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  • 3WE
    replied
    Originally posted by Gabriel View Post
    ATLcrew is so right
    That deserves a post all it's own.

    And he interjects his wisdom to us AND feeds homeless kittens.

    I only hope we provide some entertainment as he pops popcorn.

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  • Evan
    replied
    Originally posted by Gabriel View Post
    I believe that Evan refers to the fact that they had just selected a lower speed to enter the turbulent zone so the A/T had just reduced thrust. The A/T was supposed to add thrust when the selected lower sped was achieved, to keep the plane from keeping losing speed, but with the UAS the A/T disconnected and that would not happen. I remember Evan was concerned that if they didn't set climb thrust (which ironically started by taking the thrust levers OUT of the climb detent) they would stall. Not that I agree with that.
    Specifically this:

    2 h 09 min 58 - Speed handling changes from managed to selected. The selected Mach is 0.8.
    2 h 10 - Pitch attitude decreases from 1.8 to 0 in 3 seconds. In 8 seconds, the N1 commanded and the N1 change from 100% to 84%.
    2 h 10 min 05 - The A/P2 disconnects.
    2 h 10 min 08 - The FD 1 and 2 become unavailable. The A/THR disengages and the THR LK mode isactivated. The N1 are at 83 %.

    Q: Is 0-3 pitch (known values) and 83% N1 at their current weight and altitude FDnH?

    Complex modern aircraft have stealth factors. Procedures are needed to overcome them.

    Now Evan, googling some I found that ATLcrew is so right that official Airbus documentation explains why they added the "If the safe conduct of the flight is impacted" condition to the memory items and how they propose to train the pilots to specifically NOT apply the memory items unless the safety of the flight is impacted and how that relates to ground/obstacle clearance.
    I don't see that. What I see is a doc that says "If the safe conduct of the flight is impacted" is something to be "Defined During Training", It is left undefined in that document.

    However, one can extrapolate: The flowchart showing the decision tree to determine if memory items are called for involved two options:
    • Safe Conduct of the Flight Affected: Unreliable Airspeed Procedure
    • No (Safe Conduct of the Flight Not Affected): ADR Check Procedure


    The scenario it is showing for "No" is "Speed between CAPT and F/O PFD starts to diverge while in climb."

    That is NOT an "NAV ADR DISAGREE" ECAM message and a sudden loss of autoflight and reversion to alternate law caused by the simultaneous obstruction of multiple pitot tubes (an emergency at hand). That is an indication to run the ADR check procedure and to isolate a faulty unit (a problem developing). There is no indication of loss of autoflight under the NO scenario.

    Does the sudden loss of autoflight and reversion to alternate law affect the safe conduct of the flight? Absolutely!

    So, while disturbingly vague and potentially misleading, this doc seems to me to warrant the memory procedures if ""NAV ADR DISAGREE" is encountered at any altitude.

    Furthermore, the memory items continue to have separate pitch/power values for flight above FL100. So that sort of blows any theory that these memory items are only for "how that relates to ground/obstacle clearance." Wouldn't you agree?

    What did we learn from AF447? What did we learn about human factors when pilots have no memorized and practiced procedure in their head and improvise under the disorienting affects of being startled and stressed?

    Bottom line (hasn't changed): If the crew of AF447 (and every other instance of high-altitude UAS) had applied the standard memory item pitch and power values, nothing bad would have happened, whereas when left to individual pilot improvisation, anything can happen. Why do pilots (and apparently now, the industry itself) continue to resist that hard lesson and that self-evident truth?

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  • Gabriel
    replied
    I think that Jhonmicky started the fuse and ordered a large bucket of pop-corn.

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  • Gabriel
    replied
    Originally posted by ATLcrew View Post
    Sure, it was. At least FDnH enough not to mess with. Even if you got a good amount of bumpage happening, that's still plenty FDnH not to go pitching and pulling and Krishna only knows what else. The only "memory item" should have been to leave the airplane be and methodically and deliberately go through the ECAM.
    I believe that Evan refers to the fact that they had just selected a lower speed to enter the turbulent zone so the A/T had just reduced thrust. The A/T was supposed to add thrust when the selected lower sped was achieved, to keep the plane from keeping losing speed, but with the UAS the A/T disconnected and that would not happen. I remember Evan was concerned that if they didn't set climb thrust (which ironically started by taking the thrust levers OUT of the climb detent) they would stall. Not that I agree with that.

    Now Evan, googling some I found that ATLcrew is so right that official Airbus documentation explains why they added the "If the safe conduct of the flight is impacted" condition to the memory items and how they propose to train the pilots to specifically NOT apply the memory items unless the safety of the flight is impacted and how that relates to ground/obstacle clearance.

    Check the date of this document (admittedly, it is for the A320 family but I can see that the A330 UAS procedure in place when AF happened follows exactly the same structure and logic).
    http://www.smartcockpit.com/docs/Unreliable_Speed.pdf

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  • ATLcrew
    replied
    Originally posted by Gabriel View Post

    I do recall someone (don;t remember if you or somebody else) bringing to the table the fact that the UAS procedure introduced the memory items with "If needed to stabilize the flight" or something like that.

    And what is FDnH?
    It was me, and it wasn't "if needed to stabilize flight", it's a rather more forceful "if safety of flight is impacted". The purpose of this memory item is to get you away from the ground, so you can level off and troubleshoot (which is what the memory item ends with), not to start doing things things when you're seven miles away from the ground.

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  • ATLcrew
    replied
    Originally posted by Evan View Post
    Fat Dumb n' Happy. (AF447 was not FDnH when the airspeeds were lost).
    Sure, it was. At least FDnH enough not to mess with. Even if you got a good amount of bumpage happening, that's still plenty FDnH not to go pitching and pulling and Krishna only knows what else. The only "memory item" should have been to leave the airplane be and methodically and deliberately go through the ECAM.

    Leave a comment:


  • Evan
    replied
    Originally posted by Gabriel View Post

    And what is FDnH?
    Fat Dumb n' Happy. (AF447 was not FDnH when the airspeeds were lost).

    Leave a comment:


  • Gabriel
    replied
    Originally posted by ATLcrew View Post
    Do you recall me stating (on more than one forum, in fact) that the memory items didn't apply in this case? In fact, I might have even explained (in some detail, too) what the purpose of the memory items for this failure was, but, to refresh your memory, it certainly wasn't anything having to do with an airplane flying FDnH (albeit without a good IAS indication) at FL370.
    Sorry, I made a mistake. I thought that 3we's was asking if I recalled Evan's position, not yours, and I answered in that way.
    I don't recall what you said (sorry again, and if you want to explain it beyond what you've just said above, appreciated).

    I do recall someone (don;t remember if you or somebody else) bringing to the table the fact that the UAS procedure introduced the memory items with "If needed to stabilize the flight" or something like that.

    And what is FDnH?

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  • ATLcrew
    replied
    Originally posted by Evan View Post

    This is the hostile, dismissive and belittling argument I would expect from insiders like ATL, but you of all people know that this is a discussion forum for the purpose of discussion, for the sake of discussion.
    Heeeeeey! I fed a homeless kitten six years ago, so hostile my butt!

    Leave a comment:


  • ATLcrew
    replied
    Originally posted by Gabriel View Post
    That the memory items came first.

    As far as I recall.
    Do you recall me stating (on more than one forum, in fact) that the memory items didn't apply in this case? In fact, I might have even explained (in some detail, too) what the purpose of the memory items for this failure was, but, to refresh your memory, it certainly wasn't anything having to do with an airplane flying FDnH (albeit without a good IAS indication) at FL370.

    Leave a comment:


  • 3WE
    replied
    Jhonmicky:

    I remember visiting with a light plane pilot (his aircraft lacked pitot heat).

    He departed in some IMC weather and was climbing out.

    He noted he was a little fast so he nosed back a bit.

    A short time later, he was again little fast, so he nosed back a bit more.

    Again, he was a little fast.

    HOWEVER his attitude was a bit nose-high compared to where it should have been.

    BAM: "My pitot tube has iced over!" he realized.

    He called ATC and did a 180 and began a descent with known, robust power and attitude settings and made good use of his attitude indicator.

    As he was beginning an instrument approach, he saw the airspeed needle jump a bit as the ice melted off...He broke out at a nice altitude and landed visually.

    It is probably easier to do in a draggy-light plane at low altitudes than a big huge jet...then again, they do have nice attitude indicators and beaucoup power indications and a book of Acronyms and Power/Pitch settings, or maybe they even initiate occasional descent by hand, no less.

    Anyway- a real example of a real human using the concept of P+P=P to address a pitot issue and living to tell about it.

    Leave a comment:


  • Evan
    replied
    Originally posted by 3WE View Post
    You must have missed this: (How surprising)
    No, I didn't miss it. I read between the lines. Pilots are required to have special, intense and expensive training, far beyond that of motorists. So, in a similar scenario involving cars, can we provide motorists with the same level of training and proficiency? No. Not even close. Therefore, we need a purely technological, fail-operational solution. Or do you think P + P improvisation is a good idea here as well?

    Leave a comment:


  • Evan
    replied
    Originally posted by LH-B744 View Post
    Leave the elevator alone, and your aircraft will recover! That's what the experienced AF 447 Flight Captain tried to say, but the newbies called him too late..
    What? By the time the Captain arrived, the plane was in a fully-developed stall and pilot action in the form of downward elevator was MOST DEFINITELY needed. Nor was the left-side F/O's a 'newbie'.

    Leave a comment:


  • 3WE
    replied
    Originally posted by Evan View Post
    My impression is that you were looking for a purely technological solution for redundancy..
    You must have missed this: (How surprising)

    Originally posted by Jhonmicky
    It is my impression that air speed is very critical to flight management, but pilots can still aviate after the air speed is unreliable.
    I'll repeat- as you and Gabriel stack systems on top of systems, and we already see them interacting in strange ways, I want the poor flawed, slow-operating humans to know how P+P=P and that 16 degree AOA's (which can be independent from pitch) tend to cause stalls in 150s and 340s.

    Originally posted by 3BS
    ...is there anything specific you want me to tell my neighbors at Boeing to see if they can get the suggestion over to the development department? I repeat my concerns that they seem a bit disinterested regarding the subject of software modifications.
    A harsh, dismissive statement. However, it is factual, and it was a failed attempt to say that P+P=P is not a new concept and among all the aeroengineers in the world it has probably been considered. Yet, (per Gabriel) such systems do not exist. Maybe there are good technical reasons (in addition to Gabe's legal ones)? A most interesting argument that planes are built more dangerous, but in a way where you blame the pilots, and not the manufacturer.

    Leave a comment:


  • Evan
    replied
    Originally posted by Jhonmicky View Post
    So maybe someone can remind me of where the pilots turn when they no longer have air speed data. It is my impression that air speed is very critical to flight management, but pilots can still aviate after the air speed is unreliable.
    My impression is that you were looking for a purely technological solution for redundancy. That does not currently exist. Pilot intervention is always required. How does that translate to a self-driving automotive industry?

    Despite the equivocation you may be reading on this thread, there IS an established procedure for pitot failure resulting in loss of airspeed data, and all pilots are supposed to be taught this and are expected to be proficient in applying it. The procedure involves two stages with different sources of information, but is actually very simple.

    The first stage is done from memory, using what are called Memory Items or Instant Recall Items. Pilots are taught these in type-certification training and are required to have them memorized before taking control of the aircraft. There are only a small number of these trained memorized procedures (around seven on the A330) depending on the operator, comprising the most essential actions needed to stabilize the most common failure scenarios. Aside from Unreliable Airspeed (UAS - loss of airspeed data most often due to iced or obstructed pitots), examples include Sudden Loss of Cabin Pressurization, Rejected Takeoff and Fire Warning. These are scenarios where there may be no time to reference any checklists and where there may be only one chance to get it right: a correct pilot action is needed immediately. It must be done, from memory, and done correctly. The purpose of the memorized procedures is to immediately stabilize the situation without requiring the pilot to improvise.

    In addition to memory, modern glass-cockpit aircraft such as the A330 provide text message instructions including necessary pilot actions, in order of priority, in a specific part of the central cockpit display. On the Airbus jets, this is called ECAM. On Boeing jets it is called EICAS (although neither the 737NG nor the 737MAX has this system).

    The second stage is done from referencing a Quick Reference Guide (QRH) providing instructions for a large variety of failure scenarios. This part is done methodically once the plane is stabilized and there is time to safely do so. This stage provides engineering-derived pitch and power settings specific to the current weight range and altitude range, providing a more accurate and thus safer airspeed estimate. It also assures that collateral systems that might be compromised by the failure condition (steath factors) are reconfigured or shut down. The critical process of task sharing and communication involved in this stage is known as CRM (Crew Resource Management) and requires two pilots with one assigned to flying and one assigned to reading the QRH and working through the checklists. Many accidents occur when CRM breaks down, or is disregarded altogether.

    I've given a lot of thought to how similar automation failures will affect automotive safety in self-driving passenger cars. One thing aviation automation has taught us is that the transition from automation to manual control is one of the most dangerous flight regimes. If that transition is abrupt and unexpected, it can startle and disorient human thought proficiency and result in gross errors of judgment and seemingly unthinkable erroneous actions. It can also introduce steath factors that work against pilot assumptions and expectations. This is the reason pilots must be so intensely trained and tested on rare, abnormal procedures. How are we going to do that with civilian motorists? The answer is, we aren't, we can't. If we were to apply a similar safety standard to automobile licensing, at least half the population would fail to obtain a driver's license (or would lack real-world proficiency on these procedures).

    So, considering this, and considering that all systems must be expected to fail at some rate, and considering the vast number of cars on the roads at any given time, how are self-driving cars going to be considered safe? My impression is that the industry is naively (or conveniently) not considering this at all, and that 'self-driving' cars are, at this stage of human history, just a lot of new accidents waiting to happen. At the very least, critical systems must be entirely fail-operational, such that no driver actions are required to stabilize control of the car in the event of any system malfunction. That level or redundancy is what makes modern airliners so expensive to build and maintain. Are we going to build cars to this standard in a price-competitive, consumer-affordable market? I think not. I think we need to curtail the greed and opportunism that is trying to rush 'self-driving' automation to market, and to give much more time to working out new technologies for safety concerns.

    Leave a comment:

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