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Iced AoA sensors send A321 into deep dive

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Iced AoA sensors send A321 into deep dive

Old 23rd Mar 2015, 15:26
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Because they had to diagnose the problem first. "Fly the plane first" doesn't work on an Airbus
Maybe AB could design a control wheel with a thumb disconnect button to prevent the huge loss of altitude while trouble shooting the computer malfunction.
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Old 23rd Mar 2015, 15:27
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It would be bad! Sort of like the F-18 face plant problem on catapult shots. The F-18 has the option to completely disable the flight control computers with just one switch. Sadly simply impossible to accomplish on a cat shot. Several pilots were lost. Cause was stuck AOA sensors in the stall range.
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Old 23rd Mar 2015, 15:28
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Airbus could change the sensors ....
Airbus could change the programming ....
Airbus could change the computers ....
Airbus could change the switching authority ....

No. Airbus wrote an OEB ....

Groundhog day 4, or 5??
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Old 23rd Mar 2015, 15:59
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Ah, all this bad press about the Airbus and its "Logic", Some of my hapiest memories are walking out the front door into the loading bridge after a long day of trying to get this aircraft to work after a nights cold soaking in minus thirty, cant say I enjoyed climbing aboard Mr Zieglers creation very much though!
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Old 23rd Mar 2015, 16:19
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Gretchenfrage: maybe you could suggest something that doesn't involve grounding one of the worlds' most popular aircraft?

Let's not pretend other manufacturers have a perfect record. Didn't two/three jets from another manufacturer end up a smoking holes before anything was done? I took ten years from the first hull loss and it took a FAA AD to get the problem fixed.

The super simple OEB will bring the aircraft safely under control. All pilots are aware. My airline forces us to carry a copy of OEB48 and OEB48 is listed on each and every OFP. So there can be 9 copies of OEB48 on a flight deck at any one time.
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Old 23rd Mar 2015, 17:06
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This incident is a fine illustration of why a pilotless passenger aircraft isn't such a good idea.

The pilots overcame the system malfunction to safely fly and land the aircraft. Fortunately, a concierge was not at the helm.
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Old 23rd Mar 2015, 19:07
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DJ77 So, could someone in the know explain us poor non-buss drivers what would happen if an A-320 took off, say on a freezing cold day, with two AOA sensors stuck at values beyond stall AOA ?
All dead, Airbus blames pilots who did not react fast enough (there's an OEB , remember ?), blames airline for insufficient pilot training, life goes on.
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Old 23rd Mar 2015, 20:48
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Perhaps an AD to operate A320/321 and similar in alternate law below 10,000 ft to allow recovery time, to be lifted when much improved AoA sensors are fitted.

I believe this would expedite the retrofit process.

Last edited by jack11111; 23rd Mar 2015 at 21:06. Reason: Added thought.
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Old 23rd Mar 2015, 21:02
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Well I'm not sure that's a good idea at all. Protections are there to protect and at critical phases of the flight is where they have probably saved more accidents then they will avoid.

Consider S7, Aeroflot, WOW Air, Air Canada, SAS, FINNAIR and many US airlines operate in some pretty severe weather, the A320 family and have done for years without incident then the chances of two AOA sensors freezing at above the stall attitude at the same time must be tiny.
And if it were to happen there is a simple fix. Although technically the plane would be taking off in normal law and therefore the protections kick in at a speed around A-Prot and not the stall AOA - as there is no such thing in normal law.

Taking away high speed protection, low speed protections, alpha lock etc. etc. will cause a lot more problems then it will save. Remember in alternate law it is possible to stall A320s. Getting into a stall situation is a lot more likely than getting two AOA sensors frozen above A-Prot.

This would concern me greatly. I worry about some parts of the world flying Boeings due to stalling on a go around which has caused disasters and closer to home Icelandair very nearly had a 757 flight end in tears in Oslo which would likely not have happened had it been an Airbus. If we take away these protections from the Airbus then we could see more mishandled go arounds.

Last edited by mockingjay; 23rd Mar 2015 at 21:25.
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Old 23rd Mar 2015, 21:16
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"Well I'm not sure that's a good idea at all. Protections are there to protect and at critical phases of the flight is where they have probably saved more accidents then they will avoid."


Mockingjay,

Well, you're probably correct...swapping one protection for another. Better to leave this between Airbus and operators and pilots.
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Old 23rd Mar 2015, 22:53
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all airliners should have a big yellow guarded switch that when turned on immediately turns them back into an aircraft.
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Old 23rd Mar 2015, 23:51
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If I remember right,there are two small steam-age indicators. Sure,if press info is false,the old gyro might be the only way to figure out where You are. I hope they train partial panel even these days,when protections of a system seem to be failing,-and directing discussions away from problems of info gaps of flying. Programming does not, fly an airplane,humans do.

Last edited by Naali; 24th Mar 2015 at 00:22.
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Old 24th Mar 2015, 01:46
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Lightbulb More Sidesticks?

Maybe AB should add two extra sidesticks on each side:

- one as a display only to show the inputs it is accepting from the other side so you can see what other side is doing.

- one for immediate overide of all protections. PIC grabs this one for real control.
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Old 24th Mar 2015, 02:41
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Gretchenfrage: maybe you could suggest something that doesn't involve grounding one of the worlds' most popular aircraft?
Just because it would mean grounding an aircraft you keep an unsafe design afloat? What kind of aviator are you?


Let's not pretend other manufacturers have a perfect record
No, but some had their unsafe design grounded, albeit it was not an infallible AB .....

Fix it, and don't simply shove it down to the crew with a simple piece of paper.
Ever seen the safety video of the "Startling effect"? That demonstrates in a blatantly clear way how reduced pilots are during the first few seconds of a startling incident. A procedure involving switching or pushing selective buttons on a overhead panel is obviously inept for such startled moments, a button on the stick/yoke however is.

But again, it's groundhog day. How many times did we engage in these seemingly futile arguments and how many times did the AB logic prove the sceptics right, and finally how many times did nothing happen.

Bill Murray would have a field day ....
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Old 24th Mar 2015, 04:00
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An Off Switch - Coming to an Airbus cockpit near you?

all airliners should have a big yellow guarded switch that when turned on immediately turns them back into an aircraft.
The military version of the A330 has one, as do all Airbus-manufactured military fixed-wing aircraft - I believe principally for emergency/breakaway operations during re-fueling on the tankers which was a key part of the RFP process for the American tanker programme that Airbus bid on.

I should preface the rest of my reply with the following: I had completed the A320 type rating years ago (have yet to use it, but wouldn't say no if asked - money is money!) and find the design to be overall an elegant and brilliant solution to common problems and operational challenges most pilots face every day - the thing is a real dream to fly! Now the other side of that...

I believe eventually Airbus will need to add such a switch to its civilian aircraft as a simple and quick way of bypassing any and all computers that have voting power over critical pilot inputs. How long they wait will depend on 1.) how many more "incidents" such as this one (or the prior half dozen or so A330 flight control software anomalies) we are forced to suffer in the coming years, particularly serious types as on the A330 and 2.) the level of hubris that exists at Airbus HQ in Toulouse. This is not an A v B thing - Boeing shares a bit of "manufacturer's pride" as well.

We have been told time and again by "the usual suspects" here on PPrune that the digital side - the critical flight control and protections programming was structured to be so very perfect that this sort of thing was "impossible". I was always highly skeptical of those claims.

Three adages come to mind, one - man is fallible, therefore anything designed and built by man is bound to be imperfect, and two, Mr. Murphy has a way of showing up when you least want him around, and three, regarding computer systems, GIGO.

Last edited by vapilot2004; 24th Mar 2015 at 04:20. Reason: these to those makes for better prose
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Old 24th Mar 2015, 04:04
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vapilot2004

Thank you very much for sharing this information.

It shows two things:

First, that AB is very aware of the need of such a feature in time critical circumstances.

Second, that human lives seem cynically less important than military material when it comes to engineers pride or commercial impact.
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Old 24th Mar 2015, 07:41
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It is all very well having a big red button to turn the thing into an aeroplane but then the airlines would have to pay to train their pilots to fly. I said 20 years ago that every airline should own a Pitts and am more certain than ever of that.
As a retired FE I am appalled at the lowering of standards in the industry. Hurtling through the upper atmosphere is inherently dangerous and how complacent everybody has become.
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Old 24th Mar 2015, 08:04
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Gretchenfrage: Airbus most certainly is not an 'unsafe design'. A glitch has become apparent and a short term fix has been put in place.

Is Boeing had Alpha Floor protection, or equivalent' it is likely that TK1991 and Asiana 214 would not have happened and Thomsonfly at Bournemouth would not have slowed to 81KIAS and would not have came so close to disaster. Let's ground the whole 737 fleet too when we're at it. It would be a little rich saying AB were the only manufacturer flying round with known issues. Now how long did it take Boeing to admit there was a problem (and how many died/came VERY a lose to death)?

The reason why the military planes have this is for the more severe manoeuvring. Manoeuvres way beyond the scope of regular commercial flying. However as has been stated many many times on here you can achieve the same effect if you really want to.

Flight envelope protections are there for very good reason and flying with them should be the norm. I do not agree that this magic button should be on the sidestick. Taking the plane into alternate law and reducing all of the protections should take some serious consideration. You will often loose more than you will gain.
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Old 24th Mar 2015, 08:16
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Airbus should intoduce control columns that you can see what the other pilot is doing.
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Old 24th Mar 2015, 08:23
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Airbus will never introduce control columns; that would be an admission that there is something wrong with the side-stick concept.

Some here have commented that we have become complacent about the inherent danger of travelling at high speed and altitude. Well I can't comment on the complacency, but it is surely indicative of the fact that it has become a very safe means of travelling, by any standard.
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