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VirginFlyer
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 8:05 pm

FredrikHAD wrote:
estorilm wrote:
Just out of curiosity, can someone calculate a rough V/S based on 30-35 degree AOA and 800 km/h? Just curious if that may explain some of the early transponder data.


With Angle = 0 degrees being level flight you have:

Vertical speed = sin(Angle)*Airspeed
Horizontal speed = cos(Angle)*Airspeed

Vertical speed = sin(30)*800 = 400 km/h (30 degrees dive)
Vertical speed = sin(35)*800 = 459 km/h (35 degrees dive)

Horizontal speed = cos(30)*800 = 693 km/h

/Fredrik

Which when converted to feet/minute for the vertical speeds gives between 21900ft/min and 25100ft/min.

V/F
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gosheto
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 8:14 pm

longhauler wrote:
elinyc wrote:
The Russian investigators just reported that the preliminary results of the flight data recorder indicate that 1)last minutes of flight the aircraft experienced substantial variation of IAS and 2)pitot heat was off during the entire flight for all three tubes.
R.I.P.


It has happened in the past....

https://en.wikipedia.org/wiki/Northwest ... light_6231


I am sorry if my question is stupid, but why is there even a switch to turn on/off the anti-ice (or pitot tubes heating)? Why is that not always either ON or automatic? Is there a reason to have it OFF (I understand it is not always needed, but what would happen if that is always ON)
 
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inflightVideo
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 8:25 pm

FR24 business accounts show indicated airspeed fed directly from the flight deck instruments.

Image

The IAS indicator recorded an airspeed of 784 knots when the groundspeed was just 380 knots.

Unless the aircraft suddenly encountered a 400knot tailwind, the instruments weren't showing correct information. Whether this is due to pitot icing or not I have no idea - but could this be a clue?
 
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 8:50 pm

gosheto wrote:
I am sorry if my question is stupid, but why is there even a switch to turn on/off the anti-ice (or pitot tubes heating)? Why is that not always either ON or automatic? Is there a reason to have it OFF (I understand it is not always needed, but what would happen if that is always ON)


I asked essentially the same question in the last part of this thread about pitot heat. To play devil's advocate and answer, the heating mechanism will, of course, have a finite life span, and will run through that faster if it's always on. But I think that's a small price to pay. Blocked pitot tubes are very dangerous.

It would make no sense, though, to have ant-ice on all the time. I think the airplane might have to take a significant performance hit.
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 8:57 pm

inflightVideo wrote:
FR24 business accounts show indicated airspeed fed directly from the flight deck instruments.

Image

The IAS indicator recorded an airspeed of 784 knots when the groundspeed was just 380 knots.

Unless the aircraft suddenly encountered a 400knot tailwind, the instruments weren't showing correct information. Whether this is due to pitot icing or not I have no idea - but could this be a clue?

The disparity between airspeed and groundspeed could also be as a result of an aircraft being in a high speed dive which would mean there airspeed would be greater than the speed across the ground, although for it to be double would imply a ~60° angle of descent. 784 knots is pretty excessive, so I would imagine the bulk of the disparity may indeed be an instrumentation failure, for example from an iced over pitot tube which would cause airspeed to increasingly over-read as the aircraft climbed, with a smaller contribution from the descending flight path (if it was in a 30° angle of descent as has been suggested, the true ground speed would be about 87% of the true air speed). No doubt this information will be well explored in the eventual accident report.

gosheto wrote:
I am sorry if my question is stupid, but why is there even a switch to turn on/off the anti-ice (or pitot tubes heating)? Why is that not always either ON or automatic? Is there a reason to have it OFF (I understand it is not always needed, but what would happen if that is always ON)

hivue wrote:
Here in the 21st century shouldn't pitot heat be on automatically all the time whenever the airplane is moving for all commercial transport category aircraft?

My understanding is that running pitot heat continuously will wear out the heating element, and potentially damage the pitot tube over time.

V/F
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 9:11 pm

I have always wondered why faulty data on pitots have tragic consequences, really really fast, I know, Its easy to criticize from your chair at home while sipping coffee while situational awareness goes out the window due to the nature of the emergency. There is a youtube video of a female first officer (swiss landing at MIA I Think) that there is a EICAS alert and you can see how composed see is and then the alert comes and she Jumps and see the instant fear on her face. Maybe there is a need for using these terrible situations on the simulator to train the crews to remain flying the plane and use the little info they have to get out of trouble....we have seen this situations in Birgen Air, in AeroPEru, Air France and other accidents that wrong or inexistent flight data info, make things go south real fast....

I think is terrible if they forgot to follow the checklist and turn on the heat, specially in Moscow weather...but humans err and sadly this one big mistake if proven as the main reason for this crash.

May the victims rest in Peace.

TRB
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inflightVideo
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 9:31 pm

TheRedBaron wrote:
I have always wondered why faulty data on pitots have tragic consequences, really really fast, I know, Its easy to criticize from your chair at home while sipping coffee while situational awareness goes out the window due to the nature of the emergency. There is a youtube video of a female first officer (swiss landing at MIA I Think) that there is a EICAS alert and you can see how composed see is and then the alert comes and she Jumps and see the instant fear on her face. Maybe there is a need for using these terrible situations on the simulator to train the crews to remain flying the plane and use the little info they have to get out of trouble....we have seen this situations in Birgen Air, in AeroPEru, Air France and other accidents that wrong or inexistent flight data info, make things go south real fast....

I think is terrible if they forgot to follow the checklist and turn on the heat, specially in Moscow weather...but humans err and sadly this one big mistake if proven as the main reason for this crash.

May the victims rest in Peace.

TRB


The saddest part is, a faulty pitot has no impact on air going over the wings and keeping the aircraft flying. That alone would not result in such a terrible crash. Sadly in a scenario where something like this happens, I imagine everything possible happens within a few short seconds and sadly the crew rely on readings that are incorrect, and spend so long trying to figure out what's going on and there simply isn't enough time. Like you say, as much as we can sit in the comfort of our armchairs for three days plotting what may have happened and how we would have dealt with it, the crew of this flight had just a few short seconds to figure out what was going on in incredibly stressful circumstances. Incredibly sad.
 
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 9:35 pm

VirginFlyer wrote:
My understanding is that running pitot heat continuously will wear out the heating element, and potentially damage the pitot tube over time.

V/F


Running the hydraulic systems continuously will wear out their components, and potentially damage the systems over time -- unless there is an appropriate maintenance schedule to prevent that.
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Flighty
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 9:36 pm

TheRedBaron wrote:
I have always wondered why faulty data on pitots have tragic consequences, really really fast, I know, Its easy to criticize from your chair at home while sipping coffee while situational awareness goes out the window due to the nature of the emergency. There is a youtube video of a female first officer (swiss landing at MIA I Think) that there is a EICAS alert and you can see how composed see is and then the alert comes and she Jumps and see the instant fear on her face. Maybe there is a need for using these terrible situations on the simulator to train the crews to remain flying the plane and use the little info they have to get out of trouble....we have seen this situations in Birgen Air, in AeroPEru, Air France and other accidents that wrong or inexistent flight data info, make things go south real fast....

I think is terrible if they forgot to follow the checklist and turn on the heat, specially in Moscow weather...but humans err and sadly this one big mistake if proven as the main reason for this crash.

May the victims rest in Peace.

TRB

Totally agree, this is now a known failure path. But that doesn't mean that humans can deal with it without help. Too many analysis problems are thrown at the pilot too quickly, with little warning and dire consequences imminent. Rushed prioritization takes place under panic. The pilots grasp for known facts. They instinctively rely on airspeed as a first principle, which then dooms the plane and they are done. It's an awful scenario and there has got to be an ergonomic solution.
 
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 10:33 pm

hivue wrote:
Here in the 21st century shouldn't pitot heat be on automatically all the time whenever the airplane is moving for all commercial transport category aircraft?

Trouble is, An-148 has to comply with MAK/IAC certification requirements, and these are tough on pitot tube heating, AFAIK.
They are derived from Soviet requirements (they basically ARE Soviet requirements, translated into today), and are supposed to be able to withstand frost, normally not encountered elsewhere. -40oC is not too cold for those areas... You get the picture.
Also, AFAIR, insects have to burn off, if they are ingested and risk blocking the pitot tube.

From anecdotal evidence (not a pilot here, so take it for what it's worth), but it's normal to see rainbow colors on pitot tube material after a couple of years in operation, for Soviet/post-Soviet types.

So, the tubes need a lot of air flow to cool properly, and so heating is turned relatively late into the check-list. On the ground, they have few minutes to stay heated, before take-off roll (one to three, AFAIK). If there's a delay in takeoff, heating is turned off, and then re-engaged at the appropriate time, as per checklist.
AN4 A40 L4T TU3 TU5 IL6 ILW I93 F50 F70 100 146 ARJ AT7 DH4 L10 CRJ ERJ E90 DC-9 MD-8X YK4 YK2 SF3 S20 319 320 321 332 333 343 346 722 732 733 734 735 73G 738 739 744 74M 757 767 777
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 10:49 pm

So, pitot tubes need a lot of air flow to cool properly, and so heating is turned relatively late into the check-list. On the ground, they have few minutes to stay heated, before take-off roll (one to three, AFAIK). If there's a delay in takeoff, heating is turned off, and then re-engaged at the appropriate time, as per checklist.

Somebody should invent a device that regulates the amount of heat supplied to pitot tubes, so that the circuit can be left ON at all times, but the tubes are only heated when there is significant risk of them icing up. I suggest we give it a name based on some relevant Greek words, such as θερμός & στατός, or thermos + statos....
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Re: An-148 crash near Moscow kills all 71 people on board

Tue Feb 13, 2018 10:50 pm

Couldn't they still have a warning light if pitot heating is not engaged when it should be? Out of respect for the qualified people here I will stop posting in thread.
 
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 1:14 am

inflightVideo wrote:
TheRedBaron wrote:
I have always wondered why faulty data on pitots have tragic consequences, really really fast, I know, Its easy to criticize from your chair at home while sipping coffee while situational awareness goes out the window due to the nature of the emergency. There is a youtube video of a female first officer (swiss landing at MIA I Think) that there is a EICAS alert and you can see how composed see is and then the alert comes and she Jumps and see the instant fear on her face. Maybe there is a need for using these terrible situations on the simulator to train the crews to remain flying the plane and use the little info they have to get out of trouble....we have seen this situations in Birgen Air, in AeroPEru, Air France and other accidents that wrong or inexistent flight data info, make things go south real fast....

I think is terrible if they forgot to follow the checklist and turn on the heat, specially in Moscow weather...but humans err and sadly this one big mistake if proven as the main reason for this crash.

May the victims rest in Peace.

TRB


The saddest part is, a faulty pitot has no impact on air going over the wings and keeping the aircraft flying. That alone would not result in such a terrible crash. Sadly in a scenario where something like this happens, I imagine everything possible happens within a few short seconds and sadly the crew rely on readings that are incorrect, and spend so long trying to figure out what's going on and there simply isn't enough time. Like you say, as much as we can sit in the comfort of our armchairs for three days plotting what may have happened and how we would have dealt with it, the crew of this flight had just a few short seconds to figure out what was going on in incredibly stressful circumstances. Incredibly sad.


This is really important, we can speculate all we like on how we would have done things but we still need to remember that we are lucky to be here. The pilots didn't want to die and we need to approach this respectfully.

RIP
 
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 2:41 am

estorilm wrote:
https://armenpress.am/eng/news/922547/experts-decode-possible-cause-behind-russian-an-148-airplane-crash.html
ArmenPress reporting specifics of FDR information - their site won't let me copy / paste,... .

Unfortunately, for copyright reasons, my original post had to be removed.
I'll try posting again, this time picking up just the salient points from the original Interstate Aviation Committee report. This was originally in Russian, but presumably should also have been available in English, except their entire website now appears to be off-line. As a public organisation (.org) I would hope there are no copyright issues, but even so I have taken the liberty of selecting the key sentences, and re-hashing the wording, particularly where the translator clearly made a complete lash up.... :roll:
http://mak-iac.org/

Interstate Aviation Committee wrote:
A preliminary analysis ......suggests .......incorrect data on the flight’s speed on the pilots’ displays.
This in turn, could have been linked to the ice-up of the total pressure probes since their heating systems were switched off.

A special situation began to develop 2 min 30 sec after takeoff at around 1300m and 465-470 km/h IAS
At that time, the flight recorders started to record divergences between the readings of the speed sensors, Mvp1 & Mvp3

Within 30 secs, the divergences reached 30 km/h, triggering a cockpit warning "The Instrument Panel - Compare!"
This command was repeated at an altitude of about 2000m as the difference between the speed sensors’ readings increased.

After the second warning, the crew turned off the autopilot and the subsequent flight proceeded in manual mode.
Mvp1 continued to fall, reaching 0 km/h 34 seconds after the autopilot was switched off.
Meanwhile MVP3 showed 540-560 km/h.

After this, Mvp3 also fell dramatically, dropping towards stall speeds, and at the same time the a/c entered a 30-35° dive, encountering 0g during this manoeuver.. During this dive, Mvp3 increased, reaching a maximum of 800 km/h just before the crash impact at 11:27:05. Mvp1 continued to read 0 km/h

mak-iac wrote:
В момент столкновения с землей угол тангажа на пикирование составлял около 30 градусов,

"At the moment of collision with the Earth the pitch angle on the dive was about 30 degrees,"

Four to five seconds before hitting the ground, the plane rolled right 25°

Two final thoughts;
Earlier in the thread long before any information came out, there were two discussions revolving around descent rates and impact angles.
In reply to a query regarding the 22,000 ft/min descent rate...
somebody wrote:
22,000 ft/min is a straight 250mph, and therefore IMHO perfectly achievable..
Using our old friend, trigonometry, you can choose from either 250mph straight down vertical descent, or 500 mph IAS with just a "shallow" 30° dive.

The same person also commented that the CCTV footage appeared to show a relatively shallow impact angle followed by the aircraft (or significant chunks of it) bouncing back into the air thereby causing the distinctive fireball and spread of wreckage.

And finally.... I am quietly surprised at how quickly the Russians have made this FDR information available.
Can anybody tell me if this has happened in other crash situations, in Europe or the US?
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ltbewr
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 3:27 am

SheikhDjibouti wrote:
estorilm wrote:

And finally.... I am quietly surprised at how quickly the Russians have made this FDR information available.
Can anybody tell me if this has happened in other crash situations, in Europe or the US?


The black boxes were quickly recovered, were of more modern design, minimally damaged, they had a lot of data including from past flights. Then too as promptly covered by local and to international news media, I suspect the Russian government investigators were under pressure to put the recording out for domestic political needs.
 
Jouhou
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 6:58 am

I'm still curious, regardless of its relevance in this incident, what is the Vne of the an-148?


Also in response to russian government conspiracy theories, this was a domestic flight. If they wanted someone disposed of they'd be found in the backseat of their car with a bullet in the back of their head, with a death certificate saying they died of heart failure. Let's be realistic here, they might do some wild things but they wouldn't kill innocent civilians in their own country.

I'm pretty sure this was a series of unfortunate equipment failures just after takeoff where the crew would have had to been almost superhuman to have overcome, considering this all happened within a few minutes, and the crew likely did not know how grave their situation was until the last 20 seconds before impact.
 
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 8:01 am

Saratov appears to have suspended flights to Omsk after grounding all their Antonov 148's plane. Checking the flight details at flightstats.com saying that Saratov flight from Omsk to DME is cancelled. It has been cancelled since Monday and probably permanently.
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BREECH
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 8:11 am

SheikhDjibouti wrote:
As I posted earlier; 22,000 ft/min descent equates to 250mph.
So, with 300mph forward speed and 250 mph downward velocity, let's agree we are both right.

I must've missed something. How did you get from 3200 fpm posted by FR24 to 22,000 fpm?

SheikhDjibouti wrote:
Despite the proximity to Moscow, the crash did NOT happen in a populated area. The crash site is vaguely near to two small villages, surrounded by miles of farm and forest land. The bigger risk was skidding across the M5 Trans Siberian highway and taking out a couple of truckers on their way to Vladivostock...

M5 is not the Trans Siberian Highway. There is NO Trans Siberian Highway. M5 starts in Moscow and ends in Chelyabinsk, roughly 7000km from Vladivostok and 1000km from Siberia. I understand that for Western people everything to the East of Moscow is Siberia. And Russians say "Na zdorovya" when they drink. Before going to work on a nuclear reactor with their pet bears. SHEESH!
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Phosphorus
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 9:15 am

SheikhDjibouti wrote:
So, pitot tubes need a lot of air flow to cool properly, and so heating is turned relatively late into the check-list. On the ground, they have few minutes to stay heated, before take-off roll (one to three, AFAIK). If there's a delay in takeoff, heating is turned off, and then re-engaged at the appropriate time, as per checklist.

Correct. Absent airflow, these things are prone to overheat.

SheikhDjibouti wrote:
Somebody should invent a device that regulates the amount of heat supplied to pitot tubes, so that the circuit can be left ON at all times, but the tubes are only heated when there is significant risk of them icing up. I suggest we give it a name based on some relevant Greek words, such as θερμός & στατός, or thermos + statos....

There are multiple, fairly elegant solutions, to make it work. Some are based on the status of the landing gear (if it's stressed=on the ground, the pitot tube heating is off; following take-off, the pitot tube heat kicks in); some are actually having a feedback loop from pitot tube temperatures.


Flighty wrote:
Couldn't they still have a warning light if pitot heating is not engaged when it should be? Out of respect for the qualified people here I will stop posting in thread.

It's there. It indicates that pitot heating is switched on but is not functioning. Unfortunately, nothing fancier.


In all cases, please, don't forget the design philosophy for An-148: it's a REGIONAL plane, capable of operations in some of the most inhospitable areas on Earth, with little ground infrastructure. Engines are high, to prevent FOD on poorly maintained runways and taxiways. Heating a priority, because it can be bloody cold out there. Everything that could be simplified, to remove additional points of failure -- was simplified; because mechanics have difficulty fixing things in -50oC.
It wasn't conceived as a mainline airliner, with all bells and whistles. It's a regional workhorse, as rugged as possible.

I cannot help but compare this accident with Helios flight 522. A simple switch; it was even pronounced aloud during the checklist, but not set properly...
AN4 A40 L4T TU3 TU5 IL6 ILW I93 F50 F70 100 146 ARJ AT7 DH4 L10 CRJ ERJ E90 DC-9 MD-8X YK4 YK2 SF3 S20 319 320 321 332 333 343 346 722 732 733 734 735 73G 738 739 744 74M 757 767 777
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sevenair
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 10:05 am

Few things will kill you quicker than unreliable airspeed unless you’re really on the ball and action your memory items (if appropriate to the type).

Does the AN148 have any inbuilt protections? A320 have a red OEB(48) specifically for low speed protections kicking in whenever low speed is falsely sensed due to frozen sensors. Unfortunately you can not overcome the low speed protections and it could potentionally result in a hull loss, just because of a false sense of low airspeed.

The procedure is to basically turn off the normal flight mode and operate he aircraft in alternate law. The protections are lost and are replaced with a much simpler stability rather than a protection.

Does the AN148 have similar protections?
 
redcap1962
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 10:34 am

Phosphorus wrote:
I cannot help but compare this accident with Helios flight 522....


And the root cause also quite similar to AF447 :scratchchin:
 
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 11:06 am

BREECH wrote:
SheikhDjibouti wrote:
As I posted earlier; 22,000 ft/min descent equates to 250mph.
So, with 300mph forward speed and 250 mph downward velocity, let's agree we are both right.

I must've missed something. How did you get from 3200 fpm posted by FR24 to 22,000 fpm?

You did indeed (miss something). Quite a lot actually.
e.g. Posts #22, 117, 118, 120, 153,.... (I may have missed a few)
edu2703 wrote:
According to ADS-B data, the aircraft was falling with 22,000 feet per minute when the signal was lost.

{FR24} data, sampled at 10 sec intervals, is going to be quite suspect in these extreme circumstances

Dahlgardo wrote:
The 10 second sample rate is only for the playback functionality of FR24. The transponder transmits much more than that.

ADS-B is sampled several times per second - ...... {FR24} only updates once every 10 seconds on the website due to bandwidth constraints.

Here are my own edited excerpts of the final five seconds of ADS-B data....
Date...........Time.................Flight ID..Lat..........Long......Alt.....Squawk.?.?.Climb rate
2018-02-11 11:27:01z.988 SOV703 55.29968 38.38498 3850 1571 0 45 -16128
2018-02-11 11:27:02z.670 SOV703 55.29968 38.38706 3525 1571 0 45 -18496
2018-02-11 11:27:04z.458 SOV703 55.29968 38.38931 3250 1571 0 45 -19776
2018-02-11 11:27:05z.650 SOV703 55.29968 38.39256 2900 1571 0 45 -18944
2018-02-11 11:27:06z.180 SOV703 55.29950 38.39580 2475 1571 0 45 -22080
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SheikhDjibouti
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 11:17 am

BREECH wrote:
SheikhDjibouti wrote:
Despite the proximity to Moscow, the crash did NOT happen in a populated area. The crash site is vaguely near to two small villages, surrounded by miles of farm and forest land. The bigger risk was skidding across the M5 Trans Siberian highway and taking out a couple of truckers on their way to Vladivostock...

M5 is not the Trans Siberian Highway. There is NO Trans Siberian Highway. M5 starts in Moscow and ends in Chelyabinsk, roughly 7000km from Vladivostok and 1000km from Siberia. I understand that for Western people everything to the East of Moscow is Siberia. And Russians say "Na zdorovya" when they drink. Before going to work on a nuclear reactor with their pet bears. SHEESH!

You can SHEESH all you like, but again you missed some crucial earlier posts..
Shaky wrote:
FYI the M5 is part of a much larger highway network that begins in Cork (Ireland) as the E30, continues along the M4 corridor past LHR, then Felixstowe/Harwich -Hoek van Holland, on through Germany (past SXF), Poland etc, before wrapping around Moscow, passing close to SVO, DME, and also Zhukovsky, before continuing either as the Trans-Siberian highway (to Vladivostock) or route AH6 (to Busan, South Korea).or route AH7 (to Karachi, Pakistan)


The Trans-Siberian Highway is the unofficial name for a network of federal highways that span the width of Russia from the Baltic Sea of the Atlantic Ocean to the Sea of Japan of the Pacific Ocean. In the Asian Highway Network, the route is known as AH6...

BREECH wrote:
I understand that for Western people everything to the East of Moscow is Siberia
By that measure, do I assume that for Russian people, the M5 Ural Highway exists in splendid isolation, and that it is not part of a larger multi-national road network?
What do your truckers do? Drive from Moscow to Chelyabinsk, and then turn around and drive home again?

And this all comes because you are still sore at me because I disputed your "densely populated area" comment, which I now notice has been removed for some reason. Don't feel too bad - one of my posts got pulled too. I guess we are both bad boys from time to time. :lol:

Anyway, it's not been one of your better days. Never mind; you win some, you lose some. :lol
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 11:50 am

SheikhDjibouti wrote:
So, pitot tubes need a lot of air flow to cool properly, and so heating is turned relatively late into the check-list. On the ground, they have few minutes to stay heated, before take-off roll (one to three, AFAIK). If there's a delay in takeoff, heating is turned off, and then re-engaged at the appropriate time, as per checklist.


In cold conditions I turn them on entering the cockpit so the probes are ice free for the walk around. They are normally automatically on when at least one engine is running, that is Airbus.
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76er
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 12:17 pm

All the jets I've flown (Boeing) have automatic pitot-static system heating that switches on when the first engine is started. Contrary to what has been stated earlier, there is no issue with overheating, wear or performance penalties. There will be an EICAS alert when this system does not operate as designed. Engine- and wing anti-ice are a different matter.
I'm am kind of baffled that a relatively modern design like the An-148 does not appear to have this feature. This was Murphy waiting to strike.
 
pdp
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 12:30 pm

76er wrote:
All the jets I've flown (Boeing) have automatic pitot-static system heating that switches on when the first engine is started. Contrary to what has been stated earlier, there is no issue with overheating, wear or performance penalties. There will be an EICAS alert when this system does not operate as designed. Engine- and wing anti-ice are a different matter.
I'm am kind of baffled that a relatively modern design like the An-148 does not appear to have this feature. This was Murphy waiting to strike.


I think the 737 is still manual, however you do get 8 bright red warning lights on the NG about it!

http://www.b737.org.uk/probes.htm
 
Redd
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 1:40 pm

aemoreira1981 wrote:
hOMSaR wrote:
aemoreira1981 wrote:
I have to ask: WHO exactly was on that flight?


Others have already linked the passenger list. The Daily Mail has photos of a number of the people on board.

While I didn’t really look into the details and history, they seemed to be typical, run-of-the-mill passengers and flight crew. Why do you ask?


I haven't read the list yet, but there is the idea of if someone knows too much in that country.


I suggest you do some reading about the Post Stalin Soviet Union and modern day Russia. They're masters at making people go away & they don't need to bring down an airliner to do it. Absurd assumption.
 
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intrance
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 2:33 pm

The CRJ just doesn’t care what you select the pitot heat to do. It will go to full heat as soon as you take off basically. Not sure why that would not be/has not been incorporated in later designs. It’s basically only controllable on ground.
 
Dominion301
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 6:09 pm

pdp wrote:
76er wrote:
All the jets I've flown (Boeing) have automatic pitot-static system heating that switches on when the first engine is started. Contrary to what has been stated earlier, there is no issue with overheating, wear or performance penalties. There will be an EICAS alert when this system does not operate as designed. Engine- and wing anti-ice are a different matter.
I'm am kind of baffled that a relatively modern design like the An-148 does not appear to have this feature. This was Murphy waiting to strike.


I think the 737 is still manual, however you do get 8 bright red warning lights on the NG about it!

http://www.b737.org.uk/probes.htm


I know this is way off topic, but thankfully Boeing moved the pitots on the 737NGs as I had a couple of close calls (i.e. getting way too close) on the Classics when parking the loading bridge up against the aircraft. If you're 30cm off centre to the left when parking the bridge, you're getting dangerously close to knocking out a pitot on a Classic.
 
estorilm
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 6:45 pm

VirginFlyer wrote:
FredrikHAD wrote:
estorilm wrote:
Just out of curiosity, can someone calculate a rough V/S based on 30-35 degree AOA and 800 km/h? Just curious if that may explain some of the early transponder data.


With Angle = 0 degrees being level flight you have:

Vertical speed = sin(Angle)*Airspeed
Horizontal speed = cos(Angle)*Airspeed

Vertical speed = sin(30)*800 = 400 km/h (30 degrees dive)
Vertical speed = sin(35)*800 = 459 km/h (35 degrees dive)

Horizontal speed = cos(30)*800 = 693 km/h

/Fredrik

Which when converted to feet/minute for the vertical speeds gives between 21900ft/min and 25100ft/min.

V/F

Wow, cool! That number seems to be what we were looking for.

I probably should have payed more attention to those math classes. Then again this would be a fairly morbid example for school use. :lol:
 
Scorpius
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Re: An-148 crash near Moscow kills all 71 people on board

Wed Feb 14, 2018 10:23 pm

Armadillo1 wrote:
oficial info:
http://mak-iac.org/rassledovaniya/an-14 ... 18/#116661
(now offline - overloaded?)

info-only topic on russian forum:
https://aviaforum.ru/threads/katastrofa ... ija.45162/

russian text:
Комиссия Межгосударственного авиационного комитета (МАК) по расследованию катастрофы самолета Ан-148-100В RA-61704 информирует, что в лаборатории МАК была завершена расшифровка данных бортового параметрического самописца и проведён предварительный анализ информации.

Предварительный анализ зарегистрированной параметрической информации показал, что в ходе всего полета, закончившегося авиационным происшествием, обогрев всех трех приемников полного давления (ППД) находился в выключенном состоянии. Во всех остальных полетах, имеющихся на самописце (еще 15 полетов), обогрев ППД включался перед взлетом на исполнительном старте.

Взлет был начат около 11:21 (здесь и далее время UTC).

После отрыва на высоте 130-150 м (здесь и далее высота от уровня ВПП) был включен автопилот. В продольном канале автопилота выполнялся режим выхода на заданную высоту, в боковом – горизонтальной навигации. На высоте 550 м была завершена уборка закрылков.

Особая ситуация начала развиваться примерно через 2 мин 30 сек после отрыва на высоте около 1300 метров и приборной скорости 465-470 км/ч, когда стали появляться расхождения в показаниях скорости от МВП1 (модуль воздушных параметров) (ППД1) левого летчика и МВП3 (ППД3, резервный). Самописец не регистрирует значения скорости от МВП2 (ППД2) правого летчика. Существенных отличий в индикации высоты (от тех же источников: МВП1 и МВП3) не было. Через ~25 секунд расхождения достигли ~30 км/ч (скорость от МВП1 была больше) и появилась разовая команда (сообщение экипажу): Vприборная – СРАВНИ. Регистрация разовой команды на данном этапе продолжалась примерно 10 секунд, после чего прекратилась.

Примерно через 50 секунд, на высоте около 2000 метров, данная разовая команда зарегистрирована снова, причем в это раз скорость от МВП3 была больше и продолжала расти, а скорость от МВП1 продолжала падать.

После второго появления указанной разовой команды (сообщения) экипаж отключил автопилот. Весь дальнейший полет проходил в ручном режиме.

Показания скорости от МВП1 продолжали падать и через 34 секунды после отключения автопилота стали равны 0. При этом показания скорости от МВП3 составляли 540-560 км/ч.

В течение примерно 50 секунд после отключения автопилота полет проходил на высоте 1700-1900 м с изменениями вертикальной перегрузки в пределах от 1.5 до 0.5 g.

После этого, при сохранении значений скорости от МВП1 0 км/ч, начали интенсивно падать значения скорости от МВП3 (до 200 км/ч и ниже). В дальнейшем самолет был переведен в интенсивное снижение с углами тангажа на пикирование 30-35 градусов и вертикальной перегрузкой до 0 g.

Столкновение с землей произошло около 11:27:05. Перед столкновением с землей показания скорости от МВП3 начали интенсивно расти и к моменту столкновения составили около 800 км/ч. Показания скорости от МВП1 продолжали быть равными 0.

В момент столкновения с землей угол тангажа на пикирование составлял около 30 градусов, за 4-5 секунд до столкновения у самолета стал развиваться правый крен, который достиг 25 градусов.

Анализ полученной информации продолжается.

Предварительный анализ зарегистрированной информации, а также анализ аналогичных случаев, имевших место в прошлом, позволяют предполагать, что фактором развития особой ситуации в полёте могли стать неверные данные о скорости полёта на индикаторах пилотов, что, в свою очередь, видимо, было связано с обледенением ППД при выключенном состоянии систем их обогрева.

С целью определения причин выключенного состояния обогрева трех ППД комиссией по расследованию запланированы, в том числе, следующие работы:

· расшифровка бортового звукового магнитофона для получения информации о действиях экипажа, выполнении Технологии работы и реакции на сигнализации;

· изучение Технологии работы экипажа с системой обогрева ППД, включая индикацию;

· схемный анализ систем обогрева ППД на предмет возможных неисправностей и отказов;

· выкладка сохранившихся фрагментов систем обогрева ППД.



Speed sensor. Then again.
 
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Phosphorus
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Re: An-148 crash near Moscow kills all 71 people on board

Thu Feb 15, 2018 8:15 am

While we are at discussion of other types: Rosaviatsia issued a safety brief, on February 12, on 7 pitot tube clogging incidents at SVO airport, involving RRJ-85 (a.k.a. SSJ-100) on February 4-5, 2018.
Looks like airports in Moscow area are a trouble spot for pitot tubes, regardless of the type.
Page 1 of the brief here:
https://www.facebook.com/photo.php?fbid ... 136&type=3
AN4 A40 L4T TU3 TU5 IL6 ILW I93 F50 F70 100 146 ARJ AT7 DH4 L10 CRJ ERJ E90 DC-9 MD-8X YK4 YK2 SF3 S20 319 320 321 332 333 343 346 722 732 733 734 735 73G 738 739 744 74M 757 767 777
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BREECH
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Re: An-148 crash near Moscow kills all 71 people on board

Thu Feb 15, 2018 6:44 pm

NO WAY!!! Aeroperu 603 again? IF (!) true... or actually even if it's not, may I suggest a crazy idea. Let's just just stop putting SO MANY of those pitot things on each plane? I mean, one is more than enough for a safe flight. If we have two and one of them malfunctions, how would the other one(s) help. In all crashes that happened because of pitot tube malfunction (Aeroperu 603, AF447) the biggest problem for the crew was not the situation itself, but the fact that they didn't know which one to trust. I'm not a pilot but I'm trying to think from the situational awareness perspective. If I have ONE indicator, I know that it either works or not. If it works, I go on flying. If it doesn't, I act accordingly. No idea how exactly, but I'm sure pilots have some kind of "full blackout" training. Most importantly I don't waste time and crew resources thinking "what if they are both wrong?". I know there is a weak link in my theory - how do I know that it mulfunctions? I don't have an answer for that. I may sound like a broken record, but with this cockpit automation computers act more and more as an enemy or at least a distraction when things go south. Remember Asiana... what was the number in SFO? 216? 214? The pilot did several COMPUTER inputs and crashed because he didn't realize he turned the computer off. You may assign this to bad training (and Asiana DID train their pilots badly) but really. If there wasn't a computer, that plane would still be flying.

Maybe it's a good question for a separate topic, but maybe it's time to downgrade a bit on the "redundancy" and "automation" fronts? Not saying, bring back the flight engineer! But maybe three pitots are one too many?
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TheRedBaron
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Re: An-148 crash near Moscow kills all 71 people on board

Thu Feb 15, 2018 7:48 pm

BREECH wrote:
NO WAY!!! ......



While I agree on a lot of your points, a tragedy involving an aircraft its always a LOOONNGGG chain of little mistakes, that is why they say that the holes in the cheese align for an accident to happen.... after reading a lot of investigation, I always think of the RUSH to fix something out of the ordinary, and then you make more mistakes, and if you don't have the luxury of rethinking procedures or re-analyzing the situation (as we do in our confort), its easy to point fingers and draw conclusions... nobody in that flight wanted to die, but sadly that flight ended in tragedy and no amount of redundancy or automation will make flight 100% safe, that is why training is hard, check lists exist and procedures need to be followed.... there are hundreds of potential catastrophes everyday, avoided because training, checkups, checklists and procedures are followed... Sadly this tragedy will serve as an example of those little mistakes that amount to a tragedy...

Best Regards

TRB
The best seat in a Plane is the Jumpseat.
 
BREECH
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Re: An-148 crash near Moscow kills all 71 people on board

Sat Feb 17, 2018 4:17 pm

TheRedBaron wrote:
Sadly this tragedy will serve as an example of those little mistakes that amount to a tragedy..

Not so little, if you believe that transcript. The warning the pilots got (if translated from Russian) was "V instrument - COMPARE". How the heck is that supposed to help the pilots? Compare two indications and see that they are different? They know it already. I remember how British pilots who tested TSR2 told how the buttons captions was decided. They came up with ideas of how it would work for them, and then had to send it to some committee who not only rejected their (the test-pilots!!!) proposal, but came up with how they think it should be done. I just cannot believe someone in his clear mind decided to make THAT a computer warning. Instrument speed - compare. ARGH!
No friendship, love or respect unite people as much as shared hatred towards something.
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SheikhDjibouti
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Re: An-148 crash near Moscow kills all 71 people on board

Sat Feb 17, 2018 6:04 pm

BREECH wrote:
TheRedBaron wrote:
Sadly this tragedy will serve as an example of those little mistakes that amount to a tragedy..

Not so little, if you believe that transcript. The warning the pilots got (if translated from Russian) was "V instrument - COMPARE". How the heck is that supposed to help the pilots? Compare two indications and see that they are different? They know it already. I just cannot believe someone in his clear mind decided to make THAT a computer warning. Instrument speed - compare. ARGH!

Oh dear - where do I start?
"Compare two indications and see that they are different? They know it already"
How do you figure that? How do they know it already?
Pending comfirmation from a fully qualified An-148 pilot, I'm going to suggest that normally there is only one speed displayed. which in ordinary circumstances would be an average from the two primary pitot tubes. If you can explain how anybody can deduce from just one figure that the underlying instruments contributing to that figure are disagreeing with each other, I'm all ears.

Presumably, under such circumstances, and having been alerted by the audible warning, the pilots now have the option to reconfigure the display to feature data from each individual pitot tube, in order that they can make their own assessment. At the very least they know that whatever figure(s) they are looking at, they must be treated with some caution.

Secondly, the point of an audible warning is to alert the pilots to something they might not have noticed. The "dumb machine" cannot guess that the pilots already know certain things. If necessary it must repeat the obvious. I cannot imagine any pilot anywhere making a case for disabling GPWS because telling him to "pull up" was unnecessary when he could already see that he had a windscreen full of angry mountain.

Finally; I don't speak Russian. I'm not even familiar with normal cockpit warning syntax except for GPWS "sink rate" and "pull up!". Maybe when they are translated into Swahili or Urdu, those phrases take on a new meaning and cause local pilots to look at each and ask "what idiot came up with those precise words?"
Likewise, "V приборная – СРАВНИ" or "V instrument - COMPARE" presumably works perfectly for a typical Russian crew. The English translation certainly works for me. So what's your beef?

I can see a case for following up such a warning with a short checklist, the top item being, "is the pitot tube heat on?"
But equally, the failure could be due to something else such as a bird strike on a protruding pitot tube. Hence a general warning is more appropriate.

Cockpit warnings by their nature need to be short, concise, and to the point.
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Antarius
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Re: An-148 crash near Moscow kills all 71 people on board

Sat Feb 17, 2018 6:26 pm

SheikhDjibouti wrote:
BREECH wrote:
TheRedBaron wrote:
Sadly this tragedy will serve as an example of those little mistakes that amount to a tragedy..

Not so little, if you believe that transcript. The warning the pilots got (if translated from Russian) was "V instrument - COMPARE". How the heck is that supposed to help the pilots? Compare two indications and see that they are different? They know it already. I just cannot believe someone in his clear mind decided to make THAT a computer warning. Instrument speed - compare. ARGH!

Oh dear - where do I start?
"Compare two indications and see that they are different? They know it already"
How do you figure that? How do they know it already?
Pending comfirmation from a fully qualified An-148 pilot, I'm going to suggest that normally there is only one speed displayed. which in ordinary circumstances would be an average from the two primary pitot tubes. If you can explain how anybody can deduce from just one figure that the underlying instruments contributing to that figure are disagreeing with each other, I'm all ears.

Presumably, under such circumstances, and having been alerted by the audible warning, the pilots now have the option to reconfigure the display to feature data from each individual pitot tube, in order that they can make their own assessment. At the very least they know that whatever figure(s) they are looking at, they must be treated with some caution.

Secondly, the point of an audible warning is to alert the pilots to something they might not have noticed. The "dumb machine" cannot guess that the pilots already know certain things. If necessary it must repeat the obvious. I cannot imagine any pilot anywhere making a case for disabling GPWS because telling him to "pull up" was unnecessary when he could already see that he had a windscreen full of angry mountain.

Finally; I don't speak Russian. I'm not even familiar with normal cockpit warning syntax except for GPWS "sink rate" and "pull up!". Maybe when they are translated into Swahili or Urdu, those phrases take on a new meaning and cause local pilots to look at each and ask "what idiot came up with those precise words?"
Likewise, "V приборная – СРАВНИ" or "V instrument - COMPARE" presumably works perfectly for a typical Russian crew. The English translation certainly works for me. So what's your beef?

I can see a case for following up such a warning with a short checklist, the top item being, "is the pitot tube heat on?"
But equally, the failure could be due to something else such as a bird strike on a protruding pitot tube. Hence a general warning is more appropriate.

Cockpit warnings by their nature need to be short, concise, and to the point.


Not to mention, if you are certified to fly the aircraft, you went through training that assuredly taught you what that means. Heck, even SINK RATE makes no sense to the average person. I have mentioned it to non av-geeks and they give me a blank look. Yet most av-geeks and definitely ALL pilots immediately know what that means.

Error messages that are verbose and specific are necessary for an untrained mass audience. For a trained audience, such as pilots, short, concise is fine as they should know what it means.
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michi
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Re: An-148 crash near Moscow kills all 71 people on board

Sat Feb 17, 2018 8:05 pm

BREECH wrote:
...The warning the pilots got (if translated from Russian) was "V instrument - COMPARE". How the heck is that supposed to help the pilots? Compare two indications and see that they are different? They know it already. ...


When solving unreliable speed indications the first step is recognition. You have to realize, that there is somerhing wrong with your airspeed indication. A message by the computers might help and trigger the crew to use the unreliable airspeed procedure.

When you have realized that something is not right do not start troubleshooting. Fly the aircraft first! Switch off autopilot, flight dierector and autothrust/-throttle. Then use basic pitch and power values. Normally there are memory items for that.

When your aircraft is stable use all available inications in order to determine if there is still one reliable. With certain pitch&power values you will get a specific airspeed. You can also use GPS Altitude and GPS Groundspeed as a tool in order to determine if there is a reliable speed indication left.
This is the troubleshooting part of the procedure.

When done troubleshooting you might end up with a remaining reliable indication... or not. Doesn't matter really. In case the situation will not improve you willI have to fly pitch&power til touch down anyway.
Depending on the aircraft you might use some back up speed scales (e.g. Airbus BUSS) which work differently.

Flying with unreliable airspeed is no rocket science. But it depends on recognition, crew training and adherence to sop's. Good CRM is essential in solving the task.

Unreliable airspeed itself normaly isn't the single cause for a crash.
 
spacecadet
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Re: An-148 crash near Moscow kills all 71 people on board

Sun Feb 18, 2018 6:35 pm

BREECH wrote:
If I have ONE indicator, I know that it either works or not. If it works, I go on flying. If it doesn't, I act accordingly. No idea how exactly, but I'm sure pilots have some kind of "full blackout" training.


Not really... even 50 years ago, airliners had backup instruments for critical flight info. You really can't take off, fly and land an airliner with no airspeed or altitude info - not anything close to safely, anyway. You might be able to get away with it in a Cessna 172, but airliners can't really be flown by the seat of your pants, and they've never been designed to be flown that way.

The best you can do is maintain level flight until you figure out what's wrong and hopefully fix it. Maintaining level flight is possible with no airspeed or altitude instruments; it's just maneuvering and landing that can't really be done. (And in this case, that might have been enough for them to figure out that the pitot heat was off.) When you have redundant instruments displaying faulty data, it should be clear to a well trained pilot what the problem is and how to fix it - especially with similar accidents having happened pretty recently and changes in training that have happened as a result. There's really only one failure mode that can cause both pilots' airspeed indicators to display faulty data, for example.

That wouldn't be true in a plane without redundant instruments. A faulty instrument without any backup would be much harder to diagnose in the air, and much harder to determine it's faulty to begin with.

I've never heard of somebody arguing for *less* redundancy. Countless lives have been saved over the decades by instrument redundancy (and instrument systems' redundancy). An instrument going out or displaying faulty data would be a very difficult situation in a plane without redundancy; in a plane with redundancy, it should be a minor event to note in a maintenance log. If it's harder to deal with than that, then something else is going wrong.

I have a hard time seeing how plain old pilot error isn't going to be a big contributor to this crash, although it is possible that there could be some sort of system failure that made it harder to recognize what the problem was. Maybe the pitot heat was on, for example, and just didn't work. Or maybe the takeoff configuration alarm didn't work (I'm assuming there's an alarm, but if not, then that seems like a design issue). But pilot error and training seem the most likely main culprits.
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brianK73
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Re: An-148 crash near Moscow kills all 71 people on board

Sun Feb 18, 2018 7:54 pm

One would think that the automatic monitoring system should be able to detect the combination of "wildly different air speed indications" plus the "pitot heat off setting" and can come up with a more intelligent warning message.
 
KentB27
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Re: AN-148 with 71 people gone missing

Sun Feb 18, 2018 8:14 pm

sq421 wrote:
Don't mean to sound shrewd, but I think it's time the Russians take a look at the reliability of the Antonov fleet.


Why? This is the first ever crash of an An-148 in commercial service.
 
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SheikhDjibouti
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Re: An-148 crash near Moscow kills all 71 people on board

Sun Feb 18, 2018 10:23 pm

brianK73 wrote:
One would think that the automatic monitoring system should be able to detect the combination of "wildly different air speed indications" plus the "pitot heat off setting" and can come up with a more intelligent warning message.


I'm guessing you don't agree with my earlier thoughts on this.
Shaky wrote:
I can see a case for following up such a warning with a short checklist, the top item being, "is the pitot tube heat on?"
But equally, the failure could be due to something else such as a bird strike on a protruding pitot tube. Hence a general warning is more appropriate.
There are two things that happen when you get old.
1. You start to lose your memory.
2. What was I saying again?

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Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos