Lion Air crash: Jakarta Boeing 737 'had prior instrument error' - Page 1
Forum section: electronics / general

author: Homer J Simpson
author_rank: Super Contributor
timestamp: October 29, 2018, 07:54:41 pm
content: Will be interesting to see where this goes."A technical log obtained by the BBC from the plane's previous flight suggests that the airspeed reading on the captain's instrument was unreliable, and the altitude readings differed on the captain's and first officer's instruments.""Identified that CAPT [captain's] instrument was unreliable and handover control to FO [first officer]," the log reads. "Continue NNC of Airspeed Unreliable and ALT disagree."https://www.bbc.com/news/world-asia-46022390

author: rx8pilot
author_rank: Super Contributor
timestamp: October 29, 2018, 08:06:21 pm
content: The level of redundancy and fault handling automation in a brand new 737 is pretty amazing -, especially on airspeed and altitude.Patiently waiting to see what happened. I could have been similar to the Air France crash where a relatively minor malfunction led to auto-pilot disconnect and the pilot reacted inappropriately to the situation. Failing gauges in real life are really challenging to understand and react properly.

author: floobydust
author_rank: Super Contributor
timestamp: October 29, 2018, 08:23:48 pm
content: I see 737's have issues with their five(!) pitot tubes as well, going back a few years.http://aviationweek.com/awin/boeing-addresses-pitot-tube-anomaly-its-737sI don't understand why heating a pipe is so difficult to engineer, redundancy doesn't help and there are still crashes happening from a corrupted sensor.Pic "thermal imaging of a partially shorted pitot probe {heater?} shows that heat (red) does not reach the tip, where ice can form and corrupt airspeed measurements". (Credit: Irish Air Accident Investigation Unit)

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 29, 2018, 08:34:11 pm
content: Have not yet enough info on this to get an idea of what would have happened, but I don't agree with the general claim that crashes "happen from a corrupted sensor."That's sometimes the starting point, but almost never the real cause. Unless the plane is already at a very low altitude (on approach for instance) with low visibility, a bad airspeed indication doesn't itself cause a crash. An experienced pilot knows 1/ how to spot a defective pitot when it happens and 2/ that the best way of dealing with it is usually not to do anything until the measurement gets back to normal. Unfortunately, a lot of airline pilots are not as experienced as they used to be or as they should be, and sometimes they will act irrationally on commands until the plane stalls. That's pretty much what happened with the (in)famous Rio-Paris flight, for instance. The reports are all publicly available.

author: rx8pilot
author_rank: Super Contributor
timestamp: October 29, 2018, 08:58:11 pm
content: Unconfirmed information suggests this crew was rather experienced.I had a pitot tube clog on an IFR flight in a single-engine airplane about 10 years ago. The hard part of identifying the problem is that it came on rather slowly. The aircraft only had a single tube, but the pitch, power, altitude, and temp of the aircraft did not agree with the number I was seeing. My reaction was to keep the wings level, the pitch level, and the power constant while I tried to understand what was happening. Once I was pretty sure there was no fixing it - I called ATC to help get me out of the clouds with a very slow decent. All ended well, but much more confusing and intense than my training ever suggested.The systems in a 737 are massively more complex and I believe they have an automatic reversion when a single system is out of agreement. Even if it does not, the identification and response to a pitot/static error or total failure is among the most rehearsed emergency in my experience. Perhaps less so in the heavy iron aircraft with all the redundancy.

author: sokoloff
author_rank: Super Contributor
timestamp: October 29, 2018, 09:09:57 pm
content: Air France 447 was a night flight in heavy rain.Lion 610 was a morning flight in what appears to have been VFR conditions. Yes, there were clouds, but weather was reported good enough (2000-and-5) that student pilots could have been out soloing airplanes in it. You can't comfortably fly a transport jet solely by visual references, but you ought to be able to keep it out of the water, IMO.

author: boffin
author_rank: Unknown
timestamp: October 29, 2018, 09:26:03 pm
content: Quote from: rx8pilot on October 29, 2018, 08:58:11 pmKeep flying the plane in a configuration you know works. That was the experience I was given by two very high time old timers that were my instructors. AFR447 was an example of doing the opposite.I'm sure we'll find out why this plane went down, but all of the people immediate jumping to conclusions is just silly

author: nctnico
author_rank: Super Contributor
timestamp: October 29, 2018, 09:29:52 pm
content: Quote from: SiliconWizard on October 29, 2018, 08:34:11 pmSame here:https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_1951and also a Boeing 737 with faulty sensor readings.

author: floobydust
author_rank: Super Contributor
timestamp: October 29, 2018, 09:39:50 pm
content: There's so many pitot tube incidents. I question the airplane's software algorithms, a pitot tube reading wrong seems to generate alarms that confuses the crew and causes a lethal panic. The software should be able to estimate from the other sensors or roll back to GPS for speed, or just stop issuing a fake airspeed if you know the sensors have failed and can't make a concensus.737"Three of the probes are on the nose for airspeed measurements—for the pilot, the co-pilot, and as a backup—and two are on the vertical stabilizer for the elevator feel-and-centering unit. If the airspeed difference between the pilot and co-pilot probes is greater than 5 kt. for 5 sec. consecutively, the pilots receive an “IAS (indicated airspeed) Disagree” alert. ""A man with a watch knows what time it is. A man with two watches is never sure."You can't take a concensus with two sensors.So captain and co-pilot are lost as to the airplane's true speed but the backup sensor does nothing?

author: jpanhalt
author_rank: Super Contributor
timestamp: October 29, 2018, 10:15:18 pm
content: Quote from: rx8pilot on October 29, 2018, 08:58:11 pmAlmost same thing happened to me in 1975 or so. Piper Arrow. Moral is that airspeed, while very important, is not the only indicator of the aircraft's airspeed.

author: Macbeth
author_rank: Super Contributor
timestamp: October 29, 2018, 10:32:13 pm
content: This plane was brand new, just entered service in August.Apparently Lion are considered shit - possibly even worse than Ryanair if that is even possible, like they actually charge budding pilots money to fly their planes instead of paying them!!But the pilot of this plane was a pro and had at least 6000 hours flying experience.Terrible incident for all involved. Damn. We need answers.

author: jpanhalt
author_rank: Super Contributor
timestamp: October 29, 2018, 10:40:27 pm
content: Quote from: Macbeth on October 29, 2018, 10:32:13 pmSure, just like we got for MH370! Complete disinformation from the authorities who are more interested in their jobs than saving lives.

author: rx8pilot
author_rank: Super Contributor
timestamp: October 29, 2018, 10:52:50 pm
content: Boeing may be the best source of answers on this one. Since the plane is so new - ALL of Boeings customers and the NTSB are going to be asking a pile of questions.

author: EEVblog
author_rank: Unknown
timestamp: October 29, 2018, 10:56:00 pm
content: For those interested in this stuff I highly recommend the book QF32The captain takes you blow by blow through what it's like to get multiple conflicting warnings and whatnothttps://www.amazon.com.au/QF32-author-Life-Lessons-Cockpit-ebook/dp/B007KTLQ5W

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 29, 2018, 10:56:28 pm
content: Quote from: jpanhalt on October 29, 2018, 10:40:27 pmThey found the aircraft, so that seems unlikely. The stakes are much too much for it to be brushed under the carpet.

author: Nusa
author_rank: Super Contributor
timestamp: October 29, 2018, 11:29:41 pm
content: Quote from: floobydust on October 29, 2018, 09:39:50 pmGPS shows ground speed, not air speed. Not entirely useless, but they're usually not the same number.The IAS alert will tell the pilots the left and right numbers don't agree. Odds are one of them is correct, so letting the pilots know the readings is still useful. They have airspeed unreliable procedure, which involves turning off the autopilots and putting the plane in a particular power and pitch setting to maintain airspeed, at least until they evaluate the problem.QuoteThe aux pilot tube is for the ISFD, the backup flight instrument that's self-contained, including internal backup-power in the event the cockpit goes dark. So that's a third airspeed report available to the pilots.I suspect we'll find the cause of the crash is something else entirely. They will find the black boxes, so we will know eventually.

author: boffin
author_rank: Unknown
timestamp: October 30, 2018, 04:42:11 am
content: Quote from: EEVblog on October 29, 2018, 10:56:00 pmWorth watching the episode of "Mayday" about QFA32 too.

author: tautech
author_rank: Super Contributor
timestamp: October 30, 2018, 04:59:03 am
content: Quote from: floobydust on October 29, 2018, 09:39:50 pmYep, especially when the pilots and ground crew on their pre-flight walk arounds can't/don't/won't see the socks placed on them to keep the various mason wasps from building nests in them.Not all parts of the world have this problem but it's bad enough in some locations that covering the pitot tubes is mandatory but easily overlooked in pre-flight checks.

author: Brumby
author_rank: Unknown
timestamp: October 30, 2018, 05:08:02 am
content: Quote from: Nusa on October 29, 2018, 11:29:41 pmI'm no pilot, but I would suggest GPS speed determination would be pretty much useless unless you know the direction and speed of the winds in your location at your flight level.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 30, 2018, 05:09:13 am
content: Quote from: tautech on October 30, 2018, 04:59:03 amThey should make the covers striped fluorescent pink/orange/glow in the dark green balls that are hard to miss, and designed to tear away at typical flight speeds should one be forgotten.

author: tautech
author_rank: Super Contributor
timestamp: October 30, 2018, 06:07:45 am
content: Quote from: NiHaoMike on October 30, 2018, 05:09:13 amWell they do have ribbons on them but apparently that isn't always enough.https://www.aircraftspruce.com/menus/fb/covers_pitot.html

author: Berni
author_rank: Super Contributor
timestamp: October 30, 2018, 06:17:32 am
content: Yep anything that must be removed before flight is tagged bright red. This includes inside the cockpit (Small lanes often physically lock the controls so prevent the wind banging the directly connected control surfaces around)And there have been cases where a pressure sensing port on the side of a plane was covered up with tape to protect it while the plane was washed. But then someone forgot to remove it and nobody noticed it so it caused all sorts of strange readings on the instruments once the plane has taken off.

author: Nusa
author_rank: Super Contributor
timestamp: October 30, 2018, 07:19:03 am
content: Quote from: Brumby on October 30, 2018, 05:08:02 amThat was my point. On the other hand, often one does have at least a ballpark idea of that information, especially when it comes time to land the plane. And ground speed remains useful for navigation purposes.

author: station240
author_rank: Unknown
timestamp: October 30, 2018, 04:51:30 pm
content: Something really has gone wrong with this flight soon after take off.Data fromhttps://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/Graph of entire flight altitude/rate of climbGraph of takeoff altitude/rate of climbFlight is not a smooth climb to flight level, altitude and rate of climb are all over the place.Indicates flight being flown manually.Graph of last minute of flight altitude/rate of climbThis is at what appears on radar maps (and radio comms) to be at the point where the plane was to turn around to return to the airport.-33,000 ft/minute, no chance of survival.I think the altitude values don't show the true horror of what occurredMy guess is the plane in fact attempted the turn while descending rapidly, this caused it to roll over and become impossible to recover from.Various theories about causes, we can rule out engine problems, as planes with no working engines can still fly to some extent.That just leaves:A) pilot actions (combined with faulty instrumentation).B) flight control malfunction or mechanical failure.A is looking very likely, but B could also be involved or the main cause.The crash people should be looking at is Air France Flight 447, where inconsistencies between the airspeed measurements were involved.

author: edy
author_rank: Super Contributor
timestamp: October 30, 2018, 05:20:41 pm
content: I'm not a pilot and have only rudimentary knowledge about this. Hopefully not too much of a noob question.... but if a Pitot tube or aircraft speed sensor was blocked or malfunctioning, it would tell the pilot the aircraft is going too slow? So wouldn't they speed up the airplane? Wouldn't speeding up help keep it flying in the air? I would imagine the reverse would be worse, where the sensor is telling you that you are going fast and you slow down and stall.