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neilbradley1

GOL 737-800 midair

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http://www.allheadlinenews.com/articles/7005029736Suprised no one has posted about this. My dad just called me about it today and thinks he has to go down to Brazil to investigate. His intial information that he has is that it struck an Embraer aircraft and that the 737 then broke apart. The GOL jet that crashed was brand new and of a new certification for very short field operations with delivery transaction happening on September 1st.

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I am having a hard time trying to figure out how a 738 with TCAS could ever have a mid-air with another jet. Best,Randy J. Smith

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A DHL 757 and a Russian Tu-154 collided over Europe a few years back. They both had TCAS and were under ATC radar contact as well when they hit. Nothing is impossible.We are also presuming that the planes were equipped and using TCAS. Rules in Brazil may not be the same as rules in the US.

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Aparently, Radar reckoned there was 1000' between them. If so, then so did the TCAS. Radar altitudes read from Mode C transponders, the same information that TCAS uses.

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I can't stand to read the thousands of posts in a single thread at airliners.net, but I think I caught something about a 3rd aircraft maybe being involved.

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Hi Randy,I agree, this is definitely troublesome, however, there could be a number of reasons why this happened.For example, were one or both pilots actually complying with RA commands (if their equipment was set up correctly of course and said commands were in fact issued by TCAS)? This is a rhetorical question, and I am by no means speculating. Some interesting reading here (this is a tad dated, but still very relevant): http://asrs.arc.nasa.gov/directline_issues/dl4_tcas.htmand here:http://www.aeronautics.ru/news/news002/news053.htmCondolenses to relatives and friends of all involved.Kind regards,Henning| P4 3.0 GIG | Asus P4P800E Motherboard | 1 GIG DDR 400 RAM | GeForce 6600OC 256MB | 160 GIG WD JB |120 GIG WD JB | SB Audigy 2 ZS |"You know that you are low and slow when you get a bird strike from behind..."

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Well the rumour at PPRUNE is that the Legcay pilot switched off his transponder an climbed to a higher and unnassigned altitude. As somebody else wrote, this really does beggar belief. I doubt this very much, but life can be stranger than fiction. If so it must be manslaughter.

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This does make sense, except wouldn't the Legacy's TCAS still detect the 738?

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True, but for all we know they received the RA. I imagine thoough, that one airplane following an RA might not be enough to avoid the collision.

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>but I think I caught something about>a 3rd aircraft maybe being involved.Unfortunately 99% of what you read on airliners.net on their forums is utter crap. People make all sort of wild claims there, it is actually entertaining reading. One guy claims that 737 disintegrated and showered the Legacy with its part - not even realizing what sort of odds would it entail. And pretty much everybody makes the same mistake - that the only way 737 could have crashed was through a 'fatal' blow delivered to its structure forgetting that history of aviation is filled with crashes brought down by relatively minor problems that diverted pilot's attention. Michael J.

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Very sad accident.Yahoo has a good report with a slideshow detailing events (including pics of a damaged Legacy jet with the left wingtip missing)Go here and then click on "Slideshow: Brazilian jetliner crashes in the Amazon"http://news.yahoo.com/fc/World/Brazil

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There is an interesting article here, written by the reporter who was aboard the Emb 600 jet. http://www.nytimes.com/2006/10/03/business...i=5070&emc=eta1As Henning, surmised, a related story indicates that Brazilian officials are claiming the Emb 600 pilots turned off their Xponder. Some think this is a hasty conclusion however.

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For more indepth disscusion on the accident go to,http://www.pprune.org/forums/showthread.php?t=246031Btw, NO COMPOTENT pilot without a deathwish, would turn off the TCAS and leave their assinged altitude. Dave FisherCYYZP4 Prescott 3.2e 478p 800mhz 1mg CPUP4P800SE Asus Motherboard2.5 gig PC3200 DDR RAM 400MHZGeforce Ti 4200/128Maxtor 80 Gig ATA 133 HD x2WDC WD800 80 Gig HDhttp://www.precisionmanuals.com/images/forum/ng_driver.jpghttp://fs2crew.com/linepilot.jpghttp://www.jdtllc.com/images/rcv4bannersupporter.jpg

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There are still alot of unknowns on this incident:1. It appears that the ATC controller (brasilia) was not receiving transponder signal from the Legacy, but had "skin" from a radar return.There is speculation that the transponders in the Leagcy were inop or "turned off" for a period, after passing Brasilia, but resumed operation after the Legacy pilot squaked 7700 after the incident.2. there were comms problems between the Legacy AC and the ATC controllers.3. The Legacy had filed a flight plan which called for an altitude change after crossing brasilia VOR BRS from FL370 to FL360 on a new airway, UZ6. This is the same airway GOL 737 was on , in opposite direction.4. It appears the Legacy AC did not get order from ATC for FL360, or at any rate, it appears that the Legacy continued on FL370.5. The Legacy was approaching the edge of the Brasilia UTA air space and was to be transfered to Amazonica ATC. The GOL 737 was under control of Amazonica at FL370.6. The Leagacy made no maneuver prior to collision, but so far it is unknown if the GOL 737 maneuvered.7. The assumption is that whatever damage the GOL 737 received, it suffered structural failure prior to impacting the ground, based on the debris field and what photos have been released so far. http://forums.avsim.net/user_files/157911.jpgEnroute IFR chart. Brasilia is in lower right. UZ6 runs NW/SE. Incident was in vacinity of waypoints NABOL / ISTAR. Legacy continued and landed at Cachinbo AB.scott s..

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This revives a discussion some of us have had here before...about the very real risks associated with navigation systems that are far too accurate for their intended purpose.Equipped with GPS navigation, these two jets approached from opposite directions on the same track and collided. Regardless of any other pilot or ATC controller error, a radio, or transponder, or TCAS, or other system failure, one truth seems apparent to me: these two jets struck head on, in part, because their navigation systems put them perfectly into the same traffic lane, reducing their only hope for separation to the vertical plane.I think some discussion really needs to occur about these risks, and the technical solutions that could very well have saved 155 people that day. One example...by introducing a random cross-track error to the right of the assigned airway (easily done with the technology available) these jets would probably have passed harmlessly past each other. This is a pilot technique I have seen used in oceanic airspace, where pilots deliberately set a small cross track error to avoid being exactly on the same route as every other aircraft on the airway. Navigation systems should be designed to induce a limited random cross-track error when flying in the high airway structures where terrain is not a factor.Perfect lateral positional accuracy is highly desired close to the ground when the purpose is to stay well clear of terrain in IMC. Perfect accuracy at flight levels poses much more a risk than a benefit, as the only things to collide with on 99% of the world's high-altitude airways are other airplanes. A displacement of just 200 feet off the course centerline would have made all the difference in the world over Brazil.Food for thought.Bob ScottATP IMEL Gulfstream II-III-IV-V L-300Santiago de Chile

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Bob,You are absolutely correct - actually this "perfect" accuracy during enroute phase bothered some scientists enough that one of them (my friend) working at NASA Ames wrote a scientific paper on the subject proposing so called "continuous altitude rule" - a rule that would set altitude based on your heading/course. You can read an abstract and the whole article here:http://www.aviationtoday.com/cgi/av/show_m...102feedback.htmI also like the idea of the random cross-track error.Michael J.NASA Ames

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>>Equipped with GPS navigation, these two jets approached from>opposite directions on the same track and collided. >Regardless of any other pilot or ATC controller error, a>radio, or transponder, or TCAS, or other system failure, one>truth seems apparent to me: these two jets struck head on, in>part, because their navigation systems put them perfectly into>the same traffic lane, reducing their only hope for separation>to the vertical plane.>If I choose, my GPS driven auto-pilot will fly up to a mile from the centerline of an airway, etc. Otherwise, it might be within three feet or so. This feature was designed for conjested airways, although we'd normally figure altitude seperation for opposite directions.L.Adamson

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>If I choose, my GPS driven auto-pilot will fly up to a mile>from the centerline of an airway, etc. Otherwise, it might be>within three feet or so. This feature was designed for>conjested airways, although we'd normally figure altitude>seperation for opposite directions.True, most (maybe all) GPS nav systems will do that, but in every jet I've flown it's been a real pain to setup and use, because the offset must be set for each leg manually. Works OK on the NATS with 45 min between waypoints, but not so well in busy airspace over land.The random offset function I would like to see would be automatic at all altitudes above the OROCA, and would set aircraft to fly a parallel course offset to right of track by a random cross-track distance of between 200-3000m to the right of track centerline. Airways are already designed to allow 4nm deviation left/right of track based on allowable error from much less accurate conventional terrestrial radio navaids.RegardsBob ScottATP IMEL Gulfstream II-III-IV-V L-300Santiago de Chile

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Scott,From what you have set out there appears to have been abreakdown in some basic ATC procedures.Assuming the Brazillian ATC system is using ICAO procedures the both the Brazilia and Amazonica procedural controllers maintaining the 'Board' and doing the coordination for the radar controller, should have had a 'strip' on each aircraft under the boundary designator on their respective control positions. Also the strips would have been of a different colour or had some other distinguishing feature. Each strip should show clearly the current assigned level.It is also normal for coordination to take place between the two centres/controllers at least 10 minutes before the boundary position. So the Amazonica controller should have had a TERES position report and ETA for NABOL including the current assigned level of 370 for the GOL B738. A controllers normal action would be to check the times and level against any other strip under the boundary designator for a posible confliction. Similarly the Brazilia controller would have been given the TERES position eata NABOL for the Legacy jet. So at least one of the controllers should have picked up the conflict at the time of the position coordination. Also the radar controllers (if radar coverage existed) should be checking the mode C readout on the target labels. A possible scenario. Did the Amazonica controller advise the Brazilia controller during the coordination that he was going to assign the Legacy jet FL360 before the boundary and so the Brazilia controller wrote 360 on his strip for the Legacy jet??? And subsequently for whatever reason the Anazonica controller did not issue the level change instruction to the Legacy jet. But again even if the Brazilia controller had accepted the coordination, he would have told his radar controller that the Legacy jet has been assigned FL360. As soon as he had both aircraft on his display the first thing he should have checked was the mode C levels. If they were the same, do something about it. If there was no radar coverage in that area then there is no fall back, and as both aircraft would appear to have reached the NABOL at about the same time they would have been on different frequencies and the only safety net left was TCAS and or the Mark one eyeball which is not very reliable at these heights and speeds. All the little holes lined up!The ATC tapes, cockpit voice recorders and flight data recorders hopefully will eventually provide the answers to this unfortunate incident.NeilYPAD (retired ATC)

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