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Gulfstream IV jet ran off a runway while taking off

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  • #31
    For what it's worth... this post on pprune: http://www.pprune.org/biz-jets-ag-fl...ford-ma-3.html indicates the G-IV does have control locks, but they can easily be overpowered by the hydraulically-assisted controls.
    Be alert! America needs more lerts.

    Eric Law

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    • #32
      Originally posted by Gabriel View Post
      That was my thought too. Didn't ask it here because it was a stupid question

      I *think* that these beasts have hydraulic controls.
      And I *think* that these controls tend not to have gust locks because they cannot move due to external forces as long as there is hydro fluid in the actuators.
      Not a stupid question at all Gabriel. It's happened before and I'm sure it will happen again.
      If it 'ain't broken........ Don't try to mend it !

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      • #33
        Originally posted by elaw View Post
        For what it's worth... this post on pprune: http://www.pprune.org/biz-jets-ag-fl...ford-ma-3.html indicates the G-IV does have control locks, but they can easily be overpowered by the hydraulically-assisted controls.
        ...except when they can't? (Unfounded Parlour Speculation: Line person grabbed a near-by 'generic' non-Gulfstream-approved control lock made from sturdy scrap angle iron and old carpet from the pilot's lounge)

        (@ Gabriel- you read my mind on this..."big hydraulic planes don't have control locks" but given the appearance of this crash, I had to ask...and Elroy would appear to have blown that thinking out of the water)
        Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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        • #34
          Originally posted by 3WE View Post
          ...except when they can't? (Unfounded Parlour Speculation: Line person grabbed a near-by 'generic' non-Gulfstream-approved control lock made from sturdy scrap angle iron and old carpet from the pilot's lounge)

          (@ Gabriel- you read my mind on this..."big hydraulic planes don't have control locks" but given the appearance of this crash, I had to ask...and Elroy would appear to have blown that thinking out of the water)
          Even if this wasnt a stupid question, why wouldnt they abort immediately upon detecting a control surface problem on a nice long runway instead of accelerating to 168kts?

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          • #35
            Originally posted by Evan View Post
            Even if this wasnt a stupid question, why wouldnt they abort immediately upon detecting a control surface problem on a nice long runway instead of accelerating to 168kts?
            Wouldn't they have figured out something was wrong when doing the flight controls check pre-takeoff?

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            • #36
              Originally posted by Evan View Post
              Even if this wasnt a stupid question, why wouldnt they abort immediately upon detecting a control surface problem on a nice long runway instead of accelerating to 168kts?
              Actually- the answer to that question is VERY straight forward:

              You train and train and train and train...

              BEFORE V1 you abort...
              AFTER V1 you continue...

              And, what's the normal sequence of events?:

              V1- Decision GO
              Vr- Pull up
              ...and you reach V2 and take flight.

              Except this time:

              V1- Decision GO
              Vr- Crap, the controls are stuck (In fact at this point, you can theoretically be locked in to running off the end!)

              Did I say something about train and train and train and train?

              The decision is/was to GO because a safe abort may not be guaranteed after V1.

              I also see that this is a ~7000 ft runway + the 1000 ft over run that Lefty mentioned...that doesn't have all that much extra to offer if for some reason you find you can't fly after V1.

              The answer to Lefty's question is tougher- although at this point it could be a mechanical failure that happened after the control check and, indeed, nothing to do with a lock.
              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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              • #37
                I guess we need to see what the NTSB says. Clearly they must know what kind of control issue is talked about on the CVR and have some idea.

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                • #38
                  Originally posted by Evan View Post
                  Even if this wasnt a stupid question, why wouldnt they abort immediately upon detecting a control surface problem on a nice long runway instead of accelerating to 168kts?
                  If they only detected after Vr (past V1), the mindset is "commited to take-off", so the pilot probably tried to pull up, when he noticed it was hard tried a bit more force, and then a big pull, and only then he said "ok, we ain't flying".

                  Accelerations of 10kts/second are not unheard of in these planes.
                  In any event, I'd ask what happened with the "locks ==> off, controls ==> free and correct, stall barrier ==> test".

                  --- 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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                  • #39
                    Originally posted by Gabriel View Post
                    controls ==> free and correct
                    How do you do the "correct" part...I don't see the proverbial Cessnatommahawk rear window on a G-4.

                    Any chance of the control actuators having some sort of feeback mechanism that a whole $hit pot of engineers carefully designed to 'never' go into a "reverse operation mode."
                    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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                    • #40
                      Originally posted by Gabriel View Post
                      If they only detected after Vr (past V1), the mindset is "commited to take-off", so the pilot probably tried to pull up, when he noticed it was hard tried a bit more force, and then a big pull, and only then he said "ok, we ain't flying".
                      That's a bit overly dogmatic isn't it? V1 is the critical engine failure decision speed. A control surface response issue does not apply. Please tell me you don't go flying with a control surface issue.

                      But I see I spoke too soon about a nice long runway. I checked the link Leftseat posted and RWY 29 is only 7011'. That's pretty tight for a G-IV considering it requires 9,800' at MTOW (according to the Gulfstream flight planning manual). Even at 11,000lbs lighter it required 6,900'. Add a rolling, derated takeoff to that (one report is saying flaps were at 10) and I guess there really is no time to dilly dally after a failed rotation attempt.

                      Still, how do you get to 168kts in this scenario unless you COMMIT to flying despite the fact that it won't fly and only pull the throttles going into the overrun?

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                      • #41
                        Originally posted by Evan View Post
                        That's a bit overly dogmatic isn't it?
                        Not really.

                        It's mostly about the ability to safely stop without running off the end and not so much about what the exact problem is.

                        While common sense should apply and indeed if you determine that it won't fly and it's after V1, then you abort and hope for a survivable crash.

                        But Gabriel laid it out pretty well that that might have only been a second or two to figure out a problem that they had never ever experienced before and to force them to go against the 'continue' decision they had trained very strongly for.

                        Left Seat said it- on takeoff things happen VERY fast.
                        Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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                        • #42
                          Originally posted by Evan View Post
                          ...V1 is the critical engine failure decision speed...
                          Wrong.

                          I'll concede that you have part of it but consider the fundamental over-riding principle in the bold below:

                          The US Federal Aviation Administration defines it as: V1 means the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance. V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance.
                          Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                          Comment


                          • #43
                            Originally posted by 3WE View Post
                            Wrong.

                            I'll concede that you have part of it but consider the fundamental over-riding principle in the bold below:

                            The US Federal Aviation Administration defines it as: V1 means the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance. V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance.
                            Oh cue the Sweet Monkey River Flight School V1 lecture...

                            V1 is the maximum speed in the takeoff in which the pilot must take the first action ... to stop a flyable aircraft within the takeoff distance (as it patently refers to critical engine failure). Sure, go with a burst tire but if it won't fly, if the thing is on raging fire, a wing has fallen off, or the other engine starts vomiting fan blades V1 no longer applies. You definitely hit the brakes because that's your best chance of survival. If there are pilots out there who do not understand this due to Sweet Monkey River type dogma of "always go after V1" then we have a much larger problem on our hands.

                            If you rotate at 125kts (my best estimate, unless they were tankering) and it doesn't lift off by 145kts, for god's sake abort. Is there no rule of thumb for failure to lift off? I can't understand this 168kts...

                            And nice place to put a ditch btw.

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                            • #44
                              Originally posted by Evan View Post
                              ...If you rotate at 125kts (my best estimate, unless they were tankering) and it doesn't lift off by 145kts, for god's sake abort. Is there no rule of thumb for failure to lift off? I can't understand this 168kts...
                              Yes, these comments are valid and I also struggle with that 168 knot figure.

                              However, I am sitting on my couch with the cursor zooming across the jp input box at 0.168 knots and have had somewhat longer to evaluate the situation and consider options before it hits the end of the box and I have to take action and shift my eyes.
                              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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                              • #45
                                Originally posted by Evan View Post
                                If there are pilots out there who do not understand this due to Sweet Monkey River type dogma of "always go after V1"...
                                Ummmm for the record, I did not say that the correct decision was "always go after V1"

                                I used the word "training" to describe a skill demonstration that is part of almost all recurrent trainings...

                                The simulator zooms down the virtual runway and guess what happens at exactly 1 knot before V1 or happens exactly one knot after V1?

                                I'd like the professionals more accurately confirm what happens but:

                                1) I think it varies somewhat significantly- but it's a major failure of many different sorts.

                                2) I would bet that it's almost never a case of an unflyable plane after V1 where the pilot is graded on how softly he crashes into whatever's beyond the pavement.

                                3) I would bet that the pilots are almost always praised for stopping before V1 OR almost always praised for continuing after V1 and then using the rules of Aviate, Navigate, Communicate and good CRM while properly addressing the emergency using memory items and QRH checklists and making appropriate use of automation while maintaining situational awareness.

                                Below V1 Stop, After V1 Go is the recurrent training.

                                The recurrent training is not "Hey, here's a curve ball, lets see how well you crash"- that's reserved for Starfleet Captain school in the movies.

                                Always continue is not the training at Sweet Monkey River Flight School Del Norte. It is the training at almost always practiced in the simulator all airlines, and multi-engine simulator schools. I am in possession of some suggested non-traditional training scenarios from some aviation forum know-it-all that he thinks will become part of a flight school curriculum, but he's mostly just a parlour talking ass hat.
                                Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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