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  • #16
    Originally posted by Evan View Post
    Why doesn't the GWPS drop the gear automatically at the alert level (provided there is a guarded override switch)? Or would this breed further complacency?
    Because the gear in transit (either up or down) may degrade go-around performance.

    Comment


    • #17
      Evan, because basically it is a flight control, and isn't always deployed at the same point. And even if it was... what is the difference between saying "Gear Down", or

      "Gear Down Checklist"... then the other pilot going "Gear Down Checklist - Gear Lever - Down... Gear Down Checklist Complete".

      You can miss either one just as much as the other.

      The point is there is a checklist that needs to be completed prior to landing, the landing checklist... and it has on it all the items that are required. There IS a strict checklist requirement, and it must be completed prior to landing. In this case, the checklist needs to have been completed by 500ft... they were well above that when they went around.

      Aviation happens too fast, and things need to be done in different timeframes, to do EVERYTHING from a "to do list"... which is of course different from non-normal checklists which are done as "to do" lists.

      If you read the ATSB initial comments it looks like they didn't need GPWS to "have their back"... they'd already started going around.

      As to an automatic gear drop? Probably the worst thing you could have. The GPWS is designed to stop you hitting terrain, and you need the best performance the aircraft can give you, which is with the wheels safely tucked up inside the jet. The "Too Low Gear" is a very small subset of the GPWS, and in certain situations may actually preceed a full blown Terrain warning, when gear down would hinder rather than help.

      Also, of what benefit is dropping the gear? If a "Too Low Gear" warning sounds, then the crew should go around... as it is possible the gear isn't the only thing in the incorrect position.

      Comment


      • #18
        Evan,

        Checklists have been mandatory for very long. And they have to read it, not to make it by heart.

        What I meant is that, there was a time when checklists were used as to-do list. That is, one pilot calls each item and the other one DOES IT and confirm it. For example:

        NFP: "Spoilers"
        FP: (arms the spoilers and then says) "Armed"
        NFP: (if the correct status for "spoilers" is "armed" he moves to the next line)

        The current practice (I think some airlines still use the old one, but I'm not sure) is to do the things BEFORE the checklist. By when you get to the point where you do the checklist it is expected that all items on it are already done. Then one pilot calls each item and the other pilot just CONFIRMS that the item is already in the status. For example:

        FP: Arms the spoilers (at an earlier time, before the checklist)

        During the checklist:
        NFP: "Spoilers"
        FP: (verifies the status of the spoilers and then says) "Armed"
        NFP: (if the correct status for "spoilers" is "armed" he moves to the next line)

        In this second case, any event where the status of the item is not what it's supposed to be is an "Oops!". It's too late already to fix it. I mean, may be they do fix it (for example, they arm the spoilers), but the mistake is already done.

        Written checklists are much safer than memory cehcklists and let alone than no checklist. But they are not fail-safe. Several things can go wrong:

        They can fail to do the checklist (either intentionally or because they forget in the rush of the situation)
        They can skip a line (not so uncommon)
        They can do it by inertia and call an item's status just what it's supposed to be, or what "I remember I did", instead of actually checking it status.
        They can, for some reason or another (including mistake), undo an item AFTER the checklist.

        The advantage of the current practice of first do then check is clear. If pilots act professionally doing all items correctly most of the times and then doing the checklist correctly most of the times, the probability to fail on both instances are orders of magnitude lower than if you use the checklist as a to-do list (where one single mistake leaves an item undone).

        For example, say that 95% of the times you don't forget to lower the gear before the checklist and that 95% of the times you effectively do the checklist (yo do it AND don't miss the "landing gear" item AND you do it consciously checking its actual status): You will make one mistake (wither one or the other) in 1 out of 10 flights. You'll make both in 1 out of 500 flights (there the GPWS will save you).

        With the old practice, if you only lower the landing gear when the checklist is effectively done, the GPWS will have to save you in 1 out of 20 flights, or about 20 times more often.

        --- 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 ---

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        • #19
          I hear what you are saying but...

          Originally posted by Gabriel View Post
          They can do it by inertia and call an item's status just what it's supposed to be, or what "I remember I did", instead of actually checking it status.
          So, actually checking its status by moving the eyeballs from the checklist to the three green lights on the panel is how difficult exactly...? I think "inertia" is putting it too kindly. The indication couldn't be designed more clearly.

          But by then, in the case of do-it-first, check-it-later, if you get to the item and find that you didn't do it, you have to go-around, effectively freaking out the passengers and stressing out the traffic controllers, whereas if you do the checklist as a to-do checklist earlier on, you avoid this scenario (and there is no way, if a PNF calls out a checklist action, that the PF is going to fail to do it and then immediately confirm that he has done it; that would be definitively psychotic), and if you can manage to skip even one item on a relatively short checklist like that, you should probably have a job drilling holes in sheet metal instead.

          Overshooting airports, falling asleep on the job, landing on taxiways, forgetting to extend landing gear despite having a checklist you really shouldn't even need to have...

          Are truly qualified pilots in such short supply? Are they not properly screened for basic attentative skills? Or are pilots simply over-extended to the point that they behave psychotically? This seems epidemic lately.

          One day, when I drive into my garage door because I forgot to open it, I will begin to understand, but despite having worked a lot of long hours and ridiculous schedules that definitely exceed what I am hearing from pilots, and not having had a co-pilot or checklist to back me up, or a hundred souls in my backseat to worry about, this has never happened.

          Comment


          • #20
            Originally posted by Evan View Post
            One day, when I drive into my garage door because I forgot to open it, I will begin to understand,.
            Not a good analogy unless your garage door is made from something invisible. A better analogy would be have you ever attempted to drive away in your car without releasing the handbrake fully? There's an indicator showing a big red light on my instrument cluster (analogous to the three indicator lights on a control panel) and the handbrake lever is higher than it should be (similar to the gear gown switches being in the wrong position I'd guess) - but I know I've done it. Unless I feel a significant drag or if its only very lightly engaged see the light on the dash I wouldn't know.

            Comment


            • #21
              If they have indicators to read, then confirming the correct orientation of affected parts should be done? Waiting till a goaround is necessary seems too late.

              Flip side. All passengers made it. Not a shining example of aviation, but a safe one.

              Comment


              • #22
                That Airline should think about hiring me, because I've never left the gear up playing Flight Simulator in my room.........Today.........

                Comment


                • #23
                  Originally posted by Evan View Post
                  So, actually checking its status by moving the eyeballs from the checklist to the three green lights on the panel is how difficult exactly...?
                  Have you ever heard of monotnous tasks? It's a real problem in every industry and aviation is no exception. After 1000 times that you've heard the PNF challange "Gear?" and you replied "Three green", the "three green" answer comes almost like an instint. It takes an effort to actually make sure that the three lights are indeed green.

                  Of course pilots are paid to do that effort and they do it right the vast majority of the times, but they are humans you know? Everybody is vulnerable, some vulnerable than others, and the fact that something never happened to someone doesn't mean that he/she is not vulnerbale.

                  Say for example that a certain msitake happens once every 100,000 flights on average (that is that they make it right 99.999% of the times). Most pilots will never see it happen because nobody ever made 100,000 flights, but on the other hand with millions of flights per year you'll have several pilots per year making that very msitake. That's the nature of statistics: the probability that a given player will win the lottery in his whole life are nearly zero, the probablity that someone will win the lottery is 100%.

                  To make thing worse, yes, not everybody is equally skilled, attentive, commited to do the job right, etc. Now how on Earth do you screen the ones making the mistake ON AVERAGE once every 10,000 flights from those making it once every 100,000 flights?

                  But by then, in the case of do-it-first, check-it-later, if you get to the item and find that you didn't do it, you have to go-around, effectively freaking out the passengers and stressing out the traffic controllers, whereas if you do the checklist as a to-do checklist earlier on, you avoid this scenario (and there is no way, if a PNF calls out a checklist action, that the PF is going to fail to do it and then immediately confirm that he has done it)
                  Yes, that's the good thing of the to-do list. That's why the best practice in the do-first, check-later case is to visually and manually confirm the status of an item (where appliable).

                  And, I'm quite sure that in most cases a missing action later detected in the checklist doesn't lead to a go around, rather to an "oops", correction, embarrasment and your partner making a bit of fun of you, and porbably NOBODY else will EVER know of the mistake. I'm quite usre that if this very crew in this very flight had detected that they left the gear up during the checklist at an altitude above 1000ft they would have just lowered the gear and landed.

                  I'm sorry to inform you this, but in many (may be most) flights there are one or two mistakes done by the pilots. Most of them are not critical (like not listening an ATC call in the first attempt). As potential criticity increase the number of redundant layers also increases (like the landing gear, you have to set it, to check it, there is a gear-up horn and then the GPWS, but still airplanes have landed with the gear forgotten up a few times).

                  Are truly qualified pilots in such short supply?
                  Again I'm sorry to inform you this, but trully qualified piltos are still humans and make mistakes like every human (maybe just not as frequently).

                  The KLM captain at Tenerife was the best KLM pilot, to name just one example.

                  And again, there is a "pilot's quality" distribution. Some of the pilots of your airline will necesarily be the worst pilots of your airline (again, this applies to everything).

                  --- 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 ---

                  Comment


                  • #24
                    Originally posted by Gabriel View Post
                    Have you ever heard of monotnous tasks? It's a real problem in every industry and aviation is no exception. After 1000 times that you've heard the PNF challange "Gear?" and you replied "Three green", the "three green" answer comes almost like an instint. It takes an effort to actually make sure that the three lights are indeed green.
                    I don't know, Gabriel... I think the instinct you want to develop is to glance at the indicators when the challenge is read out. Instinctively. Answering a checklist item in the affirmative without first checking its status is a very bad instinct for a pilot, and I can't believe a qualified pilot would develop that instinct.

                    I also don't follow the effort part. It really doesn't take any effort to glance down at the panel, or the very least amount of effort possible. If a pilot can't expend that kind of minimal effort, why in the hell is he in a cockpit to begin with?

                    I think the checklist was never performed or the item was skipped over.

                    Comment


                    • #25
                      Originally posted by Evan View Post
                      I also don't follow the effort part. It really doesn't take any effort to glance down at the panel, or the very least amount of effort possible. If a pilot can't expend that kind of minimal effort, why in the hell is he in a cockpit to begin with?
                      I didn't mean this type of effort, but the psicologycal effort to beat the monotomy. Have you ever played "Simon Says"? It doesn't take any effort to verify if Simon said "Simon says" before executing the commanded action. Yet, everybody eventually is eliminated (including airline captains).

                      I think the checklist was never performed or the item was skipped over.
                      Maybe, or maybe the checklist was being performed, the item was called, the gear was detected not "three greens", and the go-around was initiated.

                      As a said note, I talked once with one high level instructor and he told me that he taught the NFPs, when the FP called "Gear down please", to lower the landing gear and confirm the action adding the following all in one sentence: "Gear down landing checklist standby"

                      He explained me that "It's the best way not to forget to do the landing checklist".

                      I ojected: "Yes, or to ensure that if you forget to lower the gear you also forget to do the landing checklist"

                      --- 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 ---

                      Comment


                      • #26
                        Evan,

                        You say again that it takes no effort, and blame pilots for not putting in enough effort or not taking their job seriously.

                        They do.

                        We have experts in human factors who study WHY these simple things appear to get missed, and we do everything we can to prevent it... but its not as simple as you seem to think.

                        Human nature is a VERY complex thing, and if you are doing the same thing over and over again, its nature to occasionally miss them unless you have a very robust defence... which in most cases is having two pilots, checklists, procedures... however every now and again the system breaks down. The investigation into this accident will hopefully show why.

                        Comment


                        • #27
                          I would add too Evan's points that these checks are core parts of doing a pilot's job. Are we then saying it is only "human" not to do your job?

                          Comment


                          • #28
                            Originally posted by EconomyClass View Post
                            I would add too Evan's points that these checks are core parts of doing a pilot's job. Are we then saying it is only "human" not to do your job?
                            Yes. Have you never made a mistake?

                            I don't understand why pilots are being held here to a higher standard than other people with jobs that may place many lives at risk. Go back through history - humans have been making errors since day one. It is impossible to eliminate human error. That's why we try and design systems for humans to work within to minimise the risks of the same error reccurring. One such thing airlines have in place is the checklist - implemented after the Boeing test pilot (yep, not some disinterested hack - a test pilot - threrefore assumedly a damned good pilot), didn't check something when he took off in one of the prototype B-17's and stacked it because he forgot to do something prior to takeoff. (see at end of this post).

                            My wife is an Operating Theatre Nurse - she has to check off on a list all of the instruments and swabs used are all returned before a surgeon can close a patient. Yet all round the world there are still medical instruments left inside patients. Is it because all surgeons are stupid? Is it because they do it deliberately? No, its because they are human and DESPITE the systems put in place to ensure a problem doesn't occur, occassionally it will. Humans are in the loop. Humans are falible.

                            Do you have a checklist of items to check prior to driving off in your car? Are your windows all spotlessly clean? Do you check tyre pressures each and every time before setting off? I know my car's manual recommends that tyre pressures are checked weekly - I'd doubt that 99% of drivers do it. If you don't check tyre pressures on a weekly basis (with a guage) why not? You are placing your own and other people's lives at risk every time you drive on the roads. Machinery is not infalible, nor are people. There is some bizzare statistic that only a third of the cars on the road have their tyres inflated to their correct pressure - maybe if checklists were implemented for cars the road toll would be much lower. BUT it doesn't sell newspapers that a driver had a dangerously underinflated tyre that could have caused a multivehicular accident that may have resulted in tens of deaths, instead an incident that was averted BEFORE the built in safety systems cut in has been discussed as though the pilot had a death wish for himself and everybody else on the aircraft. I don't get it.



                            From the New Yorker, Dec 10, 2007. Article titled " The Checklist" by Atul Gawande.

                            On October 30, 1935, at Wright Air Field in Dayton, Ohio, the U.S. Army Air Corps held a flight competition for airplane manufacturers vying to build its next-generation long-range bomber. It wasn’t supposed to be much of a competition. In early evaluations, the Boeing Corporation’s gleaming aluminum-alloy Model 299 had trounced the designs of Martin and Douglas. Boeing’s plane could carry five times as many bombs as the Army had requested; it could fly faster than previous bombers, and almost twice as far. A Seattle newspaperman who had glimpsed the plane called it the “flying fortress,” and the name stuck. The flight “competition,” according to the military historian Phillip Meilinger, was regarded as a mere formality. The Army planned to order at least sixty-five of the aircraft.
                            A small crowd of Army brass and manufacturing executives watched as the Model 299 test plane taxied onto the runway. It was sleek and impressive, with a hundred-and-three-foot wingspan and four engines jutting out from the wings, rather than the usual two. The plane roared down the tarmac, lifted off smoothly, and climbed sharply to three hundred feet. Then it stalled, turned on one wing, and crashed in a fiery explosion. Two of the five crew members died, including the pilot, Major Ployer P. Hill.
                            An investigation revealed that nothing mechanical had gone wrong. The crash had been due to “pilot error,” the report said. Substantially more complex than previous aircraft, the new plane required the pilot to attend to the four engines, a retractable landing gear, new wing flaps, electric trim tabs that needed adjustment to maintain control at different airspeeds, and constant-speed propellers whose pitch had to be regulated with hydraulic controls, among other features. While doing all this, Hill had forgotten to release a new locking mechanism on the elevator and rudder controls. The Boeing model was deemed, as a newspaper put it, “too much airplane for one man to fly.” The Army Air Corps declared Douglas’s smaller design the winner. Boeing nearly went bankrupt.
                            Still, the Army purchased a few aircraft from Boeing as test planes, and some insiders remained convinced that the aircraft was flyable. So a group of test pilots got together and considered what to do.
                            They could have required Model 299 pilots to undergo more training. But it was hard to imagine having more experience and expertise than Major Hill, who had been the U.S. Army Air Corps’ chief of flight testing. Instead, they came up with an ingeniously simple approach: they created a pilot’s checklist, with step-by-step checks for takeoff, flight, landing, and taxiing. Its mere existence indicated how far aeronautics had advanced. In the early years of flight, getting an aircraft into the air might have been nerve-racking, but it was hardly complex. Using a checklist for takeoff would no more have occurred to a pilot than to a driver backing a car out of the garage. But this new plane was too complicated to be left to the memory of any pilot, however expert.
                            With the checklist in hand, the pilots went on to fly the Model 299 a total of 1.8 million miles without one accident. The Army ultimately ordered almost thirteen thousand of the aircraft, which it dubbed the B-17. And, because flying the behemoth was now possible, the Army gained a decisive air advantage in the Second World War which enabled its devastating bombing campaign across Nazi Germany.

                            Comment


                            • #29
                              Originally posted by MCM View Post
                              Human nature is a VERY complex thing, and if you are doing the same thing over and over again, its nature to occasionally miss them unless you have a very robust defence... which in most cases is having two pilots, checklists, procedures... however every now and again the system breaks down. The investigation into this accident will hopefully show why.
                              Which accident?

                              The system DID work, there was NO breakdown, and there was NO accident, not even a closs call. Yes, at least the first level of the system failed, but the other levels (those that are in place for when the first levels fail) didn't.

                              Yet the investigation will shed some light about how many levels failed, how and why.

                              --- 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 ---

                              Comment


                              • #30
                                How dare pilots forget:

                                -To use the taxi diagram and confirm runway heading.

                                -To check the altimiter on a clear everglades night.

                                -To check the altimiter versus their position versus the approach plate (in how many reapeated crashes- including airiners).

                                -To check the OTHER power instruments and firewall the throttles when the plane just doesn't seem to be accelerating or climbing like it should.

                                -To turn on engine anti-ice during a snowstorm.

                                -To check the cabin pressure gauges.

                                -To set the flaps for takeoff.

                                -Please list more.

                                Humans may not apply.

                                Idiot pilots.
                                Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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