Rio flight missing?

[C]

I am rather interested to know, how a aircraft suffering "catastrophic electrical failure" was able to still send out so much information. The system that sends this information is done via the ACARS computer and uses if memory serves, VHF on radio mode control panel three. If no other radios were working, why was this one, it all goes through the same boxes and antennas?

Surely a modern aircraft still has the ability to run at least one radio (ie a VHF box) even with a "complete" electrical failure. It'd be a backward step if it couldn't - I assume the A330 has a RAT of some description.

[The-Black-Sheep]

Wouldnt the Emergency generator kick in aswell?  :-?

Alec

[expat]

I am rather interested to know, how a aircraft suffering "catastrophic electrical failure" was able to still send out so much information. The system that sends this information is done via the ACARS computer and uses if memory serves, VHF on radio mode control panel three. If no other radios were working, why was this one, it all goes through the same boxes and antennas?

Surely a modern aircraft still has the ability to run at least one radio (ie a VHF box) even with a "complete" electrical failure. It'd be a backward step if it couldn't - I assume the A330 has a RAT of some description.

[quote]Wouldnt the Emergency generator kick in aswell?

[C]

I am rather interested to know, how a aircraft suffering "catastrophic electrical failure" was able to still send out so much information. The system that sends this information is done via the ACARS computer and uses if memory serves, VHF on radio mode control panel three. If no other radios were working, why was this one, it all goes through the same boxes and antennas?

Surely a modern aircraft still has the ability to run at least one radio (ie a VHF box) even with a "complete" electrical failure. It'd be a backward step if it couldn't - I assume the A330 has a RAT of some description.

[quote]Wouldnt the Emergency generator kick in aswell?

[The-Black-Sheep]

I find it hard to believe it was terrorism to be honest. If ACARS sends out information stating that the aircraft was suffereing numerous faults, then we're surely not looking an explosive device taking it out. It would have just disappeared without ACARS sending any info what so ever.

With another recent "discovery" saying the aircraft was flying too slow, is it possible that it had stalled after flying into this thunderstorm (severe turbulence affecting the airspeed), then the stall becoming unrecoverable, maybe slipped into a dutch roll, ACARS sends out all this information about systems being affected while it's "falling" out of the sky, and because of the sheer forces being acted upon the aircraft, it breaks up. Wind then might have helped spread aircraft pieces over a large stretch of ocean.

Just a theory, I'm sure Matt might be able to point out if there is any flaws with it, but it's just an idea I guess.

Alec

[C]

I find it hard to believe it was terrorism to be honest. If ACARS sends out information stating that the aircraft was suffereing numerous faults, then we're surely not looking an explosive device taking it out. It would have just disappeared without ACARS sending any info what so ever.

Indeed. Sadly there's a very distinct possibility that we'll never find out exactly what happened either way.

With another recent "discovery" saying the aircraft was flying too slow, is it possible that it had stalled after flying into this thunderstorm (severe turbulence affecting the airspeed), then the stall becoming unrecoverable,

There's the other way too. I've flown a simulator sortie where due to faults put on the aircraft's systems we've ended up flying a lot faster than we thought we were - something that could easily lead to structural failure.

[The-Black-Sheep]

Seems to be just a matter of finding the black boxes now and listening to what the guys on the flight deck said when it all went incredibly wrong.

Alec

[C]

Seems to be just a matter of finding the black boxes now and listening to what the guys on the flight deck said when it all went incredibly wrong.

Fingers crossed.

[Dr.bob7]

Just a question but shouldnt a airline captain be able to tell if their going to fast or slow without the airspeed indicator working, i mean it would show on the GPS units with distance traveled, Ive never flown in IFR conditions like the airbus but even then it seems to me you would be able to tell if the airspeed indicator was acting weird and even then you could probably balance the speed out

[DaveSims]

Just a question but shouldnt a airline captain be able to tell if their going to fast or slow without the airspeed indicator working, i mean it would show on the GPS units with distance traveled, Ive never flown in IFR conditions like the airbus but even then it seems to me you would be able to tell if the airspeed indicator was acting weird and even then you could probably balance the speed out

GPS shows your groundspeed, not necessarily your airspeed.  In a storm system, the winds aloft could make a big difference relative to ground speed.  Also at 35000 feet, there is only about 50 kts or so between stall speed and max speed, so it wouldn't take much of a slow down to cause a problem.  The other problem is without the speed parameters being fed to the computers that control the aircraft, the plane could become difficult to handle.  One theory that I've heard mentioned by an Airbus pilot is the rudder limiter.  At high speeds the rudder movement is restricted.  If the aircraft computers thought the aircraft was going slow, if would allow more rudder movement and could allow the rudder to me overstressed.  Then you would have a situation similar to the A300 crash in NYC in 2001, where the whole verticle tail fell off.  

[expat]

Just a question but shouldnt a airline captain be able to tell if their going to fast or slow without the airspeed indicator working, i mean it would show on the GPS units with distance traveled, Ive never flown in IFR conditions like the airbus but even then it seems to me you would be able to tell if the airspeed indicator was acting weird and even then you could probably balance the speed out

GPS shows your groundspeed, not necessarily your airspeed.

[Hagar]

I'm not convinced that's peculiar to Airbus Matt. Most aircraft will automatically recover from a stall if left alone. I always understood that aerodynamics plays very little part with this type of aircraft. I remember the impressive demonstrations of the Airbus at Farnborough at an extreme alpha angle when a conventionally controlled aircraft would have fallen out of the sky. http://www.youtube.com/watch?v=0jz957KRXzQ

In your example would not the computer attempt to correct the nose-down attitude by applying up elevator? This would be the normal reaction of a human pilot in a conventional aircraft in similar circumstances & would make the situation worse.

What's always worried me about 'fly-by-wire' systems is whether it's possible for the crew to override the computer or even have any control at all in the event of a catastrophic electrical failure. When the whole system relies on a simple component like a pitot tube did they ever think to have a backup of a different type in case it goes wrong? A chain is as strong as its weakest link.

Pitot tubes are fitted to all types of aircraft & have worked reliably for many years so what's different about the ones used by Airbus?

[expat]

I'm not convinced that's peculiar to Airbus Matt. Most aircraft will automatically recover from a stall if left alone. I always understood that aerodynamics plays very little part with this type of aircraft. I remember the impressive demonstrations of the Airbus at Farnborough at an extreme alpha angle when a conventionally controlled aircraft would have fallen out of the sky. http://www.youtube.com/watch?v=0jz957KRXzQ

In your example would not the computer attempt to correct the nose-down attitude by applying up elevator? This would be the normal reaction of a human pilot in a conventional aircraft in similar circumstances & would make the situation worse.

What's always worried me about 'fly-by-wire' systems is whether it's possible for the crew to override the computer or even have any control at all in the event of a catastrophic electrical failure. When the whole system relies on a simple component like a pitot tube did they ever think to have a backup of a different type in case it goes wrong? A chain is as strong as its weakest link.

Pitot tubes are fitted to all types of aircraft & have worked reliably for many years so what's different about the ones used by Airbus?

That is the whole idea behind this aerodynamic design. If the entire fly by wire system failed then the aircraft can be flown by differential thrust alone. We have seen with for example with the Soux City crash that it was possible with a DC 10, but it is designed into the Air Bus not to be possible, but to be able to do it. This is one of the reasons why the flying control surfaces are aerodynamically neutral. Without power, they droop on the ground, but in the air without power they go naturally neutral with the airflow and cannot freeze in an up or down position. Can the pilot over rule, the answer is a big NO! Against this, outside of one very public accident, when have the computers got it wrong agaist the rather large number of pilot error accidents? As for the pitot tubes going tits up, for start there is not just one. The pilot has one, the co-pilot has one and then they have a standby. It cannot boil down to just a pitot failure. The right and left systems are separate as is the standby system. What is common to the three systems is pitot heating, but even that has different channels. Without the CDR and CVR it is just speculation and window dressing by anyone who decides to replace fleet wide pitot tubes.

Matt

[DaveSims]

Just a question but shouldnt a airline captain be able to tell if their going to fast or slow without the airspeed indicator working, i mean it would show on the GPS units with distance traveled, Ive never flown in IFR conditions like the airbus but even then it seems to me you would be able to tell if the airspeed indicator was acting weird and even then you could probably balance the speed out

GPS shows your groundspeed, not necessarily your airspeed.

[expat]

Just a question but shouldnt a airline captain be able to tell if their going to fast or slow without the airspeed indicator working, i mean it would show on the GPS units with distance traveled, Ive never flown in IFR conditions like the airbus but even then it seems to me you would be able to tell if the airspeed indicator was acting weird and even then you could probably balance the speed out

GPS shows your groundspeed, not necessarily your airspeed.