8927 Middle East 11351 Far East 21964 USA8933 Johannesburg 13205 Berne 21967 Frankfurt8936 Madrid, Berne 13210 Stockholm 21988 Berne8983 Frankfurt 13213.8 Frankfurt 8984 Berlin, GDR 13222 Tunis,Berlin, 8986.4 Europe 13225 Berlin CiaoDomeps: I'm sorry for the posting format but I don't know how to do better...;-)

[Orlaam]

Cool thanks! I'll print this list out and use it to listen.