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No Radar Over The Atlantic?

Fri May 24, 2002 3:13 pm

I was looking at a doc on Discovery Channel the other night and it was about a AC876 flying YYZ - FRA.

What my question is...the doc said that the 767 flew route 'T' (Tango) across the Atlantic (towards the west of Ireland to Dobbel/Dibbel???) but was lost to radar for the 4 - 5 hours it was in the air when it left Gander until Shanwick!!

Is this true? I know the have HF Radio but do the 600 flights flying to Europe from Canada/America each night have no radar service for the journey?

Aer Lingus, Proud to be Irish.
lmml 14/32
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RE: No Radar Over The Atlantic?

Fri May 24, 2002 3:17 pm

Yes it is. On oceanic crossings the planes are on their own. Very interesting documentary. Part 3 next week.
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RE: No Radar Over The Atlantic?

Fri May 24, 2002 3:29 pm

You saw it? I just figured how they could do that...what if the a/c drifted off track, would it have no radar so folks could see where it is?
Aer Lingus, Proud to be Irish.
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RE: No Radar Over The Atlantic?

Fri May 24, 2002 5:14 pm

That's true, there is no radar coverage over the atlantic ocean, at least part of it. But I wouldn't say that the planes are on their own.

You have different types of air traffic control: the most common is radar control like in North America, Europe, most Asia... But in some other parts of the world, there is no way to get such ATC, for different reasons. Over the Atlantic ocean for instance, you would have to put several radars on ships, which is not feasible. Elsewhere like the African continent, it's mainly because of a lack of finance.

Although you have no radar coverage, it doesn't mean there is no ATC service provided. HF Radio transmission is always connecting the pilots with an ATC centre. The main difference is that the distance separating 2 aircraft flying on the same airway at the same level is huge and speed is restricted.

The Atlantic is the most famous example of what we call "procedural control". But I can give you another unsuspected one: Have you ever flown let's say from Europe to Asia, routing through the Arabian peninsula, crossing the Indian ocean towards India?
The last Arab country you will be overflying is Oman providing radar control up to the western third of the Indian ocean. Then it is procedural control as soon as you enter Mumbay (Bombay) FIR until about 200 nautical miles (Nm) west of Mumbay.
Therefore, Oman ATC has to provide a 10-minute separation between traffic flying same route, same level. Can you imagine what is a 10-minute separation: 86 Nm! This is huge! In some other countries, this separation can be extended to 15 or 20 minutes compared to the 5 or 8 Nm separation used under radar control! (en-route)

In conclusion, I'd say that you should not feel unsafe just because there is no radar covering the pond. No radar doesn't mean no ATC!

The sky has no limit...
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RE: No Radar Over The Atlantic?

Fri May 24, 2002 6:09 pm

Also when flying over the African continent, there is very little atc coverage, and what there is is very poor and unreliable, and almost no radar coverage. Therefore every 10-20mins the a/c have to transmit their heading,position,fl,and other info on 126.9

The IATA In-Flight Broadcast Procedures (IFBP) call is.....

"All stations this is......(call sign)
Flight level.....
Northbound......(from-to) via....(airway)
Position..... at......(time in utc)
Estimated position.... at ....(time in utc)
.....(call sign)
Flight level .....
Northbound (direction of flight)"

And they just have to hope the other a/c are listening out......
"She Rolls, 45 knots, 90, 135, nose comes up to 20 degrees, she's airborne - She flies, Concorde Flies"
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RE: No Radar Over The Atlantic?

Fri May 24, 2002 8:18 pm

Over the Atlantic the gap is relatively small, when you fly over the Pacific the gap is much wider.
Radars have a maximum range (depending on type and location of both the radar and its target) which is determined by the curvature of the earth and the amount of power they can send into the atmosphere.
That range is usually several hundred kilometers for the largest ones, leaving a substantial gap in places where there is no land to place a radar station on  Smile/happy/getting dizzy
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RE: No Radar Over The Atlantic?

Fri May 24, 2002 8:29 pm

Oceanic aircraft these days are using ADS to report positions which means that no radar service is required...the aircraft's GPS position is transmitted, bounced off a satellite, and by the magic of technology the aircraft appears on a radar screen without all the messy business involved in actually building and maintaining radars. Oz and NZ oceanic flights have been doing it for years, and NAT aircraft have been testing it out.
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RE: No Radar Over The Atlantic?

Fri May 24, 2002 8:59 pm

Lets put it this way: Was there radar available to ATC in the 1930s? No. Was there ATC? Yes. Same thing in the 1940s and it seems that very few places had radar up until the mid-1950s. I can remember the first time I used TRACON going into Dallas; there were no civilian transponders and A/C were identified by making a turn to a heading at the controller's request. Even today, if Center radar goes down we can revert to the 1930s methods of ATC and fly safely. The same thing applies, on a more refined scale, in non-radar environments today.

A Controller can elaborate on that better but suffice that radar has vastly improved the capacity and the efficiency of the system but ATC can operate without it.
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RE: No Radar Over The Atlantic?

Fri May 24, 2002 9:09 pm

Just curious but how long will it be until using satellites and GPS that ATC will be able to track aircraft automatically instead of using the Inflight Broadcast procedures at Leezyjet mentions above? I know in the US there are a number of long-haul trucking companies that now use GPS and Satellite transmissions to know the exact position of their fleet at all times. The coverage should be world-wide correct?

lmml 14/32
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RE: No Radar Over The Atlantic?

Fri May 24, 2002 9:12 pm

The on board nav systems are extremely accurate. Even in the days of OMEGA (ONS) there were relatively few incidents (to my knowledge) in uncovered areas. Ever seen an aircraft flying on a reciprocal radial to you from the cockpit but, obviously (and hopefully) on a different level? It goes right above or below you. Not a metre to the left or right. That is how accurate flight computers are these days. And now you have TCAS too that tells you where everybody else is. It is amazing how they did it in the 60's and early 70's.
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RE: No Radar Over The Atlantic?

Fri May 24, 2002 9:56 pm

The cases I'm interested in are flights that go across the atlantic at odd times.For example,CO 91 TLV-EWR goes over LHR around 2 30 am and heads,usually,north to BPK to cross around Western Ireland.However,most planes are coming eastbound to Europe so I wonder how they sort that problem out.Other flights like this:Atlas,Gemini BRU-JFK,EgyptAir?,EL Al,AC,SV.
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RE: No Radar Over The Atlantic?

Fri May 24, 2002 10:34 pm

My guess is that the next-generation Galileo satellite navigation system being planned by the European Space Agency will likely include improved ability to track planes in areas of no radar coverage. This is going to be very important, especially on flights over Siberian airspace and long flights from the USA to the southern Pacific Ocean.
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RE: No Radar Over The Atlantic?

Sat May 25, 2002 4:44 am

On the Atlantic crossings, there are a number of defined routes (Tracks or NATtracks to be precise). They have defined entry and exit points as well as reporting points along the way (usually defined by Lat/Long). When an aircraft gets it's flight plan it will be on one of these tracks at a defined altitude. As mentioned before, since there is no radar coverage, each plane enters it's track at a certain time and there is a time separation between planes entering the same track to keep them seperated. They must report at each reporting point telling ATC where they are and when they expect to reach the next point. That is how ATC provides seperation between the many flights crossing the Atlantic.
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RE: No Radar Over The Atlantic?

Sat May 25, 2002 12:16 pm

There are still certain areas of the United States that lack radar coverage. The amount of traffic doesn't justify the expense. It's no big deal.
Last year 1,944 New Yorkers saw something and said something.
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RE: No Radar Over The Atlantic?

Sat May 25, 2002 5:58 pm

There's been a lot of articles in Air Transport Intelligence and other publications talking about the use of ADS-B in places where there's no radar. If I'm right the FAA has already concluded that ADS-B can provide superior performance to radar in many cases. Like I said ADS is already being used routinely in the south Pacific for oceanic flights. No radar required.
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RE: No Radar Over The Atlantic?

Sat May 25, 2002 6:28 pm

yeah its true there is no radar over the atlantic. Each aircraft gets waypoints on the route to there destination. They read this list to the ATC and back. When the pass one waypoint over the atlantic, the ATC calls the aircraft, then the aircraft needs to give the position, speed, and altitude to the tower. In the past the aircraft could also call the ATC, but they don't do this anymore. I've been in the cockpit during the whole flights from TNCC to EHAM (including take- off and landing), and its really funny when the ATC calls you, you hear this funny sound and all the lights illuminate at the radio stack!!
I hope this was a good answer to your question,

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