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| ▲ | filleduchaos a day ago | parent | next [-] | | Well, there's a very big difference between "Engine fire: some of the combustion chamber's heat and flame has breached containment" and, say, "Engine fire: the engine has exploded, catastrophically damaging your wing which is now visibly on fire". However, both things are reported in the cockpit as ENG FIRE. There's also a very big difference between "Engine failure: something has damaged or jammed enough components that the turbines are no longer spinning fast enough to produce thrust or drive the generators" and "Engine failure: the engine is no longer attached to the aircraft, which is why it is no longer producing thrust". However, both things are reported in the cockpit as ENG FAIL. (Un)fortunately, cockpit warnings prioritise the what (so to speak) and not the how or why. On one hand, this makes decision-making a lot simpler for the crew, but on the other...well, in rare cases the lack of insight can exacerbate a disaster. Depending on when exactly the engine gave out, this poor crew might have been doomed either way, but they might have been able to minimise collateral damage if they knew just how badly crippled the aircraft was. And there was a very similar accident to this one (actually involving the predecessor of the MD-11, the DC-10), American Airlines 191 - one of the engines detached from the aircraft, damaging the leading edge of its wing in the process, causing that wing to stall when the crew slowed down below the stall speed of the damaged wing in a bid to climb. If they could have somehow known about the damage, the accident might have been avoided entirely as the crew might have known to keep their speed up. | | |
| ▲ | ragazzina a day ago | parent | next [-] | | > There's also a very big difference between "Engine failure: something has damaged or jammed enough components that the turbines are no longer spinning fast enough to produce thrust or drive the generators" and "Engine failure: the engine is no longer attached to the aircraft, which is why it is no longer producing thrust". However, both things are reported in the cockpit as ENG FAIL. What is the difference? | | |
| ▲ | HPsquared a day ago | parent | next [-] | | Wider effects like damage to the wing or changes to aerodynamics. Edit: and damage to other engines, possibly engine #2 in the tail ingesting debris in this instance. | | |
| ▲ | bombcar a day ago | parent [-] | | That's the biggest, the weight gone entirely unbalances the plane; if you knew exactly what happened you MIGHT be able to keep it level (and it seems they did for a bit) but eventually airspeed drops, it tips, and cartwheels (which is apparently what it did from the videos). | | |
| ▲ | Modified3019 a day ago | parent | next [-] | | The aircraft hit the roof of a UPS warehouse, barely clearing it before coming down in the parking lot/junkyard nearby. So when we see it turning over in its last seconds (like the trucker dash cam video), it only had one wing at that point. | | | |
| ▲ | beerandt 19 hours ago | parent | prev [-] | | Deadweight or no-weight engine is a relatively negligible problem in terms of the weight-balance envelope. Cut fuel & hydraulic lines near that engine (that affect the other engines/ apus) (or less likely structural or aerodynamic problems) is what's going to shift this from "engine failure" recoverable problem to a global nonrecoverable one. |
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| ▲ | mvkel 20 hours ago | parent | prev | next [-] | | It's the difference between "I can't walk because my leg fell asleep" and "I can't walk because I have no legs" | |
| ▲ | tzs 11 hours ago | parent | prev | next [-] | | A good example of the difference it can make was the Flight 191 crash in Chicago in in 1979, which had an engine come off on takeoff: https://en.wikipedia.org/wiki/American_Airlines_Flight_191 The engine coming completely off tore through hydraulic lines, which were need to keep the slats extended. Airflow forced the slats to retract. Here's what then happened: > As the aircraft had reached V1, the crew was committed to takeoff, so they followed standard procedures for an engine-out situation. This procedure is to climb at the takeoff safety airspeed (V2) and attitude (angle), as directed by the flight director. The partial electrical power failure, produced by the separation of the left engine, meant that neither the stall warning nor the slat retraction indicator was operative. Therefore, the crew did not know that the slats on the left wing were retracting. This retraction significantly raised the stall speed of the left wing. Thus, flying at the takeoff safety airspeed caused the left wing to stall while the right wing was still producing lift, so the aircraft banked sharply and uncontrollably to the left. Simulator recreations after the accident determined that "had the pilot maintained excess airspeed the accident may not have occurred. | |
| ▲ | potato3732842 a day ago | parent | prev | next [-] | | >What is the difference? Wanting to be in the air vs wanting to over-run the end of the runway. | |
| ▲ | singleshot_ 21 hours ago | parent | prev [-] | | Hydraulic pressure |
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| ▲ | eternityforest a day ago | parent | prev [-] | | Could they add cameras to solve this issue? | | |
| ▲ | roryirvine a day ago | parent | next [-] | | During engine failure / fire situations, I would expect that pilots are likely to be too busy to have any time left over for peering at a video feed, trying to assess the state of the wing. In emergencies, information overload tends to make things worse, not better. | | |
| ▲ | ExoticPearTree a day ago | parent [-] | | Having cameras pointed at the engines/wings like rearview mirrors would be helpful. It does not add that much workload if you take a quick glance in the “mirror” and figure out what the problem exactly is. And now we have technology that allows for cameras everywhere to give a better situational awareness across all critical aircraft surfaces and systems. It is going to take a little bit of adjusting to, but it will help improve safety in a tremendous way. | | |
| ▲ | cedilla a day ago | parent | next [-] | | This would need to be tested. There's a lot going on already during normal take-offs. Now you're in a situation where the engine fire alarm is going off, probably a few other alarms, you got so many messages on your display that it only shows the most urgent one, you're taking quick glances at 50 points in the cockpit already. And how would the cameras even work? Are the pilots supposed to switch between multiple camera feeds, or do we install dozens of screens? And then what, they see lots of black smoke on one camera, does that really tell them that much more than the ENG FIRE alert blaring in the background? Maybe this could help during stable flight, but in this situation, when the pilots were likely already overloaded and probably had only a few seconds to escape this situation - if it was possible at all - I can't imagine it being helpful. | | |
| ▲ | ExoticPearTree a day ago | parent | next [-] | | You know how the tail camera works on the new planes? Something like that, which can be far away from the wings, but get the full picture. Am I saying it's the solution for everything? No. But after you go through the memory committed items during an emergency, you can take a look outside and be like "ah, I see better what the problem is". If we don't try to see how it goes, we won't know if it is a good idea or not. | |
| ▲ | wongarsu a day ago | parent | prev [-] | | It'd certainly need more thought put into it than just showing the camera view from the entertainment system. Either just one camera on the tail pointed forwards, so you have one single camera that can show the whole plane, or two cameras in the front, one pointed at each wing. Two cameras is worse than one, but they are less likely to be affected by smoke or blood splatters or whatever. Maybe give each pilot one of the camera feeds. And you'd have to fit a dedicated screen for the video feed so pilots don't need to switch through screens in an emergency. It'd take lots of testing and engineering. But especially in cases where you have multiple warnings going off I imagine that a quick view at an exterior camera can often give you a clearer/faster indication of the situation |
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| ▲ | krisoft a day ago | parent | prev [-] | | > Having cameras pointed at the engines/wings like rearview mirrors would be helpful. Helpful in what way? What are the pilots going to do with the information? | | |
| ▲ | ExoticPearTree a day ago | parent [-] | | They won't have to rely on cabin crew description of what they see over the wings or have to send one of the pilots to take a look (see UA1175). | | |
| ▲ | sim7c00 a day ago | parent | next [-] | | its super weird to me this isn't a thing, and there's resistence to the idea. I mean, if they are already masters at glacing at 100000 differnent indicators and warning messages etc. and processing them at super speeds (they really do!) then i'd say a monitor with a bunch of buttons below it to switch feeds (maybe a little more elaborate, but not tooo...) would be helpful. the problem might be getting trained and experienced pilots to adjust to it since they are already in a certain flow of habits and skills to apply in their job, but new pilots surely could learn it as they aren't so set on their ways yet and have the opportunity to build this new data into their skillset / habits. | | |
| ▲ | throwway120385 19 hours ago | parent | next [-] | | Look, information overload is a real problem. Medical devices are an analogous industry in that in an emergency nurses and doctors are getting completely bombarded with alarm tones, flashing lights, noise, and also whatever is going on with the patient. There are standards in that industry governing how you alarm, what your alarm tones sound like, what colors you're supposed to use, how fast you're supposed to flash, and so on. And people still miss alarms because there are still a ton of them all going off at once. People have an upper limit on their capacity to take in information, and that limit goes down when they are moving quickly to solve problems. Throwing more information at them in those moments increases the risk that they will take in the wrong information, disregard more important information, and make really bad decisions. So no, it's not cut and dried like you're thinking. | |
| ▲ | bronson 20 hours ago | parent | prev | next [-] | | Pilots are already overloaded so we can probably overload them a little more? | |
| ▲ | cmurf 19 hours ago | parent | prev [-] | | The entire event was over in less than a minute, and during that time there’s only one thing pilots are working on: maintaining what little control they have, and gaining as much altitude as possible without loss of control. This is consuming all mental processing, there are no spare cycles. This wasn’t a salvageable situation by having more information after the engine separated. If a sensor could have provided a warning of engine failure well before V1, that would be helpful. I expect the questions will focus on what information existed that should have resulted in aborting the takeoff. Not what information was needed to continue. |
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| ▲ | krisoft 21 hours ago | parent | prev | next [-] | | Okay. So you mean in general it would help in some cases. Not that in this case it would have helped. > see UA1175 I'm familiar with the case you are mentioning. I'm also aware that they sent a jump seater to look at the engine. But did seeing the engine provide them with any actionable information? Did they fly the airplane differently than if they would have just seen the indications available in the cockpit? | | |
| ▲ | ExoticPearTree 19 hours ago | parent [-] | | Yes, the cameras would not have helped here, but it dorsn’t mean they are useless in general. Stupid car analogy: airbags help in most cases, but not all. Are they useless? Regarding UA1175, they had someone extra, but not all flights happen to have someone extra in the cockpit. | | |
| ▲ | kelnos 13 hours ago | parent | next [-] | | > Yes, the cameras would not have helped here, but it dorsn’t mean they are useless in general. I think that statement needs the support of actual evidence. Air incident investigation agencies make detailed reports of the causes of crashes, with specific, targeted recommendations to help ensure that similar incidents don't recur. If we haven't seen recommendations for cameras like that, then I think it's reasonable to assume that the actual experts here have determined that cameras would not be helpful. | | |
| ▲ | ExoticPearTree 2 hours ago | parent [-] | | FAA/EASA can dictate what equipment new airplans should/must have. And that is done in cooperation with the manufacturers. And manufacturers have zero incentives to add new equipment, airlines zero desire to do additional certifications for pilots. It is not reasonable to assume anything. Air crash investigators are not the experts on airplanes design. |
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| ▲ | krisoft 18 hours ago | parent | prev [-] | | > airbags help in most cases, but not all. Excellent. So in what cases does seeing the engine visually do help? So far we discussed UPS2976 and UA1175 where the presence or absence of the camera didn't change the outcome. > Regarding UA1175, they had someone extra, but not all flights happen to have someone extra in the cockpit. You are dancing around my question. What does the pilot do differently based on what they see? If you can't articulate a clear "pilot sees X they do Y, pilot sees Z they do Q" flow then what is the video good for? in a sibling thread you say "There are countless situations where it can be helpful." But you haven't named even one of those countless situations yet. | | |
| ▲ | ExoticPearTree 14 hours ago | parent | next [-] | | Let's say there is a case like UA1175:
- they can see how damaged the engine is
- they can see if the wing is damaged in any way (over and under)
- is there any other damage to the aircraft (like there was a piece of shrapnel that hit the plane) In other situations:
- are the wheels out when the sensors say they are not
- have a way to visually inspect critical parts of the plane while in flight (so you don't have to do a flyover and the tower to look with binoculars at the airplane) This is what comes to mind now. Happy? Or am I still dancing? | |
| ▲ | filleduchaos 12 hours ago | parent | prev [-] | | > So far we discussed UPS2976 and UA1175 where the presence or absence of the camera didn't change the outcome To be fair, the presence of a camera might have changed the outcome of UPS2976. Depending on when the fire developed fully, rejecting the takeoff based on the sheer size of the fireball on the wing might have led to fewer casualties on the ground. This is of course under the assumption of a world where a camera feed is a normal part of the flight deck instruments and there is a standard for the pilot monitoring to make judgments based on it. |
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| ▲ | lazide 21 hours ago | parent | prev [-] | | Sure, but in this situation there is zero time for any of that. | | |
| ▲ | ExoticPearTree 19 hours ago | parent [-] | | There are countless situations where it can be helpful. You don’t have to focus on a particular one where this would not be of any use. | | |
| ▲ | lazide 19 hours ago | parent [-] | | Sure, but we’re literally in the thread discussing the exact situation it wouldn’t be helpful in haha |
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| ▲ | zuppy a day ago | parent | prev [-] | | They surely can and this has been done.
On one the flights that I took with Turkish Airlines they had a few video streams from different sides of the airplane. One was from the top of the tail and you could see the entire plane. Now... not sure how much that is helpful in this kind of emergency, they really didn't have time to do much. | | |
| ▲ | fredoralive a day ago | parent [-] | | I'm not sure they usually have the views on screen in the cockpit in flight, even if available (and an old MD-11 freighter won't have the cameras in the first place). The picture of an A380 cockpit (on the ground) on Wikipedia does show the tail view on a screen, but its on the screen normally used for main instruments. With an A380 that had an uncontained engine failure causing various bits of havok (Qantas 32?) IIRC the passengers could see a fuel leak on the in flight entertainment screens, but they had to tell the crew as AFAIK they didn't have access to the view in the cockpit in flight. |
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| ▲ | kelnos 13 hours ago | parent | prev | next [-] | | I think too many of us are used to movies and TV (and Star-Trek-like scifi) that gives the incorrect view that extremely detailed information about the state of things is available. The notification in the cockpit is likely nothing more than "ENG 2 FIRE" or similar. That could mean anything from "the fire is minor enough and we're at high enough speed that it's significantly safer to take off and then make an emergency landing", to "the engine has exploded and the wing is on fire and catastrophically damaged, so even though aborting takeoff now is dangerous and will likely cause us to overrun the runway, trying to continue would be worse". It's a judgment call by the pilot to guess which of these is the case (or any possibility in between), and given the probabilities of various failure modes, I think it's fair for a pilot to assume it's something closer to the former than the latter. | | |
| ▲ | Jtsummers 8 hours ago | parent [-] | | > I think too many of us are used to movies and TV (and Star-Trek-like scifi) that gives the incorrect view that extremely detailed information about the state of things is available. What a strange comment. I never made any such statement or claim that a science-fantasy level of technology would exist in a decades old aircraft or any aircraft. I was responding to someone who made the absurd claim that the pilots wouldn't be informed of a fire on the wing, when in fact they would be informed of that (which you seem to agree with). So what's Star Trek got to do with anything? |
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| ▲ | appreciatorBus a day ago | parent | prev | next [-] | | I’m sure they knew there was an issue, but I don’t think the sensors can differentiate between “your engine is on fire, but if you can shut it down quickly, everything will be cool.” and “half your entire wing is on fire and your engine is pouring flame out the front/top instead of the back” | |
| ▲ | positron26 a day ago | parent | prev [-] | | This puts an impractical amount of faith in the sensor wiring when the whole pylon and cowling are shredded. | | |
| ▲ | krisoft a day ago | parent | next [-] | | It is a very practical amount of fait. There are two fire detection loops for each engine.[1] Even if both fails (because they get shredded as you say it) the system will report an engine fire if the two loops fail within 5s of each other. (Or FIRE DET (1,2,3,or APU) FAIL, if they got shredded with more than 5s in between without any fire indications in between.) The detection logic is implemented directly below the cockpit. So that unlikely to have shredded at the same time. But even if the detection logic would have died that would also result in a fire alarm. (as we learned from the March 31, 2002 Charlotte incident.)[2] In other words it is a very reliable system. 1: page 393 https://randomflightdatabase.fr/Documents/Manuel%20Aviation/... 2: https://www.fss.aero/accident-reports/dvdfiles/US/2002-03-31... | |
| ▲ | Jtsummers a day ago | parent | prev [-] | | I don't know what the MD-11 would have had, again I didn't work on it. But the systems used for other aircraft would have reported an alarm based on what I saw in the video, at least they were designed to do that. The LRU receiving the sensor inputs wouldn't typically be in the wing and would be able to continue reporting the alarm condition even if the sensors fail. In fact, the lack of current from the sensor (for the systems I worked on) would have been enough to trigger the alarm if the sensor were completely eliminated. | | |
| ▲ | positron26 a day ago | parent [-] | | No reading is not quite the same as "hot", but I'm sure it did contribute to discerning simple compressor stall to whatever this was. |
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