3MilesToWRO
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LOT 787s And Their ADS-B

Tue May 28, 2013 5:49 pm

Watching recently our 787s (SP-LRB and SP-LRC) doing training flights over Wrocław I've noticed that they are visible on Flightradar24 only when higher than 1600 - 2000 meters. Looks like they switch the ADS-B transmitters on some time after take off and switch them off some time before approach. I haven't noticed this behaviour earlier, when SP-LRA was doing touch-and-gos in November.
Any ideas what is the reason?
 
BoeingGuy
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RE: LOT 787s And Their ADS-B

Tue May 28, 2013 6:16 pm

You can't individually switch off ADS-B-Out on the 787 or any model. If you mean they are switching off the entire Transponder, I can't imagine they are really doing that. You lose TCAS on your airplane, and become invisible to other airplane's TCAS (like what happened with GOL). I really doubt they are doing this, or that it's even legal in that airspace.
 
airplanecrazy
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 2:27 am

Flightradar24 depends on a network of ADS-B receivers. From their website: "Flightradar24's coverage is primarily made up of data contributed by volunteers from around the world. Roughly 1,000 aviation enthusiasts with ADS-B receivers regularly feed data to our network." Is it possible that the receiver currently covering Wrocław is far enough away that it can't "see" the signal when the aircraft is below 2000m due to the horizon? At 2000m altitude I think the receiver would be about 100nmi away.

Edit:

I just learned how to decode Flightradar24 "radars". It looks like the two receivers currently covering Wroclaw are in Prague and Krakow. The distance from Prague to Wroclaw is about 116nmi, so I think the horizon effect theory is pretty good.

[Edited 2013-05-28 19:42:13]
 
3MilesToWRO
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 7:04 am

Quoting BoeingGuy (Reply 1):
You can't individually switch off ADS-B-Out on the 787 or any model. If you mean they are switching off the entire Transponder, I can't imagine they are really doing that

I don't know what precisely can they switch, but definitely the signal disappears repeatedly below these roughly 2 kilometres and appear above. Looks like some kind of procedure step. You can see it on Flightradar24 playback between Bydgoszcz and Wrocław, yesterday starting from 9:00 UTC - SP-LRA goes from Wrocław and around 10:00 SP-LRB comes from Bydgoszcz. I've also noticed that SP-LRA coming home to Warsaw a bit later was visible all the time.

What's more, they cruise only at 5000 - 6000 meters all the time.

Quoting airplanecrazy (Reply 2):
Is it possible that the receiver currently covering Wrocław is far enough away that it can't "see" the signal when the aircraft is below 2000m due to the horizon? At 2000m altitude I think the receiver would be about 100nmi away.

No way this can be the reason unless 787 has some very strange radio antenna. Every other airplane can be traced to the very gate of EPWR. Besides, I've seen the same behaviour over Bydgoszcz.
 
BravoOne
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 8:01 am

I don't believe the 787-8 in it's current configuration is equipped with ADS-B. ADS-C, yes, but the ADS B will not be available until sometime after the -9 is in service. As I'm sure you know, ADS C and ADS B are two completely different systems and have little if anything in common.
 
3MilesToWRO
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 11:50 am

Quoting BravoOne (Reply 4):
I don't believe the 787-8 in it's current configuration is equipped with ADS-B.

So how comes Flightradar24 sees it?
 
airplanecrazy
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 11:56 am

Quoting 3MilesToWRO (Reply 3):
No way this can be the reason unless 787 has some very strange radio antenna. Every other airplane can be traced to the very gate of EPWR. Besides, I've seen the same behaviour over Bydgoszcz.

I can't explain the other flights that you have see going all the way to the ground, but I just watched a Ryan Air 737 flight from Dublin to Wroclaw (RYR4MX/FR1926) disappear at 3400m (mountains?). Earlier, I also saw another Ryan Air 737 flight to Wroclaw disappear at 2500m. The final stage of both flights was covered by Flightradar24 Radar LPKR-1 (near Prague). According to Boeing: "The ADS-B Out signals travel line-of-sight from transmitter to receiver.


http://www.boeing.com/commercial/aer...02_10/pdfs/AERO_Q2-10_article02.pd

[Edited 2013-05-29 04:59:22]
 
BravoOne
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 12:44 pm

3 Miles I really don't know about Flightradar and how he sees it but I do know that the 787-8 is not equipped with ADS-B. End of that part of the discussion.
 
Shiny
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 2:27 pm

ADS-B-Out IS available on 787!
 
BoeingGuy
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 2:34 pm

Quoting BravoOne (Reply 4):
I don't believe the 787-8 in it's current configuration is equipped with ADS-B. ADS-C, yes, but the ADS B will not be available until sometime after the -9 is in service.

You are talking about ADS-B-In. Most Boeing airplanes have been equipped with ADS-B-Out for quite a few years now. They are two different things. The feature the OP is referring to is ADS-B-Out, which the 787-8 most certainly has in its current configuration.
 
BravoOne
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 4:30 pm

Okay your talking about a ModeS squitter and that is not ADS B but just a component of the B. Get over it Jeeze!
 
BoeingGuy
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 4:34 pm

Quoting BravoOne (Reply 10):
Okay your talking about a ModeS squitter and that is not ADS B but just a component of the B. Get over it Jeeze!

The 787 has full ADS-B-Out capability. Get over it.
 
Shiny
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 7:09 pm

Correct!
As I said - ADS-B-Out is almost a standard feature and is becoming mandatory in civil airspace very soon!
ADS-B-In is a totally different story, it is not even defined yet!
 
BoeingGuy
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 7:30 pm

Quoting shiny (Reply 12):
ADS-B-In is a totally different story, it is not even defined yet!

Yeah, it is. A number of ADS-B-In applications are fully defined. Some are still being developed for future applications, especially the runway alerting stuff.
 
3MilesToWRO
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RE: LOT 787s And Their ADS-B

Wed May 29, 2013 8:24 pm

Well, I guess I must cancel the false alarm   Inspired by some of the posts I've taken a closer look and indeed - NOW I'm afraid I don't see the planes on ground level on EPWR 

It must be that quite a short time ago Flightradar24 has lost our local feed. Now what's being traced from Prague gets lost in the shadow od Sudety mountains, what's being traced from Łódź gets lost behind the Trzebnica Hills.
 
Shiny
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RE: LOT 787s And Their ADS-B

Thu May 30, 2013 11:10 am

BoeingGuy - ADS-B-In is defined and available only for on-ground application.
Airborne ADS-B-In is currently not offered by most manufacturers due to implementation and definition still in progress.

TCAS II is a totally different story and has (almost) nothing to do with ADS-B-In (for those who mentioned it).
 
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glen
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RE: LOT 787s And Their ADS-B

Thu May 30, 2013 2:50 pm

Quoting shiny (Reply 15):
Airborne ADS-B-In is currently not offered by most manufacturers due to implementation and definition still in progress.

TCAS II is a totally different story and has (almost) nothing to do with ADS-B-In (for those who mentioned it).

All our A330 since end of 2010 have ADS-B-In which is uses for ATSAW (Airborne Traffic Situational Awareness).
Quote from the FCOM:
"..The ATSAW function, also called "ADS-B IN" function, enables to display enhanced information of the surrounding traffic in order to improve the traffic awareness of the flight crew..."

ADS-B IN is not yet active with all functions which are planned, but at least newer aircraft are equipped with it.

The ATSAW display look like this:

"The horizon of many people is a circle with zero radius which they call their point of view." - Albert Einstein

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