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An-148 missing after takeoff from Moscow

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An-148 missing after takeoff from Moscow

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Old 13th Feb 2018, 14:49
  #121 (permalink)  
 
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A question from an amateur

I rarely ever post here as I am a true amateur but I have a question for the pros. Why can't pitot tube heaters be automated so they they automatically turn on at a specific external temperature ?
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Old 13th Feb 2018, 14:52
  #122 (permalink)  
 
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AN-148-100B RA-61704 11.02.2018


Last edited by Kulverstukas; 13th Feb 2018 at 16:11. Reason: Photo with something interesting on screens
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Old 13th Feb 2018, 14:59
  #123 (permalink)  
 
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Mr Joshua on multiple ac types they are automatic. I don't know about the An-148 though
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Old 13th Feb 2018, 15:22
  #124 (permalink)  
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For browsers that don't translate on the fly here's the most substantive section of this preliminary report.

As I was hinting in the early hours of this morning. 15 previous flights pitot and port heating recorded on. No heat for this take off. You'll find the point where they went manual and I described a bit of 'heave ho' going on.

Credit due, as usual, to our Kulverstukas.

Rob

The commission of the Interstate Aviation Committee (IAC) to investigate the crash of the An-148-100V plane RA-61704 informs that the decoding of the on-board parametric recorder data was completed in the IAC laboratory and preliminary information analysis was carried out.

A preliminary analysis of the registered parametric information showed that during the entire flight, which ended in an accident, the heating of all three full pressure receivers (PAP) was off. In all other flights on the chart recorder (15 more flights), the heating of the overflow was activated before take-off at the executive launch.

The takeoff was started around 11:21 (here and below the UTC time).

After the separation at an altitude of 130-150 m (hereinafter the height from the runway level), the autopilot was switched on. In the longitudinal channel of the autopilot, the mode of reaching the specified altitude was fulfilled, in the lateral channel - the horizontal navigation. At an altitude of 550 m the flaps were cleaned.

A special situation began to develop approximately 2 minutes 30 seconds after the separation at an altitude of about 1300 meters and an instrument speed of 465-470 km / h, when the discrepancies in the speed readings from MVP1 (air parameters module) (LPD1) of the left pilot and MVP3 , standby). The recorder does not register the speed values ​​from the MVP2 (PPD2) of the right pilot. There were no significant differences in the altitude indication (from the same sources: MVP1 and MVP3). After ~ 25 seconds, the discrepancies reached ~ 30 km / h (the speed from MVP1 was greater) and a one-time crew appeared (message to the crew): V instrument - CF. The registration of a single command at this stage lasted about 10 seconds, after which it ceased.

After about 50 seconds, at an altitude of about 2000 meters, this one-time command was registered again, and this time the rate from MVP3 was larger and continued to grow, and the rate from MVP1 continued to fall.

After the second appearance of the said one-time command (message), the crew disconnected the autopilot. All further flight passed in a manual mode.

The speed readings from the MVP1 continued to fall and after 34 seconds the autopilot was turned off. The speed readings from the MVP3 were 540-560 km / h.

For about 50 seconds after autopilot shutdown, the flight passed at an altitude of 1700-1900 m with vertical overload changes ranging from 1.5 to 0.5 g.

After that, while maintaining the speed values ​​from the MVP1 0 km / h, the velocity values ​​from MVP3 (to 200 km / h and below) began to fall rapidly. In the future, the aircraft was transferred to an intensive decline with pitch angles to dive 30-35 degrees and vertical overload to 0 g.

The collision with the earth occurred around 11:27:05. Before the collision with the ground, the speed readings from the MVP3 began to increase intensively and by the time the collision amounted to about 800 km / h. The speed readings from the MVP1 continued to be equal to 0.

At the time of the collision with the ground, the angle of the pitch to the dive was about 30 degrees, 4-5 seconds before the collision, the right bank began to develop at the aircraft, which reached 25 degrees.

The analysis of the received information continues.

A preliminary analysis of the recorded information, as well as an analysis of similar cases that occurred in the past, suggest that the development of a special situation in the flight could be caused by incorrect data on the flight speed on the pilots indicators, which in turn was apparently due to icing of the PAP when the heating systems are off.

In order to determine the reasons for the shutdown of the heating state of the three PDPs by the investigation commission, the following works are planned, including:

· Decoding of the on-board sound recorder to obtain information about the actions of the crew, the performance of the Operation Technology and the response to signaling;

· Study of the Technology of crew work with the system of heating of PPD, including indication;

· Schematic analysis of the heating systems of PPD for possible malfunctions and failures;

· The laying out of the remaining fragments of the heating systems of PPD.

Specialists of the commission of inquiry also continue to work at the scene of the accident, where the description of the scene of the incident is completed and the fragments of the aircraft structure are collected for further research.

In order to prevent accidents and develop operational recommendations, a brief briefing was held today at the Interstate Aviation Committee, attended by representatives of the Ministry of Defense, the Ministry for Emergencies, Rosaviatsia, Rostransnadzor, and airlines operating this type of aircraft. At the briefing, IAC specialists presented the participants with preliminary results of the investigation to take operational measures in the field of flight safety.

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Old 13th Feb 2018, 15:31
  #125 (permalink)  
 
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Originally Posted by Shaggy Sheep Driver View Post
Assuming they knew they had conflicting instrument indications (they might not have had time to deduce it was airspeed indication that was wrong) why wouldn't they fly power / attitude?

Surely they wouldn't just slavishly follow an erroneous ASI readout and ignore excessive pitch attitude indications (presumably on both main AIs and the standby AI)?
Why not - happened before (AF477?) , will happen again as long as humans are in the chain of command. Humans behave in irrational ways, sometimes.

I'm not saying that machines in the cockpit would be a perfect solution, they might solve this problem but replace it with another.
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Old 13th Feb 2018, 15:42
  #126 (permalink)  
 
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Also happened back in Dominican Republic, 1996 - Birgenair Flight 301, Boeing 757. The captain noticed his ASI was erroneous during take-off roll but decided not to abort due to the first officer's ASI "working".
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Old 13th Feb 2018, 15:48
  #127 (permalink)  
 
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Pitot Static Accidents

There's three other air carrier fatal accidents on the record in the previous millennium where pitot static systems were implicated:

Aero 08 - Erroneous Flight Instrument Information

I once discovered a dead airspeed on takeoff and took it into the air to avoid trundling into the ravine at the end of the runway. I spent half an hour sorting out what to do. Pretty simple in a 172 on a nice day. Much more difficult in a jet.
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Old 13th Feb 2018, 15:57
  #128 (permalink)  
 
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The “Zero Flight Time Training” program allows high
quality training of pilots for the entire An-148
/An-158 family without training flights on a real
airplane
http://www.antonov.com/media/archive...20OVERVIEW.pdf

Hhm....
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Old 13th Feb 2018, 16:04
  #129 (permalink)  
 
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Originally Posted by His dudeness View Post
Thats is a hell of a quick investigation....
Ah, but it's not an ""investigation" - it's a statement of the facts as derived from the FDR - and I will concur/concede that it does seem speedy.

But an "investigation" would want to know WHY the heaters were off - crew error, system fault, etc? - and also to understand the sequence by which the initial problem led to the crash. There's still plenty for MAK to do in detail, in "slow time".
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Old 13th Feb 2018, 16:07
  #130 (permalink)  
 
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Thanks for the explanations, especially the snowless photograph!

Bizarrely, just yesterday I spent an hour explaining to someone about the Aeroperú 603 crash and how a partial blockage is harder to spot than a complete one. But I thought that in that case, the readings are too low while climbing and too high while descending which doesn't seem to map with MVP3.

Regarding automated heating: that it isn't at all clear that the pilots didn't turn the heat on (or that it wasn't automated), just that they didn't manage to diagnose the issue in the first minutes of the flight.
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Old 13th Feb 2018, 16:32
  #131 (permalink)  
 
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While not exactly the same but there was Westair CRJ200 crash a few years ago in Sweden - erroneous instrument indications caused by IRS failure which was not recognised properly by a reasonably well experienced crew...
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Old 13th Feb 2018, 16:32
  #132 (permalink)  
 
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Originally Posted by PAXfips View Post
metar: uudd 111230z 13005mps 8000 -shsn few008 bkn026cb m05/m07 q1019 r14r/590293 r14l///99// tempo 1200 shsn
.. shortly after 11:20 UTC at approx. 6000 ft - were they then not VMC above clouds in daylight?
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Old 13th Feb 2018, 16:37
  #133 (permalink)  
 
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Originally Posted by RatherBeFlying View Post
I once discovered a dead airspeed on takeoff and took it into the air to avoid trundling into the ravine at the end of the runway. I spent half an hour sorting out what to do. Pretty simple in a 172 on a nice day. Much more difficult in a jet.
Indeed but that's easy - you know of the problem while still on the ground. I'm sure we've all flown circuits in light aircraft with the ASI covered over.

This would have been more subtle - airspeed indications would have been OK up until the point where the pitots froze. If the autopilot was engaged when that happened, that may have caused confusion as well (presumably they were in IMC).
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Old 13th Feb 2018, 16:49
  #134 (permalink)  
 
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From the BBC
The instruments began displaying different speed readings, probably because of iced speed sensors while their heating systems were shut off, the committee said....



Russian media reports said the plane's captain had rejected a de-icing treatment on the plane before takeoff. The procedure is optional and the crew's decision is based mainly on the weather conditions.
Russia Saratov crash: Ice on sensors 'may be cause' - BBC News

De icing is typically wings and tail, yes ? The pitot ports are electrically heated.

Though as it was snowing at the time on the ground the lack of de-icing is still maybe notable.
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Old 13th Feb 2018, 17:19
  #135 (permalink)  
 
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Originally Posted by PPRuNe Towers View Post
For browsers that don't translate on the fly here's the most substantive section of this preliminary report.

As I was hinting in the early hours of this morning. 15 previous flights pitot and port heating recorded on. No heat for this take off. You'll find the point where they went manual and I described a bit of 'heave ho' going on.

Credit due, as usual, to our Kulverstukas.

Rob
Very interesting. Sounding like another case of being unable to fly an airplane with one's own brain and hands.
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Old 13th Feb 2018, 17:37
  #136 (permalink)  
 
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Originally Posted by akaSylvia View Post
Thanks for the explanations, especially the snowless photograph!

Bizarrely, just yesterday I spent an hour explaining to someone about the Aeroperú 603 crash and how a partial blockage is harder to spot than a complete one. But I thought that in that case, the readings are too low while climbing and too high while descending which doesn't seem to map with MVP3.

Regarding automated heating: that it isn't at all clear that the pilots didn't turn the heat on (or that it wasn't automated), just that they didn't manage to diagnose the issue in the first minutes of the flight.
A blocked pitot will cause the airspeed indicator to work a bit like an altimeter. As you climb the ASI progressively reads higher and as you descend it reads lower.

I once discovered I had an iced pitot on a Pitts Special as I was climbing out (caused by water in the dynamic pressure lines rather than flying through icing conditions). The whistling in the wires was enough speed information to be able to continue the aerobatic sortie and once that was completed the ice had cleared and the ASI was working normally for landing. Being solidly VMC helped of course.
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Old 13th Feb 2018, 17:54
  #137 (permalink)  
 
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When I flew PA34 for living it was quite common to for the ASI to drop to 0 in icing conditions - even though the pitot heat was on. Once we were shown this it was a non event. We just continued to fly and after a while the indications were coming back.

Having said that, one colleague of mine, when faced with this situation for the first time, reacted on instincts and pushed the yoke full forward, sending the plane into a dive. Luckily they recovered before the ground...
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Old 13th Feb 2018, 18:01
  #138 (permalink)  
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I recall a quick Aldergrove to City, low level at night, rough as old boots. The tooter and stick shake were on nearly the whole flight, and it astonished me just how it affected my complacency about being able to accept the disruption of just one sensory input. Reacting to that warning was embedded deep in my mind, and dismissing it was bewilderingly hard to do.
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Old 13th Feb 2018, 18:10
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Have to make a comment on this one, and will not continue much as I did on AF447 thread.

Anyone here that has had the aero probes freeze/quit should have observations such as mine. If the AP was trying to obtain a commanded speed or pitch or....., then you can see the beginning of the accident when the air data went tits up.

I had the static ports freeze up one day due to simple electrical failure of the heater. So descending to the approach fix the speed went up but the altimiter remained at whatever altitude the ports froze. AHA! I had not changed the pitch attitude, and furthermore I had an inertial flight path marker that remained where it was when the ports froze. Big deal, right? Continued descent and looked at radar altimiter. Also intercepted the ILS glide path from above once the needle came off the bottom of the indicator. Ports came clear a few thousand feet AGL, altimiter came back and landed.

I have to iterate some lessons rrom AF447 and other cases where the air data or other data goes bonkers. Turn off the AP!. Maintain attitude and power that existed when crazy things happened. Don't do something! Just sit there!
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Old 13th Feb 2018, 18:23
  #140 (permalink)  
 
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Gosh, Too many children of the magenta in the air these days. In the days when every picture and the instruments were all in black and white we trained for and practiced this. At the risk of being labeled a grumpy old man why do we not train for it any more? What is wrong with power and attitude?
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