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Cargo airplane collapsed in Kyrgyzstan

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  • #76
    Originally posted by Gabriel View Post
    13 days off every month. That's too few? (plus 3 weeks vacations)
    Yes.

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    • #77
      Originally posted by ATLcrew View Post
      Yes.
      Aside from being paid to operate an aircraft, the 'days off' have always seemed an attractive aspect to this outsider...but then again, you lose quite a few of them commuting and hanging out in luxurious crash pads...so I read...
      Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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      • #78
        Originally posted by 3WE View Post
        Aside from being paid to operate an aircraft, the 'days off' have always seemed an attractive aspect to this outsider...but then again, you lose quite a few of them commuting and hanging out in luxurious crash pads...so I read...
        Also yes.

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        • #79
          Originally posted by 3WE View Post
          Aside from being paid to operate an aircraft, the 'days off' have always seemed an attractive aspect to this outsider...but then again, you lose quite a few of them commuting and hanging out in luxurious crash pads...so I read...
          Unlike ATL, Atlas although not the best, buys you a hotel at every overnight, we have gateway basing so no crash pads, buys you a ticket to and from your gateway, business class tickets on all international flights, and we are catered on every flight.

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          • #80
            Originally posted by BoeingBobby View Post
            Unlike ATL, Atlas although not the best, buys you a hotel at every overnight, we have gateway basing so no crash pads, buys you a ticket to and from your gateway, business class tickets on all international flights, and we are catered on every flight.
            I wasn't aware there were still airlines who DIDN'T pay for hotels on overnights. Apart from an occasional late-running van, I've had almost no issues at all with our hotels. If anything, some of them are, in my opinion, a little too nice.

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            • #81
              Originally posted by BoeingBobby View Post
              Unlike ATL, Atlas although not the best, buys you a hotel at every overnight, we have gateway basing so no crash pads, buys you a ticket to and from your gateway, business class tickets on all international flights, and we are catered on every flight.
              BB, Can you tell us what happens on the 744 if the vertical mode goes to GS CAP and then loses the glideslope signal? Does it then transition to V/S by default? This flight transitioned to ALT HOLD when it reached 3400 with no glideslope capture, then flew level until it traversed the mirror glideslope at 9°, which activated GS CAP but of course it flew right through that. Yet it descended on autopilot. Why does it not remain in ALT HOLD in that scenario?

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              • #82
                Originally posted by ATLcrew View Post
                I wasn't aware there were still airlines who DIDN'T pay for hotels on overnights. Apart from an occasional late-running van, I've had almost no issues at all with our hotels. If anything, some of them are, in my opinion, a little too nice.
                I meant at base, not out on a trip.

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                • #83
                  Originally posted by Evan View Post
                  BB, Can you tell us what happens on the 744 if the vertical mode goes to GS CAP and then loses the glideslope signal? Does it then transition to V/S by default? This flight transitioned to ALT HOLD when it reached 3400 with no glideslope capture, then flew level until it traversed the mirror glideslope at 9°, which activated GS CAP but of course it flew right through that. Yet it descended on autopilot. Why does it not remain in ALT HOLD in that scenario?
                  That is a damn good question Evan. However I do not honestly know the answer. I fly 10 Red Bull aircraft with the wings off in the cargo compartment from Hahn Germany to Los Angles tomorrow. I will see if any of the other crew has the answer and let you know.

                  Comment


                  • #84
                    Originally posted by Evan View Post
                    BB, Can you tell us what happens on the 744 if the vertical mode goes to GS CAP and then loses the glideslope signal? Does it then transition to V/S by default? This flight transitioned to ALT HOLD when it reached 3400 with no glideslope capture, then flew level until it traversed the mirror glideslope at 9°, which activated GS CAP but of course it flew right through that. Yet it descended on autopilot. Why does it not remain in ALT HOLD in that scenario?
                    Holy crap! I don't have a clue what you said.

                    I take comfort in two things...a. 1. A 49 year, 40,000 hour veteran does not know the answer either and 2. I do know that NONE of that excuses the need to monitor the instruments and reconcile things to the approach plate...

                    If they have to know all that crap, no wonder they forget the basics occasionally.
                    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                    Comment


                    • #85
                      Originally posted by 3WE View Post
                      Holy crap! I don't have a clue what you said.

                      I take comfort in two things...a. 1. A 49 year, 40,000 hour veteran does not know the answer either and 2. I do know that NONE of that excuses the need to monitor the instruments and reconcile things to the approach plate...

                      If they have to know all that crap, no wonder they forget the basics occasionally.
                      Put simply, It appears that in this case they were above and beyond the glideslope, so after leveling off at 3400' and 'hunting', the autopilot found the false glideslope signal instead, causing the mode to become GS CAP (glideslope capture). GS CAP is supposed to then transition to GS and ride the ILS down, but that's not going to happen with a 9° false glideslope, so instead it appears to have flown through the false glideslope, whereupon GS CAP changed to... WHAT? The a/c flew a nice 3° glidepath angle down to DH, I'm guessing in V/S mode but maybe not. But why, if the glideslope is lost (or full downward deflection is beyond the autopilot capabilities) does it not do the safe thing and revert to ALT HOLD again? If it had, this accident wouldn't have occurred.

                      Or maybe that final 3° glidepath was manually commanded by the crew...

                      Yes, it's no excuse for not piloting, but it should provide a defense against not piloting.
                      Attached Files

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                      • #86
                        Evan, note the the glideslope signal was not lost in this case.

                        If the glide slope signal was lost, I would expect the AP to default to VS hold (and the VS flag to show up). That would be sort of "fail passive" (but with the AP still engaged). The alternative would be to disconnect the AP with the plane left in trim (that would be truly fail passive), but this seems more dangerous and unnecessary. Defaulting to ALT HLD is in my opinion even more dangerous. The AP would be not only making significant pitch inputs to transition from the descent to level flight (a disconnect at this moment could leave the plane out of trim), but also the AT may be disconnected which risks a stall if the pilot doesn't apply throttle in time.

                        However, in this case what happened is that the GS needle was low (indicating the plane was above the glideslope), then (when they crossed the false 9 deg glide slope) the needle became alive, probably deflected up for a moment, then started to move down (as the plane approached the false glide slope from below), then approached the center (and the AP changed from ALT HLD to APP) and then keep moving down and deflected fully down again (as the plane was now above both the real and the false glide slope).

                        The following applies for the MD-80 AP, but I guess that all or most APs have something similar (even if only internally, transparent to the pilot). When the AP goes to APP it can be in 2 different status in the FMA (Flight Mode Annunciator): GS CAP and GS TRK. GS CAP (CAP for Capture) is a mode where the AP will try to capture the GS, that is, to maneuver the plane towards the GS deflection, and it happens in the beginning when the AP transitions to APP and at any time where the GS goes anywhere off center by more than a hair. GS TRK (TRK for Track) is the status where the GS is centered (or barely off center) and the APP is basically keeping it centered. I am not sure what is the difference between the 2 in practical terms, but I guess that GS CAP is a bit more aggressive with the interception.

                        My guess is that in this case the AP transitioned from ALT HLD to APP and remained in APP (in GS CAP) until the GA was initiated. If I am correct, we should see that the approach was not really parallel to the stipulated one, but slightly steeper (although nowhere close to the 9 deg).

                        --- 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


                        • #87
                          Originally posted by Gabriel View Post
                          Evan, note the the glideslope signal was not lost in this case.

                          If the glide slope signal was lost, I would expect the AP to default to VS hold (and the VS flag to show up). That would be sort of "fail passive" (but with the AP still engaged). The alternative would be to disconnect the AP with the plane left in trim (that would be truly fail passive), but this seems more dangerous and unnecessary. Defaulting to ALT HLD is in my opinion even more dangerous. The AP would be not only making significant pitch inputs to transition from the descent to level flight (a disconnect at this moment could leave the plane out of trim), but also the AT may be disconnected which risks a stall if the pilot doesn't apply throttle in time.

                          However, in this case what happened is that the GS needle was low (indicating the plane was above the glideslope), then (when they crossed the false 9 deg glide slope) the needle became alive, probably deflected up for a moment, then started to move down (as the plane approached the false glide slope from below), then approached the center (and the AP changed from ALT HLD to APP) and then keep moving down and deflected fully down again (as the plane was now above both the real and the false glide slope).

                          The following applies for the MD-80 AP, but I guess that all or most APs have something similar (even if only internally, transparent to the pilot). When the AP goes to APP it can be in 2 different status in the FMA (Flight Mode Annunciator): GS CAP and GS TRK. GS CAP (CAP for Capture) is a mode where the AP will try to capture the GS, that is, to maneuver the plane towards the GS deflection, and it happens in the beginning when the AP transitions to APP and at any time where the GS goes anywhere off center by more than a hair. GS TRK (TRK for Track) is the status where the GS is centered (or barely off center) and the APP is basically keeping it centered. I am not sure what is the difference between the 2 in practical terms, but I guess that GS CAP is a bit more aggressive with the interception.

                          My guess is that in this case the AP transitioned from ALT HLD to APP and remained in APP (in GS CAP) until the GA was initiated. If I am correct, we should see that the approach was not really parallel to the stipulated one, but slightly steeper (although nowhere close to the 9 deg).
                          Well, the thing is, the autopilot never transitioned to G/S mode, yet it flew a steady 3° FPA, parallel to the actual G/S, down to DH. I'd like to know exactly how it did that.

                          The AP was certainly in APP mode, LOC in lateral mode, when it passed through the false glideslope. That caused it to transition to G/S CAP for about one second (and the Russian plot I attached above suggests it did briefly try to align with the steep 9° convergence of the two G/S signals, but by then it was not possible to maintain the false glideslope and the PFD went to full downward deflection again. Immediately thereafter, the a/c entered a steady 3° descent. Was this selected guidance by the crew or a default mode transition (I doubt it was hand-flown), and if so, what was the mode in descent?

                          I don't see how reverting from a failed glideslope capture back to ALT mode would be particularly dangerous, as it would be the same as pressing ALT HOLD at that moment.

                          The G/S issue is simple, and when I say "lost the glideslope", I mean lost the convergence of the two signals that creates it. Attempting to catch the G/S from above, they would have been in the predominance of the 90 HZ signal (full downward deflection) until encountering the false 150 HZ signal (causing the upwards deflection and momentarilly triggering G/S CAP). But a moment later they would be back in the predominannce of the 90HZ signal (back to full downward deflection) and thus no transition to G/S mode. **

                          I'm sure the reason BoeingBobby can't answer this off the top of his head is because this is not supposed to happen (the plane is not designed to capture a 9° glideslope) and the autopilot behavior in this scenario (G/S CAP followed by a failure to capture) is almost certainly not documented or instructed.

                          Anyway, hoping he can shed some light on this part of the mystery...

                          **EDIT - some G/S systems reverse the phase of these side lobe signals at the 9° angle, but the Russian reports and plot seem to indicate that this was not the case. Need to learn more about that...

                          Comment


                          • #88
                            Originally posted by BoeingBobby View Post
                            That is a damn good question Evan. However I do not honestly know the answer. I fly 10 Red Bull aircraft with the wings off in the cargo compartment from Hahn Germany to Los Angles tomorrow. I will see if any of the other crew has the answer and let you know.
                            One thing I've discovered is that—apparently—on G/S CAP, the FMS commands a -.5G pitch manuever to establish the desired 3° glidepath. If the automation does not then transition to G/S, perhaps it just remains on that path... in V/S? or...?

                            Comment


                            • #89
                              Originally posted by Evan View Post
                              ...it's no excuse for not piloting, but it should provide a defense against not piloting...
                              The magenta line needs to start working vertically, and be combined with synthetic vision and maybe a good speed control and stall avoidance... cue the app joke which really means it wouldn't be too hard.
                              Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

                              Comment


                              • #90
                                Originally posted by Evan View Post
                                **EDIT - some G/S systems reverse the phase of these side lobe signals at the 9° angle, but the Russian reports and plot seem to indicate that this was not the case. Need to learn more about that...
                                Due to the nature of the lobes and their reflections, there are different slopes where the 90 hz signal has the same amplitude than the 150 hz signal.

                                The 1stt one (the original one, the "real" one) is usually at about 3 deg slope.

                                The remaining ones happen and multiples of the original one: the 2nd at 6 deg, the 3rd at 9 deg, the 4th at 12 deg, and so on.

                                The odd ones (1st, 3rd...) are "upside up", i.e. the 90 hz signal is stronger than the 150 hz signal above the slope (and vice versa), and the ILS instrument reacts normally (the needle goes down when the plane is above the slope and vice versa).

                                The even ones (2nd, 4th...) are "upside down" (inverted), with the 150 hz being dominant above the slope, so the indication in the plane is reversed.

                                This 747 intercepted the 3rd slope (9 deg), which is NOT inverted.

                                --- 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

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