sccutler
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 10:20 am

A poster above seems to believe ADS-B out data somehow includes pitot/static-derived data; it does not. The location, speed and altitude information transmitted by ADS-B units (whether 1090ES or the 978UAT) is exclusively GPS-derived.
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osiris30
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 10:34 am

Starlionblue wrote:
osiris30 wrote:
Starlionblue wrote:

As I said above, there is already a system that works, and it works in one step, so to speak. Pitch and power directly give you an airspeed without going the roundabout way from ground speed and an inaccurately forecast wind speed. Airspeed is the only thing that counts when keeping an aircraft flying.

If you don't have precise spot wind data, and you wouldn't without valid Air Data and Inertial Data, GPS only tells you ground speed. A METAR for an airport even ten miles away isn't much use. Same with a wind forecast. Same with a ground speed readout from ATC. Not precise enough to make GPS speed a good enough reference.

From the first lessons as a private pilot, you learn that at trim setting (pitch) x and power setting y the aircraft will stay in level flight, and importantly will come back to level after a disturbance such as a gust. If you're in trim, you can be confident you are flying level, or close enough. In my opinion, this reduces workload quite nicely, and more reliably than a GPS method.

Naturally, after stabilising you could also check GPS data and wind forecasts to see if you're in the ballpark.


Not arguing with you as the physics make perfect sense but am curious why it seems to go wrong so often? (relatively speaking). In aviation we are always trying to improve from best practices. Given today's tech we should be able to better safeguard planes. Even an auto pitch and power button. Something.


Because, as mentioned by INFINITI329, pitot damage can be hard to spot. If a bunch of hornets have decided this would be a neat nesting location you won't see them on a walkaround. And that's one of the reasons some kind of valid airspeed check is done on take-off in everything from a light piston to an airliner.

Pitots by their nature have to be tubes pointed into the wind, and there's crap flying around that can lodge in them, plus icing. If you think about it, the pitot-static system feels a bit agricultural in concept compared to all the solid state tech wizardry we have on board. It is century old tech. Way upthread is a reference to a project developing airspeed measurement without the need for a pitot tube, through some sort of solid state sensing. That would be massively useful.

An auto pitch and power function is an idea. However this would have to be pilot initiated, and if the pilots are going to do something they might as well set pitch and power themselves.

Speaking of automatic backup speed measurement, aircraft like the (newer) 320 and 330 have backup speed scale. If the ADIRUs disagree, the speed scale will revert from pitot-static to a pure AoA scale taken from the AoA vanes. You might not know your exact speed but you know that your AoA is "safe". A great feature. On even newer aircraft like the 350, if the ADIRUs are considered unreliable, the system automatically switches to ISIS data, and if even that is unreliable the system switches to the engine air data system. Yes, engines have their own air data systems.


See those systems are what I am talking about The continuous improvement of systems. As you know that is why aviation is so safe today. I don't accept (nor do I think we should accept) that something is too uncommon to try and fiz provided the fix is reasonable.

With the correct software you could calculate a lot of data off engine performance for example These software changes add no weight and little long term cost.

Not say this is an end of the world thing but I do think we can do better. TY for the constructive discussion.
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osiris30
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 10:38 am

Starlionblue wrote:
Ok, assuming your air data is gone, you have:
- Groundspeed from GPS.
- Altitude from GPS.
- Vertical speed derived from GPS altitude over time.
- Power setting from FADEC.
- Weight from the FM.
- Attitude from the IRs

Thinking about it, maybe you could have an automated system to set pitch and power. And from the resultant groundspeed and the calculated airspeed at that pitch, power and weight you could get a wind speed. Pretty clever.

The problem remains in those situations when the aircraft is "not aware" it has lost good airspeed data. Which is the main problem today anyway. If the system knows it has lost valid air data, it will tell the pilots, who can then apply the proper procedure. If the system doesn't become aware of the issue, that's where things are insidious.


That last part is the easy part. Just compare the two values computed vs read. It is VERY unlikely multiple tubes fail. It is usually just one. With the above method you could easily have the computer decide who is out of spec and disregard it.
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dtw2hyd
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 10:50 am

zeke wrote:
salttee wrote:
The ADS-B Data and the FDR data come from the same source and there is serious doubt about the validity of that source. The radar data is crucial.


SSR radar accuracy is around 0.03 nm and 0.07 degrees in azimuth. The altitude output for the SSR comes from the side selected by the pilots on the TCAS controller in the cockpit. There is no error correction on the data output from the aircraft with this. The radar heads in Jakarta are not properly calibrated, they have the same aircraft coming up as slightly different locations and have had to turn off the collision detection system as the system is seeing the same aircraft as being multiple aircraft.

There were many industry concerns regarding ADS-B data and radar data at the early stages of ADS-B, they installed ADS-B receivers on radar head and compared the ADS-B position data vs the radar data, the ADS-B data had a much better narrow position band, where as radar had "fat tails" like one would expect in a normal distribution found in a statistics textbook.

ADS-B transmits a whole lot of information, these include GPS derived position and altitude. These have an error detection in them, they also publish their navigational accuracy, this is called NIC Navigation Integrity Category. It also transmits what is known as Barometric Altitude Integrity Code (NICbaro), NICbaro compares the various air data sources and transmits the integrity of that data in the ADS-B data block.

ADS-B also transmits a whole range of other information such as the speed, heading, and altitude selected by the pilots in the MCP, the active waypoint in the FMC, if the autopilot is on or off, and the air data computer barometric data such as displayed IAS, pressure altitude, and V/S. Depending on the aircraft it will also transmit the geometric (GPS) derived speed, track, and altitude.

If you are interested in seeing what is exactly transmitted by ADS-B I would download FAA AC 20-165 and a few cups of coffee as it is not a short read full of technical information.


GPS by itself doesn't have error correction ability, it needs a satellite(SBAS) or ground(WAAS) based augmentation system. Not sure if Indonesia has those.

The ADS-B data block error correction is to make sure what transmitted is not corrupted during the transmission, ability to the receiver to verify. Doesn't help if bad data values are fed to ADS-B transmitter.

Am I missing anything?
 
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zeke
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 11:14 am

dtw2hyd wrote:
GPS by itself doesn't have error correction ability, it needs a satellite(SBAS) or ground(WAAS) based augmentation system. Not sure if Indonesia has those.

The ADS-B data block error correction is to make sure what transmitted is not corrupted during the transmission, ability to the receiver to verify. Doesn't help if bad data values are fed to ADS-B transmitter.

Am I missing anything?


The MMR does the work, it also does the same monitoring for RNAV routes, RNP(AR) approaches. Just like WAAS in a GA aircraft. They supply the position integrity to the Fm and transponder even without augmentation.
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WIederling
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 11:41 am

osiris30 wrote:
That last part is the easy part. Just compare the two values computed vs read. It is VERY unlikely multiple tubes fail. It is usually just one. With the above method you could easily have the computer decide who is out of spec and disregard it.


You don't catch "environment conditions are out of spec for the sensor".
( potentially AF447: if you leave the specced environment all sensors will return faulty results in unison.
All sensors agree but are wrong.)
Murphy is an optimist
 
ranold76
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 11:57 am

A3801000 wrote:
From Sky News Twitter account, just now:

'Investigators say the "black box" flight recorder recovered after a plane crash in Indonesia shows four of the Lion Air jet's flights had experienced problems with the airspeed indicator'

https://twitter.com/SkyNewsBreak/status ... 0734306305


So.... was it even looked at and repaired by Lion Air maintenance?
If this was systematic, you would think this issue would of reared it's ugly head in other aircraft operators etc.
It seems pretty unique to Lion Air.. no?
 
dtw2hyd
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 12:10 pm

zeke wrote:
dtw2hyd wrote:
GPS by itself doesn't have error correction ability, it needs a satellite(SBAS) or ground(WAAS) based augmentation system. Not sure if Indonesia has those.

The ADS-B data block error correction is to make sure what transmitted is not corrupted during the transmission, ability to the receiver to verify. Doesn't help if bad data values are fed to ADS-B transmitter.

Am I missing anything?


The MMR does the work, it also does the same monitoring for RNAV routes, RNP(AR) approaches. Just like WAAS in a GA aircraft. They supply the position integrity to the Fm and transponder even without augmentation.


I am still confused, anyone with a USB stick receiver and a laptop is collecting and feeding FR24 likes. Where does MMR come into play?

Are we venturing into ADS-C territory?
 
kalvado
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 12:23 pm

osiris30 wrote:
Starlionblue wrote:
Ok, assuming your air data is gone, you have:
- Groundspeed from GPS.
- Altitude from GPS.
- Vertical speed derived from GPS altitude over time.
- Power setting from FADEC.
- Weight from the FM.
- Attitude from the IRs

Thinking about it, maybe you could have an automated system to set pitch and power. And from the resultant groundspeed and the calculated airspeed at that pitch, power and weight you could get a wind speed. Pretty clever.

The problem remains in those situations when the aircraft is "not aware" it has lost good airspeed data. Which is the main problem today anyway. If the system knows it has lost valid air data, it will tell the pilots, who can then apply the proper procedure. If the system doesn't become aware of the issue, that's where things are insidious.


That last part is the easy part. Just compare the two values computed vs read. It is VERY unlikely multiple tubes fail. It is usually just one. With the above method you could easily have the computer decide who is out of spec and disregard it.

What we are talking about is a data sanity/integrity check. I would be more than surprised if there are no extensive data verification in modern systems.
A small problem with the system described above is that GPS is owned and operated by US Air Force, and civilian users are provided with access as a courtesy, without any warranties. Moreover, GPS signal is fairly weak and can be altered by the system operator or spoofed by the third party. So aircraft which over-relies on GPS may be considered unsafe for operations.
The other isde of the coin is reliance on automation. Pilot inability to properly respond to situations which cannot be handled by automation is reduced as automation becomes better. There is plainly less experience for the human to be collected.. So I am actually fine with idea that autopilot should have some soft fallback insead of full disconnect - just to give pilots some time to come up to speed with the problem in progress. There may be more fine print here, though.
 
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SomebodyInTLS
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 12:37 pm

michi wrote:
Regarding AF447: I have read the report. Nevertheless when I chat with people about aviation, a lot of them think, that AF447 flew directly into a thunderstorm. Of course, this is not the public. But still, there are people out there believing this untrue part of the story which was made up by some media or whomever.


There was a very irresponsible and sensationalist Horizon TV programme by BBC / PBS which claimed that the whole thing was down to a new type of weather phenomenon stemming from 20th century pollution which, under the right conditions, resulted in sudden and unexpected ice build-op on all frontal surfaces.

I thought it was bollocks at the time and sure enough - ironically only a few weeks later - AF447 was found and the true cause quickly transpired. I never heard of any kind of retraction or apology.

Horizon in the 1970s and 1980s used to be a real science programme, but with the PBS tie-up in the 1990s it became "human interest" tripe concentrating mostly on the current US instead of international / historical stories. The tag-line they introduced at the time: "pure science, sheer drama" was the tipping point for me to stop watching completely(*)... (Since I was a little kid, I had watched every episode I could before that!)

This is the kind of fake news you talk about!

(*) Obviously, with the topic being AF447 I had to see what they said that time. And was disgusted.
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mandala499
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 12:41 pm

zeke wrote:
The corkscrew motion I mentioned previously can been seen in the track from around the 500 second mark (relative to 2018-10-28 23:21:00Z). Vmo (red horizontal line is at 340 KTAS where Vmo is technically 340 KCAS) was almost reached in the turn after takeoff, TAS increased until it passed Vmo in the terminal dive.

Thanks for this Zeke!!!! The track heading is a concern... And that "corkscrew" is scary. It looks like a real corkscrew or the aircraft's roll was poorly controlled... but it does look like the former.

salttee wrote:
he radar data most certainly will provide accurate ground speeds The radar data will also be very likely to show if there was an attempt to turn before the descent.

Yes, at low sample rates. Raw ADS-B data provide higher sample rates for the ground speeds. Zeke's data shows that. There are other ADS-B systems that can capture much higher data rates sent by the aircraft. NTSC has these data, and also the radar data.

michi wrote:
Quite the opposite. Pilots must learn from accidents! But they need to know the whole picture. Early speculation does't help at all. It is not the concept of secrecy but of total understanding.
Basarnas did a good job investigating the Air Asia crash. A lot was learnt. Airbus changed their inflight reset procedures. Quite a big step with a big impact.

BASARNAS is the SAR agency.
The accident investigating agency is KNKT (or NTSC in English).
The NTSC report into Air Asia 8501 revealed the cause, and recommendations were made and they're in place with the airlines here too.

michi wrote:
I don't think that the radar data will help with the Lion Air crash, as the ADS-B Data is quite ok. Zeke did a good job in visualising this data. Nevertheless the cause of the crash is still unknown.

ADS-B data and radar plot data is already with the NTSC. The raw ADS-B data is usually of still higher density than what is available to the public through the various websites.

kalvado wrote:
Actually, GPS does provide altitude data in case of at least 4 available satellites (general purpose receiver normally sees 8-10)
Of course, this is geometric altitude above some model sea level, not barometric altitude used by airplane navigation - but this is tens feet, maybe 100-200' discrepancy, far from "won't tell anything"

And if I remember correctly, that GPS altitude is also transmitted.

michi wrote:
FDR has been read out. 1800 paramters from 19 flights.

1790 parameters for 69 hours consisting of 19 flights.

salttee wrote:
The tower radar at Soekarno-Hatta probably is a PAR radar. That's the way they make them now. They mount the phased array xmitter on top of the turntable.

Really? I didn't see one when I was there a few months ago. Just a secondary radar repeater screen, and a ground radar (and ground MLAT) display. My friends who work as controllers there or at approach don't even know what a PAR radar is.

And no, no primary radar at CGK airport. Just secondary radar.

dtw2hyd wrote:
Didn't Indonesia waste a lot of initial SAR time solely depending on ADS-B during Air Asia accident.

Just an opinion, don't ask for evidence.

We did! Because everyone believed the FR24 ADS-B displayed data which includes projected positions that last for a while in the event of a loss of signal... So people believed that, instead of downloading the tabulated data, or just call up ATC ask for the raw ADS-B data (which managed to capture the aircraft's signal down to 18000ft or so) or yeah, even the radar data (whose data refresh rate was so low it couldn't pick up the aircraft doing whatever it did in circles or something...
That projected data from FR24 caused problems, similar in what it did to MH370 in the initial stages at the airline ops.
My time since then has a bit of it been spent on getting SAR, airlines and ATC to understand what FR24 projected data means... plus ended up developing something else that's ADS-B based. :)

osiris30 wrote:
but in this instance a backup flight mode based on GPS for auto pilot and throttle could help out an awful lot in situations like this.

So, let's say you've lost airspeeds at low altitude after take off, and you have a 50kt headwind... do you think you're at V2 climb speed with Ground Speed, but hey, don't be startled of your flaps rip off or jam due to overpseed...
Now if you make that a 50kt tailwind when maneuvering to shoot an approach after the mishap... I hope you know your stall recovery procedure. :)
Better solution: Pitch and power, once stabilized, open those damned QRH table!!!!!!

salttee wrote:
Because the information Zeke is working with (ADS-B data) was derived from the planes' airspeed indicator system, the pitot tube / static port system which was the system which had been reported to have experienced a failure on the previous leg for that aircraft. So it is entirely possible that Zeke is depending on the same information that led to the crash in the first place.

Your ground speed from ADS-B doesn't use the aircraft's pitot-static system.. Your Lat/Lon from ADS-B does not need the pitot-static system. Newer ADS-B transponders can send GPS altitude in addition to the barometric altitude. The ATC radar in Jakarta is SSR only and will detect the same barometric altitude as the aircraft's.

And yes, the intermitten failure could very well be cuased by an intermittenly bad connection, such as a bad weld... just like the Air Asia crash...

sccutler wrote:
The location, speed and altitude information transmitted by ADS-B units (whether 1090ES or the 978UAT) is exclusively GPS-derived.

If only he would listen!

----

Anyways... Based on the latest press conference:
- Aircraft did not break up mid-air.
- Engines were running on impact.
- NTSC has stated they will make interim information releases. They have been criticized in the past for not doing this... causing information leakages which are uncontrolled.
- 1790 parameters over 69 hours.
- Initial FDR analysis will take 1-2 weeks.
- CVR pings are reported to be "in and out" through this afternoon's search dives.
- 4 last flights showed unreliable airspeed. They did not go into details.
- NTSC has interviewed flight crew of the last 3 flights that were successfully completed.
- NTSC has also interviewed the engineers who fixed the problems after each of those 3 flights.
- Immediate recommendation have been released to NTSC and Boeing to check and investigate this as a potential widespread issue.

On a personal front, I received messages from the BBC journalist that the misquote has been removed. (She misunderstood what I said, her colleague pointed that out because she heard the phone interview too).

Cheers everyone...
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
Amiga500
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 12:56 pm

There are other alternatives to approximately measuring air speed on the aircraft than a pitot static tube.

Even sticking a sprung drag fin into the airstream and measuring its deflection will give you a rough idea. Or deploying (in a similar manner to the RAT) a drag chute and measure the load on the cable. Both could be deployed and retracted from the cockpit and provide vital sanity checks to PS data.

There are ways and means. Unfortunately instinct has many reaching for a more elegant and complex solution than quick and dirty.
 
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zeke
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 1:16 pm

dtw2hyd wrote:
I am still confused, anyone with a USB stick receiver and a laptop is collecting and feeding FR24 likes. Where does MMR come into play?

Are we venturing into ADS-C territory?


ADS-C means contract, a link established betweeen ATC and the aircraft, not relevant here.

The MMR is the multi mode receiver which is the fancy ILS/GLS/GPS receiver found on airliners. It supplies among other items the GPS position and position integrity to the aircraft and the transponder. Within the ADS-B transmission the position integrity is also transmitted. ATC use this position integrity to change the separation requirements when the position integrity reduces.

The amount of data transmitted by ADS-B is significant, it is a lot more than what FR24 etc decode.
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osiris30
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 1:19 pm

mandala499 wrote:

osiris30 wrote:
but in this instance a backup flight mode based on GPS for auto pilot and throttle could help out an awful lot in situations like this.

So, let's say you've lost airspeeds at low altitude after take off, and you have a 50kt headwind... do you think you're at V2 climb speed with Ground Speed, but hey, don't be startled of your flaps rip off or jam due to overpseed...
Now if you make that a 50kt tailwind when maneuvering to shoot an approach after the mishap... I hope you know your stall recovery procedure. :)
Better solution: Pitch and power, once stabilized, open those damned QRH table!!!!!!

Cheers everyone...


It is amusing to see resistance to more cockpit automation from pilots. The arguments remind me of the same ones rhat were made against auto-land technlogoy, auto pilot, auto throttle, auto trim, fbw, etc. In short: What we have now works, don't change it. (not a shot, but genuinely ask yourself if you are giving an idea a chance or shooting it down because... reasons...)

Someone like yourself must surely see the benefit of providing more help. Everything you pointed out as a reason the idea would be bad would be problematic regardless of system. Pitch and power with a sudden 50kt tailwind on approach at low altitude would probably mean you go smack anyway.

Also read the rest of the discussion. Turns out with a bit of math and a bit of brains it might not to the dumbest idea ever. Certainly I would be all for anything that frees up the crew's time to troubleshoot an issue. At one time the concept of autopilot would have seemed like the dumbest thing in the world and the arguments would have been similar.
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kalvado
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 1:42 pm

osiris30 wrote:
mandala499 wrote:

osiris30 wrote:
but in this instance a backup flight mode based on GPS for auto pilot and throttle could help out an awful lot in situations like this.

So, let's say you've lost airspeeds at low altitude after take off, and you have a 50kt headwind... do you think you're at V2 climb speed with Ground Speed, but hey, don't be startled of your flaps rip off or jam due to overpseed...
Now if you make that a 50kt tailwind when maneuvering to shoot an approach after the mishap... I hope you know your stall recovery procedure. :)
Better solution: Pitch and power, once stabilized, open those damned QRH table!!!!!!

Cheers everyone...


It is amusing to see resistance to more cockpit automation from pilots. The arguments remind me of the same ones rhat were made against auto-land technlogoy, auto pilot, auto throttle, auto trim, fbw, etc. In short: What we have now works, don't change it. (not a shot, but genuinely ask yourself if you are giving an idea a chance or shooting it down because... reasons...)

Someone like yourself must surely see the benefit of providing more help. Everything you pointed out as a reason the idea would be bad would be problematic regardless of system. Pitch and power with a sudden 50kt tailwind on approach at low altitude would probably mean you go smack anyway.

Also read the rest of the discussion. Turns out with a bit of math and a bit of brains it might not to the dumbest idea ever. Certainly I would be all for anything that frees up the crew's time to troubleshoot an issue. At one time the concept of autopilot would have seemed like the dumbest thing in the world and the arguments would have been similar.


It is not about automation, I would say. this is about perception difference between those in the air for hundreds of hours a year and those who leave the ground on rare occasions.
GPS is a great tool - with its limitations. One of the limitations is that it provides all the information with respect to the ground, while the plane moves with respect to the air. And the difference, as far as I understand, is much bigger than most people realize. It is probably GPS road navigation that makes many people feel GPS is the greatest thing ever...
But in the air, GPS can be only secondary, if not tertiary tool.
There was a link somewhere upthread to some research on optical standby instrument to obtain some air data when pitots are dead. That is more inline with the concept of measuring plane to air interaction.
 
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novarupta
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 2:28 pm

kalvado wrote:
osiris30 wrote:
Starlionblue wrote:
Ok, assuming your air data is gone, you have:
- Groundspeed from GPS.
- Altitude from GPS.
- Vertical speed derived from GPS altitude over time.
- Power setting from FADEC.
- Weight from the FM.
- Attitude from the IRs

Thinking about it, maybe you could have an automated system to set pitch and power. And from the resultant groundspeed and the calculated airspeed at that pitch, power and weight you could get a wind speed. Pretty clever.

The problem remains in those situations when the aircraft is "not aware" it has lost good airspeed data. Which is the main problem today anyway. If the system knows it has lost valid air data, it will tell the pilots, who can then apply the proper procedure. If the system doesn't become aware of the issue, that's where things are insidious.


That last part is the easy part. Just compare the two values computed vs read. It is VERY unlikely multiple tubes fail. It is usually just one. With the above method you could easily have the computer decide who is out of spec and disregard it.

What we are talking about is a data sanity/integrity check. I would be more than surprised if there are no extensive data verification in modern systems.
A small problem with the system described above is that GPS is owned and operated by US Air Force, and civilian users are provided with access as a courtesy, without any warranties. Moreover, GPS signal is fairly weak and can be altered by the system operator or spoofed by the third party. So aircraft which over-relies on GPS may be considered unsafe for operations.
The other isde of the coin is reliance on automation. Pilot inability to properly respond to situations which cannot be handled by automation is reduced as automation becomes better. There is plainly less experience for the human to be collected.. So I am actually fine with idea that autopilot should have some soft fallback insead of full disconnect - just to give pilots some time to come up to speed with the problem in progress. There may be more fine print here, though.



Remember you have other GNSS service providers such as GLONASS and GALILEO...the USAF system isn’t the only one.


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dragon6172
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 2:50 pm

ranold76 wrote:
A3801000 wrote:
From Sky News Twitter account, just now:

'Investigators say the "black box" flight recorder recovered after a plane crash in Indonesia shows four of the Lion Air jet's flights had experienced problems with the airspeed indicator'

https://twitter.com/SkyNewsBreak/status ... 0734306305


So.... was it even looked at and repaired by Lion Air maintenance?
If this was systematic, you would think this issue would of reared it's ugly head in other aircraft operators etc.
It seems pretty unique to Lion Air.. no?

Just because the FDR shows airspeed problems on previous flights doesn't mean maintenance was aware of it. As a mechanic I can tell you I can't fix things the pilots don't tell me about. We know there was a problem on the immediate previous flight because of the maintenance log. I would imagine if there were three other maintenance events those logs would have been mentioned at some point already also. It could be that the other 3 events were so minor that the pilots didn't notice, but that the FDR recorded.

I am interested in the "Note" from the previous flights pilot about the STS running the wrong way. Could this be something that caught the pilots off guard?

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estorilm
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 2:53 pm

packsonflight wrote:
Starlionblue wrote:
seahawk wrote:


i did not mention the 330 checklist, I never saw it, but the Boeing checklist is 4 pages with no tables and pitch and power memory items in the front. I am saying that only after AF447 the philosophy changed in the industry and the pitch and power memory ithem is added to the checklist. In my opinion sole reliance on pitch and power is the only way to keep aircraft like Lionair safe, but you have to apply this method right away.

Regarding the thech log pages circling the internet. I never saw a tech log page with out printed number sequence for each page


As I mentioned earlier - I think all current A330 builds have the BUSS system as standard. Once you turn off all the air data reference computers, you get the speed scale on the PFD and simply "fly the green" on the speed tape.

I suppose you said an aircraft "like Lionair" so you would be true, but I still think it's such a brilliant safety feature that it deserves some more attention. :)

As far as it being so unbelievable that they'd fail a good cross-check and continue the flight, didn't that happen with a 757 a while back? Pitch and power is one of those things that sounds great in front of a computer, but is probably not a situation where I'd volunteer to be a passenger in that situation and say "yeah, they've got this.."


...as far as this plane being dispatched after four previous flights with unreliable airspeed, my jaw is still on the floor. It's not like they were getting a faulty brake temp indication on one of a hundred sensors or something, or a panel bulb failed was doing something strange. Sounds like normalization of deviance may be a serious issue with Lionair's mx group - imagine that. "someone else will fix it" or "it flew fine with the same fault on the last three flights" etc.

Just horrible. :(
 
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seahawk
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 3:12 pm

kalvado wrote:
osiris30 wrote:
mandala499 wrote:


So, let's say you've lost airspeeds at low altitude after take off, and you have a 50kt headwind... do you think you're at V2 climb speed with Ground Speed, but hey, don't be startled of your flaps rip off or jam due to overpseed...
Now if you make that a 50kt tailwind when maneuvering to shoot an approach after the mishap... I hope you know your stall recovery procedure. :)
Better solution: Pitch and power, once stabilized, open those damned QRH table!!!!!!

Cheers everyone...


It is amusing to see resistance to more cockpit automation from pilots. The arguments remind me of the same ones rhat were made against auto-land technlogoy, auto pilot, auto throttle, auto trim, fbw, etc. In short: What we have now works, don't change it. (not a shot, but genuinely ask yourself if you are giving an idea a chance or shooting it down because... reasons...)

Someone like yourself must surely see the benefit of providing more help. Everything you pointed out as a reason the idea would be bad would be problematic regardless of system. Pitch and power with a sudden 50kt tailwind on approach at low altitude would probably mean you go smack anyway.

Also read the rest of the discussion. Turns out with a bit of math and a bit of brains it might not to the dumbest idea ever. Certainly I would be all for anything that frees up the crew's time to troubleshoot an issue. At one time the concept of autopilot would have seemed like the dumbest thing in the world and the arguments would have been similar.


It is not about automation, I would say. this is about perception difference between those in the air for hundreds of hours a year and those who leave the ground on rare occasions.
GPS is a great tool - with its limitations. One of the limitations is that it provides all the information with respect to the ground, while the plane moves with respect to the air. And the difference, as far as I understand, is much bigger than most people realize. It is probably GPS road navigation that makes many people feel GPS is the greatest thing ever...
But in the air, GPS can be only secondary, if not tertiary tool.
There was a link somewhere upthread to some research on optical standby instrument to obtain some air data when pitots are dead. That is more inline with the concept of measuring plane to air interaction.


The Autopilot would do what the pilots would do, fly pitch and power, just without the need for a checklist and with the data programmed into the system. The system would also know a theoretical airspeed with no wind, the difference to the GPS speed would then give you the wind speed. Both combined can be used to calculate a theoretical true airspeed, which then can be checked against the data sensors and highlight the most likely faulty one. Airbuses already have a back up speed scale that basically works that way, just with AP off.
 
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trpmb6
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 3:17 pm

Starlionblue wrote:
Ok, assuming your air data is gone, you have:
- Groundspeed from GPS.
- Altitude from GPS.
- Vertical speed derived from GPS altitude over time.
- Power setting from FADEC.
- Weight from the FM.
- Attitude from the IRs

Thinking about it, maybe you could have an automated system to set pitch and power. And from the resultant groundspeed and the calculated airspeed at that pitch, power and weight you could get a wind speed. Pretty clever.

The problem remains in those situations when the aircraft is "not aware" it has lost good airspeed data. Which is the main problem today anyway. If the system knows it has lost valid air data, it will tell the pilots, who can then apply the proper procedure. If the system doesn't become aware of the issue, that's where things are insidious.


Need to be careful when designing a system based on data that is not real time. It's one of the reasons Pitot tubes are still used, it's a direct measurement at that specific moment in time. Ground speed data and vertical speed determined via GPS is derived from moments of time that happened in the past, and not a direct reflection of the current situation. Though, it is certainly fair to say they represent a trend and can offer valuable insight into your current situation. But I don't believe you should build a system that relies on this data due to the feedback loop potential. Have it available in the event that airspeed data is unavailable or unreliable, yes, but that's about it IMO.

(This ignores of course the issues with airspeed vs ground speed and density altitude vs true altitude)
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 3:31 pm

dragon6172 wrote:
[I am interested in the "Note" from the previous flights pilot about the STS running the wrong way. Could this be something that caught the pilots off guard?


From speaking to people who fly them the direction seems counterintuitive at times.
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Erebus
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 3:40 pm

mandala499 wrote:
- CVR pings are reported to be "in and out" through this afternoon's search dives.


Data recorder recovery continues to be challenging even after years of discussions on improving the technology.

Amiga500 wrote:
Or deploying (in a similar manner to the RAT) a drag chute and measure the load on the cable. Both could be deployed and retracted from the cockpit and provide vital sanity checks to PS data.


That's an interesting concept. Can the RAT itself be modified in any way to derive airpseed data as a backup?
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 4:34 pm

mandala499 wrote:
zeke wrote:
The corkscrew motion I mentioned previously can been seen in the track from around the 500 second mark (relative to 2018-10-28 23:21:00Z). Vmo (red horizontal line is at 340 KTAS where Vmo is technically 340 KCAS) was almost reached in the turn after takeoff, TAS increased until it passed Vmo in the terminal dive.

Thanks for this Zeke!!!! The track heading is a concern... And that "corkscrew" is scary. It looks like a real corkscrew or the aircraft's roll was poorly controlled... but it does look like the former.

salttee wrote:
he radar data most certainly will provide accurate ground speeds The radar data will also be very likely to show if there was an attempt to turn before the descent.

Yes, at low sample rates. Raw ADS-B data provide higher sample rates for the ground speeds. Zeke's data shows that. There are other ADS-B systems that can capture much higher data rates sent by the aircraft. NTSC has these data, and also the radar data.

michi wrote:
Quite the opposite. Pilots must learn from accidents! But they need to know the whole picture. Early speculation does't help at all. It is not the concept of secrecy but of total understanding.
Basarnas did a good job investigating the Air Asia crash. A lot was learnt. Airbus changed their inflight reset procedures. Quite a big step with a big impact.

BASARNAS is the SAR agency.
The accident investigating agency is KNKT (or NTSC in English).
The NTSC report into Air Asia 8501 revealed the cause, and recommendations were made and they're in place with the airlines here too.

michi wrote:
I don't think that the radar data will help with the Lion Air crash, as the ADS-B Data is quite ok. Zeke did a good job in visualising this data. Nevertheless the cause of the crash is still unknown.

ADS-B data and radar plot data is already with the NTSC. The raw ADS-B data is usually of still higher density than what is available to the public through the various websites.

kalvado wrote:
Actually, GPS does provide altitude data in case of at least 4 available satellites (general purpose receiver normally sees 8-10)
Of course, this is geometric altitude above some model sea level, not barometric altitude used by airplane navigation - but this is tens feet, maybe 100-200' discrepancy, far from "won't tell anything"

And if I remember correctly, that GPS altitude is also transmitted.

michi wrote:
FDR has been read out. 1800 paramters from 19 flights.

1790 parameters for 69 hours consisting of 19 flights.

salttee wrote:
The tower radar at Soekarno-Hatta probably is a PAR radar. That's the way they make them now. They mount the phased array xmitter on top of the turntable.

Really? I didn't see one when I was there a few months ago. Just a secondary radar repeater screen, and a ground radar (and ground MLAT) display. My friends who work as controllers there or at approach don't even know what a PAR radar is.

And no, no primary radar at CGK airport. Just secondary radar.

dtw2hyd wrote:
Didn't Indonesia waste a lot of initial SAR time solely depending on ADS-B during Air Asia accident.

Just an opinion, don't ask for evidence.

We did! Because everyone believed the FR24 ADS-B displayed data which includes projected positions that last for a while in the event of a loss of signal... So people believed that, instead of downloading the tabulated data, or just call up ATC ask for the raw ADS-B data (which managed to capture the aircraft's signal down to 18000ft or so) or yeah, even the radar data (whose data refresh rate was so low it couldn't pick up the aircraft doing whatever it did in circles or something...
That projected data from FR24 caused problems, similar in what it did to MH370 in the initial stages at the airline ops.
My time since then has a bit of it been spent on getting SAR, airlines and ATC to understand what FR24 projected data means... plus ended up developing something else that's ADS-B based. :)

osiris30 wrote:
but in this instance a backup flight mode based on GPS for auto pilot and throttle could help out an awful lot in situations like this.

So, let's say you've lost airspeeds at low altitude after take off, and you have a 50kt headwind... do you think you're at V2 climb speed with Ground Speed, but hey, don't be startled of your flaps rip off or jam due to overpseed...
Now if you make that a 50kt tailwind when maneuvering to shoot an approach after the mishap... I hope you know your stall recovery procedure. :)
Better solution: Pitch and power, once stabilized, open those damned QRH table!!!!!!

salttee wrote:
Because the information Zeke is working with (ADS-B data) was derived from the planes' airspeed indicator system, the pitot tube / static port system which was the system which had been reported to have experienced a failure on the previous leg for that aircraft. So it is entirely possible that Zeke is depending on the same information that led to the crash in the first place.

Your ground speed from ADS-B doesn't use the aircraft's pitot-static system.. Your Lat/Lon from ADS-B does not need the pitot-static system. Newer ADS-B transponders can send GPS altitude in addition to the barometric altitude. The ATC radar in Jakarta is SSR only and will detect the same barometric altitude as the aircraft's.

And yes, the intermitten failure could very well be cuased by an intermittenly bad connection, such as a bad weld... just like the Air Asia crash...

sccutler wrote:
The location, speed and altitude information transmitted by ADS-B units (whether 1090ES or the 978UAT) is exclusively GPS-derived.

If only he would listen!

----

Anyways... Based on the latest press conference:
- Aircraft did not break up mid-air.
- Engines were running on impact.
- NTSC has stated they will make interim information releases. They have been criticized in the past for not doing this... causing information leakages which are uncontrolled.
- 1790 parameters over 69 hours.
- Initial FDR analysis will take 1-2 weeks.
- CVR pings are reported to be "in and out" through this afternoon's search dives.
- 4 last flights showed unreliable airspeed. They did not go into details.
- NTSC has interviewed flight crew of the last 3 flights that were successfully completed.
- NTSC has also interviewed the engineers who fixed the problems after each of those 3 flights.
- Immediate recommendation have been released to NTSC and Boeing to check and investigate this as a potential widespread issue.

On a personal front, I received messages from the BBC journalist that the misquote has been removed. (She misunderstood what I said, her colleague pointed that out because she heard the phone interview too).

Cheers everyone...


Dang!!! I just love this guy Mandala499!!! Glad to see the BBC correct the quote. That's kind of unheard of in today's media!

As for the pings on the CVR. How much longer can we expect the CVR to release those? Isnt it a required 30 day battery supply to keep the ping system going?
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dtw2hyd
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 4:44 pm

I think CVR ping is a moot point at this stage, once main wreckage is found, CVR will be there. Unless shark ate my CVR!!!
Last edited by dtw2hyd on Mon Nov 05, 2018 4:45 pm, edited 1 time in total.
 
pygmalion
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 4:44 pm

Its a minimum of 30 days with a "worn" battery.. since this airplane was so new... I would expect a much longer time.
 
hivue
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 4:47 pm

Erebus wrote:
Amiga500 wrote:
Or deploying (in a similar manner to the RAT) a drag chute and measure the load on the cable. Both could be deployed and retracted from the cockpit and provide vital sanity checks to PS data.


That's an interesting concept. Can the RAT itself be modified in any way to derive airpseed data as a backup?


Do you really want to purposely be hanging draggy stuff out in the airstream in situations like this?
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cat3appr50
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 4:55 pm

Just to be clear, relative to the KNKT breaking comments being reported (after preliminary investigation of the DFDR data) regarding damage to the JT610 accident flight airspeed indicator, it is specifically relative to the last four JT flights of THIS SPECIFIC 737 Max 8 aircraft, registration number PK-LQP, and not with any other 737 Max 8. Some forum comments are erroneously implying issues with this specific aircraft model. Stick to the facts. In addition, IMO “tweets” from KNKT seem inappropriate. They should be specific comments either in a public media forum/announcement or on a KNKT formal company document in writing. Just my opinion.
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 5:01 pm

From not entirely analogous situations: in my quite small boat I have GPS, radar, AIS, and some smart phone location and some other vessel sensing. These are 4 almost entirely independent systems. All quite comforting when going through a heavy fog bank (which I usually successfully avoid). A recent fatal railroad accident happened because the engineer did not know where he was. For some strange bureaucratic reasoning RRs don't have GPS in locomotives - they rely on computers and central control from a person thousands of miles away. My point, a small independent GPS showing ground speed, heading, location, elevations (for aviation) seems to me essential for any sort of transportation. As a backup system it does not require a lot of attention, and what it does do very well is provide quick rough estimates of what you are doing. If it shows something far different from what you were expecting it is a warning that your are in trouble, and gives some information about getting out of trouble.
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 5:26 pm

frmrCapCadet wrote:
... GPS, radar, AIS, and some smart phone location and some other vessel sensing. These are 4 almost entirely independent systems..


AIS is worthless without the GPS position and thus a working GPS system.
AIS transponder sends GPS position ( preferably a dedicated unit ) and for class A additional stuff like heading, speed, rot, .. )
AIS data received needs local GPS position to compute things like CPA, TCPA and bearing to each target, ... all that funny stuff.
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 5:33 pm

Here's what sticks out to me. The pilots seem to have successfully controlled the aircraft once they hit 5000 feet for a reasonable length of time before something catastrophic happened.

Perhaps they finally decided that it was time to make their turn maneuver to return back, and in doing so may have caused the corkscrew type motion that was shown earlier in the thread?
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 5:51 pm

hivue wrote:
Erebus wrote:

That's an interesting concept. Can the RAT itself be modified in any way to derive airpseed data as a backup?


Do you really want to purposely be hanging draggy stuff out in the airstream in situations like this?


Why not? In the situation being discussed, you have two working engines that can be adjusted to maintain a stable flight. I'd think that drag is less of a concern here than in the actual scenario where the RAT comes into play, that is having no thrust and as a consequence, losing altitude.
 
amishfarmer
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 5:52 pm

I'm not familiar with the 737's pitot static systems but I have experience being a maintainer/flight mech for many years. If memory serves the checklist for faulty/irregular airspeed indications is to switch to another Air Data Computer and see if the indications agree. This is on military aircraft but I assume the new 737 has a way to do that as well. If you select a different ADC that should allow you to isolate faulty sensors and continue to fly the aircraft to either RTB or destination at captains choice.
Can anyone enlighten me on this pertaining to the 737? If this has been addressed already sorry for repeating it. I haven't had time to read all 17 pages throughly.
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 6:03 pm

Hi, my first question here....also not a native speaker, so sorry for my language
I assume that the information about the problems on previous flights together with the repair report was correctly passed to the flight crew, so they were mentally prepared that the fix may be insufficient and may occur again ( maybe they did a briefing about the exact situation that finally happened), how really "difficult" is to fail pitch&power flying even if you are prepared for it? Not stressed by the unexpected situation with a nice weather?
Or, from the opposite point of view, is it possible that another issue occured and they interpreted it incorrectly as a reappeared problem that resulted in wrong decisions?
 
BravoOne
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 6:23 pm

Slightly off topic but just learned that these crews are trained by Airbus under contract to Lyon Air. No reason to believe that this has any bearing on the cause of the accident.
 
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zeke
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 7:32 pm

BravoOne wrote:
Slightly off topic but just learned that these crews are trained by Airbus under contract to Lyon Air. No reason to believe that this has any bearing on the cause of the accident.


I could believe Airbus training the JT crew for their A330s, however not for the 737s.
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 8:08 pm

zeke wrote:
BravoOne wrote:
Slightly off topic but just learned that these crews are trained by Airbus under contract to Lyon Air. No reason to believe that this has any bearing on the cause of the accident.


I could believe Airbus training the JT crew for their A330s, however not for the 737s.


Business is business. Boeing use to operate a couple of AB sims for a customer that had both AB and some Boeing airplanes as well.
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 8:10 pm

frmrCapCadet wrote:
For some strange bureaucratic reasoning RRs don't have GPS in locomotives - they rely on computers and central control from a person thousands of miles away.


Trains run on tracks on the ground. It's a one-dimensional mode of transportation. GPS is not really necessary.

RR's have a lot of technology that you probably don't know about. In a modern system (and not every railroad is very modern, but most are), both the engineer and dispatcher know exactly where any train is at any given time. In most cases, they know where each *wheel* on the train is at any given time. This is accomplished with sensors on both the train and embedded in the track.

Not to mention that engineers are required to be familiar with their routes before ever taking control of a train on that route. This is not necessarily the case for pilots, whose routes change constantly. So a train engineer will know exactly where he is just by looking out the window. A pilot will not.

My point, a small independent GPS showing ground speed, heading, location, elevations (for aviation) seems to me essential for any sort of transportation.


Airliners already have this. In fact, if I remember correctly, they have to have two separate GPS receivers for redundancy in order to conduct RNAV approaches (as any modern airliner would do, since most major airports have RNAV approaches).

Every time there's an accident lately, this topic of GPS comes up and I always start to wonder if some people don't realize that airliners already have it. So to be clear for anyone who is honestly confused about this: airliners have GPS. It does all the stuff in the quote above and a lot more. It's part of any standard modern avionics suite. (I'm not sure about the interface on every airliner; there could be some differences in how the data is presented or used. But pilots are obviously trained on how to use it in whatever type(s) they're rated for.)
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frmrCapCadet
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 8:47 pm

spacecadet wrote:
frmrCapCadet wrote:
For some strange bureaucratic reasoning RRs don't have GPS in locomotives - they rely on computers and central control from a person thousands of miles away.


Trains run on tracks on the ground. It's a one-dimensional mode of transportation. GPS is not really necessary.

RR's have a lot of technology that you probably don't know about. In a modern system (and not every railroad is very modern, but most are), both the engineer and dispatcher know exactly where any train is at any given time. In most cases, they know where each *wheel* on the train is at any given time. This is accomplished with sensors on both the train and embedded in the track.

Not to mention that engineers are required to be familiar with their routes before ever taking control of a train on that route. This is not necessarily the case for pilots, whose routes change constantly. So a train engineer will know exactly where he is just by looking out the window. A pilot will not.

My point, a small independent GPS showing ground speed, heading, location, elevations (for aviation) seems to me essential for any sort of transportation.


Airliners already have this. In fact, if I remember correctly, they have to have two separate GPS receivers for redundancy in order to conduct RNAV approaches (as any modern airliner would do, since most major airports have RNAV approaches).

Every time there's an accident lately, this topic of GPS comes up and I always start to wonder if some people don't realize that airliners already have it. So to be clear for anyone who is honestly confused about this: airliners have GPS. It does all the stuff in the quote above and a lot more. It's part of any standard modern avionics suite. (I'm not sure about the interface on every airliner; there could be some differences in how the data is presented or used. But pilots are obviously trained on how to use it in whatever type(s) they're rated for.)


I follow RRs pretty closely. There have been 3 multi-fatality accidents in the last several years where the engineer did not know where his train was. One of them may have been in a tunnel where GPS is not available. You cannot tell where you are by 'just looking out the window, that is a pretty ignorant belief. Amongst other things sometimes it is dark outside.
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salttee
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 8:47 pm

sccutler wrote:
A poster above seems to believe ADS-B out data somehow includes pitot/static-derived data; it does not. The location, speed and altitude information transmitted by ADS-B units (whether 1090ES or the 978UAT) is exclusively GPS-derived.

No, ADS-B is not exclusively GPS-derived.

ADS-B reports two kinds of altitudes: barometric and geometric. Barometric or pressure altitude is the one pilots know best – this is the altitude that is displayed on the altimeter in the aircraft. Geometric altitude is calculated by GPS
https://www.faa.gov/nextgen/programs/adsb/faq/

I had previously assumed that all ADS-B data came from the plane itself, but now I find that ADS-B does have the capability of using GPS (along with aircraft derived info). If ADS-B has two sources for the same information, when we're reading ADS-B data how do we know which source is used for output? Is it true that there are many ADS-B features that are not used by all aircraft or all customers?
 
mxaxai
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 8:50 pm

ferren wrote:
Hi, my first question here....also not a native speaker, so sorry for my language
I assume that the information about the problems on previous flights together with the repair report was correctly passed to the flight crew, so they were mentally prepared that the fix may be insufficient and may occur again ( maybe they did a briefing about the exact situation that finally happened), how really "difficult" is to fail pitch&power flying even if you are prepared for it? Not stressed by the unexpected situation with a nice weather?
Or, from the opposite point of view, is it possible that another issue occured and they interpreted it incorrectly as a reappeared problem that resulted in wrong decisions?

Not too "difficult", although the increased workload might lead to mistakes in other areas.

It is certainly possible that another issue appeared, although it seems more likely to me that the issue appeared on top of an unreliable airspeed issue.
 
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Finn350
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 9:18 pm

salttee wrote:
sccutler wrote:
A poster above seems to believe ADS-B out data somehow includes pitot/static-derived data; it does not. The location, speed and altitude information transmitted by ADS-B units (whether 1090ES or the 978UAT) is exclusively GPS-derived.

No, ADS-B is not exclusively GPS-derived.

ADS-B reports two kinds of altitudes: barometric and geometric. Barometric or pressure altitude is the one pilots know best – this is the altitude that is displayed on the altimeter in the aircraft. Geometric altitude is calculated by GPS
https://www.faa.gov/nextgen/programs/adsb/faq/

I had previously assumed that all ADS-B data came from the plane itself, but now I find that ADS-B does have the capability of using GPS (along with aircraft derived info). If ADS-B has two sources for the same information, when we're reading ADS-B data how do we know which source is used for output? Is it true that there are many ADS-B features that are not used by all aircraft or all customers?


Here is a website that describes ADS-B Basic and Mode S fields. There is a quite lot of information that ADS-B provides from a modern airplane.
http://mode-s.org/decode/

Flightradar24 displays both barometric and GPS altitude with their applications (at least if you have the proper subscription). Barometric altitude is the original data field, as that is used in Air Traffic Control.
 
salttee
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 9:36 pm

Is the amount of data broadcast by an aircraft solely hardware dependent or is there a cost to the airline for using the advanced or enhanced modes? Do we know what mode flight 610 was broadcasting?

(I just use the free version of FR24, I'm not subscribed)
 
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Mon Nov 05, 2018 10:43 pm

frmrCapCadet wrote:
From not entirely analogous situations: in my quite small boat I have GPS, radar, AIS, and some smart phone location and some other vessel sensing. These are 4 almost entirely independent systems. All quite comforting when going through a heavy fog bank (which I usually successfully avoid). A recent fatal railroad accident happened because the engineer did not know where he was. For some strange bureaucratic reasoning RRs don't have GPS in locomotives - they rely on computers and central control from a person thousands of miles away. My point, a small independent GPS showing ground speed, heading, location, elevations (for aviation) seems to me essential for any sort of transportation. As a backup system it does not require a lot of attention, and what it does do very well is provide quick rough estimates of what you are doing. If it shows something far different from what you were expecting it is a warning that your are in trouble, and gives some information about getting out of trouble.

Actually, AIS and smartphone at sea are entirely GPS based.
 
frmrCapCadet
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Tue Nov 06, 2018 12:06 am

Nomadd wrote:
frmrCapCadet wrote:
From not entirely analogous situations: in my quite small boat I have GPS, radar, AIS, and some smart phone location and some other vessel sensing. These are 4 almost entirely independent systems. All quite comforting when going through a heavy fog bank (which I usually successfully avoid). A recent fatal railroad accident happened because the engineer did not know where he was. For some strange bureaucratic reasoning RRs don't have GPS in locomotives - they rely on computers and central control from a person thousands of miles away. My point, a small independent GPS showing ground speed, heading, location, elevations (for aviation) seems to me essential for any sort of transportation. As a backup system it does not require a lot of attention, and what it does do very well is provide quick rough estimates of what you are doing. If it shows something far different from what you were expecting it is a warning that your are in trouble, and gives some information about getting out of trouble.

Actually, AIS and smartphone at sea are entirely GPS based.


That is true. But remember, should the 3 GPS systems should all go down, the least of your problems will be your smart phone and AIS. The phone GPS is entirely separate from the boat electronics NMEA hubbed GPS -different battery, antenna, and electronics.
Buffet: the airline business...has eaten up capital...like..no other (business)
 
Antarius
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Tue Nov 06, 2018 12:42 am

Request - can we please split the discussion on radar to a different thread? Its tangential to this one at this point and is hard to follow the core thread subject.
2019: SIN HKG NRT DFW IAH HOU CLT LGA JFK SFO SJC EWR SNA EYW MIA BOG LAX ORD DTW OAK PVG BOS DCA IAD ATL LAS BIS CUN PHX OAK SYD CVG PHL MAD ORY CDG SLC SJU BQN MHT YYZ STS BIS DOH BLR KTM MFM MEX MSY BWI DEN
 
PlanesNTrains
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Tue Nov 06, 2018 12:50 am

Antarius wrote:
Request - can we please split the discussion on radar to a different thread? Its tangential to this one at this point and is hard to follow the core thread subject.


I second the motion.
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
moa999
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Tue Nov 06, 2018 12:50 am

Until any more info comes out, almost all discussions will be at tangents or circles...
 
nikeherc
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Tue Nov 06, 2018 1:17 am

PlanesNTrains wrote:
Antarius wrote:
Request - can we please split the discussion on radar to a different thread? Its tangential to this one at this point and is hard to follow the core thread subject.


I second the motion.


That’s not a bad idea. The problem is that nobody knows anything other than a plane went down. If we only write about facts about the crash, you can close this thread. I would not have gotten sucked into this thread, if I could let abject ignorance go unchallenged.
DC6 to 777 and most things in between
 
Antarius
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Tue Nov 06, 2018 1:20 am

nikeherc wrote:
PlanesNTrains wrote:
Antarius wrote:
Request - can we please split the discussion on radar to a different thread? Its tangential to this one at this point and is hard to follow the core thread subject.


I second the motion.


That’s not a bad idea. The problem is that nobody knows anything other than a plane went down. If we only write about facts about the crash, you can close this thread. I would not have gotten sucked into this thread, if I could let abject ignorance go unchallenged.


I'm not asking for no discussion. For example, the news says that the last 4 flights had airspeed indicator issues - plenty to discuss and speculate.

It was just the radar conversation that got really verbose and really lengthy. It's interesting but very tangential
2019: SIN HKG NRT DFW IAH HOU CLT LGA JFK SFO SJC EWR SNA EYW MIA BOG LAX ORD DTW OAK PVG BOS DCA IAD ATL LAS BIS CUN PHX OAK SYD CVG PHL MAD ORY CDG SLC SJU BQN MHT YYZ STS BIS DOH BLR KTM MFM MEX MSY BWI DEN
 
benjjk
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Re: Lion Air 737MAX8 Crashed Jakarta to Pangal Pinang

Tue Nov 06, 2018 1:49 am

ranold76 wrote:
A3801000 wrote:
From Sky News Twitter account, just now:

'Investigators say the "black box" flight recorder recovered after a plane crash in Indonesia shows four of the Lion Air jet's flights had experienced problems with the airspeed indicator'

https://twitter.com/SkyNewsBreak/status ... 0734306305


So.... was it even looked at and repaired by Lion Air maintenance?
If this was systematic, you would think this issue would of reared it's ugly head in other aircraft operators etc.
It seems pretty unique to Lion Air.. no?


Not at all. https://en.wikipedia.org/wiki/Qantas_Flight_72 is one example where a design fault can be hidden despite millions of A330 flight hours beforehand. It was a total coincidence that the problem occured on a Qantas flight, it had nothing to do with their practices.

There could be a hidden systemic issue with the MAX that through sheer bad luck came to fruition on that flight. Equally, the airline might have shoddy practices which caused the accident, or the pilots just forgot how to fly. Either way there is just too little information at this point to know, and all parties deserve the benefit of the doubt.

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