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Originally Posted by A Squared
(Post 10297129)
Maybe I'm not following what you mean by: "would not have yielded that rate"
With the timestamp uncertainty deriving the vertical rate from time and altitude would have meant a lot more crazy spikes than the one that was recorded. But yes overall the data seems consistent but i'm not quite sure what to make of that +7000 fpm spike. That +7000 spike was speculated to be a pull up that caused structural damage by .Scott. |
The New York Times reports speculation on whether a 'small metal tube' brought down JT610:
Did a Small Metal Tube Bring Down an Indonesian Airliner?As teams search for Lion Air Flight 610’s black boxes, experts speculate that a faulty pitot tube, used for measuring airspeed, may have contributed to the crash.By Russell Goldman Oct. 30, 2018 Divers scoured the Java Sea on Tuesday looking for clues that could explain why a brand new airliner fell out of the sky just moments after takeoff, killing all 189 people on board. Before Lion Air Flight 610 lost contact on Monday, the plane displayed erratic changes in its speed, altitude and direction, causing experts to speculate that a problem with the aircraft's instruments used to calculate airspeed and altitude may have contributed to the crash. Those indicators, or pitot tubes, have been implicated in previous aviation disasters, but experts said that determining the cause of the crash would ultimately require the recovery of the plane’s flight data recorders, the so-called black boxes. An Erratic Flight PathFlight 610 departed Jakarta, Indonesia, on Monday at 6:20 a.m. Soon after takeoff the plane reached an altitude of 2,100 feet before falling precipitously to around 1,475 feet, according to satellite data transmitted from the airplane and collated by the aviation website Flightradar24. Here’s what investigators what to know about the Indonesia plane crash.Moments later, the plane climbed to altitudes varying between 4,500 and 5,350 feet. The data then shows a steep decline, until contact was lost at 6:32 a.m. In a normal flight, the lines in the chart above representing speed and altitude would level off into a smooth plateau, but on Monday’s flight they fluctuate erratically. “The erratic flight path makes us suspect a problem with the pitot-static system,” Gerry Soejatman, an Indonesian aviation expert, told The New York Times. Pitot tubes [and AOA sensors - Airbubba] on an Airbus A380 airplane. The plane involved in Monday's crash was a Boeing, but the tubes are found on most commercial aircraft. Credit Pascal Rossignol/Reuters What’s a Pitot Tube?Pitot tubes, slender perforated tubes on the wings or fuselage of an aircraft, are used to determine airspeed, a measurement vital to controlling the plane: Too slow and the aircraft can stall, too fast and it can break apart.Each tube has two holes in it: a hole in the front into which the airstream flows and a hole in the side. By measuring the differences in the “stagnation pressure” at the front and the “static pressure” at the side, one can calculate airspeed. The tube is named for Henri Pitot, an 18th-century French scientist who invented the tool to measure the speed of flowing rivers. Malfunctioning pitot tubes contributed to the infamous disappearance of Air France Flight 447 over the Atlantic in 2009. Investigators attributed that crash to ice crystals forming over the tube’s intake, leading to erroneous measurements and the flight crew reacting incorrectly. Experts cautioned that it was still too early to determine the cause of the accident, and that often equipment malfunctions and human error both contribute to crashes. The PlaneMonday’s crash was the first disaster involving a Boeing 737 Max 8, an updated version of the best-selling Boeing 737.The Max 8 has been in commercial operation for only a year. The plane in this week’s disaster was first put into use in August and had logged just 800 hours in the air, according to Indonesian officials. Edward Sirait, Lion Air’s president director, said the plane had experienced an unspecified technical problem during a flight the day before. He said the issue had been resolved “according to procedure.” Experts examining the data from that flight said there appeared to be a similar problem with measuring the plane’s airspeed. A Checkered HistoryIndonesia’s aviation industry has long been dogged by accidents and accusations of malfeasance. The United States and the European Union banned Indonesian carriers for years, citing a lengthy record of crashes.The United States lifted its ban in 2016 after nearly a decade, but it was only in June that the European Union began letting Indonesian airlines fly there. Among recent notable accidents was the crash of a 2014 AirAsia flight to Singapore, in which 162 people were killed, and a 2015 Trigana Air crash in Papua, Indonesia, in which 54 people were killed. Twenty-five people were killed in 2004 in the last fatal Lion Air crash. Luckily, no one was killed in 2013 when a Lion Air jet missed the runway and crashed into the sea in Bali. https://www.nytimes.com/2018/10/30/w...air-pitot.html |
Originally Posted by Vessbot
(Post 10296202)
.
https://cimg5.ibsrv.net/gimg/pprune....b053d633de.jpg As to whether the vertical speed is credible, we have 837 ADS-B data points (after discarding eight that showed ground speed as zero). Of these 837 data points, only the last four or so (spanning about seven seconds) are questionable. But they may also be more or less accurate, especially if the engines are still turning. https://cimg9.ibsrv.net/gimg/pprune....667809521e.png |
The erratic flight path makes us suspect a problem with the pitot-static system |
Originally Posted by LaissezPasser
(Post 10297172)
I've taken the liberty of redrawing Vessbot's graph, which shows Total Energy in arbitrary units, but without the eight outlier data points that showed JT610's ground speed as 0. That was kind of cluttering things up. I plan to chart calculated g-forces when time allows — unless someone wants to beat me to it.
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And here's a detailed graph of last minute of flight (6:31 am WIB).https://cimg8.ibsrv.net/gimg/pprune....655bc217ca.jpg
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It's overwhelmingly likely that the VS spike is a data aberration. The VS goes from about -9000 fpm to +7000 and back in two time stamps (approx. 3 seconds). A swing of 16,000 fpm and back in that amount of time, for it to then continue the exact smooth downward curve it was doing before? No.
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Salute!
O.K., back to the stab trim, with some air data contributed. So I looked up as much as I could find and seems a very logical and straightforward trim implementation. Not as cosmic as the Airbus system we beat to death for AF447, but not entirely as clean as most think. There are air data inputs to the "elevator feel system" via the "feel and centering unit', so we might see a compound failure sequence. If the crew engaged AP around 2,000 feet, then the AP would hav a say in the elevator and stab control unless the humans did the override trick, huh? If the trim system had a problem, it would be compounded by the erroneous air data. My point of interest focuses upon an event about 10 or 15 seconds prior to the sudden descent. Reminds me of the 737 rudder hardover way back. Those planes did not enter a shallow dive, and went straight in with velocities I used to see when dive bombing on steep angles - 500 to 600 feet per second rates. The Russian crash two years ago showed a damned near vertical dive and it was a 737. So high vertical velocity is not all that unusual in extreme loss of control crashes, regardless of cause. At 00:41:49, the aircraft hit the runway approximately 120m from the threshold with a speed of over 600 km/hr and a nose down pitch exceeding 50 degrees. Gums posts... |
All this gleaned from FlightRadar24,a reggie spotters website that is notoriously inaccurate and never up to date....
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reply to DavereidUK
Somebody please correct me if I'm wrong (I belong to the avionics = PFM school), but the rectification action carried out for that entry in the tech log appears to have been to clean the connector plug on the elevator feel computer followed by a ground test, which was successful. Re-racking avio boxes and re-seating plugs often fixes things electronic, but they can be a convenient sign off when defects just go away. . I've not worked on the Max so it maybe totally different, but I don't think the elevator feel computer on the classic or New gen has any electronics, just hydraulic lines and pitot inputs (from the pitots on the vertical stab) Not an electronic computer as such. I think the only electric part is are differential pressure switches for fault annunciation . As I said the Max is likely a more modern set up so i don't wish anyone to draw conclusions from this. |
Despite a vessel seeing the aircraft strike the ocean and the relative low depths involved, I find it amazing that they are still unable to locate the wreck.
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If the air data source(s) were inaccurate resulting in an unreliable airspeed scenario, it’s likely the ADSB returns were also inaccurate. |
Enough of the Murder She Wrote data analysis. You never learn even when you made fools of yourselves in two accidents in Russia - particularly the Turkish 747. Some simply worship data above all even when it's rubbish. The massive reversal in VS makes so many of you salivate. Pathetic.
In the Turkish case massive reversals in ADSB vertical speed when in fact it was crashing almost straight ahead into the edge of a village. Rob |
Originally Posted by ampclamp
(Post 10297275)
Re-racking avio boxes and re-seating plugs often fixes things electronic, but they can be a convenient sign off when defects just go away.
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Salute!
Sorry, Rob, but unless we delete the word "rumor" I feel we are gonna get a lotta "instant analysis", and I am as guilty as many, but usually wait a hundred or two or thousand posts ( thinking AF447 Tech Log). If just one war story from a pilot is posted here that had something go bad and resembles the profile of a crash, it is worth looking at. Our Gee-loc problem in the F-16 back in the early 80's got spread by word or mouth before USAF finally did some good analysis. Meanwhile, we all took precautions and looked for potential maneuvers that could have dire consequences. Ditto for my leading edge flap failure, which was publically covered up due to politics. But when the next plane went down, my story spread and we never had another fatality or lost jet. Just saying. Gums. |
According to AV Herald . Ministry are saying after inspections coordinated by KNKT there will be sanctions
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Malaysian Airlines had unreliable airspeed recently on an A330 out of Brisbane. They managed to return, causing some damage to the landing gear on arrival. They didn't rush the return and used procedures to troubleshoot before making an approach.
This was at night at a relatively unfamiliar airport, MAS having recently restarted services to BNE after a prolonged break. The B737 MAX is a far more conventional aircraft than the A330 and should be easier to go back to basics on if the automation plays up. |
We amateurs should leave the speculation to the experts.
Hot off the wire at CNN.com : Aviation expert Philip Butterworth-Hayes told CNN that the data was unusual -- especially since takeoffs like this are typically controlled by the plane's automatic systems."This doesn't fit an automatic flight profile," Butterworth-Hayes said while studying the data. "Unless, the aircraft was trying to correct itself at the time for a number of reason
"This shows an unusually unstable vertical flight profile," he added. "Exactly at the same time as the speed increased there was an altitude dip, which meant that at that point there was quite some loss of control. "The plane, which has only been in operation since August 15, was carrying 181 passengers as well as six cabin crew members and two pilots, bound for Pangkal Pinang on the Indonesian island of Bangka. Former US National Transportation Safety Board air crash investigator and CNN aviation analyst Peter Goelz told CNN the data clearly showed issues with both the speed and altitude of the plane." There is something obviously wrong in both the air speed and the altitude which would point to the flight control systems," he said. "These are fly-by-wire systems [on the 737? who knew? - Airbubba] -- highly automated -- and pilots may not be able to troubleshoot failures in a timely manner." Butterworth-Hayes said that given that the plane was only two months old, the reason behind the crash was "very unlikely" to be a mechanical fault. "Airplanes don't just fall out of the sky," he said. "I can't think of any mechanical issue apart from a sudden, unexplained loss of engine power (or)complete electrical failure. It's far more likely to be an external event."He suggests that an environmental issue is to blame -- such as a microburst, or the plane hitting something like a flock of birds."Microbursts are very difficult to detect -- they're a sudden down-rush of wind, like a vortex and you can't really see it -- you hit it, suddenly your aircraft isn't performing how it should do, you start doing all sorts of recovery motions and then it's too late." |
From investigators' comments looks like the log pages posted on social media were probably authentic:
Investigators obtain ATC audio recordings of crashed Lion 73731 October, 2018SOURCE: Flight Dashboard BY: Firdaus Hashim Singapore Investigators from Indonesia's National Transport Safety Committee (NTSC) have obtained audio recordings of a Lion Air Boeing 737 Max 8 that crashed on 29 October from air navigation service provider AirNav Indonesia. Deputy chief Haryo Satmiko told the media that it was able to obtain audio recordings between the air traffic controller and the Lion pilots, but has yet to locate the flight data and cockpit voice recorders of the 737 registered PK-LQP. Satmiko was also quoted in a Reuters report as saying that the aircraft had technical problems, one of which was unreliable airspeed. Separately, NTSC investigator Ony Suryo Wibowo was quoted in Indonesian media reports as saying that it had sought information from the pilots that operated a flight that preceded JT610. Prior to JT610, the jet operated flight JT43 between Denpasar and Jakarta on 28 October. Wibowo stressed that data verification has to be made, after tweets of an aircraft and maintenance log surfaced, purportedly from PK-LQP. The crew for flight JT43 had found an altitude disagreement after take off and a sensing of difference in pressure. It flew the entire flight at 28,000ft. "We can confirm and verify that the aircraft flew from Denpasar to Jakarta, and landed safely at 20.55 local time [on 28 October]," adds Wibowo. https://www.flightglobal.com/news/ar...rashed-453162/ |
Originally Posted by via Air Bubba
Former US National Transportation Safety Board air crash investigator and CNN aviation analyst Peter Goelz
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