Air France 447

Onkel Neal · 07-05-12, 10:04 AM

http://www.popularmechanics.com/tech...ce-447-6611877

Quote:

The Airbus's stall alarm is designed to be impossible to ignore. Yet for the duration of the flight, none of the pilots will mention it, or acknowledge the possibility that the plane has indeed stalled--even though the word "Stall!" will blare through the cockpit 75 times. Throughout, Bonin will keep pulling back on the stick, the exact opposite of what he must do to recover from the stall.

I guess the world is still trying to understand how the co-pilot could have reacted so badly... and why the Robert, with much more experience, was allowing Bonin to fly the craft during the stall?

Herr-Berbunch · 07-05-12, 10:16 AM

There was a thread about this a couple of months ago, looks like nothing has changed on the blame front. Incredulous that it could've happened in this day and age!

TheDarkWraith · 07-05-12, 11:23 AM

Commercial airliners have what is called a 'shaker' on the yoke. When the aircraft is nearing a stall the yoke will vibrate/shake warning the pilots of an impending stall. If the pilot's don't take action and the computer deams that a stall is imminent it usually pushes the yoke forward to prevent the stall. It's very hard to stall a commercial airliner these days.

Herr-Berbunch · 07-05-12, 01:13 PM

I think that was one of the points, poor design and implementation of the fly-by-wire side-sticks, no feedback and not necessarily visible to other crew the sticks position. Hence one pulling back all the time and the others not reacting to that!

Catfish · 07-05-12, 01:44 PM

For what i read and heard from an airbus captain, the joysticks on both sides of the cockpit are not interlocked in a way they mirror the other's position - one does not repeat the position of the other one.
I still wonder why someone would install this "solution" in an airliner, but ..

So one stick untouched being laid back at pull position, the other will probably not react to any input.
While pilots are trained though and know this, this seems to be one of the explanations how this situation was possible to happen.

Falkirion · 07-05-12, 04:51 PM

Quote:

Originally Posted by TheDarkWraith

Commercial airliners have what is called a 'shaker' on the yoke. When the aircraft is nearing a stall the yoke will vibrate/shake warning the pilots of an impending stall. If the pilot's don't take action and the computer deams that a stall is imminent it usually pushes the yoke forward to prevent the stall. It's very hard to stall a commercial airliner these days.

I know Boeing has the stick shaker installed, but does Airbus have it installed in the cockpit side stick as well?

Stealhead · 07-05-12, 05:40 PM

I am not 100% sure that every aircraft over a certain size is required to have a "shaker" on both yokes there are also "stick pushers" that warn the pilot of a dive.Of course a crash can also be caused by an incompetent crew very easily.All large modern airliners pretty much are designed to keep the person controlling them from doing something that will cause the plane to enter an uncontrollable state but that has a limit.

NatGeo has a shown called seconds from disaster many are about plane crashes one episode about an Aeroflot Airbus crash the pilot let his kids sit in the seat and they turned off autopilot control to the ailerons and the plane of course went off course and the pilots failed to notice that the auto pilot had all but the ailerons under it control in the end they crashed the plane.

Falkirion · 07-05-12, 06:53 PM

Ah here's the info I was after. It's covered in a post in this forum discussion on Airliners.net
http://www.airliners.net/aviation-fo...ead.main/81259
Looks like Airbus doens't provide stick shakers and instead relies on their FBW computer laws to keep the plane in a controlable state.

Stealhead · 07-05-12, 09:32 PM

That is still fairly reliable and has redundancy in it just a different system.Sometimes things just go wrong though more than one redundant system can fail and even if the crew does everything correctly sometimes a crash is just unavoidable.

Two old military aviation sayings:
A fighter with two engines(jet) is better than a fighter with one engine(jet) with two engines if one fails the other one will stay running long enough for you to fly into the ground.

Always remember that there are more planes on the bottom of the sea than there are submarines in the sky.(Naval Aviation joke)

Jimbuna · 07-06-12, 06:45 AM

Having read the transcript it looks like a catalogue of errors and obviously fatal consequences.

Always take the seat next to the black box when flying.

Spoon 11th · 07-06-12, 09:01 AM

How about packing hand held GPS receiver (like cell phone) next time to have reliable indication of ground speed when pitots fail.

Tchocky · 07-06-12, 02:08 PM

Quote:

Originally Posted by Spoon 11th

How about packing hand held GPS receiver (like cell phone) next time to have reliable indication of ground speed when pitots fail.

Not a bad idea, and I see what you're getting at. Unfortunately groundspeed isn't a very valuable metric once you get into serious head/tailwinds.
Given the narrow interval between stall speed and Mach buffet speed at cruising levels there isn't much groundspeed can tell you, and adding a wind component to the calculation requires (dammit!) pitot tubes.

07-05-12, 10:16 AM	#2
Herr-Berbunch Kaiser Bill's batman Join Date: May 2010 Location: AN72 Posts: 13,203 Downloads: 76 Uploads: 0	There was a thread about this a couple of months ago, looks like nothing has changed on the blame front. Incredulous that it could've happened in this day and age! __________________

07-05-12, 01:13 PM	#4
Herr-Berbunch Kaiser Bill's batman Join Date: May 2010 Location: AN72 Posts: 13,203 Downloads: 76 Uploads: 0	I think that was one of the points, poor design and implementation of the fly-by-wire side-sticks, no feedback and not necessarily visible to other crew the sticks position. Hence one pulling back all the time and the others not reacting to that! __________________

07-06-12, 06:45 AM	#10
Jimbuna Chief of the Boat Join Date: Feb 2006 Location: 250 metres below the surface Posts: 190,525 Downloads: 63 Uploads: 13	Having read the transcript it looks like a catalogue of errors and obviously fatal consequences. Always take the seat next to the black box when flying. __________________ Wise men speak because they have something to say; Fools because they have to say something. Oh my God, not again!!

07-05-12, 11:23 AM	#3
TheDarkWraith Black Magic Join Date: Jun 2007 Posts: 11,962 Downloads: 147 Uploads: 5	Commercial airliners have what is called a 'shaker' on the yoke. When the aircraft is nearing a stall the yoke will vibrate/shake warning the pilots of an impending stall. If the pilot's don't take action and the computer deams that a stall is imminent it usually pushes the yoke forward to prevent the stall. It's very hard to stall a commercial airliner these days.

07-05-12, 01:44 PM	#5
Catfish Dipped Squirrel Operative Join Date: Sep 2001 Location: ..where the ocean meets the sky Posts: 17,766 Downloads: 38 Uploads: 0	For what i read and heard from an airbus captain, the joysticks on both sides of the cockpit are not interlocked in a way they mirror the other's position - one does not repeat the position of the other one. I still wonder why someone would install this "solution" in an airliner, but .. So one stick untouched being laid back at pull position, the other will probably not react to any input. While pilots are trained though and know this, this seems to be one of the explanations how this situation was possible to happen.

07-05-12, 05:40 PM	#7
Stealhead Navy Seal Join Date: Feb 2009 Location: Kentucky Posts: 5,421 Downloads: 85 Uploads: 0	I am not 100% sure that every aircraft over a certain size is required to have a "shaker" on both yokes there are also "stick pushers" that warn the pilot of a dive.Of course a crash can also be caused by an incompetent crew very easily.All large modern airliners pretty much are designed to keep the person controlling them from doing something that will cause the plane to enter an uncontrollable state but that has a limit. NatGeo has a shown called seconds from disaster many are about plane crashes one episode about an Aeroflot Airbus crash the pilot let his kids sit in the seat and they turned off autopilot control to the ailerons and the plane of course went off course and the pilots failed to notice that the auto pilot had all but the ailerons under it control in the end they crashed the plane.

07-05-12, 06:53 PM	#8
Falkirion Ace of the Deep Join Date: Aug 2008 Location: Melbourne, AUS Posts: 1,043 Downloads: 34 Uploads: 0	Ah here's the info I was after. It's covered in a post in this forum discussion on Airliners.net http://www.airliners.net/aviation-fo...ead.main/81259 Looks like Airbus doens't provide stick shakers and instead relies on their FBW computer laws to keep the plane in a controlable state.

07-05-12, 09:32 PM	#9
Stealhead Navy Seal Join Date: Feb 2009 Location: Kentucky Posts: 5,421 Downloads: 85 Uploads: 0	That is still fairly reliable and has redundancy in it just a different system.Sometimes things just go wrong though more than one redundant system can fail and even if the crew does everything correctly sometimes a crash is just unavoidable. Two old military aviation sayings: A fighter with two engines(jet) is better than a fighter with one engine(jet) with two engines if one fails the other one will stay running long enough for you to fly into the ground. Always remember that there are more planes on the bottom of the sea than there are submarines in the sky.(Naval Aviation joke)

07-06-12, 09:01 AM	#11
Spoon 11th Seasoned Skipper Join Date: Mar 2001 Location: Finland Posts: 689 Downloads: 10 Uploads: 0	How about packing hand held GPS receiver (like cell phone) next time to have reliable indication of ground speed when pitots fail.