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That's insane. I don't know how the guy in the car kept so calm after seeing what just happened.
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Apr 30, 2013 18:53
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I'm thinking that could be it. The dramatic pitch up isn't something a pilot would do in a stall recovery. The gear being down is also peculiar because if the pilots established positive rate of climb, the gear would've been tracking up or already been up. This is likely a problem that occurred right at rotation so ya maybe a drastic change in the CG by cargo shifting.
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Apr 30, 2013 19:00
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 Holy hell, that was just terrifying.
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Apr 30, 2013 19:07
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Apparently the plane was owned by the U.S. firm National Air Cargo out of Michigan, working under contract for the U.S. Mobility Command.
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Apr 30, 2013 19:26
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You could make a beat out of that GSM interference.
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Apr 30, 2013 19:43
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holocaust bloopers posted:I'm thinking that could be it. The dramatic pitch up isn't something a pilot would do in a stall recovery. The gear being down is also peculiar because if the pilots established positive rate of climb, the gear would've been tracking up or already been up. This is likely a problem that occurred right at rotation so ya maybe a drastic change in the CG by cargo shifting. There are still people out there who think a large commercial transport won't drop a wing, see what happens when you put in some rudder. Every loadmaster needs to see this movie... RIP to all on board.
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Apr 30, 2013 19:50
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Tsuru posted:This is actually the only possible way a 747 can come to a standstill in mid-air in a low energy state like this, barring maybe a stab trim runaway. You can see the latter is clearly not the case. With flaps 20, a rearward shift of CG of about 12 feet will do exactly this. Pilots reported that they were in a stall and that there was load shifting so ya. Most likely culprit. loving shame. Poor guys.
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Apr 30, 2013 20:02
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CharlesM posted:You could make a beat out of that GSM interference. Did anyone else notice the dog in the cab, too? That was odd.
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Apr 30, 2013 20:06
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just saw this and drat...what a thing to witness
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May 1, 2013 00:15
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onezero posted:Did anyone else notice the dog in the cab, too? That was odd. I'm guessing he's a security force of some kind, with a K9 bomb dog or something. I honestly have nightmares where I see a plane crash, it feels horrible and I'm helpless. edit: holocaust bloopers posted:Pilots reported that they were in a stall and that there was load shifting so ya. Most likely culprit. loving shame. Poor guys. I'm surprised they had time to get out a radio call. Yikes. Kia Soul Enthusias fucked around with this message at 00:48 on May 1, 2013 |
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May 1, 2013 00:46
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CharlesM posted:I'm surprised they had time to get out a radio call. Yikes. The crash wasn't as fast as it looks, and their mic switch is on their yokes, which I'm sure they were gripping hard. I'm pretty sure they were aware of what was about to happen as the stall happened....
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May 1, 2013 01:52
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Yea once that jet over-rotated, they probably had a good idea that it wasn't recoverable. First thing I would've done was check for a runaway stab emergency.
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May 1, 2013 01:55
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holocaust bloopers posted:First thing I would've done was check for a runaway stab emergency. Depends on what they picked up on the cockpit flight recorder mics, but I'm betting they could hear the shifting cargo, it was probably pretty loud or could feel it through the rudder pedals... If it was the stab, they can just glance down at the stab position gauge and tell if its locked hard. http://www.meriweather.com/flightdeck/747/ped/stab.html CommieGIR fucked around with this message at 02:03 on May 1, 2013 |
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May 1, 2013 02:00
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Well the runaway stab can be tricky. You really got identify it quickly to engage the stab brake lest you're stuck in a 6000fpm vertical velocity. Then you gotta determine if it's a pitch up or pitch down. It's a lot to grasp in a matter of a few seconds. The first time I wrecked in the sim was because of a runaway stab.
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May 1, 2013 02:07
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Rumormill, but I have a few pilot contacts through various social media. Supposedly it was 5 MRAPs secured with 11 straps each, which is apparently the minimum. This is all totally unverified rumor.
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May 1, 2013 02:12
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Hope this was a freak accident instead of an error on the loadmaster's part.
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May 1, 2013 02:14
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holocaust bloopers posted:Well the runaway stab can be tricky. You really got identify it quickly to engage the stab brake lest you're stuck in a 6000fpm vertical velocity. Then you gotta determine if it's a pitch up or pitch down. It's a lot to grasp in a matter of a few seconds. What exactly is a runaway stab?
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May 1, 2013 03:10
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Nostalgia4Infinity posted:What exactly is a runaway stab? As the name implies--it's the stab trim operating without pilot input. So like in a flight sim, you know how you dial in a unit or two of trim to keep level flight? Well imagine that wheel spinning wildly in one direction until it hits the hard stop. The fix to this is to catch it, and stop it by applying the stab brake, and then running it manually. If the trim is stuck and not operating, you can coerce a desired pitch attitude by doing split spoilers, flaps, or manipulating fuel burn to change the CG forward or aft. Hope this helps.
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May 1, 2013 03:14
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It does thank you.
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May 1, 2013 03:16
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In smaller aircraft, runaway trim can be solved pulling the associated circuit breaker, or just pushing really really really REALLY hard on the stick/yolk.
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May 1, 2013 04:00
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Is runaway stab trim something that happens a lot? I mean, it seems from the description that it'd be up there with "wings decide to fall off" in terms of frequency.
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May 1, 2013 04:52
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ctishman posted:Is runaway stab trim something that happens a lot? I mean, it seems from the description that it'd be up there with "wings decide to fall off" in terms of frequency. From the statistics available within the US, it appears to be very rare. A search of the NTSB's database only turns up 11 incidents for the phrase "runaway trim", and only a few of those were actual runaway trims (the rest were things like broken trim cables). Of those 11 incidents, only one involved an airline, which was operating a Beech 1900 turboprop. Of the four fatal accidents in the set, one was caused by the airplane being improperly loaded, one involved a pilot impaired by drugs, one was the pilot being distracted and flying into the ground, and the last was caused by improper maintenance resulting in the elevator trim operating backwards. There were three incidents that actually involved runaway trims (two piston powered aircraft, one Cessna Citation), and none of them resulted in any fatalities, since most aircraft can be kept under some level of control through use of flaps, power changes, and brute force on the controls to counteract the trim.
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May 1, 2013 05:20
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Another Aft CG plane crash. https://www.youtube.com/watch?v=OlDmMwI9cik
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May 1, 2013 06:02
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movax posted:Awesome pictures, though this one is my favourite and way funnier than it should be. At the museum, they have this out near the entrance:  
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May 1, 2013 07:09
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ctishman posted:Is runaway stab trim something that happens a lot? I mean, it seems from the description that it'd be up there with "wings decide to fall off" in terms of frequency. On a modern commercial aircraft (don't know about 747s, but I imagine they're the same) so many multiply redundant systems would have to fail to get runaway trim, it really should never happen. There's no stab brake in the flight deck either, if any of the systems sense uncommanded movement, the THS will be locked out. You basically need a failure of the jack screw to have a runaway stab. (see alaskan airlines)
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May 1, 2013 08:59
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azflyboy posted:From the statistics available within the US, it appears to be very rare. The key is that if you catch it in time, you have a fighting chance by deploying flaps, gear and whatnot. If you are too late with hitting the stab trim disco switches or the stab brake, the trim speed will end up outside of the flight envelope and you will die. I know three examples of a stab trim runaway, two due to automatics and improper aircraft operation: AF447 and THY1951. Another one which was probably a true stab runaway happened in the 1960s in Belgium, where a Sabena B707 crashed near Brussels Airport. The aircraft was approaching the airport, until it pitched up uncontrollably and ended up flying a tight spiral at high thrust and extreme bank angle. It is suspected (FDR/CVR not available) the crew tried to use high bank angle to avoid a stall, but had zero chance to avoid a crash. Tsuru fucked around with this message at 09:16 on May 1, 2013 |
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May 1, 2013 09:08
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Tsuru posted:One important (though probably obvious) distinction is that in smaller aircraft (including the Citation) you only move a small trim tab to offset the neutral point of the elevator and if you just offset the force, the aircraft is aerodynamically (nearly) identical to one that is in trim. On large aircraft the entire HS moves to avoid trim drag. Here, a stab runaway is typically an electric malfunction where the the stab moves to the forward or aft stop uncommanded. This is also the reason why yoke trim switches on Boeings and the like are always dual units, connected in serial so a failure of one will not trigger a stab runaway. AF447 and THY1951 had nothing do with stab trim runaway.
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May 1, 2013 09:41
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Tsuru posted:I know three examples of a stab trim runaway, two due to automatics and improper aircraft operation: AF447 and THY1951. I don't see how either of those accidents had anything to do with trim malfunctions. In the case of AF447, the pitch trim was functioning correctly up until impact, and the fact that the crew managed to stall the airplane (and hold it in the stall until it hit the water) is due to a mix of confusion and misunderstanding the FBW system on their part rather than any issue with the flight controls. The Turkish Airlines accident also had nothing to do with the trim system. In that accident, the crew didn't disengage the autothrottle system after it began acting on commands from a malfunctioning radar altimeter, and somehow failed to notice the aircraft had slowed to around 40kts under the correct approach airspeed. In both cases, the stab trim had likely shifted pretty far towards the nose up position before impact, but in both cases it only did so because it was trying follow commands from the flight crew, and there were no trim malfunctions of any kind involved.
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May 1, 2013 09:57
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Linedance posted:AF447 and THY1951 had nothing do with stab trim runaway. azflyboy posted:I don't see how either of those accidents had anything to do with trim malfunctions.
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May 1, 2013 10:13
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Tsuru posted:What was the position of the elevator trim on both accident aircraft? Both these aircraft trimmed up without the crew realizing. Not a trim runaway in the direct sense, but definitely a contributing cause in both accidents. On AF447 the autotrim moved the THS fully up as per the FO's sidestick inputs which led to an AOA in excess of 40 degrees, and in the case of the Turkish the autopilot GS hold mode trimmed up until the stick shaker because the autothrottle was in retard flare mode. Not a runaway trim in any sense at all. That is exactly how trim is designed to operate, and exactly how aircraft are designed to fly. If you're a pilot and don't know that, you have no business operating an aircraft. (I've met many pilots who have only the vaguest understanding of how the metal tube behind them works, but I'd bet any one of them could at least explain how control surface trim works). Finger Prince fucked around with this message at 10:24 on May 1, 2013 |
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May 1, 2013 10:20
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Linedance posted:Not a runaway trim in any sense at all. That is exactly how trim is designed to operate, and exactly how aircraft are designed to fly. If you're a pilot and don't know that, you have no business operating an aircraft. And by the way: not a pilot, just a lowly engineer. An engineer who in the wake of the Turkish crash was called upon to create a training program for our B737 crews. I don't know everything, but I like to think I have my moments.
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May 1, 2013 10:30
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Tsuru posted:That is why I chose the word "misuse". Tragic events sure enough, but Boeing's recommendation after the accident in Amsterdam was most telling: "Crews should monitor primary flight parameters at all times" or something along those lines... I wasn't questioning your knowledge, just your assertion that the THS moved "without the crew realizing". Especially on the airbus, there's no way they wouldn't realize the trim was moving, because the stripy wheels move. But that's what they normally do, because that's how they work, so pulling back on your stick will cause your stab to trim to your elevator input*. I'm not familiar with 737 auto trim systems, but I'm guessing the crew would have some sort of indication of trim movement on EICAS. In any case, the stab trim in the Turkish case is only about as guilty of operating abnormally as the autothrottles. There's a very good analysis of the CVR and crew dynamic, as well as airport specific landing operations, on that flight in one of those air crash investigation shows which gives a far better explanation of why things happened the way they did. *drat, I'm going to have to look this up when I'm at work. That's how it is supposed to work, but I can't remember what conditions you have to have to get the stab to move on the ground when you pull on the sidestick, or if you can at all (I think you can, and I think it might, but I'm doubting myself a bit).
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May 1, 2013 11:04
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Linedance posted:I wasn't questioning your knowledge, just your assertion that the THS moved "without the crew realizing". Especially on the airbus, there's no way they wouldn't realize the trim was moving, because the stripy wheels move. But that's what they normally do, because that's how they work, so pulling back on your stick will cause your stab to trim to your elevator input*. I'm not familiar with 737 auto trim systems, but I'm guessing the crew would have some sort of indication of trim movement on EICAS. In any case, the stab trim in the Turkish case is only about as guilty of operating abnormally as the autothrottles. There's a very good analysis of the CVR and crew dynamic, as well as airport specific landing operations, on that flight in one of those air crash investigation shows which gives a far better explanation of why things happened the way they did. The B737NG still has these very noisy trim wheels that are far more visible and noticeable than those on the A330, and a mechanical trim pointer connected to it, exactly as it was in 1967. The fact is, three pilots were in the FD, and nobody was looking at what was happening until the shakers went off in IMC. Their fate was sealed when the captain did not disconnect the autothrottle when taking over, leaving the autothrottle in retard flare mode and closing the throttles again when he moved both hands to the the stick to fly the recovery. Needing both hands because the elevator trim had been trimmed almost fully up by the autopilot. The A330 crash is still widely debated, but the FO's actions are questionable. He kept pulling on the stick even though the aircraft was nose high and shouting "stall" at him. This apparently is enough in alternate law to move the THS fully up, and as you know the inputs from both sides are added together, so if one crew is pulling fully up, the most the other one can do is push fully down to counteract his movement to neutral. I don't think they used the function where you keep holding the red button for 60 seconds or so to invalidate the other stick's inputs. Unfortunately I don't have access to an FBW Bus sim at this time, but suffice to say I still can't wait to try it out on one and see for myself. The problem is in normal conditions I'm sure they would have known, but this was at night, in the middle of some of the most violent CB activity on this earth, with an relieve FO or SO in the left seat. I'm not a pilot but I do know and realize that when this poo poo is thrown at you for real, you lose half of your cognitive ability because you can't see sh*t, and most of the other half to the startle factor. This is where experience and tens of thousands of flying hours normally take over. They never understood what was going on until they hit the ocean.
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May 1, 2013 11:19
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Hi. Not a pilot, but I occasionally enjoy the ability of a land-based mammal to consume a bird in mid air. It's pretty awesome. I have a question I'd like to crosspost from the GBS thread on that horrible cargo plane crash in Afganistan. Nice piece of fish posted:Wouldn't this kind of thing be preventable with a sort of breakaway failsafe on the rear hatch? Sort of "if enough weight, break open" arrangement. Or just have a system where you can take off with the rear hatch open, so that the cargo just gets ejected if it comes loose? No cargo could possibly be worth lives. Or an entire goddamn plane. Nice piece of fish posted:I'm no pilot, but it seems to me that it would be logical, at low altitude and low speed but still with enough velocity to generate lift, you'd be more hosed if your nose wants to point up and you stall, rather than if it wants to point downwards and you pick up velocity, because that at least leaves you the ability to use your control surfaces to steer the craft. Also, more margin for error so long as you're above your horizon with the nose. And while there was a helpful loadmaster in the GBS thread, I'd love for an actual pilot to tell me why the plane would still have crashed if the cargo had flown out the rear rather. As a non-piloting individual, it doesn't make as much sense to me. And I know it couldn't possibly have done so in the actual model of plane involved in this crash. So if you want to take the time to explain it to me like I'm a five-year old, I'd appreciate it.
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May 1, 2013 13:38
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Airplanes need two things to recover -- airspeed and altitude. You can trade off one for the other, but right after rotation, you have don't have such a luxury. If the cargo fell out the back as the 747 was standing on its tail, if would've still been in an unrecoverable stall. The crew did not have the altitude to spare to drop the nose, pick up airspeed, and then level off. bloops fucked around with this message at 13:51 on May 1, 2013 |
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May 1, 2013 13:44
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holocaust bloopers posted:Airplanes need two things to recover -- airspeed and altitude. You can trade off one for the other, but right after rotation, you have don't have such a luxury. Yep. That makes perfect sense. But what if instead of catching on something or stopping at the rear hatch, the cargo flew out the back at the moment the restraints failed and the cargo started moving? While the aircraft had the "correct" angle of takeoff? Would the aircraft still stall even from that movement alone? How would the cargo being jettisoned affect the plane contra the cargo all being moved to the back and stopping there affect the aircraft?
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May 1, 2013 13:52
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The plane is loaded to be balanced with cargo. What you're describing is still a massive change in the CG. Granted, a jet that suddenly drops a serious amount of weight is going to nose up because remember, the jet is balanced with a loaded weight in mind so it getting lighter will have a performance effect. Would it have stalled? Probably not. Either way, aircraft are not engineered to have break away doors like that. That's a structural weak point in the airframe that just isn't needed when the proper amount of tie downs, weight & balancing, and pre-flight checks are done.
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May 1, 2013 13:58
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Nice piece of fish posted:Hi. Not a pilot, but I occasionally enjoy the ability of a land-based mammal to consume a bird in mid air. It's pretty awesome. I am not a pilot, but I'll give it a go anyway. It would probably have been able to fly if it suddenly lost all cargo. It might not have been a good configuration, maybe too nose heavy, but perhaps better than the "we are definitely dead"-situation they were in. Having a way to eject cargo would in theory be a good way for a cargo plane to save itself, but the cost and complexity of such a system has to be considered as well. What if it accidentally flew open at 35,000 feet? How reliable will it seal in normal operations versus how reliably it needs to fly open in an emergency? How much less cargo can it carry with the added weight of the system? And what if the cargo shifts dramatically, but not all the way back to actually hit the door? And what if 747s...  ...load cargo from the front? For every plane crash, there is a possible solution in technology or in procedure. To prevent accidental load shift, good procedures successfully prevent thousands of plane crashes every year. In this case, and I am speculating widly here, the procedures were not followed in loading the plane or in maintaining the parts that secure the cargo.
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May 1, 2013 14:04
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Thanks to the both of you. I know it's a complete hypothetical, just seems like something that could have had a theoretical failsafe. But like you say, proper routines prevent that sort of crap, so that's probably a safer and easier solution.
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May 1, 2013 14:19
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Much cheaper too. A rear door adds weight which burns up a shitload of fuel through a plane's service life.
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May 1, 2013 15:13
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