Early Airbus controversies recalled
 

When the Airbus A-320 was still in planning stages, I remember a presentation in a conference on aviation psychology relating all the combinations of circumstances software code writers had to consider, such as what warnings to inhibit on takeoff when they could be a nuisance, etc., which presentations were appropriate and when, and which might not be.

The speaker said there were many combinations of events the software could not anticipate, that it would be impossible to write software for unforeseen events, and that doubtless the software itself would probably cause some problems.

Add to that the reticence of some pilot unions (was one Air France's?) about the "fly by wire" concept at the outset, with no mechanical controls whatsoever,and it seems this recent nightmare situation is an example of expressed fears of just such unknowns.

All this speculation is premature. As many have said, it seems really more a matter of "there but for the grace..." etc.

It all makes the QANTAS A-380's crew's performance, augmented by the extra pilots who were all busy, just that much more remarkable.:eek:

If there is one piece of unambiguous information this crew could have used to save their lives it is a display of AOA.


It is nothing short of negligent that this information is easily read on the flight recorder after the crash but was not accessible to the crew.


AOA information is available on every jet transport, it should be displayed constantly, at least on each EADI and additionally on a dedicated, independently powered standby instrument.

The legal community, who make the awards, see

64 New York University Law Review 1989 Final Moments: Damages for Pain and Suffering Prior to Death

You will see in the reference that the extra damages are intended to have a deterrent effect.

I'm not a lawyer, so please don't shoot the messenger.

@Greybeard
We didn't have ISIS on the A332 but on the A333 and the A343. I don't know if AF had the same ISIS, but ours only displayed the following datas:

The ISIS system displays the following information:
- Attitude
- Airspeed and mach
- Altitude
- Barometric pressure
- LS function
- Bugs
(OM B A343 - Vol 1 / OM B A333 - Vol 1)

Therefore no VS indication on the ISIS.

That's what I said earlier. I read somewhere that AoA display is/was an option on certain Boeing products, not sure about Airbus. It would be sickening to know that, in those dire moments, the single most important parameter, while present and available to the system, wasn't displayed because the customer had't ordered the software feature to do so.

IMHO, one of the outcomes/goals of the investigation, and a focus of this thread should be to make it mandatory for the AoA to be on all commercial aircraft...no exceptions.

They didn't need an AOA display on their PFD to fly the Aircraft.

I'm getting sick of repeating myself but here goes again.

This is not a new event

Let me say it again

This is not a new event

It's happened before and ALL OPERATORS HAVE PUBLISHED PROCEDURES FROM AIRBUS TO COPE WITH THE PROBLEM OF UNRELIABLE AIRSPEED.
These procedures detail what you can expect to hear and see during the event. They detail explicitly what to do.

Most competent Airline Pilots would have read about this problem, been shown the problem in the Simulator and hopefully bothered to have a think about what they would do if faced by the same event. I know I've put a lot of thought into it and so should have the AF crew.



Ok, so now we are clear.

I had no problem finding out something about this, including a memo by the flight safety officer.

Air Caraibes Atlantique memo details pitot icing incidents

And the Air Caribes memo itself, which is in French:
Air Caraibes Airbus A330 memo

oh, it's been clear before, no problem with that!

however, every indicator other than the AoA gives you secondary information with respect to a stall condition. In a dire situation like this with a tsunami of information, warning, system errors, failing systems, unreliable systems etc rolling over your head, it can be very hard to correctly interpret secondary information. Having the root cause shown to you would shortcut through the cognitive dissonance and help gain correct situational awareness.

An experienced crew would know for their a/c:--

1/ what pitch attitude they must fly AND WHAT IS NOT NORMAL
2/ what thrust setting they must fly AND WHAT IS NOT NORMAL
3/ What noise levels constitute "normal" for their cruise speed
4/ That it is simply not possible to climb 3,000 feet at heavy weights at high altitude quickly ( 7000 fpm apparently ) without Stalling the damn plane
5/ That if they entered the area at a normal speed and power settings then all they had to do was keep the pitch attitude somewhere around 2 deg nose up ( lower wouldn't matter too much, but higher does ) and the thrust around 78 to 80% N1 and they would be ok.

6/ keep the wings level and BE SMOOTH ON THE SIDESTICK.

1. A/c enters cloud with high concentration of super-cooled droplets.
2. Faulty pitot ices over on PF side "freezing" dynamic pressure sent to ADC.
3. Sudden convective event induces a climb reducing static pressure to ADC.
4. PF responds to perceived Mmo excedence with stick back.
5. Static pressure reduces causing airspeed increase.
6. Auto-trim blindly complies with pilot input increasing nose up towards maximum.
7. Repeat steps 4 to 6 until stall....
8. Stall warning stops but comes back on if PF does the right thing.
9. Software has turned off auto trim with stab trim stuck 13 deg up.
10. Software has turned off the bird, just when it would has improved S.A.
11. Checkmate to the software....

In all error chains there's always a bit of man + a bit of machine. But once this kicked off, the man didn't really stand a chance, now did he?

Hi,

I disagree ...
You can't be so affirmative.
Methink the AF447 case is enough to understand that some pilots or aircraft under certain condition need a AOA display.
So ... the solution is to go to the most safe side and have a AOA display
And also needed a stall alarm who sound with no interrupt when aircraft is in stall condition
Save lifes first .. with experienced or inexperienced pilot is a noble task
Foolproof .. as always.

well I think it reasonable to expect that this crew might have ignored that piece of information ( AOA display ) just like they ignored 3 fully serviceable BIG ATTITUDE INDICATORS right in front of their noses.

AOA
 

There is no AOA display in the A330.

Yes we know that thanks.

Actually if you have time ( they didn't ) you can call up AOA in the CMC maintenance pages.

@ Pininstauld: This scenario doesn't work in alternate law...

Absolutely with nitpcker. Until the BEA tell us WHY the aircraft was climbed so rapidly we are all 'groping in the dark' - which bit and why please?

Mainstream media coverage
 

TO ME IT IS WAY TOO EARLY TO SPECULATE ON A PROBABLE CAUSE BECAUSE ALL OF THESE DISCUSSIONS ARE BASED ON DATA THAT IS SELECTIVELY RELEASED. TOO MANY ISSUES ARE YET TO BE RESOLVED.

Pilot control versus Computer control. Flight into hazardous conditions. Simulator training. Pilot qualifications.

Too many questions. No conclusions.

Way too early for the public to be involved in hip-shot resolutions.

@nitpicker That would be the same as driving on the highway while looking down while shifting gear.

A side comment about AOA indication, valuable info for such operation:
a. It can be measured directly with a vane, but is subject to icing.
b. It can be calculated from INS measurements, generally it is the difference between flight path angle and fuselege pitch attitude.

Its absence was not a factor. A pilot can see the altitude dropping rapidly and the nose pointing up, which is sufficient information to deduct a very high AOA. A push of the sidestick forward would have been enough.

What to me is unacceptable, is an aircraft changing its response to my flight control inputs, due to some laws switching to and fro. In an ideal world it could be regarded advanced, but in the given circumstances it makes the pilot a deputy assistant to the autoflight system, as opposed to the pilot in command.

So in Cruise or other low activity times am I not allowed to look down to my right and use the CMC display on the centre CDU? You might as well remove it then!!

Please re read my post, i did say in brackets that they wouldn't have had time to check it.

Grrr

'Baby' pilot at controls
 

'Baby' pilot at controls of doomed Air France Airbus | The Australian

Is this based on info officially provided by the BEA?

Thoughts?

AOA indication?
 

I don't understand the comments regarding the lack of AOA diplayed as being an issue: is it too complicated to substract Flight Path Angle from Pitch?
Pitch-Path=AOA

That is lesson 2 or 3 from any PPL training...
Am I missing something?

AOA
 

Guess what: The A330 has been retrofitted with a' backup speed scale' (BUSS) in case all three ADC's fail. The BUSS provides a coarse speed reference, based on AOA.

Guess what, to activate the BUSS you need to turn off all 3 ADR's P/B's

I believe that the stall warning alarm on the A330 is derived from some temperature probes (hot-wire flow rate type?) and control surface status? i.e. Incipient stall is calculated. Does the algorithm still work when the aircraft has gone so far out of normal flight conditions? Is it even possible to test it in anything like a real-life situation?

@BOAC

alternate law: I thought there was a line referring to an auto-correction to prevent overspeed. I can't find it anymore. IF the PF behaved that way, it looks like a plausible scenario.

I've been in several deep stall scenario's in normal law in the sim, when preparing training scenario's in different laws. Everytime the stall would be uncontrollable, the high THS setting (max) was the cause.

There is not much THS awareness among Airbus pilots.

@ Lemain. Stall warning on the A330 is based on angle of attack.

@nitpicker Of course you could look into that screen during low workload. But what do you expect to see there, besides a normal AOA value? By the way, I agree with you that any pilot should know what are normal indications, especially attitude information.

Ah what I expect to see if I bother to look is the current AOA of my Aircraft?? I don't understand your comment.?

It stalled because it ran out of speed after climbing from 35k to 38k after pilot control inputs. The report makes no mention of any buffeting and turbulence during the climb. Where in the report does it indicate the rather significant G loading, forcing the aeroplane into it's 7000fpm climb, that would be expected with flying into the top of a Cb?

Who said that you can only get the conditions that block the A330 pitot system in Cbs?

Given the benign nature of the comms with the cabin about the impending turbulence ( "in two minutes we should enter
an area where it’ll move about a bit more than at the moment, you should watch out"), I hardly think that the crew knowingly flew into a Cb.

I'm not saying they didn't fly into the top of a Cb; merely that there is no evidence to suggest they did. As for the Sat Pic, I hardly think that could be used to claim they did fly through a Cb given the scale of the image, as CONF iture has said.

Don't see something that is not there, Thermostat. :ok:

I've just been trying to read through FCOM 1 Flight controls reversion section. After i took a headache pill I found that following any ADR disagree reversion to ALT LAW the protections lost are:-

1/ Load Factor
2/ Pitch Att
3/ High AoA
4/ High Speed
5/ Bank Angle
And 6/ Low Energy


So to me it appears that the aircraft would not have "pitched up" automatically during what it thought was an overspeed situation.

It was basically left to the Pilots to correct any perceived overspeed/underspeed.

Hi,

Interesting ... (sorry if already posted)
http://www.faa.gov/other_visit/aviat...B_briefing.pdf

Further that Low speed stability protection change from AOA to Airspeed based and the symbols on the speed tape change from Alpha prot /Alpha max to Vsw.
With the flaps/slats in use and 5 to 10 kts above stall speed the Aircraft will induce a forward demand on the elevators, which the Pilot can override.

This was not applicable to AF 447 in cruise.

So any pitch up/down demand was as a result of the Pilots alone, they did not have any protections helping them.

Also don't blame the THS trimming up to 13 deg nose up. It was a result of the Pilots demanding back stick pitch up ( to counter what they thought was an overspeed ) the speed obviously decayed during the manoeuvre requiring more and more trim to help it satisfy the Pilots demand.

Am I right in thinking that -10,000 ft/min is around 100kts down? In which case if their airspeed was <60kts a normal attitude would produce a very high AoA.

If so they may have a normal attitude displayed, unknown airspeed indication, and no stall warning. Perhaps only clue was high rate of descent which they might not have believed given normal attitude?

Edit: and think how far down they would have to pitch to get a sensible AoA back.

Yes and a very quiet cockpit with very low air noise.

Catastrophic sim training
 

Catastrophic situation: Not only some "system error" or circumstance - but also the potential consequence when it's not optimally handled. (Spin - stall - steep dive +70 degree - 80 - 90 degree bank angle. Upside down and stalled - you name it- )

To put the yoke forward when one get a shaker stall alarm - but the plane is not actually (fully) stalled - is not a catastrophic scenario -
A stall with 40 AoA and 10000 f/s sinkrate is catastrophic - especially if airplane looses pitch authority at that configuration.

I can not see why you should not practice even "drop wing" and steep diving to get out of stall etc - I did it. - at age 14 - -in a real sailplane - from 3000 feet. If it's not possible in the sim this year - why don't you make an appointment with an sailplane-instructor - he would be happy to guide you. OK it would not be the same as your wide body workhorse.- but perhaps for some take the mystery out of the stall and spin configurations. It could be great fun also.

Yes it may work if you have enough Altitude left to pull out without over stressing the wings. Certainly in their position worth a try perhaps.

But a 200 tonne Airbus heading downhill at 10,000 fpm at less than 60 KIAS is going to be near impossible to recover before you hit the surface.

You'd have to roll 90 deg, wait for the nose to drop and the speed to quickly build then hope like he'll there was enough room left to recover without over stressing the wings.......

I agree. In a sailplane the nose usually pitches down on it's own when stalled - so you quickly get used to it pointing at the ground. If that doesn't happen in a jet I imagine some bravery is required to push the nose that far down - not least when 25% of the people in the back aren't strapped in.

Why wasn't full power applied? They can't have recognised the stall.

astonmartin
 

quote you: @ Lemain. Stall warning on the A330 is based on angle of attack.
Are you saying, as I have seen similar statements in this forum, that the A330 stall warning system does not compute:- Angle of attack with modifications from airspeed, flap position and pitch rate inputs?