Machinbird

Vilas,
What you say is absolutely correct as to the overt behavior of the aircraft and apparent reason for the AF447 pitch up. As you probably know, some of us have been looking at roll PIO as a possible causative human factor in the otherwise inexplicable piloting failure that caused the AF447 accident.

Very few airline pilots have ever experienced any form of PIO event, and the mental effects on a pilot trying to fly during such an event are definitely under-appreciated.

Anyone wishing to expand their knowledge of PIO (also known as APC) would do well to obtain a copy of Aviation Safety and Pilot Control: Understanding and Preventing Unfavorable Pilot-Vehicle Interactions by Committee on the Effects of Aircraft-Pilot Coupling on Flight Safety |The concepts are understandable without having to be proficient with the associated mathematics.

john_tullamarine

Following on from Machinbird's post, the paper is available for complimentary download from the NAP website.

roulishollandais

In France at least it was the regulator who decreased the basic flying level since 1979 and deregulation - it is the true and official name of that movement- didn't work for low cost airlines first but for Air France competitors to destroy the SNPL power... These airlines at the beginning were not low cost in the today's sense but they only decreased the bill cost by flying only the trips where Air France and Air Inter were full of passengers (Paris-Antilles, Paris-Nice, Paris-Toulouse, aso) or low level fuel price trips (Marc Rochet).

The decreasing level of formation started with A320, remember the strikes of AEROFORMATION FTEs unhappy to have no more enough time for basic and classical flights, they had to use the time to teach B.A.BA of FBW button pushing.

Low cost airlines could only emerge in France when it was no more mandatory that a French airline used a French registered plane, and leasing helped to share benefits in one hand, financial risk in another... and fisc didn't see the loss of money and corrupted people organised financial worldwide Mafia hidden behind the ICAO flag.

vilas

Again and again inexperience in cockpit comes under scrutiny while in many accidents experienced pilots were handling the plane. A fat logbook is not a safety barrier and does not compensate for lack of required skill. 5000 command hrs. on a medium range automated aircraft like A320 simply translates into 2 1/2 thousand times switching the AP ON and OFF for landing. We have to understand that in aviation it is not be possible to learn everything in air by personal experience and practice. High altitude handling, practicing alternate/direct law is not possible. Pilots are retiring without having experienced an engine failure. That doesn't mean one should be unable to handle it. Some theoretical understanding and simulator practice is the only answer. Type rating needs to be expanded more at least for the beginner. Airbus has expanded the type rating for the beginners by eight sessions of handling as entry level training/MCC course in fixed base trainer but airlines have got around this by adapting a mini version in a procedure trainer which defeats its purpose. Accident due to the inability of an experienced pilot to do a visual approach shows that those thousands of hours was merely a delay in aligning of the Swiss cheese. The required skill was never acquired. Understanding the behaviour of the aircraft like Airbus FBW where there is never a requirement of knee jerk reflex on the side stick can win half the battle for you. Perhaps with declining profit margins airlines have become like other businesses, more of a commercial strategy than anything else.

VNAV PATH

For those having nostalgy of good regulatory overview, good experienced pilots and good leather cabin seats: 67 ft RA over outer marker.


http://www.bea.aero/docspa/1997/f-mc...-mc971123a.pdf

DozyWannabe

You'd sound more credible if you'd get the terminology right - "button pushing" is a feature of autoflight, *not* FBW. FBW and automation are categorically not the same thing.

roulishollandais

Point for you !
Edit add :
These students did not know the difference between automation and systems : They did not read that wonderful book cited by Machinbird and John Tullamarine : one of the best (or best !) Book to read to understand dynamic systems and feedback in aircraft's a control and design.
Unless you understand that everything is pushing button !

roulishollandais

VNAV PATH,
terrifying drift in crew management during that "autoland", and teaching in flight !
That captain thought he was a god and he was building followers not pilots.
No amazement from AOM/Air Lib ! The good cabin leather cabin seats with caviar were their best performance...

NeoFit

AB anyone ?

I agree with this very interesting post

Here is evidence of rudder efficiency

DozyWannabe

@NeoFit - As Machinbird points out, that post is not entirely correct. The PIO began long before the aircraft entered into the stall regime, and the YD was doing its best to correct for it.

Winnerhofer

Appeal Court invalidates Airbus' Counter-Report.
Crash du Rio-Paris : la justice annule un rapport d?experts défavorable aux pilotes d?Air France, Tourisme - Transport
https://www.francebleu.fr/infos/fait...nce-1447764309
http://www.mediapart.fr/files/AF447_Contrex_1_0.pdf
http://www.mediapart.fr/files/AF447_Contrex_2_0.pdf

Winnerhofer

A new book by an AF Captain with many years blames Airbus' Neutral Stability as totally counter-intuitive.

He quotes page 193 of BEA report which says that Airbus' Neutral Stability should have NEVER been certified as it is contrary to the most basic of aviation tenents.

Lorsque plus aucune protection n’existe, l’avion ne possède pas de stabilité statique longitudinale positive même à l’approche du décrochage.
Cette absence se traduit en particulier par le fait qu’il n’est pas nécessaire d’avoir ou d’augmenter une action à cabrer pour compenser une perte de vitesse en maintenant l’avion en palier.
Ce comportement, à basse vitesse, même s’il peut paraître contraire à certaines prescriptions du règlement de base, a été jugé acceptable par les autorités de certification par prise en compte de conditions spéciales et interprétations particulières ; en effet, la présence de protections d’enveloppe de vol rend tout à fait acceptable une stabilité statique longitudinale neutre.
Pourtant, la stabilité statique longitudinale positive d’un avion peut s’avérer utile car elle permet au pilote d’avoir un retour sensoriel (via la position du manche) sur la situation de son avion en terme de vitesse par rapport à son point d’équilibre (trim) à poussée constante.
En particulier, l’approche d’un décrochage sur un avion classique est toujours associée à un effort à cabrer de plus en plus prononcé.
Ce n’est pas le cas sur l’A330 en loi alternate.
Il en résulte notamment que dans cette loi de pilotage l’avion, mis dans une configuration où la poussée n’est pas suffisante pour maintenir la vitesse sur la trajectoire, finirait par décrocher sans action sur le manche.
Il apparaît que cette absence de stabilité statique positive a pu contribuer à l’absence d’identification par le PF de l’approche du décrochage.

Page 186 (English)
When there are no protections left, the aeroplane no longer possesses positive longitudinal static stability even on approach to stall.
This absence specifically results in the fact that it is not necessary to make or increase a nose-up input to compensate for a loss of speed while maintaining aeroplane altitude.
This behaviour, even if it may appear contrary to some provisions in the basic regulations, was judged to be acceptable by the certification authorities by taking into account special conditions and interpretation material.
Indeed, the presence of flight envelope protections makes neutral longitudinal static stability acceptable.
However, positive longitudinal static stability on an aeroplane can be useful since it allows the pilot to have a sensory return (via the position of the stick) on the situation of his aeroplane in terms of speed in relation to its point of equilibrium (trim) at constant thrust.
Specifically, the approach to stall on a classic aeroplane is always associated with a more or less pronounced nose-up input.
This is not the case on the A330 in alternate law.
The specific consequence is that in this control law the aeroplane, placed in a configuration where the thrust is not sufficient to maintain speed on the flight path, would end up by stalling without any inputs on the sidestick.
It appears that this absence of positive static stability could have contributed to the PF not identifying the approach to stall.
============================================================ ========================================
By A Special Contributor:
He's technically correct but that's why Airbus tells pilots, in nice big bold letters, that you have reduced protections in those modes.
I'm not sure why this is an AF447 comment...if the pilot had left the stick alone, neutral stability would have saved his butt.
It was pulling nose up that really got them in trouble, and would have on an airplane with positive or neutral stability.

A-FLOOR

The assumption that simply letting go of the stick would have saved them does not appear to hold up to scrutiny. I found this particular gem by OK465 in the A320 OEB thread from one year ago:

I'm afraid I do not have an A330 sim at my disposal to replicate his finding, but the way he describes it is exactly the way I would test this myself.

The behavior he witnessed however should not be called neutral stability. It is the definition of negative stability! The fact that the aircraft keeps trimming up silently well past the stall warning is extremely worrying.

Winnerhofer

Aftermath: It Just Doesn't Compute | Flying Magazine
https://disqus.com/by/disqus_hkf2Up0sbq/

Winnerhofer

Video - Ejectable floating black boxes - Aviation industry - Aeronewstv

Winnerhofer

From A Safe Pair Of Hands:
I have backed off from these discussions as I feel I am too much out of date.
I retired 18 years ago as a B743 Captain after a long career, 43 years, in all sorts of roles: Navy pilot, then Exec of Squadron, followed by an airline career piloting Viscounts, DC9s, F27,B727s, A300, in roles usually as a check airman or Flight Superintendent Training before management for five years.
As an old timer, I was very sceptical of FBW new aircraft coming in.
I felt there was not enough redundancy, e.g., an old control tab until converting pilots got the full experience.
My view was that converting pilots were to be hanging in there by their fingertips for quite some time, scared of their careers coming to an end in midstream and actually without a full understanding of the complexity of the equipment.
Manufacturers' salesmen had convinced management that the aircraft were safe, "Could not crash" and no need for so much training.
Kids were learning to fly in simulators, not all of good quality, and getting Airline jobs without 'Airmanship'.
I was pleased to see revival of common sense with the American Airlines video, "Children of the Magenta".

RetiredF4

Years after ..........., at last.

Understanding The Angle-Of-Attack Indicator | Business Aviation content from Aviation Week

When I and others raised this topic on the various AF447 threads, we earned only rolling eyes...

vapilot2004

If only the gents on AF447 had such an instrument at their disposal...

DozyWannabe

With respect, I remember it a bit differently. I think the consensus was that in theory it's a good idea, however in the case of this particular accident the crew missed so many cues from the instruments they did have that having an AoA indicator on top of those likely wouldn't have made much difference.

Goldenrivett

The crew were certainly very confused but I believe the Captain would have recognised that they were stalled if the aircraft had this new FWC installed.

"STALL WARNING enhancement: Stall warning will work when:
Undetected erroneous computation of pitot
Pitot out of the airflow
Pitot obstructed by ice or any foreign material at any speed (function now possible below 60 kts)"

@ DozyWannabe. I seem to remember that you argued the AoA probes would be unreliable if the IAS indicated less than 60 kts despite being airborne.