jet vs jet crash in brazil - 155 likely dead

For those of you still waiting for the regulatory fallout from the
glider vs jet crash here in the US:

http://news.yahoo.com/s/ap/20061001/..._plane_missing

Quote of interest from the article:

"The main question the investigation must address is how can this
happen with two ultramodern aircraft with collision-preventing
equipment," he said.

Gol said the jet that crashed had been delivered by Boeing Co. just
three weeks ago and had been flown for only 200 hours.

-bob

Here is a stunning article from one of the passengers of the corporate
jet:
http://www.nytimes.com/2006/10/03/business/03road.html

No words about any collision warning. Very odd.

Ramy


wrote:
For those of you still waiting for the regulatory fallout from the
glider vs jet crash here in the US:

http://news.yahoo.com/s/ap/20061001/..._plane_missing

Quote of interest from the article:

"The main question the investigation must address is how can this
happen with two ultramodern aircraft with collision-preventing
equipment," he said.

Gol said the jet that crashed had been delivered by Boeing Co. just
three weeks ago and had been flown for only 200 hours.

-bob

Ramy wrote:
Here is a stunning article from one of the passengers of the corporate
jet:
http://www.nytimes.com/2006/10/03/business/03road.html

No words about any collision warning. Very odd.

Yes, it does sound odd. Here's a question for those who know about these
planes, Brazilian airspace and/or Mode ES transponders:

- Would both the 373 and the Embraer be fitted with mode ES
transponders and TCAS systems?
- is there secondary radar coverage in that pert of Brazil?
- if a mode ES transponder is not receiving interrogation pulses,
does it still output the periodic squitter burst?
- would squitter bursts still be output if the secondary radar is
filtered so it doesn't interrogate the transponder?

Relevance to us: given that the CAA is trying to get Mode ES
transponders fitted to all gliders, etc. are there any situations when
am operational mode ES transponder is active but not sending information
and so would be invisible to TCAS or PCAS receivers? I'm thinking
particularly of cases when its in an area of poor radar coverage or is
being filtered out.

It seems to me that this could be quite a common situation for
transponders in gliders being flown at low altitudes in remote hilly
areas such as western Wales or the Scottish Highlands.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Martin Gregorie wrote:[snip] - if a mode ES transponder is not
receiving interrogation pulses,
does it still output the periodic squitter burst?

Martin, I expect an expert will answer definitively, but ages ago I
picked up this quote which explains it in lay terms:

"Mode S 'Announcement'. (thats not its proper name, which I forget, but
conveys what it does). The transponder radiates a signal announcing its
presence, to other mode S capable radar equipment in the area, about
once a second.

This signal contains a unique identifying 'Mode S Address'. This
address is hardwired into the aircraft, and unique to the aircraft.
I.E. no other aircraft, anywhere in the world, will have the same
address.

Note that this announcement is made unprompted, i.e. the transponder
does not wait to be interrogated, it just sends the signal anyway.

TCAS listens out for these announcement signals, and builds what is
called a "Roll Call" of Mode S transponders in the area."

(Furthermore, TCAS/TCAS dialogue takes place to resolve conflicts,
without any ground/ATC SSR activation. The TCAS units squitter at each
other. If TCAS detects a transponder which is not TCAS related, e.g.
in a glider, it alerts the TCAS-equipped pilot to resolve the conflict
without dialogue with the non-TCAS transponder, just using the latter's
position and height data as squittered.)

Chris N.

wrote:
Martin Gregorie wrote:[snip] - if a mode ES transponder is not
receiving interrogation pulses,
does it still output the periodic squitter burst?

Martin, I expect an expert will answer definitively, but ages ago I
picked up this quote which explains it in lay terms:

"Mode S 'Announcement'. (thats not its proper name, which I forget, but
conveys what it does). The transponder radiates a signal announcing its
presence, to other mode S capable radar equipment in the area, about
once a second.

This signal contains a unique identifying 'Mode S Address'. This
address is hardwired into the aircraft, and unique to the aircraft.
I.E. no other aircraft, anywhere in the world, will have the same
address.

Note that this announcement is made unprompted, i.e. the transponder
does not wait to be interrogated, it just sends the signal anyway.

TCAS listens out for these announcement signals, and builds what is
called a "Roll Call" of Mode S transponders in the area."

(Furthermore, TCAS/TCAS dialogue takes place to resolve conflicts,
without any ground/ATC SSR activation. The TCAS units squitter at each
other. If TCAS detects a transponder which is not TCAS related, e.g.
in a glider, it alerts the TCAS-equipped pilot to resolve the conflict
without dialogue with the non-TCAS transponder, just using the latter's
position and height data as squittered.)

Chris N.

Thanks, Chris. That clarifies it for me.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |