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Bruce
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ATC Communications

Sat Nov 20, 1999 5:27 am

Another question from my inquiring mind....

I know that when you're flying thru the U.S.A. you have radio contact with different ATC centers as you cross the country and get "handed off" from one to another as you cross their boundaries. Ok. But what if you're a long-haul ETOPS flight crossing a vast ocean with no ATC centers, like say the pacific? Who are you in radio contact with? Whose radar are you on? If you had trouble who would you call?
Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
 
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RE: ATC Communications

Sat Nov 20, 1999 5:40 am

It really depends on what location you encounter yourself in. When cruising in parts like Africa, where most communications are done only in RF frequencies, it is common for aircrafts to monitor each other and confirm data. The FMS plays a very important role in keeping constant updates of the situation. Most wide-bodied aircarfts are equipped with a NPU system, so that flgihts over water are managed with precision. In this case you would not a appear in anyone's radar if you're not within the range. It is up to airborne instruments to do the job, until you enter a specified area that is covered by a radar controlled system.

Cheers.
Leo-ERJ
 
OPNLguy
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RE: ATC Communications

Sat Nov 20, 1999 5:40 am

You'd still be yaking to ATC. Here in the USA, Houston, Miami, New York, and Oakland ARTCCs have oceanic sectors, and communications are either VHF, HF, or satcom. Other countries/regions have similar airpace adjacent to ours.

Once offshore a couple of hundred miles, you're beyond radar coverage.

In case they get into trouble, there's radio and satcom to ATC, and, of course, the airline's dispatch office using the same means...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
mirage
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RE: ATC Communications

Sat Nov 20, 1999 5:43 am

I don't know how it is over the Pacific but when crossing the North Atlantic, aircrafts change from VHF to HF communications (more range). Depending on the exact route of the flight, several ground stations can give ATC assistance: Canarias, Gander, New York, Paramaribo, Piarco, Santa Maria and Shanwick for the South central part of the North Atlantic Ocean (from Ireland coast to New Foundland and from Canary Islands to Venezuela coast.

For the Pacific Ocean there are these ground stations:
Honolulu, S. Francisco (provides coverage for Anchorage), Guam, Hong Kong, Manila, Naha, Port Moresby, Seoul, Taipei, Tokyo, Auckland, Nandi, Pascua, Port Vila, Rarotonga, Sydney, Thaiti and Wallis.

I think there are no radar coverage over large portions of both the North Atlantic and Pacific.

Source: The worldwide aeronautical communications frequency directory, Robert E. Evans

Luis, Faro, Portugal
 
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Bruce
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RE: ATC Communications

Sat Nov 20, 1999 5:56 am

So if you had an accident and crashed in the middle of the pacific ocean, no one would know you're missing until you don't show up because they're not monitoring you on radar, like they were monitoring MS990, right?? Within hours they knew that the plane went down, then up, and they had a radar spot where they lost contact so they knew where to look.

Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
 
OPNLguy
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RE: ATC Communications

Sat Nov 20, 1999 8:03 am

Bruce wrote:
-------------------------------
So if you had an accident and crashed in the middle of the pacific ocean, no one would know you're missing until you don't show up because they're not monitoring you on radar, like they were monitoring MS990, right?? Within hours they knew that the plane went down, then up, and they had a radar spot where they lost contact so they knew where to look.


You're not under continuous monitoring by radar, but you do make regular position reports via radio. Should you not make one, they'll notice. In a worst-case scenario, yes, they have more trouble finding the wreckage, but they'd still know what your filed route was and concentrate the search along it.



ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
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Across The Atlantic

Sat Nov 20, 1999 10:07 am

I am not sure about crossing the pacific. But the atlantic. You get a course from Shanwick control with a route you have to follow and the flight level. They do this very exactly and that is how they keep seperation. The will do position reports every 10 degrees of lat they cross. And if a plane did crash they have an ELT (emergency locator transpoder) which goes up with an abbrupt movement and that will be picked up by some one.]
Iain
 
Ben2
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RE: ATC Communications

Sat Nov 20, 1999 10:20 am

As OPNLguy stated, aircraft are required to make position reports at set intervals. They make these reports when they cross over fixes. Their route of flight I believe takes them over fixes with the same letter such as DINTY, DUETS, etc...(these are from the west caost). Contollers wil ask for a "DUETS estimate" and also many others, the flight then sends back their calculated crossing time and this helps coordinate to all the aircraft. Communication is normally thru HF. HF has a lot of static, and a nifty program called SEACAl or something like that enables aircraft to recognize when a controller want to communicate so they don't have to listen to all the static.
Note: This is something somebody explained to me about a year ago, so I could wrong. Please correct if I am...
 
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Bruce
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RE: ATC Communications

Sat Nov 20, 1999 12:15 pm

Makes a lot more sense now! Thanks
Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
 
pilot21
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RE: ATC Communications

Sat Nov 20, 1999 11:24 pm

Just in regard to the south Pacific, Qantas and Air NZ are now using a system called FANS, (Future Air Navigation System). This system uses a commerical version of GPS, which allows controllers in NZ and Austrialia to track aircraft on a normal radar screen, but by using the GPS system. There is also a special communications link between the pilot and controller ( I think it relies on computer messages/printouts rather then verbal communications.) The overal benefits are that firstly the plane is tracked the whole journey across. Secondly getting permission to descent, climb and avoid bad weather is much easier, because the controller can see everyone. In the past, airplanes were assigned alttiudes and headings and they had to stick with that for most of the way regardless. the system is part of the overal future Free flight programme and hopefully will be implemented on a more widely based system in the near future
Aircraft I've flown: A300/A310/A320/A321/A330/A340/B727/B732/B733/B734/B735/B738/B741/B742/B744/DC10/MD80/IL62/Bae146/AR
 
ywg777
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RE: ATC Communications

Sun Nov 21, 1999 3:29 am

When I went to HNL for a trip last Christmas. I was on CP125 and CP134 from YVR-HNL-YVR. We were talking to San Fransisco. Sanfransisco covers the whole Pacific ocean. You can hear SFO from the ground in NRT.
YWG777
 
OPNLguy
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YWG777

Sun Nov 21, 1999 4:31 am

FYI, they were undoubtedly using SFO ARINC, which provides radio coverage in that part of the world. The ARTCC (US) involved is OAK, and there is no SFO ARTCC.

ARINC (Aeronautical Radio, Inc) is also used on the Atlantic, and they have a big New York office that handles those.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
mirage
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RE: ATC Communications

Sun Nov 21, 1999 4:43 am

There's no big deal about listening S. Francisco on his trip because his flight was on the corridor between S. Francisco and Honolulu (CEP-1/2 MWARA). The only ground stations on this corridor are S. Francisco and Honolulu so, of course that flight should have been under S. Francisco control.
 
OPNLguy
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RE: ATC Communications

Sun Nov 21, 1999 5:26 am

Mirage wrote:
-------------------------------
There's no big deal about listening S. Francisco on his trip because his flight was on the corridor between S. Francisco and Honolulu (CEP-1/2 MWARA). The only ground stations on this corridor are S. Francisco and Honolulu so, of course that flight should have been under S. Francisco control.


My point was that ATC, not ARINC, controls the aircraft. ARINC is the communications entity that links ATC and the aircraft when operating over such great expanses...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
Guest

RE: ATC Communications

Sun Nov 21, 1999 5:43 am

I also forgot to mention that not only when crusing through unsurveillanced areas like over the pacific/atlantic, it is customary for aircrafts to monitor each other, but also the need for ground surveillance created the use of the differential GPS system which uses satellite navigation for tracking needs.

The system interacts with the FMS and RNAV onboard the aircraft to which there is a control feed input from the CNS modular avionics into the GPS system, which automatically gives the signal report into a specified ground monitoring system. The FMS keeps logs and constant updates of the data so that the ground base will not lose track of the aircraft. For this to happen the aircraft must also be equipped with something called GNSS, which makes primary use of satellite-based navigation. Many aircrafts make use of this system as someone here mentioned before, but it also takes ground base to update their systems for this to happen.

Cheers.

 
ywg777
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RE: OPNLguy

Mon Nov 22, 1999 6:34 am

When I went to HNL I was in the cockpit of a 767-300. The pilot was talking to San Fransisco. I heard him. I know Oakland has a ARTCC. Trust me he was talking to San fransisco.
Have a nice day.
YWG777 
 
Ben2
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RE: OPNLguy/YWG777

Mon Nov 22, 1999 10:30 am

Let's clear this up a little. Yes, OAK has the ARTCC and their controllers use SFO arinc to communicate. They often aren't called OAK center, but rather SFO radio or SFO arinc, but they are OAK controllers. Hope this clarifies things a little.

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