Originally posted by Myndee
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UPS Cargo Jet Crashes Near Birmingham Shuttlesworth International Airport
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Originally posted by snydersnapshots View PostAnd I understand, through a UPS pilot who knew and has flown with her, that she was a very good pilot.
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Originally posted by snydersnapshots View Post...we use a constant rate, VNAV approach instead of the old "dive and drive" we're all familiar with for non precision approaches...Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.
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Originally posted by Myndee View PostBeing that it was an A300, maybe the tail broke off. Then investigators can blame bad structure and flawed training manuals on the pilot using the rudder pedals!
Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.
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Originally posted by 3WE View PostI was under the impression that the airliner realm is 99.9% constant rate descent- are you aware of anyone doing "dive and drive" step-down methods?The "keep my tail out of trouble" disclaimer: Though I work in the airline industry, anything I post on here is my own speculation or opinion. Nothing I post is to be construed as "official" information from any air carrier or any other entity.
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Originally posted by snydersnapshots View PostAt the company I fly for, we use a constant rate, VNAV approach instead of the old "dive and drive" we're all familiar with for non precision approaches. In this case we would be using the localizer for course guidance and VNAV for vertical guidance. Depending on the specific approach, we may or may not add 50 feet to the MDA (I'd need to look at my Jepp charts to tell you whether we add it here or not). Regardless of whether they used a VNAV or "dive and drive," they were still WAY below the MDA obviously. I don't know if UPS uses the VNAV as we do, or the dive and drive of years past. I'll have to check with a friend who flies for UPS on that issue.
Here's a scenario I could see happening if indeed they use the VNAV technique. This is an area where I believe Boeing and Airbus procedures and interfaces may diverge, so I'm coming at it from the Boeing perspective. Any Airbus guys out there, please jump in.
I could envision a scenario where they were high, so they either put the airplane in VERTICAL SPEED or FLIGHT LEVEL CHANGE mode to get down but didn't go back to VNAV to capture the path. Another possibility is that, because they were so high, the airplane said "I can't do it, you're flying now" and reverted to a V/S or Level Change mode and they didn't pick up on it. Either way, they should have caught the MDA. Perhaps they were both looking out, expecting to be on the path and expecting to see the runway. Again, not condoning what they did, just trying to figure out what led them down the path...
Edit: also, isn't it the job of the monitoring pilot to keep an eye on the MDA and call it?
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Originally posted by snydersnapshots View PostI could envision a scenario where they were high, so they either put the airplane in VERTICAL SPEED or FLIGHT LEVEL CHANGE mode to get down but didn't go back to VNAV to capture the path.
That said, the phenomena of FLCH trap seems similar here. The A306 has (had) both V/S and LVL/CH modes. Since as Gabriel points out...
Originally posted by GabrielApparently, in the last moments, UPS was in a sort of stabilized approach at a constant smooth descent rate and constant 140kts
Stop me if you've heard this one before...
Another possibility is that, because they were so high, the airplane said "I can't do it, you're flying now" and reverted to a V/S or Level Change mode and they didn't pick up on it.
Do operators still allow dive and drive? I thought the industry finally came to its senses about that.
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Originally posted by Evan View PostDo operators still allow dive and drive? I thought the industry finally came to its senses about that.
One might even argue that actually doing the step downs and level offs might have kept the UPS folks much more active and situationally aware where you really would make "every last call out", as opposed to settling down on a nice, gentle straight glidepath, just like the one that brought them safely to the runway a zillion times before.Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.
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Originally posted by snydersnapshots View PostYou may be right--I haven't heard that much about what other carriers are doing in that regard, but you are probably correct that most airlines are doing it. Constant rate does lend itself to a much more stabilized and overall safer approach.
I remember from the days when I was practicing for Instruments rating (never finished it), with the blinder or in the ground trainer device, that whenever I did the calculation and aimed at a constant descent rate I found myself reaching the next crossing altitude before its fix (and hence having to level-off, perhaps just for a few seconds only to start the descent again) or crossing high and either reaching the MAP before the MDA or reaching the MDA too close to the runway which made the landing almost impossible. Of course, I am not such a good instrument pilot.
--- 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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Originally posted by 3WE View PostHey, there's nothing wrong with dive and drive...
Dive and drive is a high workload technique that involves significant power, pitch and trim changes. It depends on excellent CRM. Also, driving at MDA tends to require a nose-high pitch attitude that can create the illusion of being too high at the VDP, often resulting in excessive nose-down pitch and high sink rate descending below the MDA.
Do you still think there's nothing wrong with that?
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Originally posted by Evan View PostIf you fly it perfectly. Guess what most people aren't good at?
Dive and drive is a high workload technique that involves significant power, pitch and trim changes. It depends on excellent CRM. Also, driving at MDA tends to require a nose-high pitch attitude that can create the illusion of being too high at the VDP, often resulting in excessive nose-down pitch and high sink rate descending below the MDA.
Do you still think there's nothing wrong with that?
"Nothing wrong?" Sure, there's plenty wrong- you are zooming through the air at 150 miles per hour using only dials and TV screens to avoid the ground, trees and TV antennas- historically, this sort of thing has occasionally lead to crashes- from all approach types, or even flying along, not on an approach, showing off a new super jet.
But, what about complacency? It's definately easier to have the computer guide you down a nice gentle, homogenous glidepath...but at 5:00 AM if you and your copilot get hit with a simultaneious physiological microsleep moment and just keep going...historically, this sort of thing has occasionally lead to crashes.
Let's contrast that with you and your copilot out demonstrating your finely honed skills focused at the next fix, initiating a descent, initiating a level off, nailing speeds and altitudes (which by the way, airline pilots are incredibly good at!)....hey, I'm awake.Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.
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Originally posted by Evan View PostIf you fly it perfectly. Guess what most people aren't good at?
Dive and drive is a high workload technique that involves significant power, pitch and trim changes. It depends on excellent CRM. Also, driving at MDA tends to require a nose-high pitch attitude that can create the illusion of being too high at the VDP, often resulting in excessive nose-down pitch and high sink rate descending below the MDA.
Do you still think there's nothing wrong with that?
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Originally posted by Evan View PostThat said, the phenomena of FLCH trap seems similar here. The A306 has (had) both V/S and LVL/CH modes. Since as Gabriel points out...
... I would guess LVL/CH over V/S. As with the Boeing logic, you must enter a safe altitude to safely use this mode. If you have a FMS glidepath and the P.DES mode is armed it will transition as it catches that path. If you don't it will level off at the selected altitude. If you want to avoid the level-off and be a cowboy, you set the altitude for something crazy like 0' and it will fly you into the ground at your selected airspeed.
Stop me if you've heard this one before...
Both will keep you descending until you capture the selected altitude or intercept the glide slope (if the APP mode is armed) and then engage ALT HLD or APP and then the AT holds the selected speed.
The only difference is what the pitch mode aims at with the nose (in one case it's an airspeed and in the other a VS).
In both cases, if you select target altitude that is below the ground...
Remember one of the main differences between this accident and Asiana: Here the AP remained connected until impact.
--- 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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Originally posted by Evan View PostI would expect some speed variations with V/S as it gives priority to hold V/S whereas LVL/CH should maintain a constant airspeed with some variations on V/S. Is that not so?
If you are in VS with the AT engaged, there will not be speed variations (unless you are trying to "four one oh' " it or something). If the AT is off or nor available and the pilot is doing its job, the same: no speed variation.
If you set VS and there is no attempt to hold a given speed, then yes the speed will vary until, hopefully, you reach the equilibrium (probably if you set -700fpm and leave the throttles at idle and unattended there will be no equilibrium until you hit the ground in a stall).
In FLCH, if you leave the throttles at one desired setting and don't mess with them (and with the configuration), the AP will establish a steady path at the selected airspeed fairly quickly. Steady means that the VS will be constant and the one needed to keep that speed. In the long term, for example descending from FL 410 to 2500ft, changes in the drag (due to different atmosphere and the Mach number) will make that the VS will be smoothly changing along the descent to keep the IAS (the VS needed to keep 270 KIAS at 35000ft is not the same than at 4000ft).
But anyway, what's your point?
--- 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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