A320 OEB Blocked AOA probes

[pacinolove]

An Airbus aircraft encountered an all Angle Of Attack (AOA) probes
blockage during climb. With the Mach number increasing, the blockage
led to Autopilot (AP) disconnection and activation of the alpha
protection.
PROCEDURE:
CAUTION Monitor the Alpha Prot strip and the Alpha max strip when they are visible
At any time, if the aircraft goes to an unmanageable pitch down attitude despite
continuous deflection of the sidestick in the full backward position (in case the flight
crew missed the below symptoms or delayed the application of one of the below
procedures):
ONE ADR......................................................... .......................................................KEEP ON
TWO ADRs........................................................ ............................................................ ...OFF In stabilized flight path (out of maneuvers involving an increase in load factor such as
turns or pitch variations), if the Alpha Max strip (red) is visible and hides completely
the Alpha Prot strip (black and amber):
SPEED / MACH........................................................ ............................... DO NOT INCREASE
 When at or above safety altitude:
LEVEL OFF......................................................... ..................................................INITIATE
Limit speed and altitude in order to limit the Mach number and to prevent the activation
of Alpha Prot, even if the Alpha Prot strip is not displayed on the PFD.
ONE ADR......................................................... ..........................................................KE EP ON
TWO ADRs........................................................ ............................................................ ..... OFF
The AP, FDs and ATHR are lost for the remainder of the flight.
Switch two ADRs to OFF for the remainder of the flight in order to revert to alternate law to
prevent undue Alpha Prot activation.
In case of dispatch with one ADR inoperative, switch only one ADR to OFF.
FPV USE......................................................... ........................................................CONS IDER
SPEED / MACH / ALTITUDE.................................................... ...............DO NOT INCREASE
 With AP ON, and with speed brakes retracted if, during maneuvers involving an
increase in load factor such as turns or pitch variations, the Alpha Prot strip (black
and amber) moves rapidly by more than 30 kt :
SPEED / MACH........................................................ ............................... DO NOT INCREASE
 When at or above safety altitude:
LEVEL OFF......................................................... ..................................................INITIATE
Limit speed and altitude in order to limit the Mach number and to prevent the activation
of Alpha Prot, even if the Alpha Prot strip is not displayed on the PFD.
ONE ADR......................................................... ..........................................................KE EP ON
TWO ADRs........................................................ ............................................................ ..... OFF
The AP, FDs and ATHR are lost for the remainder of the flight.
Switch two ADRs to OFF for the remainder of the flight in order to revert to alternate law to
prevent undue Alpha Prot activation.
In case of dispatch with one ADR inoperative, switch only one ADR to OFF.
FPV USE......................................................... ........................................................CONS IDER
SPEED / MACH / ALTITUDE.................................................... ...............DO NOT INCREASE
 After setting the flaps lever to 0, if the ECAM displays "A LOCK" and "A LOCK"
remains displayed when the aircraft speed is at VFE CONF 1:
SPEED....................................................... ......................... MAINTAIN BELOW VFE CONF 1
Maintain the speed below VFE CONF 1 in order to prevent the OVERSPEED warning from
triggering at VFE CONF 1 + 4 kt.
The VFE CONF 1 strip is not displayed when the flap lever is set to 0.
FLAPS LEVER....................................................... .......................................................CONF 1
SPEED SEL......................................................... ...................................................... S SPEED
 When at or above safety altitude:
LEVEL OFF......................................................... ..................................................INITIATE
Limit speed and altitude in order to limit the Mach number and to prevent the activation
of Alpha Prot, even if the Alpha Prot strip is not displayed on the PFD.
ONE ADR......................................................... ..........................................................KE EP ON
TWO ADRs........................................................ ............................................................ ..... OFF
The AP, FDs and ATHR are lost for the remainder of the flight.
Switch two ADRs to OFF for the remainder of the flight in order to revert to alternate law to
prevent undue Alpha Prot activation.
In case of dispatch with one ADR inoperative, switch only one ADR to OFF.
FPV USE......................................................... ........................................................CONS IDER
SPEED / MACH / ALTITUDE.................................................... ...............DO NOT INCREASE



i have a question, why we do this action one ADR on and the other two keep off,what is the meaning of doing this?

[tom775257]

It puts the jet into alternate law, therefore stopping the (erroneous) alpha protection.

[Swedish Steve]

Angle Of Attack (AOA) probes
blockage

Is this a modified probe of some sort?
All the A320/330 I have ever worked on have the airfoil type AOA probes which fly in the wind, not the type with holes in that can get blocked.

Airbus AOA probes can freeze, but cannot get blocked.

[TwoTone-7]

The OEB notes make mention that the affected aircraft was a 330 yet some 320 family aircraft have the same probes.

[rudderrudderrat]

Hi TwoTone-7,

There are about 170 A330s fitted with these conic AOAs and over 500 A320s.

The A330 mentioned had the new "conic" plate AOAs fitted, but freezing problems have occurred previously with the old design. This example jammed at a cruise angle of attack. See:Sensor icing caught out A320 crew in Perpignan crash (http://www.flightglobal.com/news/articles/sensor-icing-caught-out-a320-crew-in-perpignan-crash-347457/)

Edit. with thanks to CONF iture.
If Pitots and AOAs simultaneously iced up then -
The pitch / power tables will resolve which is telling lies, but I don't think HAL can read those tables.

[capt. solipsist]

Actually, the probes themselves were not changed, but were equipped with conic plates that protect the probes.

It is these conic plates that have the "probe holes" in them.

[CONF iture]

The pitch / power tables will resolve which is telling lies, but I don't think HAL can read those tables.
Actually, except from consulting the Aircraft Computer Maintenance System, it is not possible for the crew to compare the different AoA readings.
It is good to remind that all pitch displays are correct and also all IAS. Only the presented limit speeds are incorrect.

But the challenge is really on taking back the aircraft control that the duped protection thought necessary to grab.

[ZeBedie]

If the aircraft pitches down and Alpha Floor activates, it'll be through Mno in no time. What happens then? Does the FBW give up and resort to Alternate Law? I guess simultaneous Alpha Floor and Mmo, with an all red speed tape could be quite disorientating!

[rsiano]

Considering the effect that this computer makes it impossible for the pilot to over ride the nose down means to me to never climb on board an Airbus aircraft. Why do the authorities permit an aircraft with this characteristic to fly?

[vilas]

Frozen/blocked Pitot/static and frozen AoA probes are two different situations. In frozen Pitot case one ADR is kept for stall warning which comes from AoA probe and not for pressure data like speed, altitude etc. When AoA probes are frozen at lower speed and aircraft accelerates to higher cruise/Mach the alpha prot threshold decrease to appx. 5degrees of AoA while the system is getting higher frozen value and that can trigger Alpha prot protection based on this erroneous data. So the only way to get out of the hard protection of normal law is to get into alternate law by switching two ADRs off. The third is kept to give you speed but if Pitots are also blocked that will also be incorrect. This AD is not very comprehensive and doesn't cover both frozen Pitot and Pitot together can mislead the pilot if Pitots are also blocked. A320s which have MOI153528/P12909 the FPV is modified to calculate FPA from hybrid GPIRS(mixed IRS and GPS position). So you can use it in this case. But without this MOD bird can only be used provided Pitot/static is not blocked and that is why the wording "FPV consider".

[glad rag]

Considering the effect that this computer makes it impossible for the pilot to over ride the nose down means to me to never climb on board an Airbus aircraft. Why do the authorities permit an aircraft with this characteristic to fly?

Because there are many other ways for non fbw aircraft to be flown into the ground as well?

[cav-not-ok]

With regards to switching off 2 ADRs, does it matter which 2 we switch off?

From what I understand, when this failure occurs, the computer has already rejected 1 ADR. Or does the computer revert back to the only ADR it has available although it rejected the ADR earlier.

The difference between All ADR off and ADR 1+2 (dual failure), should be quite significant.

[C_Star]

I don't think it matters, but it's good to leave the one operating on PF's side - found it the hard way in the sim... :}

[vilas]

cav-not-ok
What is the situation? In case of icing of Pitots if you switch of ADR2 FO looses his speed, with ADR1 Capt. looses speed. ADR3 is loss of standby. But it doesn't matter if all are faulty. With AoA blocked speeds are valid and you need it so PF should switch off the other two. What computer rejects will depend. It is a voting system so two similar reading ADRS will reject the third disagreeing ADR. But that is not always correct because in case of two faulty but similar reading ADRs the lonely correct ADR will be rejected. With all triple ADR failure or double ADR failure CAS/Mach disagree if second is not self identified you get alternate law without protections. With double ADR failure alpha disagree you get alternate law with reduced protections.

[Ber Nooly]

As a PPL I have a headache from just reading all this.

It seems such an unnecessarily complicated set of procedures to follow in the very infrequent event that you will need to. It seems too complicated for a human brain to follow in a moment of heightened anxiety. Unnecessarily so. A computer could do it, but not a human. Too much room for error when it's not a task that is practiced repeatedly.

Bring back the cables and vacuum gauges, I say!

[ZeBedie]

Can I ask again, please. When the aircraft accelerates through Mmo, due to blocked AOA with pitots working normally, what happens to the flight control laws? Alternate law (salvation) or nothing?

[Winnerhofer]

AOA are sensors not probes.
Pitots are probes not sensors.
AOA = capteurs
Pitots = sondes

[TyroPicard]

Calm down everyone...well, some of you...
This is not an instantaneous malfunction requiring superhuman ability and lightning reactions. If the probes are blocked then Alpha Prot strip will rise progressively towards the climb speed as you climb, giving you plenty of warning. The obvious solution at this point is to descend if circumstances allow, land and write up the maintenance log.
Regarding which ADRs to turn off.. in the absence of an ECAM ADR caution it does not matter.. If you turn off 1+2 you can transfer 3 to either pilot which may be an advantage. Either that or 2+3 so the Captain has valid airspeed.

[Winnerhofer]

Why no mention of BR incident December 2012?
https://www.youtube.com/watch?v=nw-0ZYHoEWw
Get this man a drink!

[Willie Nelson]

Rsiano said:

Considering the effect that this computer makes it impossible for the pilot to over ride the nose down means to me to never climb on board an Airbus aircraft. Why do the authorities permit an aircraft with this characteristic to fly?

Really? This is a misunderstanding of the system, the entire point of the OEB is to provide pilots with a specific means by which to avoid the highly unlikely scenario that has occurred less times a Kim Kardashian wedding.

I suspect many if not most experienced Airbus pilots would have been able to get the aircraft in to alternate law if push came to shove but this clears up all ambiguity.

Personally, I would take control as PIC and have the FO switch off the two ADR's closest to him. (3 and 2) however Airbus doesn't care which one, it just states that it has to be done within 15 seconds. Now people as far as what is essentially a recall goes, this is as easy as it gets.

Vilas said:

This AD is not very comprehensive and doesn't cover both frozen Pitot and Pitot together can mislead the pilot if Pitots are also blocked

Perhaps I have misunderstood what you are trying to say. If you had the jammed, stuck or frozen AOA devices at the same time as a frozen pitot or pitot/static system (if that's what you meant) surely you would apply OEB 48 first and then apply unreliable airspeed.

As you yourself said vilas: Frozen/blocked Pitot/static and frozen AoA probes are two different situations

Is this what you are referring to?

[gums]

Good frigin' grief.

Laws, modes, sensors, probes. Who gives a rodent ass?

I agree with Ber.

As a PPL I have a headache from just reading all this.

It seems such an unnecessarily complicated set of procedures to follow in the very infrequent event that you will need to. It seems too complicated for a human brain to follow in a moment of heightened anxiety. Unnecessarily so. A computer could do it, but not a human. Too much room for error when it's not a task that is practiced repeatedly.

Bring back the cables and vacuum gauges, I say! We can't bring back the cables or physical force feedback from the tubes and cables for most planes. Ultralights and many general aviation planes could easily get by and be safe and fun to fly. I relished my time in those planes, and we separated the wannabes from the folks with "touch" in short order most of the time.

I am an old fart but not one of those dinosaurs that are proud that they do not know anything about computers or such. When their system crashes on a desert island and don't know how many computers and servers and bandwidth stuff was involved so little Sally could use Facetime, they whine. So I flew the first really computerized attack jet, and then the next in line which was FBW. Big deal. I soon realized the limits of the near-artificial intelligence of the computers. I had to learn the inner workings because a) I depended on some of them to continue living, and b) I was a curious type. I also was in charge of the academics training for the first year and a half of F-16 training.

Our genesis pilots of the Atari generation in the F-16 in early 1980 was very revealing to we old farts. Our nuggets were admonished to remember what they had seen in "real" planes. You know, the ones that gave mechanical feedback( T-37) and the ones that had hydraulic control systems and feedback was just some dampers and springs ( T-38). A far cry from what I learned in the T-37 and T-33, with mechanical elevat.or and augmented roll

Ya know what? They done just fine. They exploited our avionics systems and appreciated the "protections" the FBW system provided, but they remembered basic aero and physics. They knew how to read a map and tune and interpret the VOR/TACAN/ILS and follow a paper letdown chart without a FMS. They were not "children of the magenta line". They used the cosmic avionics and such as the yutes do now with iPhones and such. They remembered how to fly and we never let them forget that.

The FBW and the cosmic avionics were there to help and not to rule.

If all we are now worried about is the definition of a probe or a sensor or whatever, then we are in dire straits. No difference whether the "sensor" went FUBAR or if the "probe" went to La La land.

The FBW systems must have a very clear reversion sequence and not have ten possible corrective actions, and then ten more once you have follwed rule 10,a,iii. GASP!!!

That's my story and I'm stickin' to it!

[FLEXPWR]

This AD does not mention icing per se. A blocked AOA probe does not necessarily mean it was iced up in icing conditions. One can refer to the Perpignan crash, as previously posted. The AOA probes 1 & 2 were blocked in clear weather, due to improper maintenance while washing the aircraft: a high pressure water jet was used to clean the fuselage, and water passed throught the first seal to lodge within the AOA probe's casings. Only after spending some time at altitude did the probes block up because the water inside the casings of AOA 1 & 2 had frozen up. Again, not ice accretion.

Due to the voting system logic, if two probes read "X" value and a third one reads "Y" value, the Y will be considered erroneous, regardless of the reality. There is no other way for the system to assess wrong ADR inputs/outputs.

This is where a pilot comes in handy. If you are lucky enough to get sufficient time to identify the failure before getting into a nose dive and and exceed VD, turning off two ADRs has a dual function: with only one ADR, the autoflight reverts to alternate, as previously mentioned, so speed protections are lost and the pilot will recover flight control authority, with the possibility of manually exceeding any high or low speed regime, as well as bank angles. That is just the way airplanes flew before FBW for the last 100 years almost. It's up to the pilot to keep the aircraft within the flight envelope.

The second function, is to force the system to use only one ADR source, thus removing any voting logic out of the equation. This should be a momentary solution, as the pilot , unknowingly, may have kept ON the ADR with a blocked AOA. Therefore, after full flight control authority has been recovered, investigating which of the ADRs has blocked AOA would be greatly beneficial, in order to get the SW working should other sh*te happen on the same flight. :ouch:

This is one of the reasons I have no time for pilots saying "We don't need to know the system in that much detail" or "I don't need to know that". We are not mere button pushers. Anyone not interested in aircraft systems should not be flying airplanes for a living. Imagine a soldier going to war, and doesn't care how his automatic rifle works, and says "nah, it's OK, you just need to pull the trigger, should work fine." See how far this soldier would go...

[vilas]

FLEXPWR, Willie Nelson
I will examine the situation again. When AoA sensors are stuck(for whatever reason) at low speed(higher AoA) position and the speed increases, when the alpha prot threshold is lowered the protection gest triggered. Will it go in dive and exceed limits? Not possible because alpha prot is a latching condition and will maintain that angle of attack which also is stuck at lower speed(higher AoA)value. The problem is not dive but involuntary/unwanted descent at alpha prot which cannot be reversed and can be critical close to ground. So by switching to alternate law you override the protection. On the PFD the actual speed will be correct but the display of Valph prot and V alpha strip will be erroneous since it is coming from AoA sensors in the wrong position. It is not possible to investigate which AoA sensor is faulty and you will have to fly in alternate law.The cockpit indication for unreliable air speed can confusing and there are many scenarios but not the one discussed above. However once diagnosed you will reject all of them fly by attitude ad thrust. This AD and OEB is intricate and meant for Airbus FBW operators so those who are not and holding PPL etc. should not read it and confuse themselves and definitely should refrain from forming any opinion about the aircraft.

[Winnerhofer]

The pitot probe just captures air...the sensor is at the other end of the tube somewhere in the air data system.
The AOA sensor actually has the resolver built right in and is actually outputting a value to the computers.

[VNAV PATH]

This airworthiness directive related to AOA is not really hot new in terms of issues. A33O and A340 had the same in 2012. (blocked AOA due to grease icing)


2 temporary revisions of airplanr flight manual were edited : TR 293 and TR 294 dec, 4th 2012, giving the same procedure as now published for A320.


Those temporary revisions can be found on EASA site.

[Ber Nooly]

Sorry, again I must poke my nose into a topic of which I have little experience, but it seems to me that amongst those that do (guys here that appear to be professional Airbus pilots, instructors and/or engineers) there is an awful lot of confusion and discussion. Surely if you guys do this for your living then there should be no discussion. A should equal A to every one of you, but instead it seems that each of you have different opinions of what this system means in the event of this sensor failing in this.mode. It does not give guys like me much comfort to know that (some) pilots might misunderstand their aircraft in certain situations.

As I said, bring back the cables.

[vilas]

Ber Nooly
A320 is a very easy aircraft to fly. Just like an ordinary calculator which any body can use but it is not easy to understand the logic and programme that goes into it. What is being discussed is not a normal operating procedure but pros and cons of a procedure in case of a very unusual situation. Unless you know something basic about A320 you should not get into this. At your stage you may have difficulty in understanding the cables of a 747 or MD11? To bring back cables you will have to get into a time machine because even the 737 is being made by Boeing under sheer pressure by customers like Southwest who wanted immediate equivalent of A320 neo.

[glad rag]

This AD does not mention icing per se. A blocked AOA probe does not necessarily mean it was iced up in icing conditions. One can refer to the Perpignan crash, as previously posted. The AOA probes 1 & 2 were blocked in clear weather, due to improper maintenance while washing the aircraft: a high pressure water jet was used to clean the fuselage, and water passed throught the first seal to lodge within the AOA probe's casings. Only after spending some time at altitude did the probes block up because the water inside the casings of AOA 1 & 2 had frozen up. Again, not ice accretion.

Due to the voting system logic, if two probes read "X" value and a third one reads "Y" value, the Y will be considered erroneous, regardless of the reality. There is no other way for the system to assess wrong ADR inputs/outputs.

This is where a pilot comes in handy. If you are lucky enough to get sufficient time to identify the failure before getting into a nose dive and and exceed VD, turning off two ADRs has a dual function: with only one ADR, the autoflight reverts to alternate, as previously mentioned, so speed protections are lost and the pilot will recover flight control authority, with the possibility of manually exceeding any high or low speed regime, as well as bank angles. That is just the way airplanes flew before FBW for the last 100 years almost. It's up to the pilot to keep the aircraft within the flight envelope.

The second function, is to force the system to use only one ADR source, thus removing any voting logic out of the equation. This should be a momentary solution, as the pilot , unknowingly, may have kept ON the ADR with a blocked AOA. Therefore, after full flight control authority has been recovered, investigating which of the ADRs has blocked AOA would be greatly beneficial, in order to get the SW working should other sh*te happen on the same flight. :ouch:

This is one of the reasons I have no time for pilots saying "We don't need to know the system in that much detail" or "I don't need to know that". We are not mere button pushers. Anyone not interested in aircraft systems should not be flying airplanes for a living. Imagine a soldier going to war, and doesn't care how his automatic rifle works, and says "nah, it's OK, you just need to pull the trigger, should work fine." See how far this soldier would go...


Well said :D

[Flagon]

Ber - if it puts your mind a little at rest, do NOT assume that all those claiming to be 'Airbus pilots' actually are. There are a lot of Walter Mittys around here.

vilas - "Unless you know something basic about A320 you should not get into this." The problem Ber and I see is that this seems to apply to a lot of the 'Airbus qualified' contributors too.

Way back I recall someone calling for a simple 'big red button' that can be pressed when HAL goes beserk, putting direct control back to the pilot with NO 'clever' software in the way so that the machine can be flown as an aeroplane while whatever has gone tits up is 'inverted'. Certainly having to start switching off bits of electronics while the machine tries to bunt you to your death does not come over as very reassuring to many. As flexpwr says
"This is where a pilot comes in handy. If you are lucky enough to get sufficient time to identify the failure before getting into a nose dive and and exceed VD, turning off two ADRs...."

[ironbutt57]

As a former "Bus TRI, I don't see it a bad idea for these airplanes to have a "Direct Law" switch...the PRIM discrepancies on the (Qantas was it?) A330, and other incidents causing the airplane to deviate uncommanded from its desired flight path, would IMHO warrant this option to the pilots..AVIATE NAVIGATE COMMUNICATE and finally MANAGE...when the aircraft systems prevent one from the "aviate" bit, it sure makes things difficult

[Jonty]

For those that want a "Direct Law/Alternate Law" reversion switch, it has one. Switching off 2 ADRs will have that very result. Its the quickest way of getting it into alternate law.

The other good one to have up your sleeve is the Emergency Electrical Config, to get in to that its 4 buttons.

The Airbus protections and computers can be switched off very quickly if required. Just be careful what you wish for.

[ironbutt57]

yes..very easily done in inclement weather, never mind the startle factor, and possible confusion,(would everybody have thought of the ADR when their airplane pitched over into a dive and did not respond to sidestick inputs?) and bear in mind, that it's not only ADR issues that can cause problems, in any event, the DFDR and CVR will yield some interesting results

[Zaphod Beblebrox]

Being a Yank, and not one prone to believe that Big Brother is watching at every moment, I still wonder if we are getting the "Truth, the Whole Truth and nothing but the Truth."

This AOA probe issue is not new. There was a proposed AD from 2012 that suddenly was withdrawn. Makes you wonder.

https://www.federalregister.gov/articles/2013/10/02/2013-23079/airworthiness-directives-airbus-airplanes

The original AD was 2012-21-51. I think the EADS Lobby is very effective in Washington. They headed this AD off at the pass and it was never issued, until just last month. That's not surprising, we have the best Congress and Government money can buy.

[Flagon]

jonty - by your own post "For those that want a "Direct Law/Alternate Law" reversion switch, it has TWO". (Or 4?) Which 2 to switch off? Which is the 'right' one?

In 'the old days', when the FMC or autopliot malfunctioned and you 'lost control', one click cured it. One click, near your thumb and not somewhere on a roof panel and you have an aeroplane back, and not a computer challenge.

What is the aversion amongst Airbus lovers to actually having control of the aeroplane? I do not understand it.

[A33Zab]

This AOA probe issue is not new. There was a proposed AD from 2012 that suddenly was withdrawn. Makes you wonder.


It was withdrawn because all conic plates should have been replaced by 'new' flat plates.

Apparently the conic plates, although suspected, were not the source of this issue after all.

Airbii crew are informed by FOT and there is sufficient explaining material on the Flight OPS section of 'Airbus World'.

[vilas]

Flagon and Jonty
The difference between pure FMS fitted conventional aircraft and FBW aircraft is mainly the protections soft in case of Boeing and hard in case of Airbus. These were basically designed so that pilot by his act cannot stall or over speed or overbank. But these parameters can get exceeded by environmental factors like angle of attack changing externally or over speed because change in wind and also by the AoA sensors or Pitot/static tubes getting fouled and triggering protections due to inappropriate data. These factors were not originally factored in the design of the aircraft so they have to come out with remedies. Immediate solution is through OEBs. I don't think airbus pilots will have objection to a switch to go into alternate law. It may come in future. Till then we follow manufacturers recommendations of switching two ADRs. EMER ELEC is not recommended so we simply don't do. EMER ELEC will knock out IR2 and IR3 after five minutes for rest of the flight and may have some other complications. Since these are not standard normal/abnormal procedures pilots discussing the event may appear divided or some may be partially incorrect but to take part in it or understand what is being said you need some knowledge of the flight control system.

[Flagon]

vilas - "I don't think airbus pilots will have objection to a switch to go into alternate law." - my choice, if I were flying the machine, would be to DL and take the computers out of the circuit completely. We are, after all, talking about an emergency situation, so if crews were simply able to establish pitch and power for stable flight with NO interference/protections that would do me!

[A33Zab]

"I don't think airbus pilots will have objection to a switch to go into alternate law."


Not to sure about that one,
IFALPA objects to a direct AoA indicator (http://www.ifalpa.org/downloads/Level1/IFALPA%20Statements/Aircraft%20Design%20&%20Operation/14POS24%20-%20Loss%20of%20Control%20related%20to%20Angle%20of%20Attack. pdf), AF pilots objects the BUSS (http://corporate.airfrance.com/en/press/af-447-rio-paris-cdg/the-buss-or-backup-speed-scale/).....

[vilas]

A33Zab
As long as they don't object to the OEB they can't object to a switch which does the same job. BUSS is not used above 25000ft. and below that generally the problem is going to stay. Any way I don't think they will install a switch but they might modify the AoA sensor or the protection. They already have modified alpha prot protection during approach and landing after an accident.

[vilas]

Flagon
Now that you know why it happens it is not such an emergency. Alternate law has no danger. Direct law is a short term configuration to give you conventional aircraft response during landing. There is no feel and it cannot be practiced in aircraft. So not a good idea to suddenly get into.

[Gryphon]

What is the aversion amongst Airbus lovers to actually having control of the aeroplane? I do not understand it.

Well, I am a Airbus lover just because is the type I'm flying now, and I always love the aircraft I'm flying (mandatory for me). And I can tell you that I always and actually have control of the aeroplane, so I cannot understand what you say.

As in any other aircraft you may have abnormal/emergency situations you have to manage. Nothing new.

my choice, if I were flying the machine, would be to DL and take the computers out of the circuit completely.

This is probably because you don't know the Airbus FBW aircrafts. If you do that you go to mechanical backup only, what isn't very wise. It's much better to go into alternate or direct law (through the computers). Maybe it sounds terrible for somebody who doesn't know about this situations, but I can tell you is quite simple.
ADR,s are controlled by pushbuttons. To push two buttons isn't difficult from my point of view.

I have flown B707 years ago (too many :{) and now A320. I love both, but for sure the Airbus is much much easier to fly (and in this one we are only two crewmembers :})

Trust me, it is just an aircraft. Of course you have to study as in any other, otherwise if you don't understand something you cannot complain. For sure there are things you don't like, again as in any other.

[A33Zab]

they might modify the AoA sensor


I would suggest a change to (A380/A350) Multi Functional Probe.

[mikedreamer787]

As a PPL I have a headache from just reading all this.

It seems such an unnecessarily complicated set of procedures to follow in the very infrequent event that you will need to. It seems too complicated for a human brain to follow in a moment of heightened anxiety. Unnecessarily so. A computer could do it, but not a human. Too much room for error when it's not a task that is practiced repeatedly.

Bring back the cables and vacuum gauges, I say! I'm stuck on the 320 Mr Nooly and the bloody thing has been a constant headache for the past 10 years.

The Frogs can't help themselves complicating simplicity and have never got their act together since day one. For example their non-normal landing performance section has been changed FOUR TIMES during my tenure and gets more ridiculously complex each time.

Also their operating manuals (called FCOMs) were changed and became an even messier dogs dinner than the original ones they replaced. Here's an example - the procedure for refuelling with one engine running. Logic would dictate it would be found in the Supplementary ops section of the FCOM. Wrong! Its in the Aircraft Loading section FFS! :ugh:

I was waiting for this latest directive to dribble down to the 320 ever since that QF 330 did its dirty dive enroute SIN-PER a few years ago.

[gums]

@ Gryphon

Good thots overall, but we have to face reality of the man-machine-interface of the aircraft.

As you know from reading my user background, I am very familiar with FBW and all it entails. And as you rightly point out, many folks do not understand. They think FBW is a glorified autopilot. It is not.


The curent architecture of the 'bus could easily allow for one or two backup modes, with last one being "direct" but with specified "gains and rate limits" based upon gear up or gear down and zero dependecne upon air data. If all the computers go tango uniform, all bets are off, but with just one and a clear indication it was the sole survivor, then a condition such as we had for the last 40 years would exist. No force feedback because most everything was a hydraulic pressure on an actuator. No auto throttle or VNAV, pure manual with the "standby gains and pitch rates". After all, no mechanical connections so you depend upon the electrons.

The current 'bus laws are confusing once outta "normal". Sheesh. Doze will jump in here and assert that the engineers programmed everything with pilot assent. But I question how many ever flew a FBW system with zero mechanical backup.

Seems that the engineers tried to preserve every "protection" they could as the overall system degraded. But there were a myriad of combinations and last thing I need is a multiple choice quiz when things go to hell in a handbasket.

So I think a reasonable reversion sequence would be:

- Loss of data, be it AoA or speed or altitude or attitude and maybe gee sensors. Autopilot disconnect and a clear indication of the reversion mode. Latch existing air/gee/AoA data as it existed for 10 or 20 seconds. Then go to the standby gains/rates and standby gee limits. No stall protection, overspeed protection, roll angle protection, no autothrottle, just a nice smooth flying jet with rate and deflection gains fixed upon gear up/down. You would think you were flying a neat design from the 70's or 80's.

What is wrong with that?

What I see from the drivers is the VNAV and other otto features that might help a single seat pilot as I was, but I was not carrying a few hundred pax.

[CONF iture]

Direct law is a short term configuration to give you conventional aircraft response during landing. There is no feel and it cannot be practiced in aircraft. So not a good idea to suddenly get into.
If flying direct law is like flying the 737 then what exactly is the problem ... ?

[vilas]

CONF iture
Love it or hate it Airbus FBW is a different philosophy. The aircraft is designed with almost complete automation and very little requirements of raw piloting skills in mind. Perhaps it came before its time. I have said it before that the protection were designed to prevent the pilot from going beyond the flight envelope and it does a damn good job of it. What was perhaps not taken into consideration was that in a dynamic medium such as the air the aircraft could be pushed beyond those boundaries without any pilot action and that is where the design is found wanting. All these protections are triggered from data derived from one sensor or the other but the present system of sifting the data to ensure it's genuineness is being proved inadequate and is the cause of all these incidents. The answer to this will come from better sensors, better system of confirmation of data or even quantum leap of technology in measurement of airspeed, AoA etc. but definitely not from cables and vacuum gauges. Surely few automobile accidents are not going to bring back horse buggies. Direct law is short term condition from gear down to landing. It may not be vastly different from 737 but since you cannot practice it on line it is not your day to day experience so you are better off in alternate law which is almost similar to every day normal law minus the offending protections.

[Willie Nelson]

Vilas wrote:

All these protections are triggered from data derived from one sensor or the other but the present system of sifting the data to ensure it's genuineness is being proved inadequate and is the cause of all these incidents.

Pretty bold statement there sport!

[Gryphon]

@ Gums

Sorry but I'm not prepared for designing a flight control system. I cannot help you in this task.

As I said there are things I would prefer in a different way (and I must say this is not the first of my wishes), as in any other aircraft I've flown.

My only intention was to fight against the legend, but you did it better:

They think FBW is a glorified autopilot. It is not.

Thanks.

[CONF iture]

The answer to this will come from better sensors, better system of confirmation of data or even quantum leap of technology in measurement of airspeed, AoA etc. but definitely not from cables and vacuum gauges. Direct law is short term condition from gear down to landing. It may not be vastly different from 737 but since you cannot practice it on line it is not your day to day experience so you are better off in alternate law which is almost similar to every day normal law minus the offending protections.


Who's talking cables and vacuum gauges, what is needed is humility as our system, logic, sensors will never be 100% accurate and reliable so we provide a simple switch to get rid of any protection or automatism if required. Yes, you the pilot may have to protect the airplane from our protections ...
If a 320 pilot needs regular practice before flying simple direct law then something is obviously wrong, what happens the day the elevators quit ... ?

And AF447 would have been much better served with direct law than any other law ...

[gums]

I forgot to include one aspect of a good HUD that helps you when the AoA vanes are unreliable.

On both HUDs I flew, we had a fuselage reference symbol at the top of the display, An actual display of where the jet was "pointing", and it could have easily been just a piece of chewing gum or a grease pencil mark, heh heh. So in fairly wings-level flight the difference of the flight path vector from that fuselage reference line was your AoA.

[vilas]

CONF iture
You are misinterpreting what I am saying. I come from cable and vacuum gauges age but when I flew a320 I liked it as much as I liked the 747. I did not say Direct law is complicated but you are more familiar with alternate law so if possible why not keep to that. Elevators quitting cannot be easier than in A320. In direct law AF447 would have been better? I am sure you are joking but I am not laughing. AF447 would have been better served if all three pilots would have left the cockpit together. And I am not joking. A330 could not handle the pilots.

[CONF iture]

I did not say Direct law is complicated but you are more familiar with alternate law so if possible why not keep to that. Elevators quitting cannot be easier than in A320
As flying on THS only is already so easy ... what's the deal about to have to trim for direct law ?

Inhibit that auto trim and AF447 reaches Paris.

[vilas]

CONF iture
I have no desire to restart AF447 all over again. AF447 wasn't going any where other than where it went. Put another two in front with same level of competence in a 747 and it will reach the same destination with another 150 Pax to give company. And sorry I meant stab jam and not elevator quitting

[tubby linton]

Nobody seems to have asked the question of WHY this is happening? Is it poor heating of the probes, or poor radars and poor manipulation and interpretation of the radar picture ? Could it be the weather becoming more extreme or is it because there are simply more aircraft in the air meaning there are more incidents?
I do not remember any aircraft of the previous generation reporting such problems.
The one thing that has surprised me is that the refined FBW laws and architecture of the A330 and later aircraft where it is very difficult to get the aircraft into Direct Law ,have not found their way back into the A320 family.

[safetypee]

tubby, yes WHY … and yes, and yes, all of the above.
The difficulty is in identifying the dominant parameters; reduced heating, power consumption, etc, vs different airflow patterns around new designs.
I would start with the technical aspects, check the changes and the assumptions made about change … ‘there will be little or no effect’, then check why the designers thought that way, what assumptionswere made in the design and operation … why.

Previous types did not have/use AOA, its only now that we rely on it that the failures are noticed.

[Mad (Flt) Scientist]

A small but important clarification I think
Previous types did not have/use AOA
.. as an input to FBW control laws.

AOA sensors to drive various functions has been around for ages, and in some cases it's a safety-critical function, equally as much as for FBW. (I'm thinking any pusher-protected aircraft here, for example). So at least some aircraft have been "watching" the performance of AOA vanes for quite some time.

But it is odd that we seem to be getting more "issues" with novel forms of icing in the relatively recent past. At least some people are suggesting that the only logical explanation is that it's a change in the atmosphere of some kind - global warming? pollution? aircraft flying in different parts of the atmosphere more often (either vertically or geographically)

I think that you can safely assume that there are indeed people asking WHY - everyone building sensors, and everyone spec-ing them, is asking themselves what they have to do extra now that they didn't do before. There are already new regulations, and more on the way. but since we still dont understand all the physics behind this, it's a somewhat empirical reaction - better than nothing, and it should help, but how do we know it's enough?

[Flagon]

MFS - safetypee has the answer, I think.

"Previous types did not have/use AOA, its only now that we rely on it that the failures are noticed."

I am convinced that the complexity of the current FBW systems leads to significant 'unexpected consequences' as designers add extra comparators and check logic to prevent malfunctions due to malfunctioning detectors, and each 'addition' adds its own failure complications such that driving to the root problem is extremely difficult. As has been said many times, having 'majority voting' was seen as the obvious and correct answer, but we appear now to be seeing 'majority errors' leading to isolation of the correctly functioning device with serious consequences.

Where then do we go? Do we add another sensor or 3 to the current group of 3 to give a 'casting vote'? Surely we unfortunately return to the need to have pilots who can

a) Easily wrest control from the malfunctioning system - DESIGN and
b) then fly the aeroplane as it should be flown until the wayward HAL can be sorted out - TRAINING.

The prevailing 'addiction' to the extremely clever FBW systems and an apparent undeniable belief in how 'wonderful' and 'infallible' it all is needs to change. We need to recognise that it is indeed 'wonderful' and 'infallible' when all works correctly, but when it doesn't, it can be a nightmare and push workload through the roof - and this does seem to be viewed as blasphemous by many.

[CONF iture]

It's reasonably straight forward and simple to intentionally get a 330 or 340 into Direct Law
Which method is preferred in the sim ?
Is it to set it on both SEC only ?

[Lonewolf_50]

But it is odd that we seem to be getting more "issues" with novel forms of icing in the relatively recent past. At least some people are suggesting that the only logical explanation is that it's a change in the atmosphere of some kind - global warming? pollution? aircraft flying in different parts of the atmosphere more often (either vertically or geographically)
It may also be that the operating norm has changed a bit: folks are more willing to risk / fly into such weather due to the much better kit that is currently available.

[Mad (Flt) Scientist]

@Flagon

Sorry, that's not the answer in my opinion - my point is that aircraft with stick pushers have been monitoring AOA (and AOA deltas side to side) for a long time now. One would have expected that those types would have been seeing AOA anomalies.

Part of the story may be that FBW aircraft are more "exciting" and so get more "press" - witness the enthusiastic discussion on these forums of the details of FBW implementations, compared to people asking about gain changers and non-linear gearings and such! So the AOA anomalies on FBW aircraft are better known.

I do agree that the more complex systems are difficult to get "perfectly right". I will say that no-one designing and certifying these systems is in any illusion over this complexity and its implications for the design - bold statements about how great a system or aircraft is coming from the mouths of marketing/sales people don't always reflect the opinion of the engineers. Any engineer releasing something is of course confident he's done the best he can, but any good engineer also knows nothing is perfect.

[Flagon]

I'm afraid I disagree. For 'a long time', stick pushers worked on IAS alone, and for an AoA driven pusher to 'malfunction' would require it to 'achieve' a critical AoA in the first place - in which case its 'shout' was probably valid!

The problems are occurring because AoA is now so deeply embedded in the control system that a malfunction has a far more serious effect then ever before. If I recall PGF correctly, a 'sensible'/working AoA was 'voted out' through the logic circuits. The 447 AoA problem was caused - only once a stupid AoA had been achieved - and the IAS logic removed the stall warning. Not really a 'problem' with the AoA sensor itself which I understand worked correctly - again, a problem with its interface with the system. Agreed they should not 'freeze' but equally their effects when so frozen should be easily negated. While AoA represents an excellent performance guide, you do NOT need AoA to fly an aircraft safely under normal circumstances.

[Denti]

Quite honestly, i was surprised how many systems are affected by a failed AoA probe in a 737. We had quite a few problems with them a few years back and one ended up well past the end of a runway as a result.

[CONF iture]

(The instructor station also had a one-touch icon to artificially put the sim flight package in Direct for handling purposes only without all the other associated effects of turning off or failing all 3 PRIMS. One-touch, kinda like the suggestions on some of these threads.)
Photos: Airbus A400M Atlas Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Airbus-A400M-Atlas/2444930/L/&sid=fade78cf9a595d5d86f167070de559ff)
It seems the A400 has such a switch - Is it the red guarded one on the left side on the upper panel ? - I don't know.
Now, following the last incidents with protections going crazy, when Airbus is going to install a similar switch on all types ... ?

[Lonewolf_50]

While AoA represents an excellent performance guide, you do NOT need AoA to fly an aircraft safely under normal circumstances. I will guess that you meant one does not need an AoA indicator for a pilot to read in order to fly. AoA will be there whether we know what it is or not. :}
/pedantic mode off

[Mad (Flt) Scientist]

I'm afraid I disagree. For 'a long time', stick pushers worked on IAS alone, and for an AoA driven pusher to 'malfunction' would require it to 'achieve' a critical AoA in the first place - in which case its 'shout' was probably valid!

I know of one type that's been using AOA driven pusher functionality since the late 70s, which was why i was saying a "long time". I'm actually quite surprised to hear of pushers functioning based on speed, since that would be no protection against stalling at elevated 'g', and stalls at 'g' have been part of the cert requirements for a long time as well.

While it's true to say that most scenarios for a stuck/frozen AOA require you to have been at that AOA when the system was working 9just before failure0 it doesn't mean that the warning will be valid. In a similar fashion to the scenario AB has laid out, I can conceive of the AOAs ona pusher equipped aircraft freezing at relatively low speeds (perhaps shortly after TO) at which point you are still well clear of pusher. if the crew was unaware and the system kept treating the AOA as valid 9albeit a constant value0 then as you accelerated and climbed the pusher activation angle would usually drop - an aircraft retracting slats would probably see a major reduction in the pusher AOA at that point, in fact. Which might bring the activation angle BELOW the frozen sensor value, triggering the pusher to fire. The only way to stop it would be to get slow and back in the original config - and slowing down is not something that comes to mind as a reaction to pusher activation.

We typically consider erroneous pusher activation as a potential loss-of-control event, so while it's not quite as bad as the Ab scenario, it'd be pretty bad news. (Its easier to turn off a pusher than to turn off FBW systems, and the pusher is only a small component of the FCS, so you degrade the aircraft less by turning it off. But it wouldn't be fun getting to that point)

[Flagon]

Could someone explain what a modern 'software controlled' flight system would do in the following circumstances?

I am in the ITCZ, in cloud, with moderate turbulence and in significant airframe icing conditions but in a (reasonably) 'steady state' condition of speed and power:-

a) Two Air Data units decide my speed has fallen significantly and I appear to be flying at an unsafe speed OR

b) Two Air Data units decide my AoA has reached levels that are unsafe

So - does the system quickly take control and manouevre my aircraft for me OR does it just alert me to the issue and enable me to fly pitch and power while I sort it out?

[NigelOnDraft]

Flagon

Details would require you clarifying deeper the exact issues, but in principle I would say:
a) This is a double failure, and (from your post) determined as such by the systems. Therefore Flt Ctrl laws will usually degrade e.g. to Altn Law, protections reduce i.e. you will be able to sort it out if you correctly assess the situation
b) If 2 ADRs determine they have a valid, and similar AoA, they will be believed and vote "out" the 3rd (potentially correct) AoA, and determine this as a single failure, hence you may not be able to directly override the ensuing protections. A major part of the unreliable airspeed drill is to potentially resolve the issue of the lone ASI being the correct one...

The 2nd scenario is essentially the recent OEB. However, the probability of 2 AoA probes going into error, in a similar fashion is low (very low). The issue the OEB raised is where the AoA probes, say "freeze", and you now alter the environment such that the frozen AoA value goes from "safe" to "hazard" e.g. reflecting reduced buffet AoA at high M number. What the OEB does is give you a course of action to degrade the Flt Ctrl laws.

It should be emphasised this has occurred once (only) in all the years of Airbus FBW Ops, and in the one case it occurred, in fact the system did drop itself into Altn Law IIRC? Easy to slam the system as a result, but as we have seen, obscure, or even simple but un-envisaged, failures in more classic designs result in (near) accidents (737 AMS, BOH etc.)

[vilas]

Flagon
Turbulence, ITCZ, airframe icing do not alter flight control laws. Like any other aircraft there is a system of redundancy to mitigate the effect of failure of a device. There are three ADRs which collect AoA info from three AoA sensors also they collect pressure data from Pitot/static probes . Normally the averaged reading of AoA info from ADR 1+2 is converted to speed as Valpha prot and Valpha max and displayed on the speed tape but these are not speeds but AoAs. If one ADR malfunctions and its reading strays it is automatically rejected and flight control laws do not change. This is termed as self detected failure. But if two ADRs fail at the same value which is different from the only correct ADR and is between these protection values then Alpha protection will be triggered and aircraft will maintain this speed(AoA) by doing whatever it takes normally pitch down but can also pitch up. Since it is treated as single failure normal law prevails and pilot cannot over ride it. So the OEB/AD tells you to get into alternate law and override. Pitot failures are also treated as ADR failures and handled similarly when single failure but when not self detected pilot has to switch of the faulty ones and fly with the correct one or has to diagnose all are faulty and apply memory items if required and/or apply paper procedure. Recognising unreliable speed is the tricky part.The ECAM will not tell you that. Erroneous AOA data can make system act on its own and with erroneous M/CAS data you must be able recognise and act immediately on your own.

[Flagon]

[vilas - not quite sure why you posted "Turbulence, ITCZ, airframe icing do not alter flight control laws." - they certainly alter 'flight'.[

Why, then, does AB not offer the option to the crew to decide what is erroneous and what to do in the 2 ADR case rather than decide on its own course of action which might be wrong?

Anyone with other FBW system experience to comment?

[vilas]

Flagon
I posted Turbulence, ITCZ, airframe icing do not alter flight control laws because they don't. What changes the laws is failure of sensors or probes due to what ever reason. Every day aircrafts negotiate these conditions successfully. These are specific cases of equipment failure(anti ice) which can be rectified. Putting FBW technology in the dock is like throwing out the baby with bath water.

[CONF iture]

It should be emphasised this has occurred once (only) in all the years of Airbus FBW Ops
It is actually the third known case of AOA sensors blocking at a similar value. In 2 cases the crew had to select ADRs off to take back control of their pilot proof Airbus.

[Flagon]

vilas - "I posted Turbulence, ITCZ, airframe icing do not alter flight control laws because they don't." - are you then under the impression that someone thought they did?

[A33Zab]

It is actually the third known case of AOA sensors blocking at a similar value


3rd on Goodrich AoA.

Goodrich Pitot and Thales AoA sensors seems to be the proper combination for Airbii.

[CONF iture]

Until some other still unknown malfunctions appear ... like in the Qantas case.
The logical way would be to implement the protection kill switch.

[vilas]

If icing of AoA sensors and Pitot/static probes have caused a few problems in some million hours the most logical thing to do is to improve the heating of those probes which should not require a technological marvel. Just because some people and many of them are non airbus pilots who are not comfortable with the idea of hard protections you introduce a Kill protection switch which will bring in the human element with human error. If a few aeroplanes are lost because of the operation of that killer switch at the wrong time then what? This cure may prove deadlier than the disease. In the interim period a method is given to override them. I do not agree you need to go in direct law at the drop of a hat. Don't bring in AF447 the only switch it needed was to switch the pilots with competent once. I say that with sadness because they lost their lives and there may be reasons why they were so.

[Denti]

If a few aeroplanes are lost because of the operation of that killer switch at the wrong time then what? This cure may prove deadlier than the disease.

As there is extensive experience with FBW planes that have a pilot override we could actually use that experience. As far as i'm aware there was no 777 incident because of that, unlike airbus where a few incidents have happened due to hard protections (bilbao, lufthansa, qantas etc).

However, given the extremely low number of incidents caused by the hard protections there is probably no regulatory need to change anything and apparently the insurance companies are quite happy as it is as well, otherwise they would require higher premiums.

[vilas]

Denti
Boeing FBW and AB FBW are based on different philosophies. AB is maximum automation with auto trim and alternate law in degraded mode. In case of double failure of ADRs or IRs when computers cannot self detect the job is given to the pilot, the direct law comes in as a short term phase and alternate law is recovered after pilot identifies and switches off the faulty component. The other case is in A320 where direct law comes in as a flare mode of alternate law after gear is down to help you land. Since there is no Q or any tactile feed back in the stick as is the case in conventional aircraft or Boeing FBW the direct law handling is different than in normal and alternate law. So there is a an interim procedure to enable you override protections, giving a switch to induce direct law in complicated situation for long term may not be a good idea and nor is it required if pilots follow correct procedures. Auto trim in alternate law driving the stab to its limit has happened as a result of mishandling and was pilot induced. Airbus philosophy has its own followers and is quite popular amongst them.

[CONF iture]

If icing of AoA sensors and Pitot/static probes have caused a few problems in some million hours the most logical thing to do is to improve the heating of those probes which should not require a technological marvel.
If it was that easy it would have been done by now since Perpignan in 2008.

Just because some people and many of them are non airbus pilots who are not comfortable with the idea of hard protections you introduce a Kill protection switch which will bring in the human element with human error.
Just train you guys with a proper procedure not a Mickey Mouse one.

If a few aeroplanes are lost because of the operation of that killer switch at the wrong time then what? This cure may prove deadlier than the disease.
Just train you guys with a proper procedure not a Mickey Mouse one.
As far as I know the unprotected 737 don't fall at a greater rate that the protected 320 then why ?

In the interim period a method is given to override them.
Nothing is interim, the procedure is here to stay forever.
As a manufacturer you have the responsibility to make it simple, not to go and play with unguarded switches on the overhead panel in the middle of a loss of control.

I do not agree you need to go in direct law at the drop of a hat.
No you need to inhibit protections going mad at the drop of that hat.

Don't bring in AF447 the only switch it needed was to switch the pilots with competent once.
It tells all how you see yourself ...

[vilas]

CONF iture
Perpignan was the result of wrong maintenance (washing) procedure. Just like the 757 or 767 I am not sure they failed to remove the masking tape from static and it resulted in fatal accident of the non FBW aircraft and Boeing shelled out a hefty sum for faulty design.
As far as 737 is concerned why has Boeing forsaken manufacturing of conventional aeroplanes and switched to FBW you can ask them. 737MAX was launched not because Boeing wanted to but their biggest customer threatened to switch to AB Neo.
whether the procedure stays or not time will tell because OEBs are not permanent changes and if it stays the alternate law meets the purpose and does not require direct law. AF447 I quoted with regret and only because you are fond of closing your eyes to crystal clear evidence of incorrect UAS and stall recovery procedure by the crew to shift the entire blame to the machine and It has nothing to do with my competence. There are any number of pilots out there who would have done what was required.

[CONF iture]

Perpignan was the result of wrong maintenance (washing) procedure.
It does not matter, the valid sensor was silently discarded and the other sensors were lying together with already the potential to wrongfully trigger a protection. Whatever the reason, maintenance or anything else, known or still unknown reasons ... a simple tool is needed to inhibit wrongfully activated protections.

Just like the 757 or 767 I am not sure they failed to remove the masking tape from static and it resulted in fatal accident of the non FBW aircraft and Boeing shelled out a hefty sum for faulty design.
What was exactly the faulty design on that Aeroperu 757 ?
You tell me ...

If there are faulty design on B products, is it good enough to keep silent on deficiencies of the A ones ?

As far as 737 is concerned why has Boeing forsaken manufacturing of conventional aeroplanes and switched to FBW you can ask them. 737MAX was launched not because Boeing wanted to but their biggest customer threatened to switch to AB Neo.
And your point is regarding the accident rates of the types ... ?

AF447 I quoted with regret and only because you are fond of closing your eyes to crystal clear evidence of incorrect UAS and stall recovery procedure by the crew to shift the entire blame to the machine
Quote ?

Actually you're the one blaming this crew 100% whatever the type they would have crashed :
AF447 wasn't going any where other than where it went. Put another two in front with same level of competence in a 747 and it will reach the same destination with another 150 Pax to give company.

[vilas]

CONF iture
I will try to answer your points but this is not slugfest between you and me nor I am promoting A or B.
Perpignan, AF447 or 757 what ever I said were not my opinions but inquiry reports. Perpignan wrong maintenance procedure, unplanned last minute execution at a dangerously low altitude without sufficient preparation, too many holes in Swiss cheese too easy to line up.
757 case if you Google it you will be able to find it was concluded that it was possible not to notice the masking tape and they had to make some changes, I didn't demand it and it didn't help that it was not FBW.
AF 447 was crew action absolved by the inquiry? Again not my opinion.
I am not saying two wrongs make one right. EASA AD or Airbus does not find it necessary to switch to direct law but alternate law which allows the pilot to override protections. As an Airbus pilot I tend to agree with it. If you think that in the 757 case same actions as were taken in 447 would have saved the situation I have nothing more to say.

[vilas]

CONF iture
Posted from Wiki Aeroperu Flight603
In November 1996, Mike Eidson, a Miami attorney from Colson Hicks Eidson, said in an interview that many of the passengers survived the initial impact and drowned afterwards. Eidson represented 41 passengers and crew in a lawsuit contending that the aircraft's manufacturer, Boeing, bore responsibility for the disaster, as the company ought to have foreseen the misuse of its products.[1] (http://en.wikipedia.org/wiki/Aeroper%C3%BA_Flight_603#cite_note-Mayday-1)[11] (http://en.wikipedia.org/wiki/Aeroper%C3%BA_Flight_603#cite_note-Landmark-11) The suit was filed against Boeing in federal court in Miami in May 1997. According to the complaint, the control panel errors were caused by careless maintenance by Aeroperú and negligence and defective design by Boeing. Boeing argued that it was not at fault, and that responsibility for the accident lay with the employee who did not take the tape off the static ports, and the aircraft's pilot for not finding the tape. Richard Rodriguez of the NTSB said that it was understandable that Schreiber did not find the tape because the maintenance worker used duct tape instead of the brightly colored tape that he was supposed to use. In addition, Rodriguez said that the pitot-static ports were high above the ground. Therefore Schreiber did not see the tape against the fuselage.[1] (http://en.wikipedia.org/wiki/Aeroper%C3%BA_Flight_603#cite_note-Mayday-1) After extensive litigation, the parties agreed to transfer the case against Boeing and Aeroperú to an international arbitration in Santiago, Chile, for a determination of the damages. The defendants agreed not to contest liability in Chile.[11] (http://en.wikipedia.org/wiki/Aeroper%C3%BA_Flight_603#cite_note-Landmark-11)
On December 13, 1999, family members of the flight's passengers received one of the largest cash awards stemming from an aviation accident outside the United States aboard a non-U.S carrier, averaging nearly $1 million per victim.[citation needed (http://en.wikipedia.org/wiki/Wikipedia:Citation_needed)] The episode "Flying Blind" from Mayday (http://en.wikipedia.org/wiki/Mayday_(TV_series)) (Air Crash Investigation, Air Emergency) stated that the manner of the crash resulting in the passengers' drowning was responsible for the large settlements.[citation needed (http://en.wikipedia.org/wiki/Wikipedia:Citation_needed)]

[CONF iture]

EASA AD or Airbus does not find it necessary to switch to direct law but alternate law which allows the pilot to override protections.
Using a poor home made procedure when an easily accessible single red guarded switch should be installed on all types. And just fine if it sets direct law - why are you that concerned by direct law after all ?

If you think that in the 757 case same actions as were taken in 447 would have saved the situation I have nothing more to say.
Had it been a 757 on AF447, three elements could have helped saving the situation :

Coupled flight control commands
No auto trim under manual flight
Therefore the continuity of the stall warning

[vilas]

I am not against the idea of having a single switch which knocks out protections But the idea of no auto trim in manual flight goes against the concept of AB FBW. Flight without auto trim for substantial amount of time will require some tactile feed back in the side stick. It is almost changing airbus to Boeing FBW. I do not think it is going happen nor it required. Coming back to 447 what would have helped and has helped in some other such events is sensible piloting and following proper procedures. But some how that is not important to you. You sarcastically used the phrase pilot proof aircraft but you are actually demanding better pilot proof systems because you support pilot's lack of skill. FBW feels the same at 35000ft. or 10000ft. but a 747 or 707 doesn't. AF447 crew the way they handled A330 could flying manually very well stall a 747 at FL350 even with valid speed. Continuity of stall warning sure nothing against it, they ignored it 50 times may be 51st time they would have heard it but the problem was not the stall warning but not knowing what to do with it. Auto trim just trims what you asked. Should a pilot ask for upward trim in stalled condition?

[NigelOnDraft]

I am a little mystified about this "big red button", especially related to Perpignan?

The "big red button" was precisely what caused Perpignan! The AoA probes froze at a sensible cruise reading, and despite clear indications as such to the crew (illogical Angle of Attack displays on PFDs), they proceeded to test AoA protections.

Due to the frozen AoA probes, AoA protection did not occur. The crew just carried on slowing down (PPL indication of approaching stall: 1), with a very nose high attitude (PPL indication of approaching stall: 2), to well below the speed clearly written in the test schedule on the Flt Deck at which the test should be "knocked off".

In effect the frozen probes acted as "the big red button", and enabled, unfortunately, the crew to kill themselves :{ It isn't a particularly good advert for the "big red button" concept to me?

[Denti]

I am not against the idea of having a single switch which knocks out protections But the idea of no auto trim in manual flight goes against the concept of AB FBW.

Actually, that is pretty much what i was trying to suggest. No, direct law, although extremely easy to fly in, isn't really needed, alternate law without protections is enough if the hard protections decide to act up. Now, the downside is, that such an event is extremely rare but we still need training for it and there is of course the possibility to use such a switch in the wrong context which could lead to incidents as well.

Nigel makes actually an excellent point, although the big difference is that the perpignan crew was obviously unaware of the problem with their AoA vanes, whereas a crew disabling the protections should be aware of what they are doing.

[CONF iture]

The "big red button" was precisely what caused Perpignan! The AoA probes froze at a sensible cruise reading, and despite clear indications as such to the crew (illogical Angle of Attack displays on PFDs), they proceeded to test AoA protections.
Time to read the report one more time Nigel ...

I am not against the idea of having a single switch which knocks out protections
Good

But the idea of no auto trim in manual flight goes against the concept of AB FBW
I suppose some protections taking over for wrong reasons is also against the concept of AB FBW ...

Flight without auto trim for substantial amount of time will require some tactile feed back in the side stick.
Why that ?

It is almost changing airbus to Boeing FBW
And the problem is ?

Coming back to 447 what would have helped and has helped in some other such events is sensible piloting and following proper procedures. But some how that is not important to you.
Quote ?

You sarcastically used the phrase pilot proof aircraft
Certainly sarcastic as the FBW Airbus was here to correct the pilot's mistakes. Airbus just forgot to mention how the pilot could be required to protect the airplane against its own protections.

but you are actually demanding better pilot proof systems because you support pilot's lack of skill.
Quote ?

Continuity of stall warning sure nothing against it, they ignored it 50 times may be 51st time they would have heard it
Surely the captain would have loved to hear it ...

Auto trim just trims what you asked.
Not in this case, the auto trim would have trimmed hands free from the stick.

Should a pilot ask for upward trim in stalled conditions?
Should a system ask for upward trim in stalled conditions ?

[vilas]

Coming back to 447 what would have helped and has helped in some other such events is sensible piloting and following proper procedures. But some how that is not important to you.
Because I don't see a word from you about the procedure 447 crew followed.
Not in this case, the auto trim would have trimmed hands free from the stick.
If 2.5 degrees pitch and something like 80% N1 was set why would the aircraft trim full up? Airbus trims for the flight path if you point the nose up and keep the stick back sure it will do what you asked for. The aircraft was not left hands free at all. TOGA was selected which is not vastly different at 350 but never the less FBW resists the pitch up it only trimmed back because pilot pulled the stick back and kept it there. Perpignan and AF447 are what not to do examples and if you support these operating styles surely you are demanding pilot proof aircrafts.

[sonicbum]

It trimmed back because dynamic pressure was decreasing and would have done so whether the SS was aft, neutral/hands-off or even forward....until the dynamic pressure trend could be reversed, which is an arduous task at 40+ degrees AOA.

So what is the aim of the stall recovery ?

[vilas]

OK465
I am not sure you know what you are saying. Can you quote some document to support your argument? Why was the dynamic pressure decreasing and how did the angle of attack reach 40 degrees with pilot doing nothing? High level handling in alternate law including stall and recovery is part of type rating now and I have done it many time it doesn't do anything of that sort.

[sonicbum]

In ALT, from 265 or so KIAS, manually fly your A330 level D simulator to a 10 degree flight path angle at 35,000', at TOGA power if you like, and then take your hands off the SS. Watch the THS trim and sit back and enjoy (:eek:) the ride, remain totally hands off at this point. (Monitor the FPV and SD Flight Control page for additional information.)

The THS will reach 13 ANU and AOA will reach 40+ hands-off. If you have the simulator Input Guidance capability selection at the instructor station, you can monitor AOA through-out on the VOR DME readout.

BTW, conversely, what do think the THS does in dive in ALT, without protections other than g limiting, with the SS full aft and airspeed (dynamic pressure) still increasing?

This is what the airplane is supposed to do. Why should a pilot try to achieve 10 degrees of FPA at 35000 ft in a normal flight ? :rolleyes:

[vilas]

OK465
In AF447 there was a failure of a component which has happened in non FBW aircraft also. The aircraft behaved the way it was designed to but the pilot not only did not handle the failure the way he should have but took the aircraft to the extremes of the flight envelope and kept it there without facing extremes of environment or incapacitation etc. In this situation the auto trim aspect of the aircraft which makes airbus such an easy aircraft to fly was found to have a negative role. Your suggestion is to redesign the aircraft for such a pilot. I am suggesting to put a better trained pilot in charge. After all we can passionately promote our views but the manufacturers and regulatory requirements and economics will govern the modifications and not what people like you and me demand. AB FBW is bête noire for some people they are entitled to it but then the discussion becomes a merry go round and not professionally stimulating.

[Uplinker]

I'm with vilas on this. FBW is an assistance tool, like the FADECs in the engines, and help prevent exceedences. (?spelling)

Problems with Airbus FBW are mostly down to pilot training, which companies are trying to reduce because it costs money - which reduces the profit they make because they refuse to charge the proper price for the tickets. That's not the pilot's fault.

(If I was an Airbus designer I would keep the system as it is but physically link the joysticks, so they both moved together, and have a disconnect function just like on the Dash 8, where the controls can be disconnected from each other in case of control problems).

Having said that, I think there needs to be some sort of review of how the voting system of three sensors is carried out. In the case of frozen AoA probes, I would think it would be relatively easy to add a few lines of software code to detect an AoA probe that had not moved at all (i.e. given out exactly the same measurement) for several minutes, while variables such as the THS, aircraft altitude, outside air temperature, IAS/Mach, and engine thrust settings had all changed. If this was found to be the case, then vote THAT probe out. If a second probe was also logged in this way as being 'frozen' or seized, then vote that one out as well and alert the pilots via ECAM and going to Alternate law.

[NigelOnDraft]

CONF itureQuote:
Originally Posted by NoD
The "big red button" was precisely what caused Perpignan! The AoA probes froze at a sensible cruise reading, and despite clear indications as such to the crew (illogical Angle of Attack displays on PFDs), they proceeded to test AoA protections.

Time to read the report one more time Nigel ...Please expand...

It does not matter, the valid sensor was silently discarded and the other sensors were lying together with already the potential to wrongfully trigger a protectionPlease could you also expand on this e.g. with an example or illustration of the point?

[CONF iture]

Please expand...
Where did you see "clear indications" ?
There was none.

The system decided to silently discard the only reliable AOA data. When you realize the importance of the AOA data for the Airbus and its protection system to work properly, the logic would be for the system to at least advise the crew as soon as a significant difference between the AOA readings is identified.
Knowing that something was wrong with the AOA data, never the crew would have proceeded with an alpha protection system test ...

Please could you also expand on this e.g. with an example or illustration of the point?
The valid sensor was silently discarded and the other sensors were lying together with already the potential to wrongfully trigger a protection.
Two AOA vanes blocked at 4 deg which is pretty close to the angle at which the alpha protection is ready to take over in altitude. The BEA did not publish the indicated alpha prot value at FL410 during that flight, it would be of interest.
What happened to Eva Air and Lufthansa could have happened already in Perpignan.

[vilas]

CONF iture, Nigel On Draft
if you keep your prejudices out you will understand the accident better. I am correcting some of your assumptions.
1. Where did you see "clear indications" ?
There was none.

Yes there were. AOA sensors 1 and 2 were blocked at earlier values when they froze and got jammed. Same values are shown on PFD1 and PFD 2 as V alpha prot and V alpha Max after converting them to speed and that display was wrong. Below I quote BEA report.
"However, the blockage of angle of attack sensors 1 and 2 at identical values had inhibited the functioning of these protections and led to an erroneous display of the characteristic speeds of these protections."
2. The system decided to silently discard the only reliable AOA data. When you realize the importance of the AOA data for the Airbus and its protection system to work properly, the logic would be for the system to at least advise the crew as soon as a significant difference between the AOA readings is identified.
Nothing gets silently discarded. This is known as self detected failure and is intimated to the crew as ADR3 fail on ECAM . However in this case it discarded ADR3 in preference to the erroneous ADRs 1 and 2 in accordance with two versus one principle and since it treated it as a single failure normal law was maintained. Such a possibility is explained in FCTM. It defies logic that when there is evidence that some thing is fishy about the ADRs(speed display and rejection of the 3rd) from which the protection arise ,the crew proceeds with protection tests at a low altitude of 4000ft without any preparation. That deprived them of the crucial time they needed to analyse indication of USE MANUAL PITCH TRIM which indicates direct law and its implications.However this is not going to change your dis Confiture about the Airbus and you are habitually going to say "it doesn't matter". That is your privilege I am just presenting the facts.

[NigelOnDraft]

vilas

Thank you for that response.

CONF iture:Where did you see "clear indications" ?
CHECK GW message is a clear indication there is an AoA "discrepency"

http://www.aghsoftware.com/p1.jpg

http://www.aghsoftware.com/p2.jpg
We cannot get away form the fact that this crew:
Were conducting a briefed Test Flight
The Test Schedule called for a Minimum FL100 (crew caried it out at 3000')
Test Schedule indicated Absolute Min spped at their weight of 107K. The crew caried on until 99K, when the Stall Warning (from the correct AoA sounded) - the VLS indication was correct to the schedule
The Alpha displays were clearly significantly different than they crew should have expected (pic above)
The ISATM schedule called for the (Test) crew to record the 3 AoA values prior starting the test. This would have shown the AoA problem
The Test was to check the functioning of the AoA protections. If you are to Test this, you must assume it will fail, and protect against it - betting your (and others') lives on it is a pretty high stakes gamble :{


I am not criticising in isolation the crew on the day. How and why they found themselves in that situation is discussed n the report. Management and Training and Supervision are clear factors. However, these are separate from the design characteristics.

[CONF iture]

Nothing gets silently discarded. This is known as self detected failure and is intimated to the crew as ADR3 fail on ECAM
Maybe the right time then for you to correct your own assumptions and to reevaluate your facts presentation as no such ECAM MSG was presented to the crew.
The crew was not aware of the ADR 3 rejection.
During the 40 minutes period before the crash an unambiguous AOA DISCREPANCY ECAM MSG could have been presented to the crew.

CHECK GW message is a clear indication there is an AoA "discrepency"
A CHECK GW MCDU MSG is certainly NOT a CLEAR indication of AOA DISCREPANCY especially when it was not possible to determine if this message was really presented to the crew.
However, an unambiguous AOA DISCREPANCY ECAM MSG would be a clear indication.

The ISATM schedule called for the (Test) crew to record the 3 AoA values prior starting the test. This would have shown the AoA problem.
The crew has rushed and was clearly poorly prepared, but how would you want them to check those 3 AOA values when only 2 are available and so only indirectly through the third MCDU ... ?

[NigelOnDraft]

The crew has rushed and was clearly poorly prepared, but how would you want them to check those 3 AOA values when only 2 are available and so only indirectly through the third MCDU ... ?I have no idea, I am a mere Line Pilot who flies A320s. If I was undertaking a formal test schedule requiring these 3 values to be recorded, I am sure my preparatory material would inform me how.

A CHECK GW MCDU MSG is certainly NOT a CLEAR indication of AOA DISCREPANCY It should be to a crew doing a test Flight about to bet their lives on the AoA protections. For a Line Crew, I might partially agree with your comment.

AOA DISCREPANCY ECAM MSG could have been presented to the crewI am not sure a Line Crew really needs this - all it could really say is "don't stall" which they really should not be doing anyway :{ That said, I suspect some form of additional internal AoA cross-checking will be incorporated to address the latest OEB - if only to detect "frozen" values when systems calculate the value should change more than x?

[CONF iture]

I have no idea, I am a mere Line Pilot who flies A320s. If I was undertaking a formal test schedule requiring these 3 values to be recorded, I am sure my preparatory material would inform me how.
Except that there is no way to do it ... but good luck.

It should be to a crew doing a test Flight about to bet their lives on the AoA protections.
Did you get that it was not possible to determine if this message was really presented to the crew ... ?

I am not sure a Line Crew really needs this - all it could really say is "don't stall" which they really should not be doing anyway.
Then I am sure the mere 320 line pilot you are would like to know something is wrong with its AOA data before he blindly and religiously follows his Airbus GPWS procedure ...

[Meikleour]

CONF iture: When I flew A330 it was possible to access the individual AOA values via the CMS using the applicable codes. I assume the A320 has similar functions?

[Denti]

Yup, those values are actually shown without the need to call them up by code, but that might be just a preset on our busses.

[sonicbum]

Are you supposed to access this kind of data during a flight ?

[Meikleour]

sonicbum: Yes, easily done in flight.

[sonicbum]

Read the question again : are you supposed to ?

[Denti]

For a test flight like that, yes, of course. In normal line operation? No, not really, just used to check on some facts or for curiosities sake.

[sonicbum]

For a test flight like that, yes, of course. In normal line operation? No, not really, just used to check on some facts or for curiosities sake.

This is the point. The thread veered from its original meaning.

[NigelOnDraft]

Except that there is no way to do it ... but good luck.Posts above appear to disagree with that? I appreciate you appear to have a grudge against Airbus and it's products, but does it really extend to accusing Airbus of writing Test Schedules asking the impossible :confused:

Did you get that it was not possible to determine if this message was really presented to the crew ... ?I do, but the likelihood is it was, and anyway, there was other, more compelling evidence.

Then I am sure the mere 320 line pilot you are would like to know something is wrong with its AOA data before he blindly and religiously follows his Airbus GPWS procedure ... I am not sure I would? The QF A380 incident, IIRC, is tending towards reducing "ECAM Messages" for everything? I spend enough of my time on the A320 dealing with spurious, unnecessary, and transitory ECAM messages. There needs to be a balance in life, some level of trust in designers and certification procedures re "fault tree analysis". To have an AoA problem such as Perpignan, ignore the signs there was such an issue, and then require a Max Perf GPWS warning I consider "improbable".

Is the Airbus FBW perfect? Of course not. Has it stood the test of time well, for the first mass market FBW commercial airliner? Yes. It has been improved, minor faults ironed out. I think we are now past the stage where the machine is the target of "blame" and "fault" - indeed for the A320 series I do not think it ever was. The FBW is well in the mature "refinement" phase.

The training and oversight / management of the operators would be a more productive target - IMHO. Perpignan an unfortunate, but clear, example - despite Airbus' efforts, man proved it is not uncrashable :{

[Clandestino]

It seems the A400 has such a switch - Is it the red guarded one on the left side on the upper panel ? - I don't know.Zee pushbutton is optional and labelled "EVAC". At least, last part of your statement is correct.

[CONF iture]

Posts above appear to disagree with that? I appreciate you appear to have a grudge against Airbus and it's products, but does it really extend to accusing Airbus of writing Test Schedules asking the impossible.
Exact same reply stands :
The crew has rushed and was clearly poorly prepared, but how would you want them to check those 3 AOA values when only 2 are available and so only indirectly through the third MCDU ... ?
But what about you actually link the document you mention ... ?

To have an AoA problem such as Perpignan, ignore the signs there was such an issue, and then require a Max Perf GPWS warning I consider "improbable".
As improbable as 2 AOA vanes would lie together to trigger a protection that a crew could do nothing about it ... except by shutting down some computers ... or how to have to publish an improbable red OEB.

[NigelOnDraft]

The crew has rushed and was clearly poorly prepared, but how would you want them to check those 3 AOA values when only 2 are available and so only indirectly through the third MCDU ... ?
But what about you actually link the document you mention ... ?
BEA Report (http://www.bea.aero/docspa/2008/d-la081127.en/pdf/d-la081127.en.pdf):Low speed checks
These are to verify, for an in-service aeroplane, the activation, at scheduled and signalled speeds on the PFD speed band, of the angle of attack protections in normal law.
The description of low speed checks in the ISATM is similar that of low speed tests in the PATM. Ground checks, then checks in flight in clean, then landing, configuration performed between FL100 and FL140, are defined. Before starting low speed checks, the crew must reduce and stabilise speed in order to record the three angle of attack values and compare them to the attitude and pitch.

[vilas]

NigelOnDraft
Once we leave the ground we are in a hostile territory because since it is not a human habitat we have no instincts whatsoever. Only birds have that and that is why we have procedures. Any deviation from them and you are like a blind man who has missed a cue. There are any number of accidents/incidents which show that whenever a pilot has surprised the airplane by change of plan the aircraft has sprung up a fatal surprise. But you won't prove a point to Conf.

[CONF iture]

Blame the crew for not doing the test above 10000ft and not recalling the characteristic speeds during the briefing, but not for not applying a procedure they didn't have.
In the meantime I do maintain that ISATM procedure is erroneous as there is no way to read the data for AOA #3

But you won't prove a point to Conf.
Conf wouldn't keep his job much longer if he was not following the procedures.
The system knew something was wrong with the data, all it needed was to advise the crew by a straightforward ECAM MSG :
NAV AOA DISAGREE

As Airbus gave so much priority to the AOA data in its system, it would be logical to at least advise a crew when one single reading differs from the 2 others.

[Denti]

In the meantime I do maintain that ISATM procedure is erroneous as there is no way to read the data for AOA #3

Why wouldn't be there any way? You can read all AoA values from every MCDU as has been explained above. It's easy enough to do, and i would expect it to be detailed in the relevant procedure.

I do agree however that an AoA disagree advisory would be a nice clue about whats up.

[Mad (Flt) Scientist]

One problem is that this was a 1 vs 2 disagree. So the system used the "2" that agreed. (Just like a pilot would I suspect, given three sources of data where 2 agreed). The most likely scenario for such a case is the "1" is bad, so ignoring it and doing nothing else is a good plan EXCEPT if you are doing flight tests. So if there was a message which just said "take no action" I'm not surprised they decided not to bother line crews with it.

A lot of this comes down to the big topic from this accident - the way such flight tests are (were, rather) conducted.

[vilas]

Conf
I said in post 46 the following
"All these protections are triggered from data derived from one sensor or the other but the present system of sifting the data to ensure it's genuineness is being proved inadequate and is the cause of all these incidents. The answer to this will come from better sensors, better system of confirmation of data or even quantum leap of technology in measurement of airspeed,"
So I had already said AB needs to change the method of identifying the faulty ADR/component. That includes change in ECAM messages or even giving the job to the crew to identify it for themselves until a new method of air speed measurement is discovered. I agree that crew was not warned of the ADR3 rejection in some cases it does which can be easily included in the ECAM and the crew advised to confirm it if it was correct.

[TyroPicard]

The 1v2 disagree can be fixed quite simply by introducing monitoring over time. The Perpignan a/c had two probes at fixed values for a long period, including speed, altitude, and config changes... if a flight test engineer had monitored them he would have noticed the fault; all we need now is software as competent as humans.

[CONF iture]

Why wouldn't be there any way?
Every single parameter is not necessarily available through the ACMS (or is it called AIDS on the 320 ?)
AOA1 and 2 are there but #3 is nowhere to be seen ...

[LEVEL600]

All three AOA are available on AIDS and test flight requires write down value for all of them in clean configuration,green dot speed and croscheck/comparation with "angle" obtained from differenece btwn. pitch and flight path angle. Maximum allowable difference is 0,5 degree. Don't know if this procedure was valid at the time when Perpignan happend..:confused:

[vilas]

One thing which I did not understand is why did the aircraft go in direct law. First the rejection of the third is no different than ADR3 fault should have come on ECAM and the second is any combination of ADR malfunctions is not suppose to trigger direct law. Nobody else also has noticed it.

[CONF iture]

First the rejection of the third is no different than ADR3 fault should have come on ECAM
Airbus thinks otherwise and wants to keep the 'magic' as long as possible and so without noticing the crew of the real situation ...

One thing which I did not understand is why did the aircraft go in direct law.
"The aeroplane's high angle of attack and the roll movements generated asymmetry, and a speed variation between ADR 1 and 2 appeared. This increasing divergence caused a rejection of the three ADRs by the FAC then the ELAC".

As that 320 was in landing configuration, the flight control system passed straight to direct law.

[vilas]

CONF iture
Thanks, I missed that it was due to being in landing conf it went to direct law. In some situations ADR3 fault would trigger. It can easily be made to trigger in all cases of fault/rejection.

[q8pilot]

HI ALL , i don't know if its going to make sense for you all , but i will try anyway , always remember your A/C attitude in all stages and power setting , use severe turbulence tables to help you , the most trusted indications are engine power and nose up or down relative to the horizon , if you see the black and red strips check your props ( pitot and static ) if you see unusual nose up or down check your AoA , always cross any increase or decrease of speed with engine power , if it does not make sense THEN trust your engines , ALWAYS
IF IT DOES NOT MAKE SENSE FLY POWER AND ATTITUDE
FORCE YOUR AC TO GIVE YOU CONTROL BACK by taking it out of normal law
we all can fly with alternate law or direct law correct ??!! then :mad: it i want to have my controls back

[CONF iture]

http://www.bfu-web.de/EN/Publications/Interim_Reports/IR2014/I1_Report_14_6X014_A321_Pamplona.pdf?__blob=publicationFile

I can understand trim up operation is frozen under auto, but why should it be under manual ... ?

[sonicbum]

Hi gents, apologies if it had already been discussed. Is there any way to reproduce in a CAE SIM the Abnormal V Alpha Protection ? Probably by failing the AOA heating and inserting severe ice accretion we should get a similar effect, as the procedure asks to switch off 2 ADRs as well, but I was wondering if there is anything else that can be done to reproduce it, obviously for training and awareness purposes.
Thanks

Edit : Correction the procedure for double AOA heat failure calls for one of affected ADRs OFF. I remember a few years back the procedure used to switch OFF all the affected ADRs and leave one for stall warning.