Some HF radio questions

[coa787]

Here's a photo that was posted from Doug not too long ago:


At the right of the photo, you will see (part of) the HF radio. You will also see three settings; OFF, USB and AM. Currently, it is selected to "USB", along with the accompanying frequency.

So, my questions are:
1. What is the difference between "USB" and "AM" and do they use different frequency ranges?

2. Do different areas of the Atlantic require the use of both settings (USB, AM)?

3. How do you know when to start/stop using the HF radio?

4. How do you know which HF frequency to tune?

Thanks

[Polar742]

Originally Posted by coa787

Here's a photo that was posted from Doug not too long ago:
At the right of the photo, you will see (part of) the HF radio. You will also see three settings; OFF, USB and AM. Currently, it is selected to "USB", along with the accompanying frequency.

So, my questions are:
1. What is the difference between "USB" and "AM" and do they use different frequency ranges?

2. Do different areas of the Atlantic require the use of both settings (USB, AM)?

3. How do you know when to start/stop using the HF radio?

4. How do you know which HF frequency to tune?

Thanks

1) USB is upper side band, and AM is AM as in radio.
2) I don't think so, pretty much always use USB
3) You get a frequency change from VHF, or you lose contact, and read your chart and go to a HF freq
4) Off the charts

[Doug Taylor]

Originally Posted by coa787

1. What is the difference between "USB" and "AM" and do they use different frequency ranges?

Just like Polar says

2. Do different areas of the Atlantic require the use of both settings (USB, AM)?

I haven't seen that.

3. How do you know when to start/stop using the HF radio?

Well, if you're on an FMC aircraft, they'll usually say, "At 50 west" or "At OYSTR contact Gander on 135.7 (or whatever the frequency is)"

4. How do you know which HF frequency to tune?

Generally, before you reach the OCA, they'll say, "Contact Shanwick on XXX.XX (VHF)" You'll check on, they'll say "Primary HF 1234, backup 4567 for SELCAL check". You'll flip over to the HF freq, conduct a SELCAL check and motor on.

Thanks

It's all good. That's why I started JC.

[coa787]

"OCA" stands for "Oceanic Clearence Area"?

[Doug Taylor]

Yeah, something like that. Or Oceanic Control Area? I'd have to look it up.

[coa787]

Doug, on your photo of the CDU, it shows a selected speed of Mach .800.

1. Is it typical to fly with a "SEL SPD" rather than an "ECON SPD"?

2. What conditions would require the use of a "SEL SPD" rather than an "ECON SPD" for cruise?

[Chief Captain]

Originally Posted by coa787

Doug, on your photo of the CDU, it shows a selected speed of Mach .800.

1. Is it typical to fly with a "SEL SPD" rather than an "ECON SPD"?

2. What conditions would require the use of a "SEL SPD" rather than an "ECON SPD" for cruise?

On the NATS (and other airspace like PACOTS and sometimes radar environments) ATC will assign a fixed cruise speed for separation. At that point, you'll enter whatever speed is assigned in the FMC, and it shows up as selected. You can't fly around in ECON CRZ, as the FMC will vary the speed as conditions change, or (more significantly) your ECON speed will be too fast or to slow for ATC.

[coa787]

What is "PACOTS"?

[Chief Captain]

Pacific Organized Track System. It's the Pacific version of the NATS.

[taseal]

I love this dude, hes just like me asking Qs about the 76 lol

[Cptnchia]

Originally Posted by coa787

Here's a very important thing to know. See the round blue light at the top right corner of the IRS panel? When that is lit it means someone is in the forward lav. Means you're going to have to hold it a little longer.

[Chief Captain]

Or, you could make a PA telling everybody to return to their seats and buckle in and prepare for an emergency descent

[taseal]

Originally Posted by Cptnchia

Here's a very important thing to know. See the round blue light at the top right corner of the IRS panel? When that is lit it means someone is in the forward lav. Means you're going to have to hold it a little longer.

haha, awesome info!

[Doug Taylor]

Originally Posted by Cptnchia

Here's a very important thing to know. See the round blue light at the top right corner of the IRS panel? When that is lit it means someone is in the forward lav. Means you're going to have to hold it a little longer.

Shake the yoke, turn the seatbelt sign on, that'll expedite things!

Not that anyone I know has ever done that...

[Capt. Caucasian]

Originally Posted by Cptnchia

Here's a very important thing to know. See the round blue light at the top right corner of the IRS panel? When that is lit it means someone is in the forward lav. Means you're going to have to hold it a little longer.

I almost lost it one day waiting for that little blue light to go out.

[fiveninerzero]

To answer your question about USB and AM, those refer to modulation; that is how the carrier rides the radio wave. With basic amplitude modulation you basically have two of the same signals on opposite polar ends of the wave. With SSB (single side band) you are able to split the signal into two separate ends and essentially halve your bandwidth usage, contributing to saving space and getting more bang for your transmission power.

USB is pretty much the standard for long-haul two way radio communication. Shortwave radio (old school BBC and Voice of America) uses the same band, but transmits in AM. AM is also what VHF and UHF (military) aviation uses.

[canadian_atc]

HF Frequencies are established by the operating agency on a daily basis, taking into account atmoshpheric conditions, even the time of day affects the proper HF frequency assignments.

As Doug said and covered everything pretty much to a "t" radar control will issue HF assignments to flights prior to exiting radar airspace.

Hopefully in the coming years using HF radios will become all but extinct. Most airliners and even most biz jets are "CPDLC" equipped (Controller Pilot Data Link Communication)

Which means the oceanic control guys can issue clearances and instructions via Datalink rather than over scratchy HF radios.

The majority of airlines these days can even accept an entire North Atlantic Clearance via Datalink, and confirm it via datalink without ever using voice procedures. There are various levels of CPDLC, some require voice confirmation and so on.

While I issue HF frequencies on a daily basis at work for NY Oceanic, and deal with the CPDLC stuff going out to the North Atlantic I thankfully don't have to work with an HF radio where I am...



I just realized that lat/long is inside my airspace...