Mid-air collision over Brasil [Archive]

westhawk

30th Sep 2006, 08:10

Brazilian Jet Missing Over Amazon Jungle

CORRECTS PLANE TYPE TO 737-800 ** MICHAEL ASTOR (Associated Press Writer)
From Associated Press
September 30, 2006 2:28 AM EDT
RIO DE JANEIRO, Brazil - A Brazilian jetliner with 155 people aboard was reported missing Friday over the Amazon jungle, aviation authorities said.

Initially, officials said they believed Gol airlines flight 1907 had collided with a smaller plane after leaving the jungle city of Manaus in the remote southwestern region of Para state. News reports said the plane struck a Brazilian-made Legacy, a smaller executive jet.

But authorities later said they were no longer certain the disappearance was caused by a collision with a private jet as they earlier maintained.

"During the afternoon, there was another incident with a Legacy airplane, made by Embraer," federal aviation authorities said in a statement issued early Saturday morning. "It is impossible to confirm that there is a relation between the incident which caused the (Legacy) crew to perform an emergency landing in Cachimbo and the disappearance of the Gol airplane."

Initially, authorities reported the collision was near the Serra do Cachimbo region in Para state but the Legacy managed to land at the Cachimbo base despite suffering damage. The aviation agency said the plane disappeared about 130 miles south of the city of Cachimbo, some 1,250 miles northwest of Rio de Janeiro.

The jetliner had been scheduled to make a stop in Brasilia before heading to Rio's Antonio Tom Jobim International Airport. Manaus is a major river city in the heart of the Amazon rainforest some 1,700 miles northwest of Rio.

Brazilian airport authority President Jose Carlos Pereira said five air force planes were searching for the missing Boeing 737 in a densely forested region and would continue to search through the night.

On Friday evening, Gol issued a brief statement confirming the plane's disappearance.

"GOL informs that flight 1907, that today left the Manaus airport at 15:35 (Brasilia time) this Friday, and was scheduled to arrive at the Brasilia airport at 18:12, has not had its landing confirmed until this moment. We are awaiting information from officials of the aviation authorities about the flight," the statement said.

Gol said there were 155 people aboard, 149 passengers and six crew members.

Pereira said in an interview with CBN radio that a local farmer reported seeing a large plane flying low.

According to the Globo news agency, some 70 family members and friends of the victims had been moved to a warehouse owned by Gol at the Brasilia airport to await news.

Seven passengers were scheduled to disembark in Rio, where airport officials had put those waiting to greet them in a separate room.

Sergio Misaci, 47, said his brother Lazaro, 58, was aboard the flight from Manaus and traveling to Brasilia to celebrate their mother's 80th birthday.

"I have all the hope in the world. We have to root for them and have faith in God," Misaci said, adding that he had lived in Manaus for six years and was sure they would not find the plane for at least 24 hours.

"The trees there are 50 and 60 meters (yards) high and you can't see anything," he said before returning home to rest for the evening.

The flight between Manaus and Rio is popular with foreign tourists but there was no immediate word on the nationalities of those aboard.

The Embraer Legacy 600 is a Brazilian-made executive jet that carries up to 16 passengers.

The Estado news agency quoted Col. Ramon Bueno, head of regional flight protection in Sao Paulo, as saying the Legacy was piloted by an U.S. citizen who had left from the airport in Sao Jose dos Campos, near Sao Paulo. The Legacy suffered damaged to its wing and tail.

He told the news agency a mid-air collision was "inexplicable."

"The two planes are very modern and have anti-collision systems, which sound an alarm to alert the plane to any obstacle," Bueno told Estado.

Bueno told Estado that if there were no survivors, it could be the worst air accident ever in Brazil. The worst to date occurred in 1982 when a Vasp 747 crashed in the northeastern city of Fortaleza, killing 137 people.

The accident occurred in the same region where a Varig 737-200 crashed in 1989 with 54 people aboard with 46 survivors.

It was the first major incident for Gol Linhas Aereas Intelligentes SA, an upstart Brazilian airline that took to the skies in 2001 with just six Boeing 737s in 2001, serving seven Brazilian cities.

----

Associated Press Writers Tales Azzoni and Alan Clendenning contributed to this report from Sao Paulo.

Vee One...Rotate

30th Sep 2006, 09:10

I'm also very suspicious in believing that a Embraer in its light way of construction could bring down a solid built Boeing.

Think kinetic energy, not size/construction. Airliner fuselages are designed to be damage tolerant but aren't built to withstand high energy impacts. I'd say a full impact could be devastating. I'd imagine that even a clip could lead to loss of control and serious damage.

I think it's too early to speculate, as hard as that often is. The details will become apparent soon enough.

Thoughts are with the friends and families of the passengers.

V1R

Wizofoz

30th Sep 2006, 10:12

TCAS/TXPDR (serviceability) ????

More to the point, pilot compliance with RA (Think 757/Tupolov, JAL near miss.)

Bokomoko

30th Sep 2006, 10:37

That area has radar control – Amazonico Center - after implementation of SIVAM and it’s been better than some years ago… BUT, I’m not sure if radar coverage AND two-way VHF radio communication have been in service without restrictions. It is not unusual to find out some problems with both. After flying for those routes several times in my life I get used to hear the same controller’s voice on different frequencies including airplanes flying on the same route using different frequencies as well. And also communication in English can be very difficult under situation beyond routine.
The worst to date occurred in 1982 when a Vasp 747 crashed… In fact it was a B727-200.

Re-entry

30th Sep 2006, 11:17

Maybe TCAS inop, ignored, or incorrectly actioned. Wait for the report.

broadreach

30th Sep 2006, 11:42

The accident occurred just about halfway between Manaus and Brasilia (a 1,200 mile leg) so it would appear that the aircraft were on reciprocal courses, well into cruise and that if either or both of them were climbing or descending it would have been due to weather.

Local news reports said that the Legacy was cleared to fl 330 and the 737 to 360.

The Legacy landed at Cachimbo airforce base which can be seen clearly on Google Earth at 09-20-09 South 54-58-03 West. The accident coordinates provided by a radio amateur last night, based on a farmer's eyewitness account, were 09-47-58 South 53-39-35 West. It is extremely remote but there are small towns and quite a lot of land has been cleared. "Cleared" does not necessarily mean turned into flat farmland, just deforested leaving stumps. The remaining forest, and there's lots of it, is very tall and dense. At the time of the accident there would still have been light.

Re news reports not confirming the collision theory, they are just that, advice that the cause of the accident has not been confirmed as a mid-air.

FlyingRabbit

30th Sep 2006, 12:00

News now saying that the Legacy pilot confirmed he collided with "something" but cannot confirm it was the Gol aircraft. According to the same news, the aircraft has not been found yet.

Blues&twos

30th Sep 2006, 12:38

I would have thought there are a multitude of ways in which a small a/c could bring down a bigger one, however well built, and sustain relatively "minor" damage itself. Apart from the obvious immediate failures that may occur to important bits like control surfaces from a glancing blow at cruising speed we don't know what might have happened to the bits of wing which separated from the Embraer. Were they ingested by one of the B737 engines? Etc etc etc.

I'm assuming this accident was caused by a mid-air, which it seems is not yet clear.

Anyone know if there was any comms with the Boeing after the problem occurred?

London legend

30th Sep 2006, 12:47

Brazil rescue planes find wreckage of passenger jet
RIO DE JANEIRO, Brazil, Sept 30 (Reuters) - Rescue planes
on Saturday found the wreckage of a Brazilian passenger jet
that disappeared the previous day with 155 people aboard over
the Amazon jungle, Brazil's airport authority said.
It said the crash site was found in Mato Grosso state "in
an area of difficult access". No further information was
immediately available.

REUTERS

weasil

30th Sep 2006, 13:05

http://www.cnn.com/2006/WORLD/americas/09/30/brazil.crash/index.html

SAO PAULO, Brazil (CNN) -- The wreckage of the Boeing 737-800 airliner that disappeared over dense Amazon rainforest in Brazil with 155 people on board has been found, a Gol Airlines spokesman said Saturday.

B737NG

30th Sep 2006, 13:06

POB was corrected down to 145 in the latest reports.

Profit Max

30th Sep 2006, 13:10

That would be the first accident of a next generation 737. Right?

P.M.

weasil

30th Sep 2006, 13:33

I think the southwest airlines accident in Midway last winter was a next gen. It was a 737-700.

FlyingRabbit

30th Sep 2006, 13:38

I think the southwest airlines accident in Midway last winter was a next gen. It was a 737-700.

yes, it was. But this one is the first hull loss for an NG. News now saying there are no signs of survivals. Very sad. And if true, this is the worst accident ever in Brazil. Aircraft had only 200 hours of flying, delivered new to Gol on Sep12.

WRC

30th Sep 2006, 14:06

Beyond being incredably sad it is quite alarming. Obviously we will give the investigators time to sort things out but I'm sure we'll all hope to learn something from the unfortunate and tragic event in the jungle.
As world air traffic rises we seem forced to depend more and more on high tech and ATS to avoid these problems, especially in target rich envirnments so to hear of such a tragedy in a remote area of the Amazon is most disturbing.
Does anyone know if this is a busy area? Was it a military EMB or US Bizjet?
Guess theres still so much more to learn. Hearts out to the folks in Brazil and at GOL.

brain fade

30th Sep 2006, 14:10

if it crossed the path of the 737 and lost a wingtip, then the tip probably hit the nose or the fin of the boeing. I suppose it could possibly survive a hit to the fin but probably not to the nose.
So sad.

alexmcfire

30th Sep 2006, 14:14

WRC seem like it´s www.excelaire.com that is the owner of the Legacy.

Fossy

30th Sep 2006, 14:19

Actually it was a Bizjet delivered yesterday from Embraer to a US operator and had been on it's ferry to the US.

WhatsaLizad?

30th Sep 2006, 14:20

The accident coordinates provided by a radio amateur last night, based on a farmer's eyewitness account, were 09-47-58 South 53-39-35 West. It is extremely remote but there are small towns and quite a lot of land has been cleared.

Using these preliminary coordinates, the crash site would be roughly 20-30 miles east of UZ6, the airway between Manaus and Brasilia. It is also in the Manaus Center airspace, (or Amazonicas if you prefer), and about 60 miles north of the changeover for Brasilia Center.

From routinely operating in that airspace, radio communications on the southern end of the Manaus airspace can be problematic. Relays and frequency hopping are the norm. If these coordinates are accurate, the southbound aircraft would be told by Manaus to contact Brasilia at the boundry point. It's possible that the aircraft wouldn't be able to hear Manaus or Brasilia in this area. My memory is a little vague on the radar contact issue in this area, but I think it is less than optimal or non-existent. Over the last 10 years, radar coverage has improved dramatically in Brasil, but can be spotty in some isolated areas.

One more note on the remote location. From viewing at night, small, isolated shacks with lightbulbs are generally separated by 50-100 miles.

Broomstick Flier

30th Sep 2006, 14:45

WRC,

N600XL is most probably the Legacy involved.

According to latest reports, the wreckage has been found concentrated in one forest area 30Km from a small village.

A possible indication the crash was result of an uncontrolled dive?

:(

AeroBoero

30th Sep 2006, 14:48

The PT-GTD was a brand new airplane. It was the fourth 737-800 SFP (Short Field Performance) that was made exclusively on request of GOL to operate the São Paulo - Rio de Janeiro shuttles. More precisely to land in Santos Dumont (SBRJ) with the 189 pax..

It was delivered around the second week of September.

* Yes the Legacy involved is the N600XL

archae86

30th Sep 2006, 15:41

One has got to wonder how two TCAS equiped aircraft
can have a mid-air?
A buried comment in the story on msnbc says "Nevertheless, radars showed the Legacy and the Boeing were flying with an altitude difference of about 1,000 feet."

Is the altitude reference for TCAS and the transponder from which traffic radar display altitude the same?

If TCAS is told a false altitude it obviously won't do the right thing.

Is there a plausible single technical fault or setting error in either of the two aircraft which could give this outcome?

Flying Mech

30th Sep 2006, 16:07

Firstly may all who died R.I.P. on the GOL 737
I presume that all crew & pax on the Embraer survived the accident? The embraer crews testimony & FDR ,CVR will provide important info to investigators. Also the Embraer survived the accident so I imagine that yhe damaged wing will yield some clues due to crossmetal contamination etc upon impact as to actually where it struck the 737

/If TCAS is told a false altitude it obviously won't do the right thing.

Is there a plausible single technical fault or setting error in either of the two aircraft which could give this outcome?QUOTE]A buried comment in the story on msnbc says "Nevertheless, radars showed the Legacy and the Boeing were flying with an altitude difference of about 1,000 feet."

Is the altitude reference for TCAS and the transponder from which traffic radar display altitude the same?

I dont know much about Embraers but from memory the 737 NG has 2 fully independebt ADC's independently powered & individual sensors & probes feeding each ADC. The output from both ADC's is constantly monitored by its own internal BITE system & if any parameter is incorrect that ADC will become INOP automatically. Each Xpndr is fed from its own ADC & the TCAS processor( single unit) is fed from the output of each Xpndr. All outputs are on digital data buses with crosstalk & feedback possibilities all monitored by internal Bite in the LRU's.
I would presume that the TCAS system on the Embraer would be very similar as TCAS in all A/C's is a FAA approved stand alone system

Rananim

30th Sep 2006, 16:46

For the Legacy to sustain surviveable wing damage in a collision with a 737 it seems likely to be a collision with the vertical stabilizer on the 73.
Very astute.
Would the TCAS need to be operative on the EMB if it was a ferry?Any comments?

PaperTiger

30th Sep 2006, 16:52

Would the TCAS need to be operative on the EMB if it was a ferry?Any comments?I had a similar thought. I believe executive Embraers are delivered "green" to the US (FLL ?) for finishing. I don't know if this includes the avionics fit too - probably - but surely a minimum panel for delivery would include TCAS ? Definitive answer welcomed.

FIRESYSOK

30th Sep 2006, 16:57

Even if the Embraer did not have ACAS installed and serviceable, surely it had a mode C transponder at minimum. That would allow another ACAS equipped aircraft to respond to a threat. Now, it is possible to have ACAS deferred per the minimum equipment list. That would leave no protection whatsoever besides radar with SSR and/or position reporting. Pure speculation at this point to think that any of these situations existed. RIP

Fossy

30th Sep 2006, 17:04

Fossy

30th Sep 2006, 17:18

source: http://www.embraer.com/english/content/home/

IMPORTANT INFORMATION
São José dos Campos, September 29, 2006 – Embraer was informed today of a mid-air collision involving a Legacy 600 aircraft which it manufactured, serial number 965, owned and operated by one of its clients.
According to unconfirmed reports, the collision occurred in the Serra do Cachimbo region, in the State of Pará, Northern Brazil. Following the collision, the Legacy 600 landed at the Cachimbo Air Force Base, with no injuries on board.
Embraer has offered to cooperate with aeronautical authorities in any way possible in the investigations of the cause of this accident. To that end, a team of Company technicians is preparing to leave for the region.

IMPORTANT INFORMATION #2
São José dos Campos, September 30, 2006 – Embraer is deeply moved by the accident involving the 737-800 aircraft built by Boeing, flown by Gol Linhas Aéreas, and a Legacy 600 executive jet, built by Embraer and owned by one of its customers, during a transfer flight abroad.
Embraer joins in heartfelt sympathy with the families of the victims and Gol Linhas Aéreas at this painful moment.
Once again, the Company reaffirms its full support to aeronautical authorities for the investigations leading to an explanation of the causes of the accident.

Broomstick Flier

30th Sep 2006, 17:19

It seems like, that some of you guys have the thinking, that Bizjets are not equipped like an airliner, which isn't the fact at all.

More likely the opposite in some cases, I've seen bizjets that have quite a decent avionic kit.

London Mil

30th Sep 2006, 17:58

It also seems that there is an assumption that two aircraft equipped with serviceable TCAS would not have collided. May I suggest that, given the Uberlingen mid-air, TCAS is not a guarantee in itself.

FlyEGNT

30th Sep 2006, 18:01

Reports of possible 5 survivors found. My thoughts with the families of those lost.

20driver

30th Sep 2006, 18:39

Some years back I read a WSJ article about an TCAS issued alert over Asia. The alert came late and the planes did not have time to respond fully. Turns out it was a good thing. One of the units had a miswired pin. The wires were reversed and this caused the reverse instructions of the desired one to be issued. Seem to remember the article mentioned Rockwell as the supplier of the offending unit.

Could just be a simple equipment malfunction making itself known at a really bad time.

20driver

NigelOnDraft

30th Sep 2006, 19:07

20d... Involved a BA -400, and I'd spoken to one of the crew. As you say, the other aircraft (cannot remember airline involved) had a Alt/ADC => TCAS wiring / logic fault so reporting wrong FL. Was v frightening, as you can imagine, since the "conflict resolution" very nearly actually caused 2 aircraft well separated to collide.

I cannot remember his words, but it was pure fortune, maybe some lateral separation (but very little), and maybe slightly slow reactions on the part of the "other" aircraft, as well as becoming VMC that "saved" the day. Exemplary following of SOPs by both crews could have led to a major (2 x widebody) collision.

However, it was investigated, was sometime ago, and one would hope such an "own goal" has been designed out (as suggested earlier with the checking systems).

I always find it ironic that the light aircraft I fly show on the panel the FL beng pushed out by Mode C.... no airliner I have flown does :{

PaperTiger

30th Sep 2006, 19:17

All Embraer are outfitted in SJC (Sao Jose dos Campus) by Embraer. So the aircraft was fully furnished and even if would not, TCAS is not a system which will be installed during the completion, since it's a standard part on all large aircraft (over 5,7 tons). It seems like, that some of you guys have the thinking, that Bizjets are not equipped like an airliner, which isn't the fact at all.Thank you and no, not what we (I anyway) were thinking at all. I've seen bizjet panels.
A midair is probably the second most frightening prospect (fire is no. 1) we face. How two a/c ostensibly under positive control and with all modern systems can still run into each other simply boggles my mind. There has to be more to it. Please.

ATC Watcher

30th Sep 2006, 19:53

Nigel and 20d : the Gillham box error that caused the incident you are ref to, has been identified and corrected in the meantime and is very unlikely to happen again , and definitively not with modern avionics , as the 2 a/c involved were brand new.

Even if one ACAS unit did not function , was u/s , not fitted, etc.. its SSR +mode C will be enough to activate the other unit and prevent the collision.

So the cause , if indeed there were a collision between those 2, lay probably elsewhere.
If ,as one report indicated, the a/c were level and on RVSM, and if the Go was above the Legacy, many scenari can be drawn. Sudden Decompression is one that come to mind.

Only the FDR/CVR of the 2 will draw some light.

jondc9

30th Sep 2006, 20:25

I have seen airplanes visually prior to getting any indication on TCAS. HOW/WHY? Possible transponder problems, possible blanking of tranponder antenna by wing or other part of plane, indeed some cargo planes only have transponder antenna on bottom, I followed a cargo DC10 for 3 minutes with nothing on TCAS...this may have changed since then as even cargo planes are getting better equipment.

one post indicating the biz jet wing hitting a vital surface is a thought...perhaps too if the biz jet wing hit the canopy/cockpit of the boeing, killing both boeing pilots, add decompression, other failures including an autopilot disengagement and bang.

I didn't see altitudes published if anyone has them...and if there was a collision and RVSM is a component of the cause, maybe we should go back to 2000' at higher altitudes for seperation.

sad crash

jon

aimscabinet

30th Sep 2006, 20:59

if either or both of them were climbing or descending it would have been due to weather.

Just speculating ... I believe CBs in that area can have very high tops, so it would be unlikely that any one of them would be changing levels due to weather.

Local news reports said that the Legacy was cleared to fl 330 and the 737 to 360.

Again, I am not familiar with the region, but based on the probable route of both airplanes, shouldn't the Boeing be flying at some odd level and the Legacy at some even one?
:ugh:

AeroBoero

30th Sep 2006, 21:19

Press at this time is confirming that are no survivors amongst the 155 people on board the 737.

Also, amongst the people on board of the Legacy was a New York Times reporter, Joe Sharkey.

The names of the Legacy crew and passengers are being withheld at this time (exception to the reporter name).

Now is waiting to see what the FDR and CVR contains when they are recovered.

Checkers

30th Sep 2006, 21:40

I have seen airplanes visually prior to getting any indication on TCAS. HOW/WHY?

A TCAS alert is, triggered by either a rate-of-closure limit (Tau) or a proximity limit (DMOD and ALIM). So you could have two aircraft maintain a reasonable separation within visual range, not come any closer (i.e., maintain a large time-to-convergenec) and not have a TCAS alert. However, the intruder should still appear on the display.

Between FL200 and FL420, the tau envelope will be around 48 seconds for a TA and 35 seconds for an RA. Also, a TA or RA will be issued if the aircraft are within ±850feet & 1.3nm, and ±600feet & 1.1nm, respectively. The relative altitude boundaries also apply to the Tau protection envelope (so if one aircraft was transmitting an altitude off by more than 850 feet, an alert might not happen when it would have otherwise).

six7driver

30th Sep 2006, 22:11

I believe TCAS Traffic advisory manoeuvers have a 5 second and 1/4g compliance requirment, strengthened or reversal Resolution advisory manoeuvers have a 3second and 1/2g compliance requirment. Either way have flown much in that part of the world, very common to hear Brazilian pilots talk in portugese to ATC, and talking to English to non domestic Aircraft, which doesn't contribute much to the situational awareness of crews who are operating in the same airspace. Maybe a contributing cause if it was in fact a collision. Sad news.:(

Sou Mineiro

30th Sep 2006, 22:42

Here you can see some images from the place where the GOL aircraft crashed:
http://www.dac.gov.br/salanoticias/noticiasGol.asp
DAC s the former brazilian civil aviation department, succeeded by anac - national civil aviation agency.

rlsbutler

30th Sep 2006, 22:46

May I float the idea of "Cruise Climb" ?

Does anyone in modern civil aviation know what I am talking about ?

If an aircraft captain wants to add a lot of extra miles to a long ferry, the procedure works. Step climbs are a poor relation. I imagine that it would always be difficult to get clearance for the pure cruise climb and, in an area of poor radio coverage, he might say "What the Hell".

I have done this myself long ago (another country – besides, the wench is dead).

This forum has not yet established the destination of the Legacy flight. If it was direct from Sao Paulo to Long Island (the Excelaire base), the ferry would be over 4100 nm. Is that feasible for this aircraft ?

Supposing a captain takes liberties as I am suggesting, he should do the decent thing and sidestep away from any airway centreline. But perhaps the Legacy was (at a narrow angle) crossing the 737, to route East of Manaus.

Changing the subject: closing, head on, does the TCAS in each case direct a clearing turn in accordance with Rules of the Air or is there an attempt to increase any height separation ? If so who goes up and who goes down ? With the aircraft closing at more than 10 nm per minute and with huge turning circles, is the current TCAS system able effectively to resolve the hazard ?

Broomstick Flier

30th Sep 2006, 22:46

RiverCity

30th Sep 2006, 22:50

What do you folks make of this?

Its pilot reported seeing, "out of nowhere, a large shadow" passing his plane.

Could there have been a third plane, one which did not want to be seen, flying dark? Or is there a possibility that the 737 somehow lost its nav lights? Far out, I know, and maybe the ferry pilot is trying to save his @<hidden>, but perhaps others on the ferry plane might have something to say about it.

Broomstick Flier

30th Sep 2006, 23:01

rlsbutler,

The ferry flight was routed SBSJ-SBEG-onwards (probably KFLL). Cruise climb is not an usual procedure on this particular airspace, and I doubt the pilots of the Legacy had this in mind.

RiverCity,

At the time radar contact was lost with the B738, it was around 1940Z/1640LT, so not dark yet. What is really puzzling is the fact that no information on the ATC actions prior the accident have been made public.

jondc9

30th Sep 2006, 23:22

scurvy

yes I can see your point regarding upset and RVSM...more details willhelp clarify.

CHECKERS, regarding TCAS, our TCAS system was very advanced and not just one that issued alerts. to those who dont' know, some TCAS sytems can display planes farther out than the minimum required by technical order...indeed some TCAS can and will only show alert traffic and resolution advisory...not other planes.

eventually the DC10 mentioned did show itself as we went to one side of centerline...aparently empenage was blocking transponder signal. cargo planes at one time did not need TCAS and did not need to have more advanced transponder antenna mountings on both top and bottom

And what if either of these brand new planes had tansponder antenna wiring faults not previously noted...as on top of the plane...ATC would probably work fine on bottom. who else would know?

satpak77

30th Sep 2006, 23:52

any chance the crews over-reacted to a TCAS alert bent their airplanes, causing damage to both, one obviously resulting in a crash.

When jet aircraft can be brought down by seagulls, and I see a RJ hit a 737, and land safely, with no injuries to occupants, in cruise flight, Mach .78 or so, but the 737 crashes, I gotta wonder....

the CVR's will be interesting

satpak77

1st Oct 2006, 00:04

Brazilian CAA made public the first images from the crash site:

http://aerovisionphotos.com/photos/acidenteGOL3.jpg

http://aerovisionphotos.com/photos/acidenteGOL2.jpg

Very dense forest and I can see no sign of fire

remember, this is a 737-800, one of the biggest 737's made. You can barely see the wreckage. the trees are 20+ feet tall. Along with ants, jaguar cats, monkeys, boa contrictors, etc.

lovely

Its been a few years since I flew in and out of Manaus, but that whole area is mostly non-radar, and ATC is poor quality, at least back in 2000, 2001 time frame. I do recall looking down at the jungle and checking the oil temps and PSI every 5 minutes. I would rather crash in the ocean than the rain forest.

at least people can come rescue you in the ocean

no joke

** I don't see any obvious signs of a fire, nor any apparent tree damage, consistent with a flat pancake style crash.

Wonder if they even crashed with the wings (fuel and engines) attached to the airplane.

CHIVILCOY

1st Oct 2006, 00:04

Brazilian CAA made public the first images from the crash site:
http://aerovisionphotos.com/photos/acidenteGOL3.jpg
http://aerovisionphotos.com/photos/acidenteGOL2.jpg
Very dense forest and I can see no sign of fire
Unusual pictures, not the usual destruction of a severe impact crash site one would expect to see.

jondc9

1st Oct 2006, 00:26

from a UK times online article just posted:

<<There was confusion over the part that may have been played in the disaster by the executive jet, an Embraer Legacy. Its pilot was reported to have said: “I practically did not see the plane. When I saw something it was nothing but a shadow. I felt a shock, which made me lose part of a wing.”

However, radar showed the two planes flying about 1,000ft apart. The federal aviation authorities refused to confirm that the crash and the emergency landing were linked but aviation experts said the 737 may have been taking evasive action. >>

''shock made me lose part of the wing''...still an amazing event...I recall when TCAS first came out I asked: what if you get a TCAS RA that says climb and you are already at your max altitude?

a good answer was never forthcoming

pull up into a massive stall/upset?

by the way, TCAS does not give turning solutions, yet.

after a plane loses an engine, part of the checklist is to switch TCAS to Traffic Advisory only as you no longer have the performance capability to respond to all TCAS RA's.

Viator Curiosus

1st Oct 2006, 00:43

The 737 don't generally have fuel dump systems, can the 737-800 dump fuel?
Would the pilots then have dumped, or been able to dump, fuel in an attempt to avert a fire on crashing?

I am not sure, but judging by the first picture and the markings, it looks like a part of the forward section of the main fuselage. Where is the rest in relation to this section?

My thoughts are with the families.

VC

broadreach

1st Oct 2006, 00:58

"News" is beginning to seep out. On a local aviation forum there's the following (free translation):

According to a CAB specialist the American Legacy pilot said, during the post-accident debrief, that he'd decided to climb from FL370 to FL390 to gain speed and range, without informing ATC, and that he'd switched off the transponder (for reasons unknown). That would have impeded the 737's TCAS from reacting to the Legacy's presence and delayed ATC's warning that a collision was imminent since, with the transponder off there would be a lag for radar to correctly track the Legacy.

Please note, a very free translation, picked up second-hand. The original text follows for any who might care to dispute it:

Quote
Segundo um especialista da Aeronautica, no depoimento, o piloto americano do Legacy disse que teria decidido subir do FL370 para FL390 para ganhar autonomia e velocidade e não teria avisado o controle da força aérea e também desligou o transponder (motivo desconhecido), impedindo assim que o TCAS do avião da Gol funcionasse e que os controladores pudessem avisá-lo com antecedência do choque iminente, visto que com o transponder desligado o radar demora para obter informações da aeronave.
Unquote

Along with all the unbiased speculation surrounding this accident there will undoubtedly be an increasing element of biased speculation, with blame thrown about, particularly when the lawyers get involved. The Legacy crew will be at the centre of this. Don't, however, knee-jerk and write off the above as the beginnings of an ass-covering exercise; assume that the debriefing people would have most likely have been airforce, pilots, fluent in English and focussed only on gaining whatever knowlege/insight was available as quickly as possible, without regard for blame. Keep that in mind; ass-covering will come soon enough.

And, just speculation on seeing the first aerial photos and what seems like absence of fire: if the aircraft went in pretty much vertically from fl 300+ as some reports have said, it could well not have been intact at all, i.e. little fuel in the hot parts. Whatever explosion there might have been would spread outwards and, in a wet forest of trees 30+metres high, leave little evidence visible from the air.

6000PIC

1st Oct 2006, 01:22

...And if that`s the case , he`s had his last flight.

jondc9

1st Oct 2006, 01:23

broadreach

if your information is true, this will be one of the most heinous breaches of IFR procedures in history. I would not rule out jail time for pilot if true.

again only IF TRUE

while I don't doubt the veracity of broadreach, as we all know, early reports can be wrong.

AeroBoero

1st Oct 2006, 02:03

Unfortunately these sorts of procedures are not uncommon between the pilots here. Switching of the transponder and going to a different altitude or level than the one assigned is not uncommon. There was a Brazilian pilot inside the Legacy.

IF - and I repeat - IF this is true..it can be explained why such modern equipped aircraft collided in flight.

Add also the language problem. We mainly speak Portuguese in R/T here. Could also have been a factor.

Pom Pax

1st Oct 2006, 02:33

A photo of what would appear to be part of the fin and in the wider view perhaps some other parts would to me suggest a debris field.
Explosive decompression has been mentioned, the Lockerbie debris trail was about 70 miles long.
Reports of seeing "aircraft" flying at low altitude, larger pieces of debris viewed at a distance could give the impression of "flying" still having forward momentum.

Bokomoko

1st Oct 2006, 03:10

Unfortunately these sorts of procedures are not uncommon between the pilots here. Switching of the transponder and going to a different altitude or level than the one assigned is not uncommon.
I've never heard it before with airplanes flying on upper levels and under radar control, and sorry mate, but based on your statement all Brazilian pilots are a bunch of irresponsible and stimulate that kind of procedure...:mad: :yuk: There was a Brazilian pilot inside the Legacy.
When an aircraft has any problem with its transponder Brazilian ATC controllers immediately request a check and if it remains on primary mode they usually inform to all essential traffic including its altitude and direction. Ok, Brazil has many problems including poor English communication but so far its reputation in terms of aviation safety is still one of the best of the world.

cesar

1st Oct 2006, 03:29

It´s in the Brazilian press, O Globo newspaper - link below, that both crew (Pilot Joe Lopore and co-pilot Jan palldino) and pax (Henry Yendle, Ralph Michielli, New York Times reporter Joe Sharkey, David Rimmer and Daniel Bachmann) on the Legacy were American.
After being intervied by Brazilian military in the air force base where the jet landed, they were ferried in an Embraer jet to the city of Cuiaba in order to be heard by the police. "O Globo" also reports that all seven only left the plane in Cuiaba about half an hour later, after another Legacy aircraft (carrying the American Vice-consul and an Embraer attorney) landed there.

The link (in Portuguese):

http://oglobo.globo.com/pais/mat/2006/09/30/285915657.asp

misd-agin

1st Oct 2006, 04:26

According to a CAB specialist the American Legacy pilot said, during the post-accident debrief, that he'd decided to climb from FL370 to FL390 to gain speed and range, without informing ATC, and that he'd switched off the transponder (for reasons unknown). That would have impeded the 737's TCAS from reacting to the Legacy's presence and delayed ATC's warning that a collision was imminent since, with the transponder off there would be a lag for radar to correctly track the Legacy.

********************************************************

Not a lawyer but if this is true I wouldn't be surprised if they're charged with murder/manslaughter/etc.

satpak77

1st Oct 2006, 04:49

...And if that`s the case , he`s had his last flight.

something like that would probably cause the wheels to get into motion for local prosecution of criminal negligence, etc

Dr. Red

1st Oct 2006, 04:52

I recall when TCAS first came out I asked: what if you get a TCAS RA that says climb and you are already at your max altitude?
a good answer was never forthcoming
Try this ACAS II Bulletin (http://www.eurocontrol.int/msa/gallery/content/public/documents/acas/ACAS_Bulletin_1.pdf) which seems to answer your question. Refer to events 5 & 6 (pg. 3). The conclusion is... "DO NOT react contrary to an RA [but] if there is some doubt of the ability to respond to a “Climb” RA, at least remain level, do not descend."

I'm sure we can all think of scenarios where this is not the ideal answer, but it seems the 'least bad' choice, all else being equal. Hope this is of some help.

Loose rivets

1st Oct 2006, 05:44

The sad fact is that, since time immemorial, crews have been shoving up, down and sideways to effect some personal advantage. Almost always, the holes don't line up.

etrang

1st Oct 2006, 06:44

Right Way Up

1st Oct 2006, 07:14

Misd-agin,
If and this is a big if, this scenario is true, I only think manslaughter charges can be brought as murder requires intent.
I have been told that this sort of thing happens alot across Africa especially during a certain season.

HEATHROW DIRECTOR

1st Oct 2006, 07:42

<<he'd switched off the transponder (for reasons unknown). That would have impeded the 737's TCAS from reacting to the Legacy's presence and delayed ATC's warning that a collision was imminent since, with the transponder off there would be a lag for radar to correctly track the Legacy.>>

There would be no "lag" that would of consequence if a return was visible. There are two types of radar but I do not know if Brazil ATC has both - Primary radar shows a response whether or not the a/c has a transponder and secondary shows coded returns from a/c transponders - usually displayed as a label beside the radar target of the aircraft. The display to the controller in each case is updated very frequently - certainly frequently enough for ATC to safely handle extremely busy terminal areas. If the ATC radar does not display primary returns then an a/c with no transponder will not be seen, ie if the pilot switches off his transponder the radar information is lost completely, although a trace of the a/c track could remain for a minute or so. In a positive control situation, if an aircraft disappears from radar for no reason then ATC will attempt to find out why.

As for pilots switching off transponders and changing their flight levels without ATC clearance... such utter irresponsiblity beggars belief.

Capt Pit Bull

1st Oct 2006, 07:57

Jondc9

A few answers for you:

A couple of pages back you asked why sometimes you can see traffic but it isn't displayed.

Its certainly possible that there may not be line of sight to antenna, although less likely now that an upper antenna is required as well as a lower. Much more likely is "Interference Limiting Mode" where in, as part of the overall design strategy of reducing the ammount of ssr transmissions (to decongest the frequencies), TCAS does not continuously interrogate all intruders. Unless the aircraft is in full time tracking, it is not displayed. TCAS may, for distant traffic, or medium range traffic that is closing slowly, and even for fairly nearby traffic that the range is opening on, decrease the interrogation rate. Interference limiting mode is invoked when the TCAS reckons the ssr freqs are becoming congested, so typically in higher traffic densities. If you've ever seen more than 1 blip disappear at once, thats probably interference mode kicking in. [reference - manufacturers bulletin - TCAS: Common causes for traffic disapearance]

I recall when TCAS first came out I asked: what if you get a TCAS RA that says climb and you are already at your max altitude?

a good answer was never forthcoming

pull up into a massive stall/upset?

I ought to be surprised that a good answer was never forthcoming, but sadly I'm not. It seems that a sizeable part of the community feel "TCAS - if you get an RA, follow it" meets the necessary knowledge level and neatly ticks the box in the training requirement.

Firstly, TCAS has inbuilt performance based inhibitions. Based on possibly several inputs, increase climbs and climb RAs can be inhibited.

However, these inhibitions are not comprehensive and ultimately the Pilot has an overriding requirement to protect the aircraft. The answer to your question is the same as to any other RA that presents Hazard: Get as close as you can to the RA, and whatever you do don't manoeuvre opposite. Even if you can only get another couple of hundred feet, its worth doing. Bear in mind RAs only nudge you a few hundred feet from your original flight path (unless the other guy manoeuvres towards you). We are not in the realms of zoom climbing thousands of feet.

As Dr Red quotes in fact.

etrang,

Can anyone explain what possible reasons a pilot might have for switching off a transponder?

Apart from when being naughty of course. Still seem to be a few folk around that turn to standby when changing code, not sure if that practice has been stamped out yet. The other reason will be as per anything else electrical - if it, or some other box nearby, has got smoke pouring out of it.

I hasten to add that non of the above is intended to be comment on this accident, but rather answering TCAS related questions that have been raised.

pb

M609

1st Oct 2006, 08:34

As for pilots switching off transponders and changing their flight levels without ATC clearance... such utter irresponsiblity beggars belief.

If correct, lock him up, and throw away the key! :mad:

woodpecker

1st Oct 2006, 08:41

A few years back, during a very smooth Atlantic crossing, someone (never did find out his callsign) on the chat frequency was asking for ride reports at 36000' having just passed 30W. All the responses were "smooth ride" all the way across. One American pilot, who it would seem had worked out that he was two minutes ahead of this traffic and at 37000' on the same track suggested perhaps he was sitting in his wake turbulence (remember vortices descend at about 500'/min).
The chap thanked him for the information and suggested he had tried cruising 500' higher and it was much better. The frequency was then bombarded by others wanting to know who he was and why he was not adhering to is cleared cruising height! He decided not to offer the information.
I hope the American pilot in front of him, who was one of many asking for his callsign, took it further.

BEagle

1st Oct 2006, 08:49

"The supposed reason being that if you are not quick enough changing the code, the box automatically goes to standby."

Huh? No understand. I thought the problem was that if you are interrupted during squawk change, you may display an incorrect squawk. How does 'the box' know when it should 'automatically go to standby'?

We've had 'active' and 'stby' VHF NAVCOMs with changeover buttons for years - why don't many transponders do this?

In an aircraft I'm involved with, the centralised system has a transponder page. The new squawk is entered with the rotary knob and then transferred to the active window by pressing the line select key. None of this 'going to standby' business! And it is not possible to switch off the transponders either!

I cannot believe that any professional pilot would deliberately switch the transponder off and lie about his real flight level......

dudduddud

1st Oct 2006, 09:09

Anyone care to guess why he would have done that? Language barriers? Does Brazillian ATC regularly deny foreign a/c more optimum cruise levels? Might the plane not have been properly equipped for flight at those levels?

rlsbutler

1st Oct 2006, 09:48

According to the maker’s blurb, the Embraer Legacy 600 with full fuel should have made Sao Paulo – Long Island with one intermediate stop anywhere between Manaus and Puerto Rico. With 7 passengers and crew, they should have offloaded some fuel and so narrowed that choice of staging airfields. If as Broomstick Flyer reports (#70) they intended to land at Manaus, they would have had no practical reason to squeeze range and speed performance by climbing illegitimately. But they would almost certainly have had to make another stop - Fort Lauderdale for instance as BF also suggests. By climbing beyond Manaus they might have made the ferry’s three stages into two. Any sign that they refiled after take off – to land at Caracas for instance ?

Notwithstanding BF, I suggest again that, once the captain in such a situation goes over to the wild side, he would get what he is looking for more effectively by cruise climb than by a step change of altitude. How he covers his tracks is another matter.

brain fade

1st Oct 2006, 09:59

QDMQDMQDM

1st Oct 2006, 10:08

Capt Pit Bull

1st Oct 2006, 12:11

Blackcap,

Thanks for the info. And without in any way wishing to shoot the messanger, I'm horrified.

I don't understand the design philosophy in the first case. A transponder head that Turns Off the active squawk because you get interupted changing it? Thats almost incredible. I can't see any rationale for that. Make the standby code blank, make it flash, I'd even at a push accept the box reverting to conspicuity, but standby? <boggles>

So there is now an SOP whereby, during an emergency descent, the need to set 7700 is making the aircraft invisible to ATC and other aircrafts TCAS, and incidentally also disabling the aircrafts own TCAS. Thats insane, even if its only for a few seconds.

I don't suppose you could offer the manufacturer and model of the control head?

pb

Flight Safety

1st Oct 2006, 12:14

Since these were both brand new aircraft (200 hours for one, and ferry delivery for the other), I thought of another possibility.

Many years ago now, I knew of a concept in electronics known as "infant mortality". The idea was that brand new electronics experience a higher failure rate than equipment that is still new, but has been in service for several weeks or months. Similarly, sometimes new owners of brand new (just delivered) autos sometimes have to sort out problems before the autos perform correctly.

In the airline business, do you guys experience similar issues where you sometimes have to sort out a brand new just delivered aircraft? I'm not talking about sorting out a brand new model just introduced, but rather sorting out a brand new line aircraft of an existing model, where the existing model has basically been sorted out.

Could any brand new aircraft issues, have contributed in any way to this accident?

Gregm001

1st Oct 2006, 12:31

Since these were both brand new aircraft (200 hours for one, and ferry delivery for the other), I thought of another possibility.

Many years ago now, I knew of a concept in electronics known as "infant mortality". The idea was that brand new electronics experience a higher failure rate than equipment that is still new, but has been in service for several weeks or months.

I was of the belief that most manufacturers will burn in equipment, which will take it past this phase. Also the life cycle is sometimes described as being like a U curve, with very high failure rates at the beginning of the lifecycle and also very high hfailure rates at the end of the lifecycle.

Capt Pit Bull

1st Oct 2006, 12:47

Forget,

Thanks for that.

Well, at least its good to know that its not intended to work that way.

Though the AD requires crew to check its functioning correctly after a 4096 change. As I read it the AD does not require a change to SBY whilst making a 4096 change.

pb

G4G5

1st Oct 2006, 13:40

My question would be,

If the pilots admited to placing the transponder in STBY, what happens to them now? Under Brizillian law can they be charged for a criminal act?

WindSheer

1st Oct 2006, 14:07

Thoughts and wishes to all the families involved....:(

Given the a/c types involved in this incident, it should not have happened!
Sadly it has happened, and will happen again...!

aimscabinet

1st Oct 2006, 14:25

I am not a commercial pilot, but if these two aircraft were on an airway on reciprocal headings isn't this accident an argument for an SOP of cruising on an offset track, say by 1NM? Even, extraordinarily, over the Amazon basin.

QDM

In fact, in some parts of the world (Africa, NAT, India, Bangladesh), ICAO recommends the use of the offset track. What we do is to set one or two miles (usually one) right of track on the FMC and voilà ... you have a decent lateral separation from the opposite traffic.

fox niner

1st Oct 2006, 14:26

:ooh: Please, someone...Tell me it isn't true that the ferry-flight guys turned off their transponder AND climbed to another flight level...someone??

I - can - not - be - lieve - it!!

unheard of, ever!

That is the same as driving a car on the wrong side of the road with your headlights off, at night!

CaptainSandL

1st Oct 2006, 14:35

Scurvy,

The mods for the SFP include the following:

• Flight spoilers to be capable of 60 degree deflection on touchdown by addition of increased stroke actuators. This compares to the current 33/38 degrees and will reduce stopping distances by improving braking capability.
• Slats to be sealed for take-off to flap position 15 (compared to the current 10) to allow the wing to generate more lift at lower rotation angles.
• Two-position tailskid that extends an extra 127mm (5ins) for landing protection. This allows greater angles of attack to be safely flown thereby reducing Vref and hence landing distance.
• Main gear camber (splay) reduced by 1 degree to increase uniformity of braking across all MLG tyres.
• Reduction of engine idle-thrust delay time from 5s to 2s to shorten landing roll.
• FMC & FCC software revisions.

There may be others that I don’t know about but I would doubt that they would be significant. My point is that none of the above should have any effect on stall margins on a clean wing.

S&L

aimscabinet

1st Oct 2006, 14:36

My question to you is unrelated to the TCAS thing:

So, you have flown in that area? What sort of flight levels would you guys fly from Sao Paulo? It appears that you would be flying Northwestbound, thus EVEN levels, is that right?
I read a few guys talking about the fact that the legacy would be flying at some odd level. Could you elaborate on that?

God bless them all

Many thanks

jondc9

1st Oct 2006, 15:28

one more thing about TCAS:

In the three types of planes I flew with TCAS,the transponder had to be selected to TCAS position (TA or RA) thus turning on the tranponder & TCAS

should the legacy pilot have turned the transponder off or to stby the legacy pilot would have turned off his TCAS unit denying himself a TCAS warning while cloaking his plane to other TCAS units & ground secondary radar.

unfamiliar with Legacy

thoughts?

Zero"G"

1st Oct 2006, 15:33

Unfortunately these sorts of procedures are not uncommon between the pilots here. Switching of the transponder and going to a different altitude or level than the one assigned is not uncommon.

By all means incorrect information and absurd statement.I flew 32 years in major Airline in Brazil and never even heard such a thing.
Airline Pilots and training in any Airline in Brazil,will dump you to the lions,even if you think about it.
Who the hell do you think you are to make a statement like that?
The name says it all...aero bueiro..piper cub like plane..He has no clues to what he is talking about.Just a imature individual afirming something he has no idea how the training and operations of any airlines work.

Shame on you!

misd-agin

1st Oct 2006, 15:33

All we have so far is - "According to a CAB specialist the American Legacy pilot said, during the post-accident debrief, that he'd decided to climb from FL370 to FL390 to gain speed and range, without informing ATC, and that he'd switched off the transponder (for reasons unknown)".

None of this makes any sense. Neither the act - or the (seemingly immediate) admission. If a guy is capable of making himself deliberately TCAS invisible in order to stretch a few miles extra range then he's more than capable of lying to cover his tracks when found out.

............without informing ATC, and that he'd switched off the transponder (for reasons unknown)".

I smell mucho rats here.

Thats' why I put "if true" in my post. So far it's just that one report. News report today has a quote "we were at FL370..."(paraphrased). Full investigation to follow...

It doesn't make sense. But unfortunately non-sensical stuff does occur.

misd-agin

1st Oct 2006, 15:37

A few years back, during a very smooth Atlantic crossing, someone (never did find out his callsign) on the chat frequency was asking for ride reports at 36000' having just passed 30W. All the responses were "smooth ride" all the way across. One American pilot, who it would seem had worked out that he was two minutes ahead of this traffic and at 37000' on the same track suggested perhaps he was sitting in his wake turbulence (remember vortices descend at about 500'/min).

Contrails don't descend much, if at all.

I've had to offset slightly to avoid turbulence from contrails. Offset out of the contrail and the ride improved immediately.

misd-agin

1st Oct 2006, 15:44

Jon Dc9

Re RA at max alt. If it says climb- you climb. Absolutely. That is sop in my company and I am an Embraer pilot.

because.......

Max cert FL in the -145 is 370 at least in our company but I know the a/c can be ferried safely at up to FL410 in order to gain range etc. It's not illegal as it's a non-revenue flight. Therefore a bit of a pull-up even at maxalt is a bit of a non event.

If the -145 pilot needed or wanted a higher FL he only needed to ask. So I see no reason for him to turn off the squawk. After all if the reason for no climb was because the higer FL was occupied by the 737, he'd hardly want to go up there, would he?

High altitude flight makes a/c weight very critical, especially at higher AOA(slow, G's, turning). Speed can literally mean life (Pinnacle ferry flight crash).

"Therefore a pull-up even at maxalt is a bit of a non event." Caution is advised if you're at, or close to the max altitude the a/c can be flown at for that weight, regardless of what it's certified to.

Every year several(many?) flights have altitude/speed issues caused by flying to high for a given weight or too slow for the altitude and/or weight.

jondc9

1st Oct 2006, 15:50

apu hunter

I by no means wish to question your statements about transponder use, but if you have never seen it and the other chap has, it is possible. perhaps not widespread, perhaps only a few bad eggs. again, I find the idea of cheating on altitude/transponder very troubling.

Many,Many years ago a movie on this subject came out called, "THE CROWDED SKY" with Dana Andrews as an airline pilot who cheats by 500' in a DC6 or 7 ,can't remember, and ends up in a MAC with Efrem Zimblist Jr. Flying a navy version of a T33.

also, in the USA I have seen a pilot or two turn off altitude reporting if going through an asigned altitude and correcting to avoid trouble with ATC/FAA.

I didn't respect those guys either.

brain fade

1st Oct 2006, 16:23

misd again

1.It was a ferry so unlikely to be heavy.
2. the a/c can easily climb to FL 410
3. Even if the above 2 don't apply, once the a/c picks up a bit of speed the manoevre is easily accomplished.

The Emraer is unusual in that it CAN take off at MTOW and climb straight up to FL370.

Our company advice is firm. Even at max cert alt (FL370)
FOLLOW THE TCAS!

I don't even wish to hint at not following it. All doubt was removed after the terrible Swiss MAC.

Khaosai

1st Oct 2006, 17:27

Broomstick Flier

1st Oct 2006, 17:37

Brazilian Air Force just released the first images from the Legacy

Judge by yourself:

http://www.dac.gov.br/salanoticias/fotos/legacy4_fab.jpg

http://www.dac.gov.br/salanoticias/fotos/legacy2_fab.jpg

http://www.dac.gov.br/salanoticias/fotos/legacy1_fab.jpg

http://www.dac.gov.br/salanoticias/fotos/legacy3_fab.jpg

For me it looks very unlikely that the Legacy is responsible for the 737 crash, unless a 100cm piece of winglet is enought to bring it down.

I guess that this images and the lack of distress call from the Gol crew points to a very sudden problem with the Boeing..

Food for thought, for sure

Mr @ Spotty M

1st Oct 2006, 17:44

Have a look at the second picture, it looks like the tip of the horizontal Stab also hit the B737.

TransonicDrag

1st Oct 2006, 17:47

For me it looks very unlikely that the Legacy is responsible for the 737 crash, unless a 100cm piece of winglet is enought to bring it down.

I guess that this images and the lack of distress call from the Gol crew points to a very sudden problem with the Boeing..

Food for thought, for sure

A 100cm piece of dense composite hitting a light-weight aluminium skin at 1000 knots? I think that would hurt.

GOLF-INDIA BRAVO

1st Oct 2006, 18:01

Not being an expert, a thought! would it not depend on where the contact was made on the Boeing, say the rudder , an aileron or leading edge of a wing
which could affect the stability of the aircraft

G-I-B

172driver

1st Oct 2006, 18:04

Now wait a minute - where and how would the 737 have to be hit by the winglet to be brought down :confused: Looking at picture 2, there are, IMHO, two possible scenarios:

1) the part of the winglet that was sheared off hit the stab
2) the wing of the 737 hit the Legacy winglet and the 737 winglet (assuming this particular one has them) hit the stab.

While I'm not a heavy-iron driver, I cannot really imagine either scenario to be enough to bring a 737 down. :confused:

Ex Cargo Clown

1st Oct 2006, 18:05

One or both of the aircraft weren't in straight and level flight.

To clip the edge of the wing and the edge of the stab is impossible if they were both level.

I'm trying to work out the geometry of the collision, and it must involve either a violent climb or steep turn from one or the other aircraft.

Profit Max

1st Oct 2006, 18:13

What about the engine of the 737 hitting the Legacy winglet, and the winglet of the 737 hitting the Legacy stab?
But probably the wing of the 737 is too long for that.

HyFlyer

1st Oct 2006, 18:17

Read the thread, and just wanted to correct a few wrong images.

Legacy (the new verion) with the A1E engines can carry full fuel and 8 pax.
This Legacy version (same as in accident) can also climb from MTOW direct to FL390.

As aircraft was ferrying back to US (New York) it probably didn't need to take off from Sao Jose with full fuel, as it would have to do a re-fuel along the way anyway, (max range with full fuel and 8 pax is 3,250nm (at M0.74) or just a little over, subject to final completion weight and cruise speed.--MTOW take off, at up to 37C as engines have a high flat rating) and if crew were so keen on best cruise, then judging fuel load, with only 7 pax aboard , would have probably given them capability of getting the FL410 (the ceiling for this aircraft) fairly quickly. However, as I don't know the refueling airport I can't judge this. Likely cruise speed (and we can wait to get the actual data) would be around M0.78/M0.79....

Loved the line comparing a Legacy with a Lear 45.....like comparing a Bentley with a mini cooper !

Find it very hard to believe that any pro pilot who'd turned off TCAS to climb to non approved FL, would then admit to such in public, after causing a mid-air......let's wait for the FDR to tell this little tale......

The Legacy winglet is composite, with a small metal bracket, the tail section is however more substantial, but it only seems a fairly small section was lost.

I had friends on that Legacy, and am only glad to learn they are safe. It is however, so terribly sad that so many perished on the 737. Lets just hope that the search finds some alive eventually......

flash8

1st Oct 2006, 18:20

[I]

In fact, in some parts of the world (Africa, NAT, India, Bangladesh), ICAO recommends the use of the offset track. What we do is to set one or two miles (usually one) right of track on the FMC and voilà ... you have a decent lateral separation from the opposite traffic.

Need (minor) Random offsets built into the FMC, been saying that for years.

DH121

1st Oct 2006, 18:21

Maybe the 737 was overstressed in trying to avoid the collission?

Ex Cargo Clown

1st Oct 2006, 18:22

What about the engine of the 737 hitting the Legacy winglet, and the winglet of the 737 hitting the Legacy stab?
But probably the wing of the 737 is too long for that.

The wing would have gone through the Legacy's stab.

Does anyone know the kind of forces that would cause a structural failure on a Legacy winglet ?

There is something very fishy about all of this, the 737 would have had an awful lot more momentum than the bizjet and as anyone who has seen a prang on the apron knows, winglets are pretty frangibile structures. I cannot imagine many parts of a 737 not being able to lop off a winglet with only minor damage.

Ex Cargo Clown

1st Oct 2006, 18:25

Last second Hi-G collision avoidance, in a Right turn the starboard side would be under most Centrepetal force and would therefore be under most stress.

Failure of the winglet and outer side of the stab ???

Anyone know what kind of force this would need ??

jondc9

1st Oct 2006, 18:28

hy flyer

I too would be surprised if someone admitted turning off transponder to illegally change altitude.

looking at the number 2 picture does show damage to horizontal stab as well as the winglet.

legacy was quite lucky, a few more inches on the stab and they might have lost control.

if the legacy was in a steep left turn, or it was crossing at a 90 degree angle to boeing, the winglet or the stab might have hit the cockpit/canopy of the 737 killing the pilots.

hyflyer, I do hope you will post what you learn from your friends regarding the transponder scenario.

tragic to be sure...

I've been in the jumpseat observing how a crew handled a near mid air ( with a toy balloon, but boy did they jump),I spotted it, called a toy balloon at 11 o'clock, I can imagine spotting a plane and over controlling the plane I was in to react to something unexpected at such a flight level.

j

Rippa

1st Oct 2006, 18:30

Sorry to hear of this tragic event.
I spent 10 weeks flying in this area back in 99 and if my memory serves correct it is an area which requires IFBP. Things however may have changed since then.
Condolences to those involved.

Khaosai, that area had a lot of improvement since 1999. At mid 2002 I belive, the Porto Velho center, Manaus center and Belem center were merged into Amazonico (amazonic) center. At this time, Amazonico center has full radar survillance and VHF service (no HF anymore), in order to prevent drugs from getting in Brazil via air, from unknown traffic, witch was pretty normal a few years ago!! In fact, there is a policy of shotting down airplanes that are unknown...(after intercepting, etc...).The most recent news here in Brazil reports that the Legacy had switched off the transponder in order to go up....(I dont buy this one....). Very sad moment for Brazilian aviation!

TransonicDrag

1st Oct 2006, 18:47

The wing would have gone through the Legacy's stab.

Does anyone know the kind of forces that would cause a structural failure on a Legacy winglet ?

There is something very fishy about all of this, the 737 would have had an awful lot more momentum than the bizjet and as anyone who has seen a prang on the apron knows, winglets are pretty frangibile structures. I cannot imagine many parts of a 737 not being able to lop off a winglet with only minor damage.

The winglet is about a feet wide. Now imagine that such a winglet hits in its strongest direction a fuselage which is itself not very strong. A fuselage is build to withstand the pressure difference and the flight loads, but not intended to have high area pressure.
It's like a a sharp knife cutting through the metal. Think of apron damage.

Profit Max

1st Oct 2006, 19:00

It is possible even in level flight that the two collided causing the damage as in pic 2 above.
I made a simple illustration:
http://i101.photobucket.com/albums/m70/profitmax/738andLegacy600.png

If the picture can't be seen, it is saved here:
http://s101.photobucket.com/albums/m70/profitmax/?action=view&current=738andLegacy600.png&refPage=&imgAnch=imgAnch1

Profit Max.

172driver

1st Oct 2006, 19:20

Profit Max this is exactly the scenario I had in mind - you just did a great job illustrating it :ok:

Now, the question remains - would that be enough to bring the 737 down ???

HyFlyer

1st Oct 2006, 19:26

Does anyone know the kind of forces that would cause a structural failure on a Legacy winglet ?

Having seen great pix of one taken off on the tarmac in South Africa I can say that any 8 year girl fed on minimum 2 decent meals a day could do some serious damage to it !

Love the word frangible....just about sez it all......

international hog driver

1st Oct 2006, 19:26

Forces required to remove a winglet are not that much I have a pic of a BBJ winglet left in the horizontal stab of another aircraft on taxi.

The leading edge cuts in like a knife through butter but once it hits something hard (Spar etc) then the composites come apart pretty easily.

Given the closure speed head to head would be 1600km + then a winglet will go through the front a 737 with no problem, if it went right in the front it would go through the cockpit floor and subsequent control cables before it hit the nose gear support structure and entered the e&e bay. Game over after that.

I had a look at my NG FCTM for non normals and basically is say your on your own.

All conjecture at this stage anyway those 3 view pics could certainly be different if the 737 had even just a little bank on it….., some one hit something over Brazil and a lot o people have lost their lives, the final report will certainly make for interesting reading.

HyFlyer

1st Oct 2006, 19:30

hy flyer
hyflyer, I do hope you will post what you learn from your friends regarding the transponder scenario.
j

I'll post anything real and worthwhile for aviation safety f and when I have it...but even though the site is called PPRUNE put the emphasis on the PP rather than the R.

Fly straight, blue side up and transponder ON!

nooluv

1st Oct 2006, 19:38

Profit Max. Your scenario is possible apart from the fact that the collision would have occurred on the right side of the 738!

regards nooluv.......

Profit Max

1st Oct 2006, 19:44

Profit Max. Your scenario is possible apart from the fact that the collision would have occurred on the right side of the 738!Couldn't find pictures of the Legacy from behind - imagine the 738 coming towards you and the Legacy flying away from you.

Obviously, there will be other possibilities of how an impact could have happened. I just wanted to illustrate that even if both planes fly level, are on the same FL, flying in exactly opposite directions, the damage as observed on the Legacy can be explained.

P.M.

Danny

1st Oct 2006, 19:59

This thread is about to get shut down. Far too many indications of enthusiasts debating the scenarios whilst showing a severe lack of even basic physics understanding.

If you don't understand the concept of kinetic energy then please leave this debate alone. Those that fail to grasp even the rudimentary idea that a collision, whether it was just a winglet striking another part of a bigger aircraft or whatever, involves tremendous forces. It's not Hollywood fantasy.

Perhaps the easiest example is why can a bullet that weighs only a few grammes pass through sheet metal? Precisely why a winglet or any other part of an aircraft striking another aircraft, especially head on can do tremendous damage even if only the winglet or a small part of the empennage is what you see in the photos.

So, please, if you're going to speculate at least do a bit of basic study before making me and no doubt many others cringe with embarrassment before posting such ill informed comments or conclusions. It was a requirement that you at least had some basic grounding in physics before you could get your ATPL licence and too many posts on here are showing up the posters as obviously not having those basic requirements yet feel they can take part in the debate. Well, no thank you. I may still have to restrict this forum and threads such as this to those with the qualifications to at least hold a professional licence. :=

ATC Watcher

1st Oct 2006, 20:01

I would have thought that by now the Brazilian ANSP would have released at least the last clearances issued to both aircraft to eliminate any ATC mishap possibility.
Anyone has heard or seen anything in the Brazilian Media on this issue ?

Ex Cargo Clown

1st Oct 2006, 20:16

I don't know whether that was aimed at me Danny, but I am well versed in Physics.

I undestand the concept of momentum and kinetic energy. But the one other factor in the damage that can be cause is force and this is squarely proportional to surface area. For the winglet to have done what many on here believe to have happened ie slice into the 737's wing probably up to the spar it would have had to be a collision square on or there or there abouts to maximise force, and hence penetrating power. The failure of the winglet would tend to suggest this wouldn't be the case. Let's not forget for all the damage a bizjet will do with its kinetic energy, the 737 will do the same with it's as well with more due to greater mass.

That is the head on straight and level scenario. I'm sure there is a lateral component to this, and as the previous diagrams have shown this will take either a climb or bank from one or both. If so, why such a maneouver ??

nooluv

1st Oct 2006, 20:24

You are right Danny. But does anybody know what the headings of the two aircraft involved in the accident were? They could be head on, from the side, from behind etc..

RiverCity

1st Oct 2006, 20:33

If the bizjet pilot is telling the truth, the Boeing was above him. He said, if I remember correctly, he saw a shadow above him.

Sunfish

1st Oct 2006, 20:48

Could I respectfully ask if the primary mode of navigation for both aircraft was GPS?

jondc9

1st Oct 2006, 20:49

no luv and river city

if headings were known (even assumed no wind conditions) and sun angle at time of day, this might support a non head on crash.

and if only the PILOT(not copilot)to of the legacy recalls the shadow, perhaps the boeing was at his 9 o'clock position. sun at back of boeing casting shadow

anyone have approximate headings from departure to destination on these 2 flights, no wind magnetic will do nicely.

to the chap who made the nice picture, I applaud your effort...I wish your magic computer could shift the image to show the legacy 90 degrees to boeing, the winglet striking the bottom of the boeing and the horizontal stabilizer hitting the cockpit.

unlikely that the legacy overtook the boeing from behind.

I recall the physics of flight being discussed with reference to helicopters and bumble bees, SIKORSKY said something like: according to physics the bumble bee can't fly, BUT because the bumble bee doesn't know PHYSICS, he goes around flying quite nicely...same too the 'copter.

regards

jon

Broomstick Flier

1st Oct 2006, 20:54

Both planes were on UZ6 airway, which is 154 southbound (the 737) and 334 northbound (the Legacy).

If someone has Jepps available, take a look at SA(HI)-4, the collision happened close to TAROP intersection.

SeniorDispatcher

1st Oct 2006, 20:55

This just hit the old in-box...

http://i80.photobucket.com/albums/j193/joaovitor/gear.jpg

RiverCity

1st Oct 2006, 21:00

I was thinking of the "shadow" as actually being the underbelly of the 738, but being seen so quickly as it appeared from the bizjet's blind side (above and behind), being interpreted as a shadow in the brief seconds before colliding.

BTW: I worked at Sikorsky's factory and saw him occasionally. Heck of a nice guy.

jondc9

1st Oct 2006, 21:02

broomstick flyer

thanks for the course they were on...I don't have south american jepps.

so much for the 90 degree theory.

perhaps the legacy hit the boeing at exactly the right angle to cut vital control cables or hydraulic lines... or even a glancing blow to the cockpit

does anyone have the winds aloft for this time, altitude and position?

I would also like to see a picture of the belly of the legacy in case contact was made there., though the shadow bit throws that off too.

Khaosai

1st Oct 2006, 21:07

Hi Rippa,

thanks for the info on the airspace improvements that have been made since my time flying there.

Rgds.

J.O.

1st Oct 2006, 21:10

This just hit the old in-box...

http://i80.photobucket.com/albums/j193/joaovitor/gear.jpg

Interesting that from that picture it certainly appears that the Boeing had the main gear extended. Makes one wonder why that would be? Could it have been an attempt to gain control of an out of control (i.e. spinning) aircraft?

jondc9

1st Oct 2006, 21:17

hobie

1st Oct 2006, 21:25

shift the image to show the legacy 90 degrees to Boeing, the winglet striking the bottom of the boeing and the horizontal stabilizer hitting the cockpit.

this might give you an idea of the relative levels .....

http://img413.imageshack.us/img413/4523/738collisionxj9.jpg

Rippa

1st Oct 2006, 21:32

J.O.
you make a good point, or could cable to uplocks been pulled by slicing action of winglet
this will be a case of a bullet hitting a bullet.
has Brazil released any ATC radar data yet? didn't someone say that the radar showed 1000' seperation?
is it possible the pilots forgot to set 29.92 inches and were 1000' off, then switched off transponder to correct everything and just got banged?
harkens back to that film I mentioned, "the crowded sky".
somehow I have to think the legacy was on top to survive.
j
Jondc9,
Brazilian airspace is very different from the rest of the world (or at least very different from USA airspace). Usually, we set QNE (29.93 or 1013.2 hpa) a few minutes after takeoff, around 6000 feet (varies from one place to another) when climbing and QNH, when descending, around FL 040. The airspace in question is RVSM, but has very few traffic on daytime...gets a little busyer at night, due to international flights from South america (Chile Argentina, Brasil,etc...) to USA and north america, but even then, it could not be classified as a busy ACC. Very often CB's on route...big Cb'...

Regards

PS: The investigation is beeing conducted by the Military authoraties....do not expect any real info before 90 days.......

Blues&twos

1st Oct 2006, 21:35

Just had a thought which I don't think has been added to the pot yet. Is it possible that the B737 had a problem prior to and at the time unrelated the MAC? In attempting to deal with this problem departed from its assigned level?

I appreciate that this would be incredibly incredibly unlucky....but then at the end of the summer I have to clean swatted flies off my car aerial....

Added later: Mind you this doesn't explain why the Legacy couldn't take avoiding action in response to TCAS, does it?

Carnage Matey!

1st Oct 2006, 22:01

AFAIK mode C transponders all give their altitude readouts referenced to 1013.2/29.92 so even if they had forgotten to set standard on the primary altimeters the TCAS should still have functioned in the correct sense.

satpak77

1st Oct 2006, 22:20

speculating, but any chance that the cockpit windows were impacted by the Legacy? At closure of Mach 1.4+, it would be all over, forget running checklists and donning O-2 mask.

Also, anyone have an online link for ICAO rules on squawking XXX when IFR but non-radar, in South America. In Peru it was 2000 code.

thanks

Sunfish

1st Oct 2006, 22:40

I would like to draw your attention to Danny's post regarding Kinetic Energy. There needs to be zero speculation about exactly where the two jets touched. You can safely assume that at the closing velocities involved, it simply doesn't matter. It's purely academic and discussion is of no possible value.

For the record, winglets and wingtips are deliberately designed to fail at much lower loads than the rest of the wing - to protect the integrity of the wing structure.

jondc9

1st Oct 2006, 23:16

carnage

of course that is how mode c works, but could this have been the reason the legacy pilots are alleged to have shutoff the transponder?

as to lowering gear on a 737 emergency descent, it is an option, but one must reduce to gear speed first.

and I posted earlier slicing into the windshield/canopy/cockpit might have been part of the equation.

I have heard that new planes may have altimeters improperly set and the pilots didn't catch it on checklist.

AS to kinetic energy and all that JAZZ, please remember that a C172 brought down a PSA B727 near San Diego about 34 years ago, someone even got a pulitzer prize winning picture of it in flames. A c172 has much less mass and speed behind it than a legacy so it can happen.

jondc9

1st Oct 2006, 23:21

hobie

thanks for that picture...hit the engines with winglet and stab hits cockpit

ouch

but wait for the paint marks I suppose

thanks again!

jon

jondc9

2nd Oct 2006, 00:07

stuff on PSA mid air near San Diego, almost 28 years ago to the day.

http://en.wikipedia.org/wiki/PSA_Flight_182

amazing picture

PJ2

2nd Oct 2006, 00:13

speculating, but any chance that the cockpit windows were impacted by the Legacy?

Satpak77;

I don't think so. Damage to the Legacy is on the left tips of two extremities...the winglet perhaps a foot+ and horizontal stabilizer, mere inches. If the diagram of the 737 and Legacy relative sizes posted earlier is referred to, it can be seen that the horizontal stabilizer could not impact the cockpit area without substantial damage to the Legacy and that evidence is not there. The winglet could not impact the cockpit area of the 737 at least in any substantial way on a straight-on heading as there would simply be far more damage to the Legacy than is apparent.

Considering a collision with the vertical stabilizer with the Legacy at a steep (evasive) bank angle, the Legacy's winglet and horizontal stabilizer are too far apart to have sustained damage by such a strike unless the winglet struck the 737's vertical stab and was in turn struck (instantaneously, much like the shuttle foam strike) by the horizontal stabilizer.

Given the distribution pattern of the main wreckage (close, with large wing sections intact so no high-speed impact-, no engines - either close by hidden by jungle or separated in flight due possibly due to high lateral loads-, gear down in a possible attempt to stabilize the aircraft), a collision with the vertical stabilizer is one possible scenario. All the fuel inspection panels are off perhaps due to very high pressures generated in the wing section on impact. In-flight break-up cannot be ruled out of course, as the photographs do not yet show all the wreckage.

A tragic day for aviation and a very sad for all families of the victims.

SM4 Pirate

2nd Oct 2006, 00:27

Looks like they're confirming it was a MAC...
http://noticias.terra.com.br/brasil/interna/0,,OI1168682-EI7792,00.html Rough translation:

The Anac (National Agency of Civil Aviation) confirmed in this Sunday that the fall of Boeing 737-800 of GOL that crashed on Friday in the north of the Mato Grosso was provoked by the collision with an airplane Legacy model, Embrear.

According to Denise Abreu, director of the Anac, there is little possibility of finding survivors. "It will take a miracle to find survivors".

In accordance with process, they have successfully removed the black boxes of the Legacy. "The boxes of voice and data are in perfect condition".

From this Sunday, the Anac created a contact list for passengers that will be co-ordinated by Laura Perdigão. It promised information to the families at least two times a day.

The director also informed that North American authorities are in contact with Brazil to help in the inquiries of the accident. According to it, this type of intervention is absolutely normal in cases involving aircraft of two nationalities. The Legacy manufactured in Brazil, had been bought by a company of the United States, and therefore, it is not under the Brazilian authority.

RobertS975

2nd Oct 2006, 00:39

One of the pax on the biz-jet was allegedly a New York Times reporter... has he filed any stories yet? It is obviously rare when you have a reporter so involved in the story.

punkalouver

2nd Oct 2006, 00:55

Maybe the 737 was overstressed in trying to avoid the collission?

It is possible to lose control during an evasive manouver like this 727.

http://aviation-safety.net/database/record.php?id=19961107-0&lang=en

SeniorDispatcher

2nd Oct 2006, 01:08

One of the pax on the biz-jet was allegedly a New York Times reporter... has he filed any stories yet? It is obviously rare when you have a reporter so involved in the story.

His most recent was 9/26, and nothing since then.

http://topics.nytimes.com/top/reference/timestopics/people/s/joe_sharkey/index.html

I'm looking forward to hearing his account, assuming that he writes one...

RatherBeFlying

2nd Oct 2006, 01:17

My recollection of the San Diego accident was that the C-172 was first impacted by the B-727 nosewheel from where it contacted the leading edge and severed the hydraulic lines for all three systems.

Where the hydraulic lines are located in new B-737s I do not know.

discountinvestigator

2nd Oct 2006, 01:48

I have a little bit of experience in the area of mid-air collision investigation.

Firstly, this is not the first, or the last mid-air. Remember that we had a loss of control following a near mid-air in Nigeria with the B727 about 10 years ago. So, if the Boeing crew did detect the Legacy and pulled/pushed/whatever, loss of control is not unknown. We have also had a relatively recent collision with a B737 and a Cessna twin where both survived in Namibia. Small aircraft do hit big aircraft and survive.

I have the T-shirt for the German mid-air collision.

Second, remember that there are slight nose up attitudes to take into account.

Third, the pilot statement is entirely compatible with those I have talked to/read and the theory for detection. You don't see the one you are going to hit. Get a hold of a copy of the old Bureau of Air Safety Investigation report (now Australian TSB) into See and Avoid. A brilliant piece of research.

Fourth, remember the cross wing factor. If you are going to try to avoid, then most pilots bank to turn rather than pull/push for head on encounters, this makes it worse! Draw it out on a piece of paper and you will see that the wings form an X shape and are thus more likely to hit one another.

Fifth, I would make a first guess at the Legacy being slightly lower than the Boeing. This could give you a tail hit on the underside of the wing and the winglet in the engine. However, please remember, this is just an alternative way of getting that damage. The tail of the Legacy just impacts one of the flap drive pontoon aerodynamic fairings, leading to not much damage.

The Boeing looks in pretty good shape, albeit the wrong way up. The engines have gone which is not unusual but would imply more of a loss of vertical stabiliser and then massive yawing, or loss through impact. However, with both engines gone, it may well be more the descent phase. Certainly the 757 in Germany lost the engines for that reason.

The vertical speed of the Boeing does not look great and it was certainly not a nosedive into the ground in one piece. 737 old generation could suffer in flight break up if power dived towards the ground. It just does not look bent enough for that. However, trees can do a lot of deceleration!

Anybody got any idea why the fairings to the front of the main gear are missing? Are they actually there and have just rotated in the accident to leave the area exposed?

The port wing has lost all of the inspection panels but the right wing has not. The port wing appears to carry significant damage, probably in the ground impact and may well have twisted off at that point, whereas the starboard wing in still attached.

The broken link on the left main gear may support the inverted left wing down stop as the gear might be weaker in this direction, when compared with the reverse fitting on the other side.

Ah well, time will tell.

Ranger One

2nd Oct 2006, 01:48

This thread is about to get shut down. Far too many indications of enthusiasts debating the scenarios whilst showing a severe lack of even basic physics understanding.
If you don't understand the concept of kinetic energy then please leave this debate alone. Those that fail to grasp even the rudimentary idea that a collision, whether it was just a winglet striking another part of a bigger aircraft or whatever, involves tremendous forces. It's not Hollywood fantasy.
Spot on Danny. Let's throw a few rough assumptive numbers in here so people can get a clue.
Assumption: Legacy winglet weighs 20kg.
Assumption: MAC was something relatively close to head-on, with a closing velocity of 400m/s (assuming both aircraft were cruising at something like 450kts).
Now, the equation for kinetic energy is:
http://upload.wikimedia.org/math/2/3/1/231cfd9416f4736f5ee8d102ee84cb22.png
Note that Ek is proportional to the *square* of the velocity. Plug the above numbers in, and we get an energy in the winglet of 1,600,000 joules.
For comparison, take a 2 ton (2000kg) car travelling at 45mph - say 20m/s. That has an energy of only 400,000 joules - which would be the same number as the winglet energy if the Boeing was stationary WRT the Legacy, i.e. they were on headings 90 degrees apart rather than reciprocal.
How would YOU like four cars at 45mph hitting your office? That's the kind of energy we're talking about, folks. The only reason the Legacy got away so lightly is that the winglet *was* frangible, and the structure failed, as designed, before much of the energy was transferred to the Legacy. It mostly ended up in the Boeing...
(I've had a couple of beers so if I've made any horrific errors of sign or magnitude someone please correct me)
R1

broadreach

2nd Oct 2006, 02:01

Following up on my earlier post (#77 in this thread) re a report quoting the Legacy captain saying he'd turned the transponder off and climbed without advising ATC, a subsequent news report covering the crew's deposition to police at Cuiabá, has the crew stating they were in stable cruise at FL 370, the level to which they had been cleared by ATC. The same article mentions the crew's stating their TCAS gave no warning.

Another news article quotes a farm labourer who saw the 738 coming down saying it was "tumbling" or "spinning" (in Portuguese, "rodopiando").

Other articles indicate the wreckage was concentrated in a 1km2 area or "spread over 10km2".

Re geometry and, for what it's worth, someone has posted a theoretical simulation of winglet contacts on youtube: http://www.youtube.com/watch?v=wRKtG3qoUcU&eurl=

Someone in an earlier post mentioned trees in the forest where the 738 crashed being over 20' tall. More like 40m tall, ie the forest canopy at a height equivalent to a 13 storey building. Reports from the first airforce rescue team helilifted in indicate there was fire. But that height of forest canopy would have muffled any explosion.

Just a note re ANAC, Brazil's new civil aviation agency. Very recently created, mostly political nominees and probably somewhat over their heads in this, likely to be playing catch-up with the military people directly involved in the investigation. Don't expect much real information to be forthcoming from that quarter. On the other hand I would certainly expect a rapid stream of hard information coming through directly or otherwise from other sources including airforce over the next few days.

discountinvestigator

2nd Oct 2006, 02:27

Can somebody remind me what the birdstrike criteria are for the engine of a 737 diameter. One kg and 200 kts strikes me from memory. I will repost the right answer when my bird specialist is awake.

20kg of winglet down the engine may well cause total detachment, in the designed failure manner shown on the photos.

OK, looking at the simulation, I could go with that, as opposed to my blind thought on the underside/engine strike on the 737. Sometimes you forget how big the 145 is. It just feels very small when you get to sit in one for a while at my height!

The impact of the frangible winglet with the wing will easily lead to the winglet of the Legacy being smashed off, no problem. The outer element of the T tail being lost as well, fine. However, when the winglet has smashed its way through the slats, it comes across the main wing box. These are very very strong. Something just feels funny about the winglet doing sufficient damage to destroy enough of the wing to make a difference at this point. Certainly when compared to the fin of the 757 (two tonnes of Seattle's finest) hitting the front of the 154 wing root, it did not do that much damage to the wing box, from memory. Maybe the ironworks from Tupolev win out over the NG wing here.

Now, the loss of the winglet on the NG wing is an interesting proposition. I would have assumed that the change in lift at the wing extremity should be counteractable by normal roll control systems. No doubt Mr Blended Winglets will be busy for the next few days.

At least these aircraft should not have the Gillham code and the FL 350/370 problem.

Also remember that when you see an aircraft 1000 feet below you, it looks as if it is on the same level, such is the deception of the false horizon and the nose up attitudes. At least in some cases.

Does anybody know what the factory acceptance tests are for TCAS. Just wondering if the Legacy had a failed unit of some form or other, and they had never seen another aircraft on the display, because they were not expecting to. So, plug in the bench tests stuff and it looks ok, but is there a practical air test of it? Not necessarily in terms of resolution, but just being aware of other traffic?

ExSimGuy

2nd Oct 2006, 03:15

Danny, I hope you won't lock or delete the thread. I know it's all speculation at this point in time, but the "Hollywood ideas" get shot down by more informed posters (and the originators educated, along with others of us) and it keeps a centralised source of info as it comes in (like the post above about the light jet being "straight and level with (implied) the transponder on")

Certainly a good point comparing that "light piece of composite" with it hitting an aircraft (or my car!) at around 1,000 mph

ESG

willfly380

2nd Oct 2006, 03:25

just like to share this. a few days back a b737-400 came to about 200ft within to a su35 fighter plane . it was so close i believe that the boeing capt had to firewall the engines in order to avoid hitting the fighter. the fighter had some tech problems[i have no clue]so had his tranponder on , hence they got a TA immediately followed by an RA. now we all know about RAs issued being in the normal operating capability of the airplanes, but this was really really necessary to go to the forward stop [ thrust lever position]to avoid as the fighter was zooming. the fighter pilot i believe also did a stellar job and infact turned around to check if the boeing was ok . on finding him still flying he resumed his flight.I am here not trying to fix blame or comment on actions taken, just sharing to educate the fellow pilot, the 734 was grounded for a boroscopic inspection on landing.

Loose rivets

2nd Oct 2006, 03:56

I personally doubt that the impact scenarios discussed latterly in this thread would down the Boeing. In the mathematical model earlier, the energies would be theoretically focused to contact surface areas. This would not happen, though such a hypotheses has to be built from some foundation of course.

The very nature of the structures involved would mean that the air would play a very significant part, not only in the destruction of these airfoils, but also in the dissipation of energies after collision: as the component parts were distorted and started splitting, the first leakage would cause an almost explosive swelling and resultant disintegration of the winglet before it had progressed very far into the Boeing's wing.

As we all know, many severely damaged aircraft have made it back to base, some older slower types having less than half of one wing left on a given side. There has to be a vulnerable and indeed vital component having suffered damage. Aircraft have so many Achilles' heels.

ManaAdaSystem

2nd Oct 2006, 05:07

This just hit the old in-box...
http://i80.photobucket.com/albums/j193/joaovitor/gear.jpg

Very interesting picture!

Gear down could mean;

A: He was trying to land. This means he had some control of the aircraft.

B: There is an option of lowering the gear for/during emergency descent on the NG if structural integrity is in doubt. Gear down speed is .82 so normally below your cruise speed.

C: Damage to the uplock(s).

lomapaseo

2nd Oct 2006, 05:25

willfly380

2nd Oct 2006, 05:30

it appears from the photos that there was no or little fire. was it raining real heavy at the time there ?

jondc9

2nd Oct 2006, 10:23

I can think of two fairly large jets being brought down by collision with smaller planes

PSA 727/C172 San Diego, mentioned earlier

DC9/Piper Archer over LA/ Ceritos california.

the small planes involved were much smaller than the large jets involved. the odd thing about this incident is that the legacy survived with such little damage.

perhaps the legacy created a force upon the boeing's rudder, causing a reversal like the crash near Pittsburgh, PA. perhaps the legacy cut vital lines (hydraulic or control)

j

brain fade

2nd Oct 2006, 10:34

Perhaps, as the Embraer crossed in front of the 73, the left winglet gashed the No2 engine and the left side stab tip cut into the flight deck. The stab is a lot stronger than the winglet which would explain the fact that it seems to have little damage.
This would explain the lack of any RT after the incident.

lfbb

2nd Oct 2006, 10:36

Very interesting picture!

Gear down could mean;

A: He was trying to land. This means he had some control of the aircraft.

B: There is an option of lowering the gear for/during emergency descent on the NG if structural integrity is in doubt. Gear down speed is .82 so normally below your cruise speed.

C: Damage to the uplock(s).

Looks like the right wing is "intacted" while the left wing was ripped off... maybe a failed forced land where they hit a tree and flipped upside down. In this case don't you think that to try to ditch on a river would be a better option if you had a chance to?

discountinvestigator

2nd Oct 2006, 10:36

I am well aware that modern engines do not usually "blow up" and detach themselves from wings. However, the accident is well beyond design case. The design case is for engine seizing, bird strikes and general turbulence/manoeuvring. A winglet ingestion is well beyond the bird strike case. It is likely that the engine internals would disintegrate if the winglet were to enter.

The main reason for engines falling off would be massive yaw rates. The 757 over Germany seemed to suffer from this. As you may be aware, the yaw rate criteria are significantly less than in other dimensions. The engines have detached and relatively cleanly, which indicates the design break off manner. I know that throwing winglets into engines is not part of the certification of the aircraft, and with the kinetic energy impacts being discussed, it is a possibility, and that is all.

I was looking at possible geometry of encounters which could lead to the damage seen on the surviving aircraft. It is not unusual in mid-air collisions to get some angle of bank involved at the last moment for head on encounters. Hence the damage could be representative of a collision of winglet with engine.

What has caused all the inspection panels to blow out from the port wing and not the starboard? That, in itself, may indicate a wing encounter rather than engine. However, I would need more photographs.

Does anybody know if the NGs can survive detachment of a single engine or is the roll moment too large for the control authority?

blackmail

2nd Oct 2006, 11:51

hello discountinvestor,
yes & the answer is in the nonnormal qrh title: "engine fire, severe damage or SEPARATION" recall/checklist items.

rlsbutler

2nd Oct 2006, 12:35

We have alluded to low and medium altitude incidents, reviewing straight impacts of various sorts.

Is someone out there equipped to consider the implications of transonic airflow when two wings are passing as in this high altitude situation ?

In the very tightest case you have two boundary layers passing at relative supersonic speeds. Further apart there will surely be venturi-effect acceleration between the nearest parts of each aircraft, perhaps generating a local shock wave. Might this be sufficient to cause wing panels to pop out ?

If that might happen, hinges and control surfaces might also be affected.

broadreach

2nd Oct 2006, 13:11

lomapaseo

2nd Oct 2006, 13:29

Pressure vessel decompression is of little significance in the breakup. There really is no such thing as a hole in the fuselage causing a decompression to finish the job.

With so little damage to the plane that landed the most one would expect is extremely localized damage to the B737. However the real issue is what came first. If the B737 was first ala the breakup of PA103 or TWA800 then it's possible (I have no idea how probable) that small debris might have struck the other plane.

From the pic, the damage to the left wing of the B737 doesn't look like impact damage, but instead more like buckling and overload ala the video of the B777 wing overload test.

Mercenary Pilot

2nd Oct 2006, 13:48

Legacy's winglet shearing hydraulic/electric lines in the 738's horizontal stabilizer.

That wouldn’t bring a 737 down because it has manual reversion of the flight controls.

Looking at the damage to the EMB and the way the 737 crashed (upside down with the gear out) maybe the EMB winglet sliced through just forward of the AFT pressure bulkhead causing an explosive decompression. The mass flow of air may have then caused extensive damage to the tailsection similar to the JAL123 accident. Dropping the gear may have been an attempt to regain control.

If the 737 had lost pitch control due to damage to the tail, it would presume it still had roll control. As mentioned, the 737 does NOT need hydraulic fluid to remain controllable. With the majority of the tail missing, it’s doubtful whether the flight crew could control the aircraft with roll and thrust alone.

This is obviously just pure guesswork on my behalf and I hope the investigators find and release the cause ASAP so we can debate rather than speculate.

Condolences to all involved.

London Mil

2nd Oct 2006, 13:52

.... awww shite :(
.
... if that is accurate, then it seems (in this case) serviceable TCAS was more important than ever !! :sad:
.
.. what of the TCAS OFF selection issue?? and the supposed climb of the Embraer?? ... anything in the local press about that stuff??

SDD, from a report into the Uberlingen mid-air:

Such was the case in this mid-air collision. The TCAS worked as designed. But, as in most accidents, a range of insidious policy, training and procedural issues are involved. This accident was no exception. It was one where other breakdowns overwhelmed the last ditch defense that TCAS was intended to provide.

Too early to assume, methinks

ekw

2nd Oct 2006, 14:14

..(nose to nose) how do you get to the horizontal stab of the 738 with the wing tip and horizontal stab of the Embraer???? :uhoh:

If the 738 pilot pulled back with full throttle couldn't his tail sink into the bizjet? (power lag).

Iolar

2nd Oct 2006, 14:17

Were they flying on an airway?
One could also raise the general question concerning the wisdom of flying directly on a bidirectional airway in RVSM airspace (in this instance uncrowded), considering the accuracy of modern navigation systems, and not somewhat offset? Is it allowed to track offset to an airway centerline? Does exact navigation reduce the error margins for MAC in RVSM airspace in the event of a level bust?

jondc9

2nd Oct 2006, 15:15

mercenary pilot is right to a degree, the 737 does have manual control reversion in a limited sense...NO RUDDER control with loss of hydraulics, elevator and ailerons would remain unless the cables were sliced too.

mercenary brings up a good point about the 747 that lost chunks of tail due to failure of aft bulkhead (pressure bulkhead, not properly repaired). however it should be noted that the 747 flew for a bit of time after this happened.

I think the more we talk about it, the more we see that this was quite an accident, with so many possible answers.

sometimes the simplest is the answer, which is why I keep coming back to the boeing pilots being killed by a piece of the legacy, followed by decompression, autopilot disengagement and loss of control.

I have a feeling we will know the answer sooner than later on this one.

AlexL

2nd Oct 2006, 16:14

I generally hate to speculate on these things, but having said that, heres my tuppenceworth.
If its true that the 737 was climbing throught the embraer flight path with a significant pitch attitude, and the emb was straight and level, then a scenario which fits its that the emb winglet clipped the horizontal stabaliser of the 737, not the wing. Neither would have seen each other, apart from the emb would have seen the 737 flash over his head for a few milliseconds. The winglet could concievably remove the entire stabalizer, but even if not at that altitude and speed a sudden trim change, and / or aileron damage could cause a major upset which would be difficult if not impossible to recover with a damaged stab

Blues&twos

2nd Oct 2006, 17:06

fox niner

2nd Oct 2006, 17:30

The gear can be lowered without hydraulic power. once again, the 737 can be brought to a safe stop without a drop of hydraulic fluid on board.

Evidently, the 737 was unable to stay aloft. What's more interesting is the reason why the two planes met each other. That is the primary cause of the accident, not the fact the landing gear was up/down, of whether they had loss of system A and/or B. Neither is it relevant to know exactly HOW the two planes collided. That is all secondary....

- Who didn't follow the RA, and why?
- Who caused the planes to be up there in the first place?
- Did ATC clear them? Did one of them climb / change level without informing ATC?
- Did one of them indeed turn off their transponder?
- Was ATC aware of an impending collision?

If these questions are answered in due time, will we all know the cause of the accident...

FN

PJ2

2nd Oct 2006, 18:06

ekw;

Re, "If the 738 pilot pulled back with full throttle couldn't his tail sink into the bizjet? (power lag)."

and,

AlexL;

Re, "If its true that the 737 was climbing throught the embraer flight path with a significant pitch attitude, and the emb was straight and level, then a scenario which fits its that the emb winglet clipped the horizontal stabaliser of the 737, not the wing. "

That's not possible at these speeds and with these aircraft.

We must remain aware of the environment and the numbers here..ie, the speed involved and the viscosity of the air at these speeds...in short, the physics of this as has been strongly emphasized earlier in the thread.

The pitch attitude of almost all transport aircraft in level flight is typically 2 to 4 degrees NU (nose-up) depending upon type, (the L1011 is slightly higher as it uses the fuselage for lift as well; most other transports would tend towards the 2deg pitch attitude). Keep in mind physics as was emphasized earlier in this thread: - The air at these speeds is extremely "thick"...very "hard", as sensed by an airframe travelling at these speeds. (That's what "ram effect" is about, as well as temperature rise resulting from ram effect etc) This pitch attitude does not change markedly when climbing or descending...in descent we might see 1 deg to perhaps 0 (level pitch attitude) for a 2500fpm descent. Minute changes in pitch attitude have a large effect on rates of climb and descent.

There is no physical possibility therefore, that the horizontal stabilizer was struck due to "pitch attitude" of the 737 during a climb keeping in mind the Legacy's damage pattern. Neither could the other scenario, a "sudden pull-up" as was mentioned just above, possibly present an attitude at which the horizontal stab would be momentarily "exposed" to the oncoming aircraft. It's physically impossible for that to occur.

Assuming both aircraft were cruising at about 450kts TAS, the closing speed of the two aircraft would have been approximately 1519fps, (900kts x 1.69 approx). At that speed, the time to travel the length of the 737-800 (the effective time of available contact with each other) is approximately .09 seconds (138ft / 1519fps). It can be seen that even if it were possible to pull up to an attitude which would expose the tailfeathers, the time "available" for such a change in attitude to occur with a subsequent collision as described is simply not there.

The thread has also covered the airway/head-on issue, although it seems to keep coming up. As described earlier, the aircraft were on UZ6 near the TAROP intersection (Jepp SA (HI) 4), the 737 heading south, the Legacy heading north. The altitude issue is still unresolved however, and is additionally clouded by the transponder/TCAS issue which should be cleared up with the testimony of the surviving crew, the CVRs and the DFDRs.

Scurvy.D.Dog,

Re, ".. the centre section photo does not reveal anything meaningful."

I disagree. The evidence that the center section provides for us is enormous.

First, it is relatively intact. That means the descent was not "high speed", but instead had relatively little forward speed. That means that there was no vertical "dive" but some other scenario, likely inverted (as per the evidence) and possibly stalled (conjecture at this point) though the DFDR will tell us for sure, (this of course assumes that the electrics remained operational). This also means that the horizontal stabilizers were likely intact and also that both wings were likely intact, (no spiral or otherwise uncontrolled high-speed dive).

Both engines are off the wing and therefore are either near the wreckage having been thrown off on impact (and hidden by the jungle in the photo), or somewhere along the path of flight having been thrown off by lateral 'g' forces at some point during the descent. If the engines are found (very difficult in the jungle as we know) a long distance from the main wreckage, I suspect the vertical stabilizer will be found that way as well, (the photos seen so far don't reveal the relative positions of the vert stab and the center section). In other words, we may have a similar scenario as AA587 in New York (Oct or Nov 2001 if I recall).

I did observe earlier in the thread that the fuel tank inspection panels were all off on the left wing and surmised that that may have occurred on ground impact with the enormous instantaneous pressures thereby derived. I doubt if this is the result of any winglet-to-wing collision as again the geometry of such contact doesn't support the theory...the panels are inboard of the engine and any internal pressures generated by the winglet impact would also have compromised the left wing to such an extent that a spiral high-speed dive would have resulted.

Another possibility is complete mid-air disintegration in which case all conjecture above about collision paths etc becomes academic.

As to TCAS/Transponder issues, they will have to wait for the formal investigation or at least reading of the DFDRs and CVRs. I am unfamiliar with South American flying and am reading the contributions in the thread with great interest.

Fox Niner...just read your comments and agree fully, with the minor qualifier that knowing how the aircraft hit may lead us to the immediate antecedents. Whether such discoveries would provide "learning" in order to prevent future such accidents is likely doubtful in this case. I think that the answers to your questions will be where the real learning, and hopefully subsequent change, lies.

Rev Thrust

2nd Oct 2006, 18:13

sometimes the simplest is the answer, which is why I keep coming back to the boeing pilots being killed by a piece of the legacy, followed by decompression, autopilot disengagement and loss of control.
Aha! But then who extended the gear?
The gear can be lowered without hydraulic power. once again, the 737 can be brought to a safe stop without a drop of hydraulic fluid on board.

Fox Niner... does that make the context behind Blues&Two's question a little clearer?

I read it that he was saying, basically, that if the pilots met their end at the instant the Legacy hit, as per JonDC9's suggestion, then (notwithstanding the hydraulic situation), the gear would not have been in the down position in the photograph we've all seen.

I have to say I think Blues&Twos has a pretty sound point, tbh.

Poor souls.:sad:

av8boy

2nd Oct 2006, 19:48

FYI: Here's an excerpt, not from the (copyrighted) Jepps, but rather, the freely available US Government H4...

As noted earlier, we're talking about the neighborhood of TAROP intersection. Just as an aside, I'd be interested to know if SBR620/the Cachimbo test site might have been doing anything that might have spilled out of their airspace and been some sort of factor in this accident...

http://www.atcmuseum.org/images/H4_excerpt.gif

I've also uploaded the entire H4 here: http://www.atcmuseum.org/images/H4.pdf. Note that it is about 4.25 megs.

Dave

CHIVILCOY

2nd Oct 2006, 19:58

For what it is worth and I doubt it should be taken seriously.

Clarin, one of the the national Argentine newspapers is reporting as follows.(rough translation)

One of the aeroplanes was authorised by the tower at Brasilia to fly at 37000 feet,the other was authorised by Manaos to climb from 35000 feet to 39000 feet and that the collision was caused by a lack of communication between the "towers"

Make of it what you will, I just thought you may want to see what's being reported down that way.

jondc9

2nd Oct 2006, 19:59

who would have lowered the gear?

if all the hydraulics ran out and the cable to the uplocks had been yanked by the impact, the gear could have free falled.

there may be other answers too

and, was the NOSE gear found down?

I believe one of our forum members suggested that something went wrong with the 737 prior to any collision. this should not be discounted yet/

why?

if a rapid decompression had happened and a descent started and that descent took the 737 into the legacy, we may have a clue

again, this is just to sort of cleanse the pallet of the mind...I admit that when I first heard this story, my first thought was that that LEGACY had hit the 737...the story seems to be falling to the 737 hit the LEGACY...we shall see in time.

jon

PJ2

2nd Oct 2006, 20:16

jondc9;

Re, "the cable to the uplocks "

Help me out here...this is the second or third reference to "cable" uplocks...is the 737 not equipped with hydraulic uplocks like all other conventional transport category aircraft?

Cheers,
PJ2

jondc9

2nd Oct 2006, 20:26

dear P2J

you ask a fine question, and just to be sure I got out my 737 manual (200 series, but I doubt much has changed, please corect me if I am wrong).

from the manual:

Manual extension is provided by three emergency landing gear extension handles located under an access door in the cockpit floor. Pulling a handle to is full extension will unlock the uplock on the associated landing gear.

To assure that free fall of the gear is unimpeded by trapped hydraulic pressure, the landing gear handle should be in the OFF position.

I hope this helps. Tongue twister there: unlock the uplock...should be used to find out if pilot is drunk! (kidding to all of you drunk pilots).

SeniorDispatcher

2nd Oct 2006, 20:57

Someone previously asked if Joe Sharkey, the NYT reporter onboard the Legacy, had written anything post-accident, and this link just got forwarded to me. He doesn't say much that's new, but some folks might find something useful within it...

http://www.joesharkey.com/

PJ2

2nd Oct 2006, 20:57

jondc9;

Ok thanks. To be clear then, the normal uplocks are hydraulically-driven (vice mechanical and spring action), but the emergency gear extension is achieved by cable?

The cable routing is almost certainly well inboard (fuselage, then outboard to the gear). Whether the collision and/or the subsequent accident sequence had anything to do with inadvertent gear extension or whether the crew extended the gear then, remains to be determined. Thanks for the info.

SeniorDispatcher

2nd Oct 2006, 21:07

Looks like they have found the CVR and DFDR of the 737..

http://g1.globo.com/Noticias/Brasil/0,,AA1295444-5598,00.html

172driver

2nd Oct 2006, 21:29

Looks like they have found the CVR and DFDR of the 737..
http://g1.globo.com/Noticias/Brasil/0,,AA1295444-5598,00.html

BTW, the page the above link leads to also contains a link to some video footage, apparently shot from a helicopter. Perhaps some of you guys can make something of it.

mini

2nd Oct 2006, 21:31

How is the timebase of data recorders "set"? i.e will it be possible to synchronise events downloaded from the data recorders from both aircraft?

ATC Watcher

2nd Oct 2006, 21:34

For Portuguese readers:
http://oglobo.globo.com/pais/mat/2006/10/02/285929322.asp
The article indicates the Legacy was at FL370, still under Brasilia ATC, while the 738 had requested and been cleared by Manaus ATC to climb from FL350 to 390.
.

If this is correct, it start to shed some (credibile) light in the puzzle, which eliminate the hollywood theories and the cow boys swiching off Xponders and deviate from assigned level without clearances !

Speculations :Lack of estimate ( therefore knowledge )of the Legacy to Manaus ACC , or no coordination of the 738 climb to Brasilia ,or too slow rate of climb undetected, or intentional/unitentional level off during the climb, etc, I have seen all of those many , many times in my carreer.

As to TCAS, only the both FDR/CVRs will tell us why the system ( i.e humans , procedures or technics ) malfunctionned.
TCAS has never claimed it will be error free and will cover for every case.

SeniorDispatcher

2nd Oct 2006, 21:36

Some hi-res photos now up on the military's site...

http://www.fab.mil.br/imprensa/Noticias/2006/10_out/0210_fotos_resgate.htm

Sunfish

2nd Oct 2006, 21:54

With the greatest of respect to those wondering why the main gears were down, it is possible that they were not lowered intentionally at all. If in fact, there was an explosive decompression, the floor may fail and the various control cables are right underneath.

brain fade

2nd Oct 2006, 21:58

I'm glad that the allegations about the Embraer crew behaving recklessly seem to be losing credence.
I never believed them.:ok:

PJ2

2nd Oct 2006, 22:04

Senior Dispatcher;

Thanks for the link. They're excellent photos. Wonder where the original ones showing the vertical stab might be...Still wondering if the wreckage is separated by a substantial distance...

Sunfish;

Now that the photos show more of the jungle "ahead of" and "behind" the wings, where is the rest of the fuselage?....

Checkers

2nd Oct 2006, 22:04

How is the timebase of data recorders "set"? i.e will it be possible to synchronise events downloaded from the data recorders from both aircraft?

A GMT/UTC is recorded from either the Capt's Clock, ACARS, or an internal clock on the Data Acquisition Unit. However, synchronization will probably be done based on ATC tapes and radio-keying parameters from each aircraft.

Buster the Bear

2nd Oct 2006, 22:04

How can two aircraft collide considering all the 'in built' safety contained within two brand new airframes? Add to the equation, within extremely 'quite' airspace compared to Europe and North America?

If this was a freak chain of events culminating in such carnage, those involved were shockingly unlucky.

For whatever reason, TCAS/ACAS has not prevented a mid air collision, why? A question no doubt on the lips of many folk?

A glancing blow over millions of square miles that is just jungle.

archae86

2nd Oct 2006, 22:12

However, synchronization will probably be done based on ATC tapes and radio-keying parameters from each aircraft.
In this case would it seem likely that the initial contact event itself will provide one clear synchronization point?

anawanahuanana

2nd Oct 2006, 22:26

I may not be an ATPL, but I have been a licenced engineer on the 737 and EMB135/145 for a good few years now, and so if I may, I'd like to put forward my theory about all this. Just to see....

I think that the 737 was in a turn to the right, possibly an avoidance turn iaw aviation practice. I think the EMB stab tip struck the l/h wing inboard / #1 engine area, causing substantial damage to it. This led to either structural faliure of the engine pylon, or the engine loads generated allowed it to seperate as designed. The winglet of the EMB tore a hole in the underside of the 737 causing a decompression.

The upset of the 737, combined with the decompression led to loss of control of the aircraft and subsequent overspeed, which is why the gear was lowered by the crew in an attempt to create a bit more drag to slow their descent. The aircraft eventually broke up mid-air and the centre section fell upside down vertically into the jungle.

This would explain the trees around it being intact, ie: no forward speed on it, and also the fact that the wing tank access panels on the l/h wing appear to have suffered more than the opposing side (being blackened from maybe a post crash fire, or possible fire when the wing was damaged?). Obviously it is a distinct possibility that the damage to the leading edge and pylon area of the left wing were caused when it hit the forest, but it may be the case that the #2 engine has departed the aircraft in the designed manner during the uncontrolled descent, ie: the rest of the wing area around the pylon is undamaged, but the area of the #1 looks far worse.

Not putting this out there as the ultimate truth. Just wanted some rational arguments against my theory to help my understanding.:(

Pom Pax

2nd Oct 2006, 22:45

Assuming that the fuselage has been found any initial pictures might be too distressing for immediate publication and nothing is likely to be available until the area has been sanatised.
Also to find anything it is virtually necessary to first fly immediatly over it and then lower a number of chain saw operators.

mini

2nd Oct 2006, 22:53

jondc9

2nd Oct 2006, 23:02

what follows is something quoting an article in a south american newspaper...if true, it makes some sense

also, being granted such a large altitude for enroute is sometimes known as a "bock altitude" clearance. ie: maintain block Fl350-FL390.

read on.

ouch if true:

Rio de Janeiro - A lack of dialogue between two control towers was likely to blame for Brazil's worst ever plane crash last week in which 155 people died, the Brazilian daily O Globo reported Monday.

The mid-air collision between a Boeing 737-800 and a smaller twin- engine plane occurred because both machines flew into a so-called border region in the state of Para which was jointly controlled by two towers, O Globo reported citing an anonymous official in Brazilian air traffic control.

The two control towers did not speak to each other about the planes entering the same airspace and offered similar flight altitudes to their respective planes, thereby causing the crash, according to the report.

The US pilot of the smaller Embraer Legacy plane managed to make an emergency landing at a military landing site in Para.

Rescuers said there was no hope of finding survivors as they began the arduous task of removing bodies from the crash site of the Boeing plane, whose wreckage was discovered early Saturday in a remote, heavily forested area of the Amazon.

Brazilian President Luis Inacio Lula da Silva called for three days of mourning Saturday.

Air traffic control in Manaus allegedly suggested the Boeing maintain a flight altitude of between 35,000 and 39,000 feet, while the tower in Brasilia recommended an altitude of 37,000 feet for the Embraer Legacy flying in the opposite direction.

A full investigation into the cause of the accident would take about three months, given the difficulty of reaching the crash site, the authorities said.

The worst previous aviation accident in Brazil was in June, 1982, when a Boeing-727 of the Vasp airline crashed into a mountain in the north-eastern state of Ceara, killing all 137 people on board.

hmc_320

2nd Oct 2006, 23:22

some news.

-gol 737 cvr and fdr have been found late this afternoon.
-legacy crew are now not allowed to leave brazil and their passports were apprehended

SeniorDispatcher

2nd Oct 2006, 23:42

It appears some bodies were found in another section of aircraft 1km away...

http://g1.globo.com/Noticias/Brasil/0,,AA1295701-5598,00.html

bubbers44

3rd Oct 2006, 01:48

I heard another airline report my position over Swan Island in the carib just north of Nicaragua one minute from my position time, same altitude, IFR, and asked him his heading and continued knowing he was not on my wing. That was before GPS. I wish we could have those several mile errors now after this incident. The big sky theory doesn't work any more with GPS. I used to suggest to my students to not fly right on the centerline of an airway to avoid conflicts back when I was instructing. That is where everybody else is.

discountinvestigator

3rd Oct 2006, 01:50

From Checkers "A GMT/UTC is recorded from either the Capt's Clock, ACARS, or an internal clock on the Data Acquisition Unit. However, synchronization will probably be done based on ATC tapes and radio-keying parameters from each aircraft."

Wouldn't it make sense to have data recorders take their time stamp from the GPS equipment?

PS, I haven't sussed how to do the quote thing...

It depends what recorders you have got hold of and which type they are. In general, there may be a timestamp at the start and then the recorders all seem to run at slightly different rates if they are the older generation, say 1 in 60 difference, so you get 59 to 61 second minutes. You can work out relative speeds and then timestamp with the same ATC transmission. They you have to coordinate all the different ATC clocks etc.

Having got the reference time frames, then you need to work out when each data block was obtained, as the time that it writes to the memory or tape can be different. There could be a significant difference between each vital parameter here.

It can be quite a job just doing this part, without any analysis whatsoever.

anawanahuanana

3rd Oct 2006, 01:54

Mini:
The recorders get their time information from the Captains clock in the NG. The Captains clock time comes from the GPS system.

SeniorDispatcher

3rd Oct 2006, 03:11

Joe Sharkey's account in the October 3th NYT....

Riveting, absolutely riveting....

http://www.nytimes.com/2006/10/03/business/03road.html?ei=5094&en=27b19cf639280f8b&hp=&ex=1159848000&partner=homepage&pagewanted=all

broadreach

3rd Oct 2006, 03:25

Further to Senior Dispatcher's post above, the Globo article quotes Brazil's defense minister as informing that 100 bodies were found in the "tail section" of the aircraft 1km away from where the wing centre section fell. No precise definition of "tail section" is given; it could be most of the fuselage including the over-wing part which does not seem to be connected to the wings in the photographs thus far released. 100 out of 153 in the main cabin may seem like a lot but it could also turn out to be a clue to what happened to the Gol aircraft immediately after the collision, e.g. the effect of centrifugal force in a spin.

Woomera, I'll go with RiverCity's interpretation of "living on borrowed time". And it doesn't seem at all unreasonable to ensure the Legacy crew stick around until their role in events is established.

A few personal impressions: one, that Gol's crisis management has been excellent, the airforce are doing a good job of informing and ANAC (Brazil's equivalent to CAB) are too new in the job to be more than a hindrance. Two, that cause is rapidly narrowing down to lack of ATC coordination. I do think all the basics of this accident will be known in well under three months.

Airbubba

3rd Oct 2006, 05:37

Joe Sharkey's account in the October 13th NYT....

Riveting, absolutely riveting....

Obviously, you meant the October 3 NYT... I agree...

westhawk

3rd Oct 2006, 05:39

Mr.Sharkey's account of events as experienced from his perspective is quite a read indeed. His description of his interaction with the flightcrew and fellow passengers is completely consistent with normal flying interupted by (to them) a completely random and unexpected event. His visit to the cockpit, and recollection of the idicated altitude of 37,000' moments before the collision is interesting. I presume he is well aware of the import of that statement.

On a related note, I was unaware that flight over the Amazon region is still conducted at non RVSM flight levels for direction of flight. Now I know. I tend to agree with some other posters that a "tipping point" has been reached in the matter of the "cowboy antics" theory of this accident. The recovery of the data from both aircraft's data and voice recorders will put the final nail in that coffin and finally put that irresponsible and inflammatory rumor to rest.

Once it has been established just who was cleared to do what by whom, the matter of the TCAS and what, if any warning was or was not provided to either or both crews in time to avoid a collision will become a primary matter of focus. If indeed no warning was recieved by either crew, the angle of the sun probably provided the GOL crew the best opportunity to see the other aircraft, perhaps indicating that a last second avoidance maneuver was attempted, consistent with one of the theories regarding the relative attitudes of the aircraft at the point of collision. Time and investigation will tell.

As to the matter of the main gear position after the Boeing came to rest, Examination of the uplocks themselves will likely indicate whether they simply failed in overload or were released by other means. The CVR may not be easy to listen to for those unfortunate enough to find it their duty. I have heard just one such unedited post-crash CVR audio and would not care to repeat the experience. I tend not believe that the currently available evidence supports that any contact took place between the Legacy wing and the Boeing cockpit. I picture them fighting to the end, however long that took. Whoever listens to that audio will likely be the first to know.

The NTSB has today assembled a team consisting of three NTSB accident investigators, and representatives of the FAA and the Boeing company to assist in the investigation, in accordance with ICAO procedures.

This will certainly be worth following. The spectre of mid-air collision should always be in the minds of aviators. Events like this serve to drive that point home. Whatever happened to cause this accident, I wanna know.

Respects to all the victims of this tragedy,

Westhawk

ironbutt57

3rd Oct 2006, 07:16

Beginning to look a bit like either no tcas or RA not complied with...reports the 737 was assigned a block altitude 370-390 emb 370.. adjacent controller handling the emb not aware of this conflict.... uberlingen revisited???

mary_hinge

3rd Oct 2006, 09:27

From the news:

Recovery teams in Brazil have located both the cockpit-voice and flight-data recorders from the Gol Boeing 737-800 which crashed in the Amazon on 29 September, apparently after a mid-air collision with a corporate jet.

Military personnel have been concentrating on removing the remains of victims from the crash site – near Peixoto de Azevedo in central Brazil – to the air base at Cachimbo.

But the Brazilian ministry of defence, aeronautics command, adds: “The voice recorder and digital data recorder of the Gol Boeing 737 have also been found – these will be sent to the accident inquiry commission to be analysed.”

None of the 155 occupants of the aircraft, operating domestic flight 1907 between Manaus and Brasilia, survived the crash which appears to have followed a mid-air collision with an Embraer Legacy business jet.

CargoOne

3rd Oct 2006, 10:34

Ref what if RA Climb is issued when already at max FL.
Although I'm not an avionics engineer but I did occassionally whitnessed TCAS programming (because most or all TCAS processor units are out-of-box devices they need to be programmed after installation to particluar airframe to reflect actual indicators/controllers/transponders/etc config). One of the settings should be entered at programming stage there is AIRCRAFT MAX FL. Normally it would be the max certified FL. As I was told by engineers, this setting is to prevent TCAS to issue RA Climb when aircraft is already at max FL. So I believe this answers the question in general, however TCAS knows nothing about real time FL limitations due to weight or temperature.

alemaobaiano

3rd Oct 2006, 11:06

Folha Online http://www1.folha.uol.com.br/folha/cotidiano/ult95u126635.shtml

They are reporting this morning that the Legacys planned route involved a level change when they turned onto airway UZ6 from UW2, from FL370 to FL360. Mr Sharkeys account indicates that the Legacy was still at FL370 shortly before the collision.

They also state that ATC were receiving primary returns (no altitude or identification) only from the Legacy for 15 minutes at or around the time of the collision and that the pilots of the Legacy reported a communcations failure shortly before the collision. The reason being floated for this is that the pilots were showing off for the new owners and had turned off TCAS for this reason.

Folha also comments on possible communications errors between control centres and the fact that this region is not noted for reliable radar and communications cover.

As ever, there will be a sequence of events that worked together to bring down GOL 1907, some human, some technical, the avoidance of any one of which would have saved lives. The full details will only be known when the FDR, CVR, and ATC data has been analysed.

BTW, being held after a fatal accident is normal here, and in many other countries, and is not an indication of guilt or culpability.

Newforest

3rd Oct 2006, 11:32

Your folha link doesn't work, maybe this one will.
http://www.folha.uol.com.br/

Flight Safety

3rd Oct 2006, 11:46

If the "tail" section with 100 bodies was located 1 km away from the center wing box section, then it appears the aft fuselage might be basically intact. It appears that the center wing box is missing the aft fuselage in the photographs. I don't see much of the foward fuselage attached to the wing box either. Because it appears that the center wing box (with wings attached) fell without much forward velocity, this suggests that the 738 may have broken up not long before ground impact, since the center wing box and the aft fuselage seem to be basically intact. I would think a higher altitude breakup would cause smaller pieces to be scattered farther. A mid-air breakup suggests loss of control, but this is all speculation.

This link suggested that a mid-air breakup was indeed the case.

http://www1.folha.uol.com.br/folha/cotidiano/ult95u126632.shtml

This is a link to a number of articles on the accident, from folha online.

http://www1.folha.uol.com.br/folha/especial/2006/voo1907/

410

3rd Oct 2006, 12:03

If the reporter's version of events is to be believed, (I admit, there's no guarantee his rcollections will prove to be accurate), the two aircraft seem to have been on reciprocal tracks on the same airway, so one single mistake by one person, be it a controller or a pilot, was enough to cause this tragedy when coupled with some as yet unknown malfunction to a TCAS system.

Long time Ppruners will be familiar with these threads from the very early days of Pprune.

http://www.pprune.org/go.php?go=/pub/tech/MidAir2.html

http://www.pprune.org/go.php?go=/pub/tech/MidAir.html

This stuff was written ten years ago, (I know, because I wrote it), and still there is amazing resistance within the industry from pilots, ATC and regulators to offset tracking.

roturb

3rd Oct 2006, 12:25

410
you often get resistance when a paradigm shift is required. With increased navigation accuracy, the performance of the entire system needs also to be improved so that the increased accuracy can't ensure that two aircraft will be EXACTLY in the same space at the same time. TCAS (assuming it is actually fitted and working) only goes part way and is expensive. Lateral offsets will also assist. But what is really needed is a paradigm shift with 'surveillance' where it is no longer an 'eye in the sky' (i.e.ATC) but the pilots themselves that know exactly where other aircraft are in relation to their own and can plan ahead, rather than take last minute evasive actions based on third parties or TCAS. So what we need is 'surveillance' in the cockpit i.e. ATC-like information on traffic displays with ALL aircraft suitable equipped. Coupled with this is mutual ATC-pilot and pilot-pilot 'rules' as to how to behave (i.e. like TCAS does). And the technology must be affordable and in ALL aircraft. I beleive there is real urgency to deliver this technology to cockpits and overcome political issues such as funding and equipment mandates.
As they say, if you think safety is expensive...

discountinvestigator

3rd Oct 2006, 12:32

1. the list of equipment to be recovered also includes some of the TCAS brains as they may contain some data of interest, not just ATC tapes/strips, CVR and DFDR. The maintenance QAR as well, if available.

2. Remember that with both aircraft on GPS navigation you have increased the lateral overlap, and with Reduced Vertical Separation Minimum, you have increased the vertical overlap.

3. The mid-air geometry does not matter much if you have two perfectly serviceable aircraft hitting one another at high speed.

loulou

3rd Oct 2006, 12:44

Now navigation system on new aircrafts are so accurate, that aircrafts fly always excactly on the centerline of the airway With a few inches precision, at the exact altitude.

So if by misunderstanding both aircrafts fly the same airways at the same alt but in opposite directions (providing tcas doesn't work) there is a 100% chance they will touch each other.

I heard that on new airbus when flying to remote aeras such Africa, the navigation system is randomly selecting a track not exactly on the airways centerline but within a few Nm offset to reduce the risk of such collisions.

I am exact or wrong, someone could confirm what i said.

barit1

3rd Oct 2006, 12:53

It was common practice in the 70s to offset altitudes 100-200 feet over Africa.

410

3rd Oct 2006, 14:03

I think I said it 10 years ago in one of the two links I posted above, and if not, I certainly said it in other posts here on Pprune back then when I was pushing for the adoption of offset tracking, preferably an inbuilt, automatic offset in FMCs at cruising levels. I said then that nothing would change until 300+ North American passengers died. (This was after the USAF C141 hit a Luftwaffe TU154(?) head on off the West African coast in circumstances that might well prove to have been very similar to what led to this tragic crash.)

At the time, I mentioned that a handful of military aviators dead just wasn't enough to shake up the system. I pray to God that 155 South American dead will be enough to force 'The System', (and that 'System' includes all of us), into recognising that ultra accurate IRS/GPS navigation systems have made accidents like this more rather than less likely.

We've had official permission to fly offset over India now for a year or two. I don't believe I have EVER seen ONE other aircraft employing offset tracking in all the time it's been allowed, and I know of very few people who actually use it in trans Atlantic airspace (NATS) unless it's to avoid wake turbulence of an aircraft immediately ahead.

jondc9

3rd Oct 2006, 14:18

410

isn't it funny ( tragically so) that if planes were on VOR airways, that VOR's would have enough slop in receivers and autopilot couplers that no one would be right on the centerline.

I recall reading how in the Aural Range days (.- -. ) how pilots would fly to one side as the definition of the beam was sharper.

to barit 1, being 100 feet off on altitude would have been enough wouldn't it?

I read just today that the crew of the legacy said their TCAS did not issue a warning.

While it is too soon to know for sure, couldn't a bonafide failure of equiment, including the new transponder in this brand new plane be part of the equation ? This would accomplish the same thing as if the pilots had turned off their transponder. AS the legacy survived, a check of the transponder, TCAS, and cables/antennas are in order.

R Slicker

3rd Oct 2006, 14:23

It is quite common for aircraft on delivery to be granted exemptions from carrying items like fully functioning TCAS and even transponders. If you don't have a transponder and rely on pressure altimeter (set to departure QNH instead of 1013.2) then TCAS on the other a/c has no chance. BTW, QNE is not a pressure setting (earlier post), it is the flight level equivalent of altitude at very high airports.
RS

Johnbr

3rd Oct 2006, 14:35

Hi everyone,
I´ve been too busy flying these last few days,so I haven´t look at all posts here,just the few last ones.Anyways,flying jetliners in Brazil for the last 20 years,I´d like to offer some comments on things I´ve just read here.First,someone said something regarding a "block altitude" between 370 and 390...NEVER heard or seen anything like that in this country,in fact,ATC here is very,very conservative when it comes to flight levels,sometimes generating even complaints from pilots flying at very different speeds requesting same levels(i.e. the airplane ahead faster requesting same FL).Sometimes we do have in that particular area some comm dificulties,but to my recollection,there´s no radar gap or "blackout" in that airspace.Another point is,although i do not fly for GOL,I do know many of its pilots,for we have worked for the same airline in the past,and believe me,the operational discipline in the airline is very,very tight.There´s no doubt at all,that someone screwd up big time on this accident,but I guess we just have to wait for the result of the investigation,cuz quoting the media when aviation matters are concerned,at least in Brazil,it´s absolutely foolish.

alemaobaiano

3rd Oct 2006, 15:43

quoting the media when aviation matters are concerned,at least in Brazil,it´s absolutely foolish.

Quoting the general media anywhere is perhaps not the best thing to do, but that doesn't stop people doing it as it is our only source of information. The media here is very similar to that in many other countries, there are responsible news sources and sensationalist ones and hopefully the professionals on this board can spot which is which before quoting their material.

lenstrad

3rd Oct 2006, 17:32

The wing and tail of the Embraer Legacy 600 were damaged in what seems to have been a collision with a Boeing 737 in Brazil on Friday

J. SHARKEY
Published: October 3, 2006

With the window shade drawn, I was relaxing in my leather seat aboard a $25 million corporate jet that was flying 37,000 feet above the vast Amazon rainforest. The 7 of us on board the 13-passenger jet were keeping to ourselves.

Without warning, I felt a terrific jolt and heard a loud bang, followed by an eerie silence, save for the hum of the engines.

And then the three words I will never forget. “We’ve been hit,” said Henry Yandle, a fellow passenger standing in the aisle near the cockpit of the Embraer Legacy 600 jet.

“Hit? By what?” I wondered. I lifted the shade. The sky was clear; the sun low in the sky. The rainforest went on forever. But there, at the end of the wing, was a jagged ridge, perhaps a foot high, where the five-foot-tall winglet was supposed to be.

And so began the most harrowing 30 minutes of my life. I would be told time and again in the next few days that nobody ever survives a midair collision. I was lucky to be alive — and only later would I learn that the 155 people aboard the Boeing 737 on a domestic flight that seems to have clipped us were not.

Investigators are still trying to sort out what happened, and how — our smaller jet managed to stay aloft while a 737 that is longer, wider and more than three times as heavy, fell from the sky nose first.

But at 3:59 last Friday afternoon, all I could see, all I knew, was that part of the wing was gone. And it was clear that the situation was worsening in a hurry. The leading edge of the wing was losing rivets, and starting to peel back.

Amazingly, no one panicked. The pilots calmly starting scanning their controls and maps for signs of a nearby airport, or, out their window, a place to come down.

But as the minutes passed, the plane kept losing speed. By now we all knew how bad this was. I wondered how badly ditching — an optimistic term for crashing — was going to hurt.

I thought of my family. There was no point reaching for my cellphone to try a call — there was no signal. And as our hopes sank with the sun, some of us jotted notes to spouses and loved ones and placed them in our wallets, hoping the notes would later be found.

I was focused on a different set of notes when the flight began. I’ve contributed the “On the Road”column for The New York Times business-travel section every week for the last seven years. But I was on the Embraer 600 for a freelance assignment for Business Jet Traveler magazine.

My fellow passengers included executives from Embraer and a charter company called ExcelAire, the new owner of the jet. David Rimmer, the senior vice president of Excel Aire, had invited me to ride home on the jet his company had just taken possession of at Embraer’s headquarters here.

And it had been a nice ride. Minutes before we were hit, I had wandered up to the cockpit to chat with the pilots, who said the plane was flying beautifully. I saw the readout that showed our altitude: 37,000 feet.

I returned to my seat. Minutes later came the strike (it sheared off part of the plane’s tail, too, we later learned).

Immediately afterward, there wasn’t much conversation.

Mr. Rimmer, a large man, was hunched in the aisle in front of me staring out the window at the newly damaged wing.

“How bad is it?” I asked.

He fixed me with a steady look and said, "I don’t know."

I saw the body language of the two pilots. They were like infantrymen working together in a jam, just as they had been trained to do.

For the next 25 minutes, the pilots, Joe Lepore and Jan Paladino, were scanning their instruments, looking for an airport. Nothing turned up.

They sent out a Mayday signal, which was acknowledged by a cargo plane somewhere in the region. There had been no contact with any other plane, and certainly not with a 737 in the same airspace.

Mr. Lepore then spotted a runway through the darkening canopy of trees.

“I can see an airport,” he said.

They tried to contact the control tower at what turned out to be a military base hidden deep in the Amazon. They steered the plane through a big wide sweep to avoid putting too much stress on the wing.

As they approached the runway, they had the first contact with air traffic control.

“We didn’t know how much runway we had or what was on it,” Mr. Paladino would say later that night at the base in the jungle at Cachimbo.

We came down hard and fast. I watched the pilots wrestle the aircraft because so many of their automatic controls were blown. They brought us to a halt with plenty of runway left. We staggered to the exit.

“Nice flying,” I told the pilots as I passed them. Actually, I inserted an unprintable word between “nice” and “flying.”

“Any time,” Mr. Paladino, said with an anxious smile.

Later that night they gave us cold beer and food at the military base. We speculated endlessly about what had caused the impact. A wayward weather balloon? A hot-dogging military fighter jet whose pilot had bailed? An airliner somewhere nearby that had blown up, and rained debris on us?

Whatever the cause, it had become clear that we had been involved in an actual midair crash that none of us should have survived.
In a moment of gallows humor at the dormlike barracks where we were to sleep, I said, “Maybe we are all actually dead, and this is hell — reliving college bull sessions with a can of beer for eternity.”

About 7.30 p.m. Dan Bachmann, an Embraer executive and the only one among us who spoke Portuguese, came to the table in the mess hall with news from the commander’s office. A Boeing 737 with 155 people on board was reported missing right where we had been hit.

Before that moment, we had all been bonding, joking about our close call. We were the Amazon Seven, living now on precious time that no longer belonged to us but somehow we had acquired. We would have a reunion each year and report on how we used our time.

Instead we now bowed our heads in a long moment of silence, with the sound of muffled tears.

Both pilots, experienced corporate jet pilots, were shaken by the ordeal. “If anybody should have gone down it should have been us,” Mr. Lepore, 42, of Bay Shore, N.Y., kept saying.

Mr. Paladino, 34, of Westhampton, N.Y., was barely able to speak. “I’m just trying to settle in with the loss of all those people. It is really starting to hurt,” he said.

Mr. Yandle told them: “You guys are heroes. You saved our lives.” They smiled wanly. It was clear the weight of all this would remain with them forever.

The next day, the base was swarming with Brazilian authorities investigating the accident and directing search operations for the downed 737, which an officer told me lay in an area less than 100 miles south of us that could be reached only by whacking away by hand at dense jungle.

We also got access to our plane, which was being pored over by inspectors. Ralph Michielli, vice president for maintenance at ExcelAire and a fellow passenger on the flight, took me up on a lift to see the damage to the wing near the sheared-off winglet.

A panel near the leading edge of the wing had separated by a foot or more. Dark stains closer to the fuselage showed that fuel had leaked out. Parts of the horizontal stabilizer on the tail had been smashed, and a small chunk was missing off the left elevator.

A Brazilian military inspector standing by surprised me by his willingness to talk, although the conversation was limited by his weak English and my nonexistent Portuguese.

He was speculating on what happened, but this is what he said: Both planes were, inexplicably, at the same altitude in the same space in the sky. The southeast-bound 737 pilots spotted our Legacy 600, which was flying northwest to Manaus, and made a frantic evasive bank. The 737 wing, swooping into the space between our wing and the high tail, clipped us twice, and the bigger plane then went into its death spiral.

It sounded like an impossible situation, the inspector acknowledged. “But I think this happened,” he said. Though no one can say for certain yet how the accident occurred, three other Brazilian officers told me they had been informed that both planes were at the same altitude.

Why did I — the closest passenger to the impact — hear no sound, no roar of a big 737?

I asked Jeirgem Prust, a test pilot for Embraer. This was the following day, when we had been transferred from the base by military aircraft to a police headquarters in Cuiaba. That’s where authorities had laid claim to jurisdiction and where the pilots and passengers of the Legacy 600, including me, would be questioned until dawn by an intense police commander and his translators.

Mr. Prust took out a calculator and tapped away, figuring the time that would be available to hear the roar of a jet coming at another jet, each flying at over 500 miles an hour in opposite directions. He showed me the numbers. “It’s far less than a split second,” he said. We both looked at the pilots slouched on couches across the room.

“These guys and that plane saved our lives,” I said.

“By my calculations,” he agreed.

I later thought that perhaps the pilot of the Brazilian airliner had also saved our lives because of his quick reactions. If only his own passengers could say the same.

At the police headquarters, we were required to write on a sheet of paper our names, addresses, birthdates, occupations and levels of education, plus the names of our parents. We were all also required to submit to an examination by a physician with long hair who wore a white gown that draped almost to his shins. We were required to strip to the waists for photographs front and back.

This, explained the physician, whose name I did not get but who described himself to me as a “forensic doctor,” was to prove that we had not been tortured “in any way.”

Again gallows humor rose despite our attempts to discourage it.

“This guy’s the coroner,” Mr. Yandle explained later, and then added, “I think that means we are actually dead.”

But laughs, such as they were, died out by now as we thought again and again of the bodies still unclaimed in the jungle, and how their lives and ours had intersected, literally and metaphorically, for one horrible split second.