dodgy-alan 1,587 Posted February 11, 2018 Report Share Posted February 11, 2018 An-148 crashed shortly after take off. 70+ dead, no survivors. Aircraft less than 8 years old. Putin has ordered immediate enquiry, thoughts go out to all those affected by the tragedy. http://www.bbc.co.uk/news/world-europe-43024235 Link to post Share on other sites
allardjd 1,853 Posted February 12, 2018 Report Share Posted February 12, 2018 That's a bad one. RIP the victims and hopefully some peace for their families. Seems unlikely to have been WX on a departure, though it can't be complexly ruled out. Extreme icing might be a possible cause but most airliner types can and sometimes do climb through icing levels quickly enough to avoid serious problems. Bird strike(s) maybe or some kind of failure - or the ever-possible "human-caused" issues. Should be an interesting investigation. John 1 Link to post Share on other sites
allardjd 1,853 Posted February 12, 2018 Report Share Posted February 12, 2018 Here's what appears to be factual so far... Captain decided not to de-ice before departure. Normal departure and climbout to about 6,000', into IMC WX. Fairly rapid descent a short time later, reportedly just after having been cleared to a higher altitude. High speed impact at a shallow angle, almost flat, with relatively flat, heavily snow-covered terrain causing huge fireball and scattering the wreckage in a large "fan" area. Aircraft essentially disintegrated. Recorders have been found. Photos of them show impact damage, fairly heavy, but no fire damage and no reason to think they will not be readable. Impact was much like the Hawker Hunter crash in the UK some time ago, pretty flat, at a high speed and probably trying to pull up. No information about any communications from the aircrew indicating problems so far. Now the speculation... The most credible speculation of cause I've read so far is iced pitot(s) resulting in a pitch and airspeed excursion; broke out of clouds too low to recover - but it's just that - speculation. Nobody knows much of anything yet. There's an unconfirmed report that several high-ranking members of Rosatom (a Russian atomic energy company) were aboard and also one person who was a "source" in the Trump dossier affair, fueling speculation that they were "eliminated" to prevent them being called as witnesses if the US Uranium One scandal and other issues involving the Clintons were ever to get investigated. I'm not putting much stock in this part of the story yet. In any disaster, some crazy conspiracy theories always seem to emerge on the fringes. John Link to post Share on other sites
brett 2,301 Posted February 12, 2018 Report Share Posted February 12, 2018 Sad news, my prayers go out to all that lost their lives and their families. The high speed shallow angle before impact does suggest wing and frame icing and an attempt at altitude recovery but as usual assumptions are just that. Link to post Share on other sites
dodgy-alan 1,587 Posted February 12, 2018 Author Report Share Posted February 12, 2018 Some witnesses say the aircraft was on fire before it hit. Link to post Share on other sites
allardjd 1,853 Posted February 13, 2018 Report Share Posted February 13, 2018 There's video of the impact fireball from quite a long distance but no indication of any smoke or flame prior to the initial fireball on that. Can't rule it out definitively but no mention of it on PPRUNE. They are indicating also that there is no evidence of any kind of in-flight break-up, reinforced by the shape of the debris field and given the flight path, they don't consider it likely any tail-feathers came off before impact. Occam says loss of control in clouds, consistent with bad airspeed and V-V data, but still speculative, of course. John 1 Link to post Share on other sites
J G 927 Posted February 13, 2018 Report Share Posted February 13, 2018 What was the pilot thinking about when he declined de-icing? Given the conditions as evidenced on the crash site photos, my money is on icing. 1 Link to post Share on other sites
allardjd 1,853 Posted February 13, 2018 Report Share Posted February 13, 2018 I doubt it was airframe ice, at least any ground accumulation. He made it to 6,000' and was in level flight there. I'm leaning toward the idea of pitot ice, which may have begun on the ground, but once he was in IMC its effect on his flight instruments became critical. John 1 Link to post Share on other sites
allardjd 1,853 Posted February 13, 2018 Report Share Posted February 13, 2018 They've gone pretty quiet at PPRUNE on this one, but one guy has published an analysis of ADS-B data from what FR24 (Flight Radar 24?) published. It's pretty unremarkable except it shows a fair amount of blundering around trying to level at 6,000'. He's used lat-long data points to extrapolate ground speed, which is kind of imprecise, and tells little about airspeed, particularly if altitude changes are also going on. He notes there are a lot of missed data points and bad data included, which he's either filtered out or interpolated around. There's an image of the flight track over the ground, apparently based on the above or something like it. The path is smooth right up to the point of impact; a slight right dogleg right after takeoff, possibly indicating a cross-wind from the left, but still essentially flying the runway heading, a straight leg, a smooth turn to the left and straight on to the point of impact. The last straight leg to impact is pretty long compared to the rest - it's the bulk of the flight path. So, some altitude excursions of several hundred feet around 6,000' but ground track doesn't show any unusual anomalies. Haven't seen it compared to the flight plan/ATC instructions but there's nothing obvious that indicates any kind of heading excursions. Heading doesn't depend on pitots - airspeed does. Altitude is generally affected because pilots would probably use pitch changes as well as power to chase erroneous airspeed and/or altitude instrument readings until they figure out which widgets are lying to them. If the static port(s) is affected, your best chance at maintaining level flight if you don't have a horizon is pitch and power, ignoring airspeed and altitude indications. John 1 Link to post Share on other sites
allardjd 1,853 Posted February 13, 2018 Report Share Posted February 13, 2018 Well, that was quick! https://www.rt.com/news/418664-russia-plane-crash-cause/ "The crash of An-148 passenger plane in the Moscow Region may have been caused by incorrect flight speed data due to icing, the Interstate Aviation Committee (IAC) said after deciphering the flight data recorder. On Tuesday, the IAC announced it had completed the deciphering of information contained in the one of the black boxes – the on-board data flight recorder – of the crashed plane. It is still working on the other black box, the voice recorder. The preliminary analysis suggests that the “incorrect data about flight speed on the pilots' indicators, which in turn was linked to the icing of the pitot-static [sensor] system” led to a “special situation” with the plane, according to the IAC statement." I'd missed a couple of pages of new comments when I said above that they'd gone quiet at PPRUNE. John 1 Link to post Share on other sites
brett 2,301 Posted February 13, 2018 Report Share Posted February 13, 2018 Seems too easy of an explanation for a pilot with his experience but stuff happens. Link to post Share on other sites
dodgy-alan 1,587 Posted February 13, 2018 Author Report Share Posted February 13, 2018 Just an unfortunate accident then by the sounds of it. however I doubt we'll ever really know the truth, Russia likes to keep things covered up. 1 Link to post Share on other sites
allardjd 1,853 Posted February 14, 2018 Report Share Posted February 14, 2018 It fits the scenario, including the WX and the fact that the AC was not de-iced before flight. Being in clouds with the airspeed indicator toes-up is not a good place to be - worse yet if you don't know it's giving you bad information. Pilots are trained and have hours and hours of responding to what's being displayed on the panel and ignoring an airspeed indicator that's giving bad information is a lot harder than it sounds. Many pilots carry rubber suction cups in their flight bags designed to cover inoperative panel gauges for just that reason. If it's one of the six-pack, seeing but not responding to one that you know is broken is half-past difficult even if you know it's bad. Eye-hand muscle memory has to be consciously overcome and it's not easy. It's a bit easer to manage flying the aircraft if the bum gauge is covered up, but first you have to figure out that it's bad. If the airspeed was indicating low it's not too hard to believe that they did the instinctive thing, pushed up the power and pushed the nose over. You would too, right up to the moment you figured out that the airspeed indicator was bum-doping you, and even then it would be hard to ignore an AIS that says you're five knots from the stall and decreasing. I'm inclined to take this one at face value. John Link to post Share on other sites
allardjd 1,853 Posted February 14, 2018 Report Share Posted February 14, 2018 Oh boy - the FDR contained data for the previous 16 flights, including the accident flight. On the previous 15 flights all 3 pitot heaters were recorded as ON. For this flight they were all OFF! Yikes!!! It doesn't take Sherlock Holmes to figure this one out. John 1 Link to post Share on other sites
dodgy-alan 1,587 Posted February 14, 2018 Author Report Share Posted February 14, 2018 There endeth the lesson! I always make sure pitot heat is on no matter what the weather is like. 1 Link to post Share on other sites
wain 879 Posted February 15, 2018 Report Share Posted February 15, 2018 surely that would be SOP given the weather and location, it's also probably on most checklists saying either on or check conditions.... Link to post Share on other sites
allardjd 1,853 Posted February 15, 2018 Report Share Posted February 15, 2018 Maybe the CVR tapes will contain a clue why they were not turned on. It wouldn't be the first time someone acknowledged a checklist item without actually performing the action, or confirmed an item as being in accordance with the checklist when it wasn't. I think the Palm Air crash in the river at Washington DC many years ago was one example of exactly that - not pitots but cowl de-icing that affected engine EPR indications. John Link to post Share on other sites
Captain Coffee 2,030 Posted February 15, 2018 Report Share Posted February 15, 2018 Just...wow. So, forgetting that basic detail seems ridiculous...even unbelievable to some extent. Like Alan I turn them on for Every Flight, because it gets cold up there every flight regardless of how warm it is down here. With actual snow on the ground and poor weather ahead all around...I just don't believe it. I agree that human error is possible, but that sounds implausible for even inexperienced pilots in the typically horrendous conditions encountered in winter in Russia. Because we all watch crime dramas and can write a plausible fictionalized account of this event...: (Hello, the reason for this call is we have your lovely daughter Mishka. Say goodbye to your daddy Mishka before his flight dear. We have your attention, good. We have a question for you; would you prefer for her to say goodbye to you, or would you rather say goodbye to her...Leave the pitots off if the former, have a nice flight if the later. Good day comrade. Click) 1 Link to post Share on other sites
allardjd 1,853 Posted February 15, 2018 Report Share Posted February 15, 2018 If you assume that it's not just forgetfulness, inattention, etc, the next most plausible thing, given it's Russia is Vitamin V. John 1 Link to post Share on other sites
Captain Coffee 2,030 Posted February 15, 2018 Report Share Posted February 15, 2018 1 hour ago, allardjd said: If you assume that it's not just forgetfulness, inattention, etc, the next most plausible thing, given it's Russia is Vitamin V. John Vodka..or Vladamir? Link to post Share on other sites
allardjd 1,853 Posted February 16, 2018 Report Share Posted February 16, 2018 Vodka. John Link to post Share on other sites
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