Qantas jet's plunge

[multiweb (Marc)]

Originally Posted by acropolite

Cosmic rays sounds to me like a lame excuse, (no pun intended) given the number of scary incidents and losses they should be engineering commonsense changes to the flight control systems.

I still remember seeing footage of an aircraft autolanding in to a forest at an airshow when the pilot had intended to simply do a low pass. Pilot error, yes if he had fully understood the flight control system it wouldn't have happened, but the pilot didn't deliberately crash the plane, the flight computer did.

That was a pilot error on an A320 years ago in Northern France. He disabled the computer that was telling him he was too low as he was doing a "fly by" demo for the media. He did get too low and didn't get enough thrust to clear the trees but he was in manual flying mode (not!). Whether people like it or not fly by wire is the safest alternative. A good example is the space shuttle. No one could land this brick. Or the stealth bombers.

[mac (Matt)]

I don't fly Qantas on long haul flights anymore. They seem to have too many maintenance problems on their big planes. Haven't had any troubles flying them domestically in NZ though.

[avandonk]

Ultimately it is the job of the flight crew to control things regardless of systems failures. The flight envelope at cruise at high altitudes does not allow much room for any error. Autopilots are not as smart as the blokes in the front seats. Even a Pitot tube icing up can kill you unless you have smart pilots.

As for cosmic rays affecting three computers simultaneously. I find that hard to believe.

Why the Qantas flight did not end in disaster was due to very competent pilots.

Bert

[Nesti (Mark)]

Originally Posted by Peter Ward

Sir Issac couldn't fly for Sh*t. He'd never even seen an aeroplane
AND also predicted refractors would have chromatic abberations

After 20 years on Boeing (non-FBW) types , I have to say I moved to Airbus with some reservations.

But, I must admit I am a convert.

The A380 has six levels of redundancy in the flight control system....

Even with a *total hydraulic system loss* the aircraft is very flyable.

You'd die in a B747 with the same failures.

Careful - There was nothing that Newton couldn't understand...the technology of the day was his only limitation.

You're speaking from an operators point of view, I'm speaking from a maintainers point of view, we're bound to have a difference of opinion. You talk in terms of, 'what would happen and how would I react if'. I talk in terms of, 'how do I prevent if from occurring and what else is if associated with'.

"You'd die in a B747 with the same failures", so why are fly by wire aircraft falling out of the sky if they're so good???

How often do you fly (simulator time does not count) with a "total hydraulic system loss"??? Is this part of post maintenance test flight procedure?

[GrahamL]

thanks guys .. my irrational view on flying is once again reinforced
in that I'll sit up the back thanks if I ever have to fly .. I'm sure its safer as no matter how much you guys up front or on the ground stuff up these suckers just never seem to reverse into mouintains or the
ground

[TrevorW]

It's not the flying that kills you

[multiweb (Marc)]

Originally Posted by TrevorW

It's not the flying that kills you

Damn right! It's the food they serve you in the plane!

[gary]

Originally Posted by avandonk

As for cosmic rays affecting three computers simultaneously. I find that hard to believe.

Hi Bert,

When you read the Australian Transport Safety Bureau first and second
Interim Factuals, the current working hypothesis does not suggest that
the redundant computers all took a hit at the same time. Rather than the
computers, one of the primary focuses of investigators has been on instrumentation
upstream from the computers, in particular with a unit known as the
air data inertial reference unit (ADIRU). In the most recent report, they state that
one of the ADIRU units "provided erroneous data that was not
detected by the ADIRU itself" and that "the flight control computers did not
filter spikes in angle of attack data in a specific situation".

My understanding from the reports is that they are investigating the software
and have issued patches to the flight control primary computers so that they
don't respond the way they did to the erroneous data.

What apparently still is a mystery is how and why the ADIRU malfunctioned
and a reading of the reports, which are available from the ATSB web site,
gives some small insight into the extraordinary effort investigators and
engineers have been putting into trying to understand what went wrong.
There are other subtleties and puzzles including a similar malfunction
on another flight but which had a different model of ADIRU manufactured by
a totally different manufacturer.

The interim reports don't make it clear as the investigation is ongoing, but
despite complex redundancies with the ADIRU's and primary computers,
there might have been some unforeseen scenario where a single point of
failure still led to the event. Hopefully time will tell.

What is also compelling reading in the reports for those of us who sit rear of the cockpit
is the part of the story to do with keeping your seat belt fastened whilst
seated and cruising. As the report states, it can be a real mistake to have
the seat belt loose, as it is designed to be worn snug to avoid abdominal
damage and in a worse case scenario where you apparently give it 20cm
of slack, the buckle can get caught on the arm rest, un-clip and you undergo
a negative G maneuver with your head into the luggage racks.

So next time Peter or one of his good colleagues recommend over the PA to keep
your seat belt on at all times when seated, it sounds like advice to be heeded.

[DJDD]

From the article:

"
But changing seatbelts would be a massive undertaking for Qantas — and all airlines.
With about 220 planes in the Qantas fleet, carrying up to 300 people per plane, the airline would need to replace more than 60,000 buckles.

"


so, this might cost QANTAS, what, $600,000 maybe $1million?
perhaps another instance of an airline crying poor early to avoid costs.





as for the cosmic ray...interesting...maybe I can use that excuse when our servers go down at work...sorry, boss, it was the cosmic rays...

[Nesti (Mark)]

Originally Posted by gary

Hi Bert,

So next time Peter or one of his good colleagues recommend over the PA to keep
your seat belt on at all times when seated, it sounds like advice to be heeded.

You're damn right!!!

I've been strapped in by a 4 point harness and it's been near impossible to do my job properly when you're being bounced around rough enough. Being rattled around like dice inside a cup is not a good way to be.

[pgc hunter]

Cosmic Rays...sound ridiculous. Every single airliner the planet should be equally "affected" by "Cosmic Rays" at high altitude going by this theory, so for this to be a plausable explanation, every airliner on Earth would be suffering the same consequences.

[Nesti (Mark)]

Originally Posted by DJDD

so, this might cost QANTAS, what, $600,000 maybe $1million?
perhaps another instance of an airline crying poor early to avoid costs.

These are the pitfalls of deregulating the market and allowing TOO MUCH competition - what suffers?? Maintenance then training suffer.

I believe the greatest hazard to aviation in general is actually healthy competition. You need time and money to be able to put up your hand and say "I'm not happy with...or no, let's do this by the book...or no, let's just replace the unit". Alaska Airlines 261 was the sadest case of cutbacks...a handful of grease per plane and nothing would have happened.

[avandonk]

Originally Posted by gary

Hi Bert,

When you read the Australian Transport Safety Bureau first and second
Interim Factuals, the current working hypothesis does not suggest that
the redundant computers all took a hit at the same time. Rather than the
computers, one of the primary focuses of investigators has been on instrumentation
upstream from the computers, in particular with a unit known as the
air data inertial reference unit (ADIRU). In the most recent report, they state that
one of the ADIRU units "provided erroneous data that was not
detected by the ADIRU itself" and that "the flight control computers did not
filter spikes in angle of attack data in a specific situation".

My understanding from the reports is that they are investigating the software
and have issued patches to the flight control primary computers so that they
don't respond the way they did to the erroneous data.

What apparently still is a mystery is how and why the ADIRU malfunctioned
and a reading of the reports, which are available from the ATSB web site,
gives some small insight into the extraordinary effort investigators and
engineers have been putting into trying to understand what went wrong.
There are other subtleties and puzzles including a similar malfunction
on another flight but which had a different model of ADIRU manufactured by
a totally different manufacturer.

The interim reports don't make it clear as the investigation is ongoing, but
despite complex redundancies with the ADIRU's and primary computers,
there might have been some unforeseen scenario where a single point of
failure still led to the event. Hopefully time will tell.

What is also compelling reading in the reports for those of us who sit rear of the cockpit
is the part of the story to do with keeping your seat belt fastened whilst
seated and cruising. As the report states, it can be a real mistake to have
the seat belt loose, as it is designed to be worn snug to avoid abdominal
damage and in a worse case scenario where you apparently give it 20cm
of slack, the buckle can get caught on the arm rest, un-clip and you undergo
a negative G maneuver with your head into the luggage racks.

So next time Peter or one of his good colleagues recommend over the PA to keep
your seat belt on at all times when seated, it sounds like advice to be heeded.

So what you are saying is the aircraft systems had an erroneous angle of attack which was fed back into the aircraft autopilot and then caused a stall with a very high rate of initial decent say 20,000 ft per min.

Interesting!

Bert

[multiweb (Marc)]

Originally Posted by avandonk

So what you are saying is the aircraft systems had an erroneous angle of attack which was fed back into the aircraft autopilot and then caused a stall with a very high rate of initial decent say 20,000 ft per min.

Interesting!

Bert

I have a feeling your air-conditioning is not working properly.

[avandonk]

Originally Posted by multiweb

I have a feeling your air-conditioning is not working properly.

Have you ever stalled a jet airliner from cruise altitude? My brother has and 20k feet/min is conservative.

Bert

[Nesti (Mark)]

Originally Posted by multiweb

I have a feeling your air-conditioning is not working properly.

LOL...not everyone has a requirement to pipe 6000 BDU of frozen ram-air into their rooms to keep their PS2/XBox/Gaming super computers at optimum temperature ya know.



Good thing you do tho, coz you'll need it as a Morgue when I'm done with you on MW2!


Back to Henny Penny planes...

[Nesti (Mark)]

Originally Posted by avandonk

Have you ever stalled a jet airliner from cruise altitude? My brother has and 20k feet/min is conservative.

Bert

Hang-on, that's only 101m/sec vertical speed...363kph...you're right, that's quite small.

I would think 35,000 to 40,000 would be getting extreme.

Heck, a toy can do 2/3rds of that no sweat...at 1min mark is boom flexing at around 250kph.

http://www.youtube.com/watch?v=w7q9Pk7kH9c

[multiweb (Marc)]

Originally Posted by Nesti

LOL...not everyone has a requirement to pipe 6000 BDU of frozen ram-air into their rooms to keep their PS2/XBox/Gaming super computers at optimum temperature ya know.



Good thing you do tho, coz you'll need it as a Morgue when I'm done with you on MW2!


Back to Henny Penny planes...

Bring it on! Women! Nah I've got a ceiling fan, like a chopper. You gotta be "in the zone" man

[multiweb (Marc)]

Originally Posted by avandonk

Have you ever stalled a jet airliner from cruise altitude? My brother has and 20k feet/min is conservative.

Bert

I rest my case. Chill up. Couple of beers, blood pressure check..

[stephenb (Stephen)]

Just a thought? How many of the passengers who were injured/claiming compensation, did not have their seatbelts fastened?

I do not believe any major commerical passenger airline is more risky than the other. There is a risk to all flight travel, and in the end, it is humans who design, build, test and fly the aircraft and its components. And as a passenger you accept that small risk when you board.