Mid-air collision over Brasil

[aimscabinet]

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?

[Scurvy.D.Dog]

.. light MAC damage could cripple a large aircraft (flight deck, empennage) without fatal damage to the other aircraft (outboard wing, non-critical areas of the fuselage)!

… add FL360 to that and the critical areas are any part of the pressure vessel … explosive decompression ….
.
jon … I wonder about those aspects also, perhaps you can add WX into the question marks regarding RVSM?!?! … it would not take much of an upset at that height to lose/gain 1000ft
.
Worldpilot ... thankyou!

[AeroBoero]

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]

Originally Posted by jondc9

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]

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]

Images on GOL crash from 09/29/2006

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]

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]

Images

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

[RiverCity]

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 @, but perhaps others on the ferry plane might have something to say about it.

[Broomstick Flier]

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]

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]

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]

Originally Posted by Broomstick Flier

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]

Originally Posted by Broomstick Flier

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]

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]

No Fire?

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]

"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]

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

[jondc9]

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]

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.