Page 4 of 5 FirstFirst ... 2345 LastLast
Results 61 to 80 of 87

Thread: Lear 35 down approaching Teterboro

  1. #61
    Senior Member 3WE's Avatar
    Join Date
    Jan 2008
    Posts
    4,986

    Default

    Quote Originally Posted by Evan View Post
    My feeling is that most stalls occur due to inattention to airspeed
    Dude...do not say that around Gabriel.

    You do realize it undermines one of THE GOLDEN fundamental rules...

    By the way- while I kind of agree with your statement, one might argue that 'most' stalls occur while turning final with a strong tailwind/crosswind where your airspeed may actually be close to target...

    Regardless, "inattention" is still a big part of it and as I've said before, maybe an "EARLIER heads up (not a warning) you are getting a little AOAish" might help in some instances when folks blow through stall warning AOA's straight to full stalls...Then again, maybe that's over kill...
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  2. #62
    Senior Member Evan's Avatar
    Join Date
    Jan 2008
    Posts
    6,562

    Default

    Quote Originally Posted by 3WE View Post
    By the way- while I kind of agree with your statement, one might argue that 'most' stalls occur while turning final with a strong tailwind/crosswind where your airspeed may actually be close target...
    In a commercial airliner? One could argue that?

  3. #63
    Senior Member Gabriel's Avatar
    Join Date
    Jan 2008
    Location
    Buenos Aires - Argentina
    Posts
    6,867

    Default

    Quote Originally Posted by Evan View Post
    My feeling is that most stalls occur due to inattention to airspeed, so I expect that inattention to also extend to the AoA indicator.
    It doesn't necessarily matter. The understanding and awareness of AoA at any moment in a flight goes beyond whether you are looking at the AoA indicator or not at the moment.

    Let me give you an example. There was an accident in Argentina, Austral 2553, where the pitot heat is believed to have been off, they entered a stormy are and the pitot got progressively frozen with progressively low false airspeed readings. The pilots first firewalled the throttle. When the airspeed didn't increase (it did, but the indication was still going down) they started to descend to trade altitude for speed, which they did but the indicated airspeed was still falsely trending down. Approaching the stall speed and fearing a stall, what did they do" Extend the slats... at possibly about Mmo (that's an estimation, no one knows for sure how fast they were going but imagine a DC-9 in a descent at full thrust). The result? One slat segment separated creating an uncontrollable asymmetric lift. They ended up crashing at about the speed of sound with an almost -90 degrees pitch. During the initial part of the dive, the indicated airspeed recorded buy the black boxes kept going down, a result of the static pressure reducing with the lower altitude and the total pressure being fixed by the pitot that by then was a small air-tight sealed container. Halfway into the dive, the recorded airspeed went up 200 knots in a couple of seconds, something that is even physically impossible even if you think of the DC-9 in free fall under its own weight, add full thrust, and neglect drag. Thats the piece of evidence that confirmed that the pitot had been frozen up, and unfroze at that point.

    I have a very good understanding of AoA, and a very good awareness of it when I am flying, even without an AoA indicator. I want to think that it would have never crossed my mind that we were about to stall. Pitch 2 degrees nose up and vertical speed zero? That's 2 degrees of AoA. We are not about to stall no matter what the indicated (or even the actual) airspeed is. Take Air France. We are 10 degrees nose up but going down a few (or a lot) of thousands of feet per minute? We are stalled, no matter what. Not only I cant believe that this pilot was, in his own words, "been pulling up all the time", but that neither of the other 2 pilots even mentioned the word stall in all the sequence. The only thing saying the word stall every once and then was the stall warning, which they seem to ignore.

    I want to think that I would never ever crashed these planes in that way. Maybe in several other ways, but not like that. My understanding and awareness of AoA would have kept me from doing so. EVEN WITHOUT AN AOA INDICATOR.

    Now, my good understanding and awareness of AoA comes from somewhere that most pilots don't go through. I am an aeronautical engineer, I was an assistant teacher in Aerodynamics, and, perhaps more importantly, I read, listened, talked, discussed debated, and reflected on the subject a lot. And I mean A LOT. As you know.

    My point is that flying AoA on a daily basis can help give pilots this level of understanding and awareness of AoA that some pilots evidently lack.

    I also think you have to decide whether pilots are going to fly by airspeed or AoA
    You don't. V1 and Vr can be speeds, initial climb can be established based on AoA, approach and landing can be based on AoA.

    And thus far the AoA indicator has been called the barberpole.
    The old airspeed indicators, except for single-engine general aviation airplanes, didn't even have a stall speed marking, because the stall speed, even the "official" one, depends on weight and CG.
    The 1st generations of EFIS displays had the "fixed" barberpole which was not really fixed but depended on the airplane weight.
    New generations incorporate load factor to make a "dynamic" barberpole, so the barberpole goes up when you pull up (i.e. increase the load factor, like in a turn. That actually gets closer of what would be an AoA indicator.
    Another great addition was the PLI (pitch limit indicator) in the primary flight display, which show graphically how much you can pitch up before the stall warning activates. Very useful for escape maneuvers. That is actually a disguised AoA indicator, but is actually based in vane AoA.
    Automation has been using AoA behind the scenes for ages, and its use only increases.
    And of course we have stall warnings that are fully based on AoA, some times a simple on-off, some times with multiple stages.

    In other words, in the last decades we have recognized, without admitting it, the importance of AoA, and we have made a multitude of things short of displaying the frigging AoA to the pilot.

    Now we've started. LOC (loss of control, not consciousness) accounts for 40% of the fatal GA accidents (including the Learjet one).
    The NTSB and FAA recognized the importance and value of AoA, and the FAA took measures to promote the development of affordable AoA indicators. Now we have a handful of brands and solutions available and they are starting to be installed. The feedback so far seems to be very good. We will need until it gets installed in good numbers before we can validate that this is really working.

    I believe that is a matter of time before we have AoA displayed in commercial cockpits, which can be done with just code since all the hardware is there and can be presented in a very easy, non-intrusive and very intuitive way right there in the attitude indicator in the form of an airspeed vector pointer.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

  4. #64
    Senior Member 3WE's Avatar
    Join Date
    Jan 2008
    Posts
    4,986

    Default

    Quote Originally Posted by Evan View Post
    In a commercial airliner?
    Ok.

    In an airliner, it seems that most stalls are caused by inexplicable relentless pull ups...

    Not inattention to airspeed.

    Asiana beautiful-afternoon-to-shoot-landings in 172s (and hand fly them in 777s), excepted.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  5. #65
    Member
    Join Date
    Jan 2008
    Location
    MA, USA
    Posts
    863

    Default

    Maybe the trick is to present the information differently.

    Install an AoA indicator, but instead of labeling it "AoA", label it "likelihood of crashing %". Mark the bottom of the scale "0.01". Put a hash mark just below critical AoA and label it "0.02". Put a hash mark just above critical AoA and label it "99.9".
    Be alert! America needs more lerts.

    Eric Law

  6. #66
    Senior Member 3WE's Avatar
    Join Date
    Jan 2008
    Posts
    4,986

    Default

    Quote Originally Posted by Gabriel View Post
    Blah blah blah blah (not arguing, just making a short summary)
    To me, one key point is that (from what I have read), big airliners ease into stalls...

    You are just sitting there, trimming up and up (or maybe the autopilot is doing that for you) and the sensory inputs on wind noise, and mushiness are not there...

    ...nor is there that awesome 172 wheeze where you are getting a little wind over the stall reed, but it's not actually in full clarinet mode.

    So maybe an AOA indication could be nice...then again Evan's (and my) ASI (and warning systems) are supposedly contributing clear, useful near-stall information like they always do.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  7. #67
    Senior Member Evan's Avatar
    Join Date
    Jan 2008
    Posts
    6,562

    Default

    Quote Originally Posted by Gabriel View Post
    I believe that is a matter of time before we have AoA displayed in commercial cockpits, which can be done with just code since all the hardware is there and can be presented in a very easy, non-intrusive and very intuitive way right there in the attitude indicator in the form of an airspeed vector pointer.
    You are aware that they already exist (at least as options) in commercial cockpits, especially those with a HUD. The 737 option adds a small, circular indiction in the corner of the PFD. I guess the only argument against having this standard would be clutter. The PFD is already a festoon of information.

    But what is the advantage of flying an approach by AoA vs flying it by reference speed? Again, I see the AoA indicator as useful for performance aircraft that execute tight maneuvers, or for very rare upset recovery awareness. And I'm not opposed to it. I just don't think it will solve the stall problem we seem to be having on things like sleepwalking approaches and freestyle go-arounds.

    I wouldn't buy a car without a tachometer, but it's not necessary for the average driver. I used to have an old 1972 Mercedes. I drove it across the Sierra Nevada mountain range by the water temp gauge. The more indications the better is my philosophy.

  8. #68
    Senior Member 3WE's Avatar
    Join Date
    Jan 2008
    Posts
    4,986

    Default

    Quote Originally Posted by Evan View Post
    You are aware that they already exist (at least as options) in commercial cockpits.
    Gabriel is aware that they do not_exist in a number of cockpits.

    Given all the bazillion things you DO get information on, AOA is theoretically kind of important.

    Do they have toilet paper roll bearing oil pressure and temperature indications up there for all the Lavs, or is that just annunciator lights?
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  9. #69
    Senior Member Evan's Avatar
    Join Date
    Jan 2008
    Posts
    6,562

    Default

    Quote Originally Posted by 3WE View Post
    Do they have toilet paper roll bearing oil pressure and temperature indications up there for all the Lavs, or is that just annunciator lights?
    There is a TOO LOW TOILET PAPER aural warning, but it is inhibited below FL600.

  10. #70
    Senior Member Gabriel's Avatar
    Join Date
    Jan 2008
    Location
    Buenos Aires - Argentina
    Posts
    6,867

    Default

    Quote Originally Posted by Evan View Post
    You are aware that they already exist (at least as options) in commercial cockpits, especially those with a HUD. The 737 option adds a small, circular indication in the corner of the PFD.
    Yes, I am aware at least for the PFD in the 737. Didn't know about the HUD.

    I guess the only argument against having this standard would be clutter. The PFD is already a festoon of information.
    Yes, that's why I proposed the "very easy, non-intrusive and very intuitive way right there in the attitude indicator in the form of an airspeed vector pointer" type.
    I think that where I am pointing and where I am going are 2 of the crucial things that I would like to have presented in the PFD. One of them is. The other one typically isn't.

    But what is the advantage of flying an approach by AoA vs flying it by reference speed?
    For a given configuration you approach always at the same AoA no matter the weight or CG. Today you need look-up tables to set the Vee speed, and they are not taking the GC into account so you get only an approximation to the ideal Vref. Plus, in gusting winds conditions, the AoA is more stable than the speed.

    I wouldn't buy a car without a tachometer, but it's not necessary for the average driver. I used to have an old 1972 Mercedes. I drove it across the Sierra Nevada mountain range by the water temp gauge. The more indications the better is my philosophy.
    Yes, because RPM in a car is a far analogy to AoA in an airplane (not!). Would you like an indicator in the car that tells you how much of the available coefficient of friction you are using? I would.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

  11. #71
    Senior Member Gabriel's Avatar
    Join Date
    Jan 2008
    Location
    Buenos Aires - Argentina
    Posts
    6,867

    Default

    As a side note, IF the plane is equipped with a sideslip vane my proposed indication gets rid of the ball (slip indicator) and replaces it with a better version that fixes a shortcoming of the ball which gives false indications in case of asymmetric thrust or drag, which can be kind of important in a multi-engine plane when an engine fails (but probably more in smaller GA piston or turboprop multi engine planes).

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

  12. #72
    Senior Member Evan's Avatar
    Join Date
    Jan 2008
    Posts
    6,562

    Default

    Quote Originally Posted by Gabriel View Post
    Yes, because RPM in a car is a far analogy to AoA in an airplane (not!).
    Well, in the sense that you can use it to get the maximum performance without blowing things up, it sort of correlates.

    Would you like an indicator in the car that tells you how much of the available coefficient of friction you are using? I would.
    Something tells me YOU wouldn't need an indicator. Just a calculator.

  13. #73
    Senior Member Gabriel's Avatar
    Join Date
    Jan 2008
    Location
    Buenos Aires - Argentina
    Posts
    6,867

    Default

    Quote Originally Posted by Evan View Post
    Something tells me YOU wouldn't need an indicator. Just a calculator.
    My airplane AoA awareness is much better than my car friction coefficient awareness, even with orders of magnitude more hours behind the wheel than behind the yoke.

    On the other hand, a given wing in a given flaps configuration stalls ALAWAYS at the same AoA. A car doesn't skid always at the same coefficient of friction.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

  14. #74
    Senior Member Evan's Avatar
    Join Date
    Jan 2008
    Posts
    6,562

    Default

    Quote Originally Posted by Gabriel View Post
    On the other hand, a given wing in a given flaps configuration stalls ALAWAYS at the same AoA. A car doesn't skid always at the same coefficient of friction.
    I get your point about that. So why didn't we train pilots to fly by AoA 100 years ago? It doesn't seem that difficult to invent an AoA vane.

    My point is that, to keep things simple enough to be safe, I think we have to make a choice to fly primarily by EITHER a target AoA or a target airspeed.

  15. #75
    Senior Member Gabriel's Avatar
    Join Date
    Jan 2008
    Location
    Buenos Aires - Argentina
    Posts
    6,867

    Default

    Quote Originally Posted by Evan View Post
    I get your point about that. So why didn't we train pilots to fly by AoA 100 years ago? It doesn't seem that difficult to invent an AoA vane.

    My point is that, to keep things simple enough to be safe, I think we have to make a choice to fly primarily by EITHER a target AoA or a target airspeed.
    Understood but I just don't agree. Speed is simpler and better for some things AoA is simpler and better for other things. You don't say we should choose between vertical speed and slope, or between heading and track.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

  16. #76
    Senior Member Evan's Avatar
    Join Date
    Jan 2008
    Posts
    6,562

    Default

    Quote Originally Posted by Gabriel View Post
    Understood but I just don't agree. Speed is simpler and better for some things AoA is simpler and better for other things. You don't say we should choose between vertical speed and slope, or between heading and track.
    No, but I'm sure you are familiar with the old saw: 'airspeed is life'. I think pilots should have a single parameter to focus on for a given aspect of flight. For example, you fly a final approach by airspeed, keeping a close watch on airspeed, not glidepath or vertical speed. As long as your speed is health and your pitch is where it belongs (windshear aside), your glidepath is good and your AoA is in the safe range, and you cross the threshold at the right speed and sinkrate. I'm saying, don't add to the parameters a pilot must monitor. Choose one or the other.

  17. #77
    Senior Member 3WE's Avatar
    Join Date
    Jan 2008
    Posts
    4,986

    Default

    Quote Originally Posted by Gabriel View Post
    Understood but I just don't agree. Speed is simpler and better for some things AoA is simpler and better for other things. You don't say we should choose between vertical speed and slope, or between heading and track.
    Speed is used for sooooooo many things- Traffic spacing in particular (and historically timed approaches), wind gust factors, and etc.

    AOA is going to be relegated to a secondary use.
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

  18. #78
    Member
    Join Date
    Jan 2009
    Posts
    251

    Default

    Quote Originally Posted by Gabriel View Post
    Yes, I am aware at least for the PFD in the 737. Didn't know about the HUD.


    Yes, that's why I proposed the "very easy, non-intrusive and very intuitive way right there in the attitude indicator in the form of an airspeed vector pointer" type.
    I think that where I am pointing and where I am going are 2 of the crucial things that I would like to have presented in the PFD. One of them is. The other one typically isn't.


    For a given configuration you approach always at the same AoA no matter the weight or CG. Today you need look-up tables to set the Vee speed, and they are not taking the GC into account so you get only an approximation to the ideal Vref. Plus, in gusting winds conditions, the AoA is more stable than the speed.


    Yes, because RPM in a car is a far analogy to AoA in an airplane (not!). Would you like an indicator in the car that tells you how much of the available coefficient of friction you are using? I would.
    In most cars the RPM gauge is not necessary because you can hear the engine and in a standard you can feel it as well. There are clues about the available coefficient of friction from the instant you start to accelerate, brake, or steer depending on how you do it, especially if you know your car. That will all go away when we drive by wire...

  19. #79
    Member
    Join Date
    Jan 2008
    Location
    MA, USA
    Posts
    863

    Default

    Quote Originally Posted by Schwartz View Post
    That will all go away when we drive by wire...
    Especially when "we" are the Whizbang Model 7000b self-drive computer.
    Be alert! America needs more lerts.

    Eric Law

  20. #80
    Member ATLcrew's Avatar
    Join Date
    Sep 2013
    Posts
    894

    Default

    Quote Originally Posted by Evan View Post

    Sully could have used it. Anywhere you have to fly at the limit of lift, such as extending a glide or a low altitude stall and ground avoidance situation. I also agree that it would be useful in building AoA awareness. I'm not opposed to it. Why would anybody be opposed to it?
    I'm not opposed to it. In fact, I'm so not opposed to it that I'm even aware that the 320 series actually has one. It's not marketed as such and is not normally displayed, but it's available for anyone who wants to use it.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •