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propilot83
Topic Author
Posts: 625
Joined: Sat Jan 27, 2001 2:41 am

ATC Communication Over Oceans

Thu Apr 30, 2009 5:20 am

Does anyone know if airliners are able to communicate with ATC over the Pacific Ocean, Indian Ocean, and Atlantic Ocean? Lets say for example, a plane flying from Los Angeles to Sydney, halfway, if there was an emergency does the airplane have the capability to communicate with ATC somewhere over the Pacific in regards to distance and range for the VHF and UHF radio communications? In other words, is there any type of ATC Center near the middle of the Pacific, Indian, or Atlantic ocean that communicates with overseas flight?
 
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LAXintl
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RE: ATC Communication Over Oceans

Thu Apr 30, 2009 5:26 am

HF radio.

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From the desert to the sea, to all of Southern California
 
KELPkid
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Joined: Wed Nov 02, 2005 5:33 am

RE: ATC Communication Over Oceans

Thu Apr 30, 2009 5:26 am



Quoting Propilot83 (Thread starter):
Does anyone know if airliners are able to communicate with ATC over the Pacific Ocean, Indian Ocean, and Atlantic Ocean?

Traditionally, this is done using HF radio, which propogates well beyond line of sight by bouncing off of the ocean and the Earth's ionosphere....however, times are changing, and lots of these communications are going over to satcom (Satellite-based communications).

HF reception has always been a little hit-and-miss: you never know, in real time, what the propogation conditions are, and things like sunspot activity control HF propogation.

You can also communicate with other aircraft (line-of-sight only) on the international VHF calling frequency: 123.45. It is probably always possible to relay important messages via other aircraft, you'll eventually get to someone who has clean reception with say, Shannon or Gander control. If you have a good shortwave receiver, you can listen to these communications, by the way...
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
jgarrido
Posts: 258
Joined: Thu Mar 08, 2007 4:40 pm

RE: ATC Communication Over Oceans

Thu Apr 30, 2009 5:37 am

Airliners flying over the ocean are in now way on their own. They are still under the control of ATC. Some routes can be very busy. Others less so, but still there is enough traffic so that there would be big problems if there wasn't ATC to keep track of who is where.

HF or high frequency is the primary method of communications. Oakland and Anchorage Center are responsible for a large portion of the Pacific Oceanic airspace, but they don't communicate directly to the planes though HF. ARINC is a private company which has radio operators which take request and position reports from the pilots of the HF radios and passes it along to air traffic controllers. Vice versa controllers pass info and instructions to the planes via ARINC.

The future is in CPDLC (controller-pilot data link). Which uses satellites (operated by ARINC in the US btw) to send text message directly between the cockpit in the plane to the controllers working those planes.
 
modesto2
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RE: ATC Communication Over Oceans

Fri May 01, 2009 5:55 am



Quoting Jgarrido (Reply 3):
The future is in CPDLC (controller-pilot data link). Which uses satellites (operated by ARINC in the US btw) to send text message directly between the cockpit in the plane to the controllers working those planes.

CPDLC is a neat system. I've seen it working on the B777 and allows clear communication between the pilots and ATC. For example, ATC will issue an instruction like "climb and maintain flight level 380" and the pilots have the option of accepting the message and/or sending a reply. Similarly, the pilots can initiate contact with ATC via these text messages. CPDLC avoids the sometimes poor quality of HF communications and relieves the pilots of monitoring the frequency. Similar to SELCAL with HF communications, the pilots hear an ACARS chime in the cockpit when receiving a message from ATC.

Traditionally, aircraft communicate with ATC via HF radio (as others have already detailed). CPDLC seems to be the wave of the future.
 
DingDong
Posts: 65
Joined: Tue Jan 16, 2007 5:45 pm

RE: ATC Communication Over Oceans

Fri May 01, 2009 3:09 pm



Quoting Jgarrido (Reply 3):
HF or high frequency is the primary method of communications. Oakland and Anchorage Center are responsible for a large portion of the Pacific Oceanic airspace, but they don't communicate directly to the planes though HF. ARINC is a private company which has radio operators which take request and position reports from the pilots of the HF radios and passes it along to air traffic controllers. Vice versa controllers pass info and instructions to the planes via ARINC.

Speaking of which... Wink

http://i678.photobucket.com/albums/vv149/AnetDingDong/barrow-arinc-hf-site.jpg

That photo was taken on New Year Day 2009. Many thanks to the (ARINC) Barrow, Alaska HF site maintainer for taking us out on the tundra south of Barrow to see this! Extremely talented and a great guy.

Apologies for the poor picture quality; 'twas the best I could do given the fairly demanding conditions in the darkness at -36 F.
DingDong, honey, please answer the doorbell!
 
113312
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RE: ATC Communication Over Oceans

Sat May 02, 2009 2:00 pm

Many transoceanic planes, today, can send/receive data messages via AIRINC. Depending upon installation, this system can use VHF, HF, or SATCOM. While HF (SSB) has been used for long range voice communication for decades, many newer aircraft can now use SATCOM for voice communications as well.
 
PER744
Posts: 394
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RE: ATC Communication Over Oceans

Sun May 03, 2009 1:26 am

It's also important to point out that International HF is operated as a network. HF frequencies are shared by a number of ground stations. An aircraft may be in the Australian FIR, but communications may be passed through an HF operator in Sri Lanka, or any one of a number of other locations.

The station able to communicate with the aircraft most efficiently holds what is called 'Primary Guard', which basically means they're responsible for all comms.

There are also domestic HF frequencies to serve remote areas that aren't within VHF range, or for aerodromes that don't have VHF on the ground.

Due to the unreliable nature of HF frequencies, there will usually be around 4-5 nominated HF frequencies for an area, some (or possibly all) will not be useable at any given time.
 
Sasha
Posts: 861
Joined: Tue May 18, 1999 3:26 am

RE: ATC Communication Over Oceans

Sun May 03, 2009 1:52 pm

I thought ETOPS-aware flight routes actually catered for radio comms. i.e. were designed with radio comms in mind. Oh well.
An2/24/28,Yak42,Tu154/134,IL18/62/96,B737/757/767,A310/320/319,F100,BAe146,EMB-145,CRJ,A340-600,B747-400,A-330-300,A-340
 
PER744
Posts: 394
Joined: Sun Mar 09, 2003 11:38 am

RE: ATC Communication Over Oceans

Mon May 04, 2009 6:31 am

Sasha: VHF range is a couple hundred miles maximum and is line-of-sight, routes are often designed in respect to comms, navaids, etc, but it's not possible to ensure VHF coverage of all major routes, especially Oceanic.

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