Airbus crash/training flight

[Dani]

Thanks, BOAC, I was not blaming you for promoting this flight technique, I was trying to make my position more clearly.

It is fairly clear to me that the crew had little idea they were stalled.

You might be very true with this statement.
But what else than stalling are you doing if you are "flying" fully configured at idle power with less than 100 (sometimes less than 40) knots? (This is once again not challenging your statement but hinting to what the pilots should have known at that moment).

Dani

[BOAC]

Originally Posted by NoD

How did this crew, prepared (?) to do this test, and understanding (?) the principles behind it, and hazards associated with it (?), slow the aircraft to 92.5K without asking "what's going on here"

- a question I have been pondering.

1) Poor preparation for the 'exercise' - no apparent recognition that systems might fail and what to do if they do
2) IMO incorrect actions at the stall
3) In view of MFS's post (2 Mar 12:50) I have to say we may not actually know what the crew were seeing for IAS, and, indeed apparently we cannot assume it to be correct?

[captplaystation]

A little off thread, but the link provided by NoD to the Easy upset is equally as terrifying as the resume of what happened to the XL.
Having apparent difficulty restoring a normal pitch attitude the aircraft was rolled to 91 degrees of bank whilst heading rapidly downhill . . . WTF ? ?

Nothing in my upset recovery training has ever led me to believe that this would be a "good idea".
Bravo Boeing, 440kt

[BEagle]

Interesting that the CAA has just released the following AIRCOM on the topic of these types of flight: http://www.caa.co.uk/docs/33/AIRCOM_Draft_Final.pdf

[rmac]

Related to the comments on the use of rudder to enter and recover from spin.

Is it possible that sitting somewhere in the back of everyones brain is the primary stall exercises in initial flying training where students are taught to prevent wing drop at the stall by using rudder when the ailerons are no longer effective and there is a chance that this learned behaviour may out itself in unpredicted situations ?

[BEagle]

students are taught to prevent wing drop at the stall by using rudder

Surely no-one still teaches that nonsense, do they? I wonder how many people it killed?

[Lemurian]

jimjim :

Thing appears to be that on the aircraft type in question; the elevator trim *is* a "primary" control in that it is required to be varied for normal manoeuvering.

Thank you for enlightening me of something I've been flying for the past twelve years, 'cos that's really new to me.

Of course, mostly the pilots don't see the behaviour as "triming" (and it surely is not trimming in the traditional sense) since it gets taken care of by the computer. Except this time.

Do you see anything wrong with the Mach trim you'd find on most of the pre-FBW airliners ?... I thought not... So where is the difference ?

Can anyone see a reason that the seperate trim control lever/wheel/switch exists on this type? Since the stick commands "g" (or load factor) surely the seperate trim control is anachronistic? Does it belong in the same bin as the mixture levers?

It's because of the different reversions to the flight control laws.
I've seen it used in Alternate and I've seen it in direct and it's your only choice in emegency back-up.
Although it's available, I've never seen it used in normal law.

These things have already been explained earlier on this thread. How you missed them is beyond me.

[BGQ]

Assumptions!!!

"No, the trim did not remain "stuck", the trim did exactly what it was designed to do in Pitch Direct Law - it stayed put but was movable by the crew."

What evidence do you have to back your stated fact that the THS was movable by the crew? Do you know whether or not they attempted manual trimming?

[BGQ]

Correct but undesirable in any aircraft

"The THS setting is not "programmed" to be left at an extreme setting - the autotrim was doing it's job perfectly and the THS setting was the natural result of the low speed, the a/c was in trim."

I think a lot of pilots are missing the poibt here. The fact that the aircraft trimmed the THS to this position without giving feedack to the pilots is a large part of the problem. Can you imagine any pilot deliberately trimming to such an extreme position especially knowing that the recovery if any significant amount of thrust was applied would be extremely difficult.

This is why when carrying out approach to stall manoevres, stalling manoebres and aerobatic manoevres pilots limit stabiliser trim settings.

[captplaystation]

Ask anyone who flies a 737-800 (and I am talking manually & hopefully fairly competently ) & with a bit of thought they will come to the conclusion that they do indeed use the stab more in the manner of a primary flying control as opposed to merely a load-alleviator (is that a word ? well never mind you know what I mean )
The difference of course, is that on the 737 you are left in no doubt of the need to alleviate the load,due to the fact that your perfectly formed little biceps are getting fed up. . . on the A320 . . . it is perhaps merely perceived not through the dildoesque piece of plastic in your hand, but by the fact all you see through the windsheild is sky. . . . . that mon brave . . is what we call progress ( in Toulouse in any case )

[Lemurian]

The fact that the aircraft trimmed the THS to this position without giving feedack to the pilots is a large part of the problem. Can you imagine any pilot deliberately trimming to such an extreme position especially knowing that the recovery if any significant amount of thrust was applied would be extremely difficult.

All nice and well said, just forgetting the fact that the flight laws were changed. Had they stayed in "normal law", the same auto-trim would have worked the other way during the recovery.

Ask anyone who flies a 737-800 (and I am talking manually & hopefully fairly competently ) & with a bit of thought they will come to the conclusion that they do indeed use the stab more in the manner of a primary flying control as opposed to merely a load-alleviator

That's pushing the ball a bit far, but the 737 is quite sensitive to thrust changes, on top of the configuration and speed changes the old ones used to show, hence the use of the wheel.

. it is perhaps merely perceived not through the dildoesque piece of plastic in your hand, but by the fact all you see through the windsheild is sky. . . . . that mon brave . . is what we call progress ( in Toulouse in any case

Had you had the experience of a 320 in "direct law", you'd have discovered that the airplane would let you in no doubt at all about the need for manual trim.

What is amusing on this sexual hint of yours is that, somehow you could disregard the recent plunge (10,000 ft if I recall) of an out-of trim 737-700...
Boy ! how more prejudiced could someone be ?
As for the "moving" vs "unmoving" throttles, it apparently didn't save that THY aircrew (not forgetting the automatics' kirks on the 737, of course).

[Mad (Flt) Scientist]

Originally Posted by BOAC

- a question I have been pondering.

3) In view of MFS's post (2 Mar 12:50) I have to say we may not actually know what the crew were seeing for IAS, and, indeed apparently we cannot assume it to be correct?

Actually, since it's stated to be CAS and is (I assume) the ADC output/display input speed (it's most likely the FDR is picking up the ADC output) I'd consider the most likely interpretation of the CAS values to be:

1. The output from the ADC, accurately measured (given sample rate issues etc)
2. Most likely also the value presented to the crews provided (a) they had selected the appropriate source for display (most (all?) multi ADC multi display a/c allow crew to reconfigure the ADC sources for display, to allow for ADC failures) and provided (b) that the values were not interpreted as "out of range" by display software and displayed at "limit of range" values - for example, some a/c won't display airspeeds close to zero, and instead apply a lower limit of about 20-30 knots, since the airpseed is meaninglessly nonsense at such values anyway.
3. With the a/c at high (but perhaps also erroneously sensed) AOAs, any ADC corrections which are a function of AOA may be incorrect. Therefore the CAS output by the ADCs may not be representative of the pressures actually sensed by the ADCs.
4. Also, with the a/c at high AOA (and perhaps also sideslip) the air data probes themselves may not have been accurately sensing the freestream pressures any more, so even if the ADCs had no correction errors, the raw pressure data, and thus any derived speeds, are suspect.

In other words, the data probably are a decent representation of what the crew saw, but may have little relationship to the true aerodynamic conditions of the time.

[captplaystation]

Lemurian,
merely pointing out that , unwittingly, the pitch trim is "almost used " as a primary flying contol on the 737 (I.E. it is used when manually flying simultaneously/almost as an aid to, the elevators.) The same I am sure is happening in the A320.
My point is , because of the auto-trim (which I believe is active to maintain a "stick-neutral" feel even when flying manually in the Airbus - at least in normal law ? ? ) you don't develop/maintain the same habit of having to use the trim manually to supplement the elevators, which in the 737 is of course permanently there as a constant reminder that the elevators are chicken-feed in comparison to the stabiliser (even with the A/P engaged you can hardly fail to be aware of the activity of this stone-age wheel clanking around next to your thigh ) something that might have saved the XL crew if they had been mindful of this fact ?
In terms of Easy/THY. . . what to say. THY, perhaps another point for the anti-automation brigade ? No, for me just a reminder that whatever you fly you have to know what it is (or isn't ) doing on your behalf, unfortunately they seemed to be oblivious to the tactile cues that were there
And Easy? phew, some very similar lessons here in the test -flight sphere.
No1 - Altitude is your best friend No2 - Expect the unexpected No3 - Large excursions/control forces reflect the mass of the vehicle you are manipulating, not your own mass.
Mistakes can & will be made with both Boeing & Airbus, it is my feeling that the Boeing one's should perhaps be easier to identify & rectify, but someone will always find a way not to.

[Lemurian]

Mistakes can & will be made with both Boeing & Airbus, it is my feeling that the Boeing one's should perhaps be easier to identify & rectify, but someone will always find a way not to

In spite of some clever footwork,it really doesn't seem you're right, does it ?

merely pointing out that , unwittingly, the pitch trim is "almost used " as a primary flying contol on the 737 (I.E. it is used when manually flying simultaneously/almost as an aid to, the elevators.) The same I am sure is happening in the A320.

No, normally, you don't have to.The aircraft does for you what you have to continually do manually on the 73.
It's only on a vastly degraded mode that the comparison in handling can be made.
What I find disturbing is how quick you seem to have resolved the whole investigation, and to me, that smacks of some arrogance.
Most of the Airbus pilots posting on this thread have refrained, for lack of data, to put the finger on one of the aspects of the flight. There only seem to be an agreement on :

• The low starting altitude for the low speed test.
• The AoA # 1 and 2 sensors,failure, leading to FAC #1 and 2 "Fail" status.
• The stabilizer position frozen in the setting it achieved just prior to the "Stall" warning.

I personally posited that, at least after the first stall, the crew had achieved a recovery, but not completed it.
I also believe, for experience, that past the entry into that very high pitch, followed by severe banking,low Gs... the crew had all that was necessary for some severe spatial disorientation.
I can't begin to imagine what happened inside that cockpit (multiple warnings, unusual attitudes, conflicting informations...)
(These assumptions are mine and only mine)
Questions are posed, and you have no right to make any judgement either on the crew or the aircraft state before we get more data.
I much prefer the attitude of those advocating more training, more stringent test requirements...etc... Their obvious object is air safety, not a childish intent to prove that as the hairy 500 pound- gorillas, they'd have gotten out of such a situation, or that it wouldn't have happened with another brand.

Just my two cents .

[HarryMann]

I personally posited that, at least after the first stall, the crew had achieved a recovery, but not completed it.

I gained that impression too.. reading it like a novel almost, having fought the good fight I found it heartrending to see that good work thrown away almost as success seemed within their grasp. Maybe because I've been in a similar situation - and admittedly succumbed after getting close to a solution (not talking airliners here of course!)

NB: These modern turbofans giving unprecendented levels of thrust at low airspeeds, in situations like these, seem to be a double-edged sword, mounted so low in relation to the aerodynamic & mass centres.

[captplaystation]

Lemurian, you either can't or don't choose to understand what I said.
As previously stated, the A320 is just as dependant on pitch trim for pitch control as the 737.
Given the size of their elevators and the travel available in comparison to the stab, it couldn't be any other way.
In the Airbus this is (in normal law) always done automatically, so will perhaps be at the periphery of your awareness, whether flying manually or in autpilot.
In the Boeing you have to do it manually if you are hand-flying, in automatics it is difficult to ignore due to the proximity of a great big wheel whirring noisily round.
You "could" therefore be more peripherally aware of the activity & therefore need for, pitch trim in most phases of flight in a 737.
Do you see any reason to dispute that simple statement.

[NigelOnDraft]

captplaystation

As previously stated, the A320 is just as dependant on pitch trim for pitch control as the 737.

I cannot confirm or deny that statement, primarily since I have not flown the 737, nor explored these areas in an Airbus.

I would, however, add that Lemurian's

I personally posted that, at least after the first stall, the crew had achieved a recovery, but not completed it.

I agree with, indeed separately come to the same conclusion and posted as such. For a period of time (~5s), they had full power achieved, full nose-up stab, full nose down elevator, ~100K and attitude reducing and speed increasing. AoB was even under control Therefore I can only conclude, at their weight/CG the elevators were outpowering the full nose up stab + full Power.

There were then some control inputs (let go of full forward stick, applied full rudder in a stall/near stall) that seemed to generate the "departure".

As an aside, I have flown the 757/767 and

You "could" therefore be more peripherally aware of the activity & therefore need for, pitch trim in most phases of flight in a 737

does not apply... it only had the trim switches and a dinky little indicator. You therefore did not see the trim in action. OTOH the A320 (and 340 etc.) do have a trim wheel, and you do see it working. It is not quite so unsubtle as the 737 one, nor has the 737 audio effects

So refering to

I personally posited that, at least after the first stall, the crew had achieved a recovery, but not completed it.

might I ask

Do you see any reason to dispute that simple statement.

NoD

[sindhu]

Airbus crash

HI
The New Zealand pilots' union says it feels more confident about the French investigation of the Air New Zealand Airbus crash now its own expert is joining the French team. An interim report released yesterday by the French civil aviation authority, the BEA, suggesting pilot error caused the crash, has upset Air New Zealand and the Air Line Pilots' Association (Alpa), which is sending its own pilot expert investigator to France.
"This gives us greater confidence in the accident investigation process under way," said Alpa executive director Rick Mirkin, who stressed the investigation had reached no conclusions.
Speculation on the cause of the accident would not only be improper but potentially misleading and damaging to the feelings and reputations of parties involved, he said.
The New Zealand Transport Accident Investigation Commission already has an investigator on the French team.
The crash on November 27 last year killed all seven people on board; two German pilots and five New Zealanders, four of them Air New Zealand staff and the other, a Civil Aviation Authority inspector.
Two of the Air NZ engineers on the flight were from Christchurch.
The pilots had taken the aircraft for a check flight as required by the lease under which XL had hired the aircraft from Air New Zealand.
The German XL Airways pilot and co-pilot were in charge of the aircraft although Air New Zealand pilot Brian Horrell, 52, was "in the middle seat" issuing instructions for the tests required, the report said.
The flight was shortened because some checks could not be performed in general air traffic and, on its approach to Perpignan aerodrome, it plunged into the sea.
The report, which is essentially a safety briefing, suggests the Airbus crew was flying too low and doing complicated checks while also preparing a landing approach to the aerodrome.
The crew did not want to land at Perpignan, but intended to "go around" and carry on to Frankfurt.
The German captain at one stage questioned doing the slow-speed tests but began them three minutes before the crash after descending from cloud.
An Air New Zealand spokesman last night denied its captain on the flight deck had asked the German pilots to carry out a slow airspeed test at a dangerously low altitude.
"The report gives some information about the German pilot asking the New Zealand pilot a question it does not outline specifically what was recorded on the flight-data recorder," he said.
The pilots needed to do a slow-speed test to check that an automatic thrust would activate when the slowest safe speed was reached.
Although Airbus's delivery manual specified the checks should be done at 10,000 feet to 14,000ft, the crew had the aircraft at about 3000ft.
The report says a lack of rules about such check flights have meant crew qualifications are not stipulated and test procedures can be improvised.
Air New Zealand chief executive Rob Fyfe has criticised the release of the report before the victims' families have seen it, and its findings. He would complain to the director of the investigation and to France's Ministry of Transport about the way the report was published.
The airline had not been allowed to give any insight into the actions of the crew and nor had its specialists been given access to the flight recorders' data.

Army Wives|Wounded Warriors

[Lemurian]

Mad(Flt)Scientist

In other words, the data probably are a decent representation of what the crew saw, but may have little relationship to the true aerodynamic conditions of the time.

I agree. But it's not, and IMO by far, the only picture of the events in this cockpit.
First of all, the first stall was probably (a big "probably" )announced by the # 3 AoA... But we don't know for certain what happened to that sensor and its behaviour -to me - is suspect :
Look at the report :
"...At 15 h 45 min 19 s...The stall warning stopped...
At 15 h 45 min 20 s, the airplane’s pitch was 7°, its speed was 138 kt..."
That stall warning was awfully long, wasn't it, seeing the acceleration of the airplane out of the low speed range ?
If, as I suspect, the # 1 and 2 AoA sensors were blocked by some sticky stuff and/or icing, the same should have, or could, rather, have happened to the # 3 which sits very close to #1...
So, at least on that first stall, we may have some conflicting informations presented to the crew : an IAS is the "safe" range and a stall warning...

[NigelOnDraft]

So, at least on that first stall, we may have some conflicting informations presented to the crew : an IAS is the "safe" range and a stall warning...

I am intrigued by your <<an IAS is the "safe" range >>. For a fairly dull "line crew", seeing IAS reducing through 100K, but no sign of the Alpha Prot/Max/VLS symbols, that might have a degree of "understanding".

For a Test Crew, briefed and prepared (?), and knowing that Alpha Max was to be 107K +/-3K it is, to me, incomprehensible

Please bear in mind the aircraft was a slight descent, 99K and a pitch attitude of 18.6nu... surely some alarm bells should have been ringing..

NoD