Comments on: Air France 447, update on pitot system

By: Chip

Chip — Wed, 10 Jun 2009 21:21:52 +0000

Curt;
Reading the ATSB report for QF 72, I’d have to agree it is starting to point that way. I’m still going through the ATSB preliminary report, there is a lot of good info. See wht you think I’m linked to it on my latest post.

By: Curt

Curt — Wed, 10 Jun 2009 07:03:31 +0000

I believe the FBW will emerge as the culprit. Especially after reviewing the posts about the QF72 incident. Being a software engineer for 25 years and working on embedded system software I know there is no such thing as defect-free software. Especially when dealing with unforeseen boundary conditions (inputs that no one every expected to see – such as two or three failed ADIRUs). Also, I seem to remember how Airbus used CAD to minimize the material used in load-bearing structures in order to save weight. The result is an airframe just strong enough to meet design constraints but minimum capacity to handle over-stress beyond design limits. That’s why I am not surprised to see a tail in the water that likely failed due to side loads in excess of design limits.

By: Andrew C.

Andrew C. — Tue, 09 Jun 2009 20:06:50 +0000

Chip,
thanks for making the Adiru info a seperate post, I think that this could be one of the problems the crew was trying to deal with. It certainly fits some of the ACARS messages.

And you summed it up much better than I could have. Nice post!

By: Chip

Chip — Tue, 09 Jun 2009 18:35:34 +0000

Andrew;
Thanks for your point. It is significant enough IMO that I put up a seperate post.

By: Chip

Chip — Tue, 09 Jun 2009 13:46:37 +0000

Andy;
I read that when researching the QANTAS 72 upset. I agree with you apparently the flight control designers never watched 2001 a Space Odyssey.

By: Chip

Chip — Tue, 09 Jun 2009 03:03:37 +0000

Rick;
See and avoid in the daylight is easier, I suspect we will get the answers when they pull up the black boxes. The pingers are actually good for another 22 days, so I think they will find them.

By: Rick

Rick — Tue, 09 Jun 2009 01:40:46 +0000

Yes I believe you’re right, and I appreciate your follow up posts this evening. Very informative. As always, there seems to be a cascading series of issues that led to complete breakdown. I still think that night flying was in the mix.

By: Andrew C.

Andrew C. — Mon, 08 Jun 2009 22:03:56 +0000

While digging around the internet trying to get a better understanding of what could have happened, I found this very interesting article: http://www.bangaloreaviation.com/2009/01/easa-issues-updated-emergency.html

‘… on board of their aircraft not to limit their actions to turning off the affected ADIRU off, but to completely de-energize it under all circumstances …’
This sounds really scary: not only does a disengage not fix the problem, but the Adiru needs to be completely de-energized – and to top it off, you might get the de-energized light, but the darned thing could still be wreaking havoc without the crew knowing about it!

By: Chip

Chip — Mon, 08 Jun 2009 19:24:33 +0000

Rick;
Look closely at the paint stripes. IMO the rudder is still there. I’m watching Fox News they just put up a picture of the tail it looks almost complete. A diver was pushing up on the rudder and it was pivoted in the picture at the hinge attachment points. This tail did not impact the water at high speed, it seperated from the aircraft prior to impact and then fell like a leaf into the ocean, IMO.

By: Rick

Rick — Mon, 08 Jun 2009 18:11:39 +0000

nytimes.com has a picture of the vertical stabilizer…the rudder does not seem to be present. Please take a look at that shot and it will be interesting to get your opinion.