"Passenger 9".....The nom de plume says it all.

Wingswinger is correct:

In the Habsheim event, A-FLOOR was inoperative below 100 ft RA as per design.

The A320 test flight was indeed a departure from the scheduled flight test profile (I believe due to perceived time pressures) combined with AoA issues.

@mockingjay:

Passenger 9 gave you the answer:

It would not have helped here. Be careful what you wish for, as per design .....

I the Habsheim A320 FDR showed the pilot commanding (stick position) a pitch up before they went into the trees and the flight controls moving in the opposite direction! Explain that please.

@Pax 9:
 

They were on their total energy limit (Engine thrust) at that time, any altitude gain (Potential energy) would have been traded for airspeed (Kinetic energy) resulting in a stall, it would have crashed at the tree line.

They were too low and too late....

Simplistic I know, but does the AOA sensor overide all other info to the pilot.
On one previous accident, the aircraft was straight and level, engines producing normal thrust, but the pilot was convinced the a/c had stralled, and crashed.

Exnomad, prime example of pilots not being pilots. Pilot probably did not know what a real stall was therefore not knowing how to recover. Xbox/FMS drivers.

As with many other sensors, there are 3 AoA sensors.

If 1 sensor provides a differing value to the other 2, in general it will be "voted out". That works well for 99% of failure cases.

The rare problem is where either all 3 sensors give differing values, or where 2 give a similar, but incorrect value. This is behind AF447 and OEB48.

AFAIK, in the A320 one out of range AoA value will generate a stall warning, but not flight protections.

It is fine to blame the aircraft for not working out the 2 failed scenarios, but pilots will not usually be much better, especially at night / IMC :{

Yes they would, experienced pilots will know with a given power setting at a given altitude we should see X speed more or less. If I feel a buffet with this much nose up attitude and with this power setting I will expect X. With experience I will know what to expect and will act accordingly. Experience is the key word here. Fly the freaking machine first however we need proper training and experience.

The A320 that crashed into the mediteranian was XL 888T on a check flight. The aircraft's lease was up and XL was in the process of returning it to its owner.

There were three problems that led to the crash:

1. the maintenance crew had washed the plane with a high-pressure hose, thus pushing water into the AoA sensors,

2. the crew did flight tests without authorization and at a dangerously low altitude and

3. the crew did not realize that their plan correctly identified the problem with the AoA sensors and fell back giving the pilots manual control over everything, including crucially the trim.

Had either the PF or the PM read the message on the annunciator and understood it (the CVR indicates that they didn't even read it) they could have trimmed the nose down and the plane would have remained entirely stable.

Also, the crew might have monitored the IAS and realized that the stall protection had not kicked in, long before the speed would have dropped so low.

The chain of problems that led to AF447's crash were: 1. flying through a thunderstorm,

2. pitot tubes freezing,

3. the PF not following procedure in the case of frozen pitot tubes and instead pulling up and

4. said pilot keeping his sidestick pulled back thoughout the stall and drop out of the sky DESPITE the more experienced PM having said several times that he was taking control and that the nose had to be brought down. (In fact FO Bonin did only announce that he was still pulling back on the stick at FL040, at which point it was far to late to do anything.)

The incident this thread is supposedly about was solved by pressing two buttons on the overhead and there was never any real danger to anyone.

Really, people should stop with the blind the hysteria. FBW has saved lots of people's lives and many disasters would not have happened, had the plane had Airbus' system.

Ok, I am going to have to,say it. Or if people had basic flying skills. That would have saved lives. Case in point; your number 4. That was a prime example of the lack of basic flying skills.

& as for the 330 crashed by the test pilots. Funny old thing no protections in ALT* But all the AB aeroplanes are lovely to operate, not so sure to fly. They are fascinating machines & you do need an above average knowledge of the systems to be totally safe. Again well done the crew.

Leaving the Airbus out of it, it did not work that way with the 2x 757 accidents?

We really don't know do we. Like I said before dude, I am not blaming Airbus. I am blaming the steady decline of pilot proficiency. Airbus just fills in the gaps with automation. Is it working? I don't know. When you see pilots do dumb things like pulling up so much to clear a storm and it quits flying is bad enough. But failing to recognize the following condition is absurd. I am not blaming Airbus.

I was looking into this matter tonight. And I found on this page that Airbus claims it only happened two times ever.
https://safetyfirst.airbus.com/overs...9-application/
Whereas this is clearly false.
There is this case for example where the AOA protection malfunctionned :
https://en.m.wikipedia.org/wiki/Iberia_Flight_1456
(prevented a go around that was required)
I also know from primary data that this happened at least two or three times in another european airline (this time with the same freeze as the Lufthansa 321).
The article in the first post says it happened several times at lufthansa as well.

So, why is airbus making such unsupported claims ?

Is it perhaps more probable that Wikipedia is lying?

To be pedantic , Wikipedia is the platform, the contributors might have lied.
I use Wikipedia all the time - but it does warrant a cross check.

Wikipedia requires links to supporting documentation or the article gets a big flag for being unsubstantiated.

The good thing with wikipedia is that you can always verify their claims. Just google the report :
https://www.mitma.gob.es/recursos_mf...006_a_eng1.pdf
You even have the curves.

So my question stands :)

Same goes for the press articles about the lufthansa incidents. It's less reliable than this final report for an accident, but it's still something.
I also know for sure that some cases happened several times to another european airline following probe freeze, but it didn't leak in the press. The logic is simple.
The probes freeze at a given AOA, with comparable values (at least two probes frozen at the same time).
The airplane climbs. The mach number increases. The aoa limit decreases when mach increases.
The aoa limit becomes lower than the frozen AOA. The airplanes dives down.
It's sort of similar to what happened to the B737 max (sort of).

I wonder why those 2 crews on the MAX didn’t think to “turn the auto pilot off, and point it in the right direction”? Oh, wait a minute…

There was no rush. That 4000 feet was one minute. It took them approximately one minute of troubleshooting the problem to solve it when there was no imminent danger. Sounds like it was handled appropriately.

Deep dive?

The autopilot was not on in the Max accidents. To have survived they needed to disable the trim system via the large red guarded trim disable switches and adjusted power to maintain an appropriate aiespeed. They did neither. Still with the auto trim interruption system via stick position and counter trim the Captains on both flights were able to maintain control until they handed the aircraft over to very inexperienced co pilots.

Is that quite complete? I believe they needed FIRST to return the aircraft to (approx) stable trim, i.e. reverse any MCAS input, THEN disable electric trim.

Can't believe that it would be hard for software to detect frozen AoA sensors. If you change the eleivator or thrust and there is no effect on AoA sensors at a certain point the data should he figured as unreliable. To only count on the pilots, that they push the right two buttons at the right time might not always work out.

Only about 50% of that is true - you need to read the reports and especially attend to the FDR graphs and compare all three flights, each progressively worse; Ethiopian particularly badly handled. Underlined is true, strikeout is false, underline strikeout is partly true. Not going to rehash the reports.

Clearly engineers have their own failures too.
For the boeing case, they didn't even take care to have enough probes.
On airbus they have more probes, which make it far less likely, but they still have some occurences.

It's true that some pilots on some incident occurences mismanaged trim problems. For example, one never figured out that his trim switch was reverted.
I think trim is one of the most important flight control. Especially on jetliners where the THS has a larger pitching power than elevators. (Which isn't true on most light airplanes, it seems).
Because of that, even if it's very rare that this control should be closely monitored, there should still be a THS position indicator somewhere obvious in the cockpit. Above the PFD for example.

Also one can wonder about why the THS could go so far pitch down on the MAX. It's understandable it needs to go very high pitch up, for very low speeds and forward CG. But an airplane already at maximum speed and normal CG shouldn't have a large nose down THS margin, should it ? What's the use of that ?
It should also slightly reduce cost and complexity to have a smaller amplitude for the THS.

Bottom line, keep the autopilot on during high altitude over speeds. You are more likely to just get yourself into trouble with inappropriate pitch inputs that were not necessary anyways. Just accept the overspeed, realize that it not dangerous, maybe use some speedbrake and then write it up as appropriate.

As for the faulty AoA concern, alpha prot strip increase is a slowly increasing value as Mach slowly increases because the AoA vanes are stuck in place instead of slowly moving toward what I will call the cruise altitude position. This particular event appears to be a sudden increase in the alpha prot strip likely due to some g-loading in turbulence causing vane movement. I suppose one wants to recognize the difference between g-induced alpha prot strip increase and stuck vane increase in alpha prot strip (recognize the circumstances likely to produce both).

I agree with the conclusio to keep AP on.
However, it still doesn't make it acceptable that some pilots would be unable to properly control the aircraft in case they wanted to disengage it.
Forgetting the thrust while nose up and failing to push it down too when needed is not acceptable.

The protections did not “fail”on the Iberia Bilbao accident. The aircraft behaved as designed at the time. The ELACs did not like the rate of pitch change and in anticipation of high nose event limited it. Airbus modified the ELAC standard after the incident and provided Iberia with a new A319. All details on the final report.

Sorry to chime in late on this thread...just noticed it.

@Meikleour said it all, "the THS can be moved manually to control the pitch at all times,"

The Airbus as with Boeing and all modern airliners uses lots of sensors to assist pilots and make the flying task easier. Sometimes failures make those helpful little angels turn into devils and cause problems.

But us old and experienced pilots should not be phased when something weird happens say in pitch. The first thing to do when the aircraft does something unexpected is, as Airbus recommends, disconnect the autopilot.

However, if you still have pitch control problems such as limited authority using the elevator control...well the only other primary control surface that is that gigantic all-flying-tail that we use for trim.

The elevators are small and so the pitch effect is for refined pitch adjustments. The all-flying tail is huge is is used to trim out the very large pitching moments associated with flap selection and the large CG and speed range of an airliner.

So if the elevators are insufficient to control pitch, then simply grasp the trim wheel and control the pitch using the all flying tail (trimmable horizontal stabiliser THS or whatever it's called on your jet).

If something else is automatically controlling the all flying tail (THS) and fighting you...turn it off!

In case of surprise...forget the yellow brick road, the magenta line, the magic of the autopilot, digital flight control stability and augmentation, or whatever and...

Fly the aircraft by manually controlling the surfaces that are needed for the situation.

In case of doubt or surprise, ignore the magic and you fly the aircraft...don't let it fly you!

We normally set the trim wheel for take-off and then we forget it all about it. Watch that little sucker from time t time next time you go flying...it will explain a lot as to what is going on.

(And in jet upset it may or will become the primary pitch control).

They didn't fail, they worked as designed, but they failed the crew. It's funny you can use the same word in English for two slightly different concepts. They failed the crew.
The mere fact that they decided to change/improve the law, shows that they admit that it was not perfect.

In the end, and what matters, the bad design of the protection led to an accident.
The exact origin of this bad design, be it coding, mechanical failure, electrical failure, freezing, does not really matter. The protection unduly limited legitimate stick orders and led to an accident.
Hence they failed. They failed at doing their job properly.

Airbus talks about cases of "improper AoA protection activation".
If you think an activation leading to an accident was proper.. Good on you. Stop thinking that anything designed by the manufacturer is perfect.

They were not Airbus Test Pilots - they were a regular crew from XL Airways, with observers from Air New Zealand and the NZ CAA, doing a leasing/ownership handover flight. This, along with the Easyjet B737 Maintenance Test Flight serious incident in the UK, was the catalyst behind regulators enhancing Maintenance Check Flight procedures and crew training - precisely because the crews that perform these tasks are generally NOT test pilots (nor need to be).

If you look at the FDR data, you will see an AOA of 15°. The max AOA of the A320 is supposed to be 17°.
So why did the flight control law refuse to go up to this ?
The small margin between their actual alpha and alpha max could have allowed to fly over. Could have, I didn't run any simulation.

If the software observes that AoA remains completely constant on two sensors despite the significant flight control inputs produced by alpha protection, meanwhile the third sensor shows changes in its readings consistent with the commanded manoeuvre, isn’t that a pretty good indicator that those 2 sensors are frozen?

There needs to be an indication that the mechanism of each AoA sensor is reliable, independent of any other sensor reading.

For example, one could use electromagnetic coils to modulate a small variation of torque on the AoA vane to see if it moves as expected. If + and - torque yields no + and - change in the AoA sensor reading then the sensor is flagged as unreliable. Subsystem testing could continue to be used on the off chance the sensor frees up, and then return it to the voting pool. This could also be used on the ground before departure and runs less risk than using the entire plane as a roller coaster to check the sensors or hoping for a situation that would change the AoA a meaningful amount over digitization noise.

It does raise the question - since all three sensors aren't identical in reading, what does the flight control software do with the readings? Does it average them, take the two that are closest and average them, take the middle one? What is the fallback if one is eliminated? Average or flip a coin and pick one? They are within some margin of each other, but then what if one more is eliminated? It cannot be disagreement on reading, right?

The majority of pilots these days survive because the aircraft don’t fail 99.999% of the time and they just follow the SOPs designed for the weakest pilot in the weakest operation with the autopilot doing the flying for 99.999% of the time.

This isn’t the fault of the pilots; it’s the fault of training departments filling the training syllabus with inane rubbish like watching an RNAV approach with the AP on for twenty minutes or ten minute briefings in a full motion simulator doing laps of the hold with again the AP on.

Remember the Children of the Magenta? Well they grew up and became today’s training department managers and chief pilots. It ain’t the fault of the line pilots for the last 10-15 years. They only do what they are told/trained to do.

Attitude is a reflection of leadership and leadership in training is non-existent in the majority of airlines these days.

With regard to the specifics of this thread; the problem can be solved by doing two easy things 1) turn off the affected system 2) fly the aircraft manually.

1) Most crew wouldn’t know what hit them if this kind of failure occurred - see all above examples 2) most pilots can’t fly the aircraft manually.