I think you guys are on the wrong track with all the "ATC clearance" and GPWS talk. I have no doubt that a standard EGPWS would be going ape down in amoungst those mountains. I think it is highly likely they were fully VFR, sightseeing, when they got badly caught-out. EGPWS (or whatever the equiv is in the Sukhoi) is not designed to provide terrain avoidance guidance during low-altitude sightseeing flights. I can even imagine that the system had been disabled, as one would do during a handling demonstration, to prevent the annoying "nuisance" warnings that would be going off eg "bank angle", Too low gear", terrain ahead".

Very good point, Bloggs. And good to see A Van here.

No way can you compare the terrain warning of the commercial jets with those we had/have in the military implementations. We looked way ahead and even had a display that showed selected terrain clearance versus the terrain ahead - a side look "slice", if you will. We also had the "soft ride" and "hard ride", which determined how far out you had to pull up.

By the time you get the warnings in a commercial jet you better have the energy and quick reactions to do something instantly.

The CVR shall tell the tale,

Decades ago I was a F/O in a DHC-6. Caught in a downdraft 1500 ft above MEA. Night, no radar. Max power, but still descending. Thought it was the end but came out in a familar valley 2000 below MEA.

DHC-6 is not a SSJ.

But after that, the 727,737,747,757,767's that I have flown, I have always treated mountains and wind with respect.

Except Funchal.Worst airport in the world. Who thought of placing an airport there?

I found turning around the most buttock-gripping thing about it. Seagulls look so minute waaaaaaaaaaay below.

To Capn Bloggs (your post # 480):
According to first feedback from those who examined the voice recorder, the TAWS was enabled (i.e. its «voice» is heard in the record). By the way, TAWS used in Sukhoi SSJ is T2CAS from Thales/L-3, AFAIK.
Regarding sightseeing, it looks unlikely. First, Gerry Soejetman refers in his blog to his friend who was onboard the first demo flight that day. That person says that there was no sightseeing, no «pilot bravado», no outstanding maneuvers – just a smooth short flight. Second, the weather conditions were deteriorating at the time of the second demo flight. And if there were no sightseeing at the clear sky conditions before, what reason would be to do it when the weather got worse?
Coming back to the TAWS issue and rough onboard terrain database, I would not line out the situation when the crew was not ignoring the system warnings and followed the instructions, but in reality the situation was worse than predicted by the system, and their unluck was measured in some 20-30-50 meters in altitude on the slope, as seen in photos.
So, IMHO at the moment, «innocent but deadly», as Gerry entitled his article, seems to be an appropriate wording. Hopefully the data recorder would be found to clarify the picture....

I agree with Capn Bloggs. I fly an aircraft with EGPWS and all the other kit but there is a big warning in the front of the book saying, in effect, "don't use this for navigation". The look-ahead terrain function is a life-saver but its purpose is to encourage you to get the hell out of there, not to examine it at low level and thread your way around the peaks, such as they might exist in the database. If you had no other choice, e.g. a technical problem that left you below MSA in IMC despite all your efforts, then steering the aircraft using the terrain map might be the best option out of a bad lot...

If they took a low-level route up the side of the peak, I'd have thought the plain old GPWS would have being going mad as well with mode 2 & 4 warnings. It would be possible, if you were descending directly towards the crash site, not to trigger the warnings until very close due to the terrain underneath not getting in radio altimeter range until almost the last moment.

re: Terrain avoidance question
 

A Van ... on the accuracy of terrain maps
Thanks for the very informative "response". [Actually I think we posted simultaneously. I certainly didn't see yours before I posted, and I doubt that you saw mine.]

Capn Bloggs
I think you guys are on the wrong track with all the "ATC clearance" and GPWS talk. I have no doubt that a standard EGPWS would be going ape down in amoungst those mountains.
I think it is highly likely they were fully VFR, sightseeing, when they got badly caught-out. EGPWS (or whatever the equiv is in the Sukhoi) is not designed to provide terrain avoidance
guidance during low-altitude sightseeing flights. I can even imagine that the system had been disabled, as one would do during a handling demonstration, to prevent the annoying
"nuisance" warnings that would be going off eg "bank angle", Too low gear", terrain ahead".
You may very well be right, but you misunderstand the purpose of my post.

From ideas thrown up in this thread there seem to be a variety of possible scenarious, all with some plausibility:

a) A "demonstration" of T2CAS.
b) A "white knuckle" ride intentionally at or below T2CAS warning levels, with T2CAS turned off.
c) A "highly scenic" ride intended to be near but above T2CAS warning levels, with T2CAS left on.
d) A "scenic" ride intended to be well above T2CAS warning levels, T2CAS on.
e) An intentional flight into a mountainous region flying below the peaks, with no intention of getting near the ground, T2CAS on.
f) A flight planned to be well way from the mountains, which strayed into them, T2CAS on.

To me it seems worth exploring all of these scenarios, and testing them all against the evidence -- as and when it appears.
I was simply exploring scenario (f).

I am certain that scenario (b) would greatly appeal to some salespeople, and accept your belief that some pilots would go along with the idea.


vovachan ... reported [a press release?] which, after google translation, states:
the warning system on dangerous ground proximity TAWS has been enabled and working.
If true, this argues against scenario (b) being the case for this flight.

In the spirit of full reporting ..The press release goes on to say:
"Preliminary analysis of the received speech to the registrar of the board 97 004 information shows that the premature failure of systems and
units of the SSJ-100 aircraft before the collision with Mount Salak, according to the decoded data to date, have been identified,"
Which I read as saying that there were [unspecified] system failures. At the moment I choose the believe that this is simply a translation error.

The word has been going around for quite a few years that some pilots use it to build their own IFR departure out of uncontrolled airports rather than use the FAA's published ODP (obstacle departure procedure). The FAA amended FAR 91.175 in June, 2010, to make this practice illegal for commercial operations.

T2CAS, good as it is, is in no way comparable to TFR as found in Tornado IDS, F-111, B-1, etc... anyone that thinks that is, well, nuts. I'm not sure anyone actually said this, but I am getting a vibe that a few think you can ride it in a similar way.

While a B-1 at some 600MPH+ with 'hard ride' selected might make it through such a mountain range with less than 500ft clearance, it is wholly reliant on the fidelity of the terrain database and based on that alone TFR will figure the safe limits. And remember this is an autopilot mode.

While T2CAS certainly borrowed some elements from TFR technologies, it is in many ways the analogue to a stall warning - the point is to avoid the stall in the first place, once you're in it, then it has failed - same with T2CAS - the point is to keep away from the terrain in the first place - not white-knuckle it through. Somehow I doubt this was what was going on.

A-Van raises a good point on the fidelity of the terrain database in this region. This may be the critical 'hole-in-the-cheese' for this accident. While the crew no doubt were highly experienced, if the T2CAS (TAWS...) only has DTED0 for this area, the warnings become significantly more error toleranced. I am not familiar enough with the T2CAS system to know if the current area of database fidelity is factored into algorithm, but given the serverity of the terrain this may indeed be a case of the warning coming to late or quite possibly not at all (since pole spacing for Level 0 is ~ 900m, meaning the terrain height is only known on a 900m grid) - therefore abrupt terrain features may NOT be in the database AT ALL...

Winds
 

It's been said several times on this thread that the weather, day to day, is highly repetitive. Could someone familiar with the area please comment on the (also presumably repetitive) winds to be found in the area?

I'm concerned that the col, or valley, or caldera, which seems to be the likely crash site might be downwind of the summit. If so, this could lead to downdrafts on all three sides of the col.

An update today (from Avherald):

On May 24th Russia's Rosaviatsia (Civil Aviation Authority) released a report dated May 22nd stating that a descent from the mountaineous area's minimum safe altitude of 10,000 feet to 6,000 feet had been pre-arranged. The flight was continued at 6,000 feet until the aircraft impacted a slope rising up to 7254 feet MSL. The investigation is ongoing in all directions with a controlled flight into terrain (CFIT) being a likely scenario. Rosaviatsia reported that CFIT accidents typically are the result of one or more of the following factors:

- Execution of flight below safe altitude as result of deliberate action of the crew or loss of situational awareness
- Lack of response by the crew to (GPWS/TAWS) alerts of terrain closure
-Clearance by ATC to descend in mountaineous terrain in absence of accurate position data
-Erroneous altitude indications due to incorrect pressure setting or system malfunction.

Sukhoi later added, that based on preliminary analysis of the cockpit voice recorder data a paper was signed by both Indonesia's National Transportation Safety Committee and Russia's Interstate Aviation Committee investigation the crash. The paper stated that no system malfunctions were detected prior to impact, the aircraft's Terrain Awareness and Warning System (TAWS) was operating and provided the crew with information about hazardeous ground proximity.

Re Sam’s update….

I am familiar with both investigative agencies involved here (KNKT, Indonesia, and MAK, Russia) and, though I have more respect for both (especially MAK) than many “Western” observers, the latter part of the quoted press release smacks of a problem both agencies still have.

Signing a joint statement this early in the investigation, and with NO DFDR information available, (basically as a PR move for Sukhoi) saying that no technical malfunctions were detected prior to impact, is both unwise and unprofessional. If Sukhoi wants to issue such a statement, fine; but for the investigative agencies to do so at this point is a different matter, regardless of whether the statement ends up to be true or false in the end.

(Edited to add: My comments apply only IF the quote from Sukhoi is correct re both agencies signining a statement.)

I think that respected MAK is not acting in this accident. I believe that special goverment board was estabilished to take a part in indonesian investigation.

Plus about hundread men from Ministry of Extraordinary Situations of Russia had arived to Indonesia to help with local works. Few days ago they leaved the crash site and fly back on their Il-76 to Russia. You can only speculate if it is only coincidence that they lived in the moment, when CVR indicated CFIT as very probably cause of accident and determine aircraft technical problems as unlikly.

grizz (#492), releasing such a statement is not unusual. Protocol requires that the investigating authority makes the statement; the manufacturer is a participant in the process, although usually requests such info to placate airworthiness authorities and operators / prospective operators at the earliest and most appropriate time.
The CVR is quite capable of determining ‘at this time’ that there were ‘no indications of …’ (details may have been lost in translation). E.g. no systems alerts or warnings heard, no crew calls for emergency procedures, and no unusual/unexpected noises.

Also, protection provided by EGPWS/TAWS is significantly different depending on position source information. GPS direct is best.....FMS (even with GPS in the suite) is a "degraded" position.

Does anyone know.....what is the position source on the aircraft/interface on this aircraft?

The facts to date do not support this as a major factor, but.........as usual, wait for the (hopefully) unbiased factual/final report.

Has the NTSB asked to be party to this investigation?

Yes, there are representatives of MAK participating as accredited representatives in this investigation (as is the usual practice).

Safety Pee...Thanks for your comment. I am aware of the protocols in these instances; my point was that issuing a "jointly signed statement" at this juncture (if that in fact occurred) which makes statements about things that there is as yet no evidence of, is quite different than issuing updates of factual confirmed information.

I have been involved in many investigations where pressure was applied early in an investigation by interested parties for the agency to issue statements saying that so far "there is no evidence of this", or "no indication of that", etc.

Most state investigative agencies strive to avoid such statements, for several reasons, the most important of which is: The need to be (and appear to be) completely independent of any influence from any source, from the time of the accident until the release of the final report.

A second, but potentially more critical reason, is that there have been occasions wherein DFDR data added causal information not available through a CVR analysis, or a wreckage analysis.

grizzled & safetypee

we are probably dealing with a single party releasing a statement rather than joint.

The difference being that "no-objection" by an ICAO recognized investigator-in-charge

To confirm I would like to know the source of the news article

To clarify previous posts, there are numerous images taken by a photographer on the flight deck during a flight on 08/05 2012, the day before the crash and on 04/05/2012.

MobileMe Gallery

There were other photographers on board I wonder if they were allowed the same access?

If flying low no better viewing/ filming viewpoint than from the cockpit.

Were crew-ground communiques critical?
 

Genlemen,


Who may, please, comment on what crew had to do and not to do in case the communications with the ground ATC was broken or delayed?


Assume that the picture drawn by Gerry Soejetman is close to reality:
http://2.bp.********.com/-cg7Nm_jPuv...-R2.-RZjpg.jpg


and let's consider the right point of orbit depicted in the above picture. Looks like having received OK from ATC to change the altitude to 6 Kft and make a right-hand orbit staying within Bogor training area, the crew implemented this maneuver and tried to get in contact with ATC once again requesting execution of the next step(s) of the flight plan. Most likely (at least as suggested by Gerry and it sounds reasonable) the crew was planning to make a right-hand U-turn and then continue descend towards Halim.


Assume now that the ATC did not react to the crew at that point (e.g. was busy as it was a rush hour). What the crew had to do in this situation, i.e. a demo/experimental flight, Indonesian airspace with potential specifics vs Russia, Europe, US? Repeating the right-hand orbit once again waiting until the communication is re-established? Go on implementing the flight plan (U-turn and further descend)? Keep going with the same course and altitude? If the latter, the crew would be moving towards the mountains as it likely happned. And if they were under VFR, this might not be a problem – e.g. they might be thinking «OK, let's wait for ATC and then make a turn after we pass the peak». But immideately after entering the mountains, they found themselves in a bad weather and the problems began. Perhaps, they reported change to IFR, even tried to get up to the Grid MORA, but not pulling up steep enough.


Is there anything obviously wrong in the above considerations? Sorry again if any wording sounds silly; my background is Air Force and astronaut training, too far from the civil aviation.

Bogor Training area...
 

Having followed this thread from day one here are my observations...
First answering A Van what I would do once established in the Bogor training area and lost communications with ATC... I would maintain VFR and continue orbiting that area. From previous posts I gather that the Bogor treaining area has a ceiling of 6000' and can only be used in VMC conditions. If ATC does not respond, try approach, tower etc. Been there before.
My second observation is that fotos of the three types of data recorders were published in this thread. The two - CVR and a combined version of CVR/FDR look almost identical. I have not heard of an official anouncement that crews are still actively looking for the FDR. It also sounds very suspicious that Russia has recalled most of their search teams. After all they would be most interested in the FDR data.
As Karel X [post 493] states the Russian search team consisted of 'Ministry of Extraordinary Situations' people. Could it be they found the FDR and without fanfare delivered it to MAK. Now it would be almost impossible for MAK to admit they have it. Or maybe they just asertained that it was a combined CVR/FDR and left. I can't imagine that once one was found, the other can not.
Does anyone know how far apart they were mounted?

The datas (FDR, CVR) will hopefully show in the future, what led to the disaster.

Lots of assumptions here. But given they apply, then staying in the orbit, or climbing in that orbit would have been an option. To continue with further descent when unaware of the terrain is suicide.

No good plan, you might hit something or run out of fuel.

If flying VFR, there is no sound reason to enter IMC with an air transport aircraft in mountaneous terrain. I would try both, stay out or get out of the mountains (climbing above MSA would be apropriate, would improve communication with ATC as well) and stay VFR by all means, and continue VFR on the planned routing. until communication with ATC is established.

There should be no need to pull up steep. When familiar with the performance of the aircraft planning ahead, staying clear of obstacles and maintaining VMC saves the day.

We should ask the question, what the task in the Bogor training area was. It´s kind of unusual to use a training area just to reverse course. That could have been done also under IFR in a level turn.

The descent in the wrong area finally brought them down to an altitude, where hitting ground was possible.

When being checked out on a new type, my LTC likened some of the traps one could fall into as a 'long dark corridor.'

I think this was almost a literal interpretation of the analogy. A nice easy VFR flight around the mountain and a turn one ridge too early - perhaps with that orographic sheet masking the left ridge.

With the speeds and times we've suggested there could well have been just a few seconds of utter disbelief as it became apparent there was no opening ahead. No real time to do anything in an aircraft that refuses to be pointed at the stars.

A_Van,

Welcome to PPRuNe. For some strange reason, the word "b l o g s p o t" is banned. Here is a TinyURL pointing to the picture you refer to:

http://tinyurl.com/6m5cteu

I reckon you've nailed it.

The Australian Army lost a Twin Otter in PNG a few years ago doing exactly that. Turned up the wrong valley on a training flight and couldn't outclimb the rising terrain. Accident Report

yep...one turn too early... kinda what I was referring to a few pages back.....

97004 wasn't registered as civil aircraft, it's experemental.
MAK is not working on this case, stop mentioning it.
It's entirely in hands of Ministry of Industry and Trade (MINPROMTORG).
MINROMTORG doesn't have expertise for such cases, so you shoudn't expect anything from them. It'll fall entirely on Sukhoi and NTSC to investigate this case.

Indeed, following my notion in 313 that both pilots might have been looking at a ridge on their side* - comfortable with the fact they were passing a solid mountain - dash8flyer presented in post 316, fine graphics of a scenario that I find the most plausible.

My recent post is really just an amplification of what I feel is still the most probable series of events, but with the image of that vertical sheet of cloud brought to the fore, allowing the logic that both pilots may have assumed the ridge on their right was the only one.


* Above, in terms of both pilots seeing a ridge on their side only, I had in mind them still having to look down slightly during the first part of the valley. Neither pilot would have been able to see the ridge on the opposite side until that terrible moment when ridge heights were visible from both sides.

Under the penalty of getting one of those Edit thingies, I must add that of course the above scenarios do imply a fairly serious limit to forward visibility.





.

Yeah, Rivets, you might have the most plausible scenario.

In a galaxy far away, we flew in similar terrain and had similar WX during half the year if we were west of the Annames Mountains. We had downward sloping terrain to the west, so flying north we were fairly sure that turning and climbing to the west would get us outta trouble. OTOH, we had terrain-following radar that looked out miles ahead. We could set a terrain clearance and get vertical guidance to use or not use. I don't foresee this in our commercial jets, and the terrain warning systems in use today don't seem to offer as much "protection/warning" until late in the game. out...

a new angle?
 

Tabloid: Superjet Downed by U.S. Industrial Sabotage | News | The Moscow Times

:confused::rolleyes:

Boris Badenov is at it again.

Problem report: 27 pages indicated but I cannot see beyond 25
 

My view of this thread has been stuck on page 25 for 30hrs or so.
The footer now indicates that this is page 25 of 27.

Any ideas? [And will I be able to see them if there are any?]

Bits clipped out by the mods don't give the page back.

More precisely:
Posts erased, either by the mods or by their author, are kept into the database (and still available to mods & admins). They also are still accounted for by the board regarding pages count but each page displays the correct number (20) of visible posts. This causes a mismatch.
As a commun user, you're not able to see thoses erased posts, nor to go to the "apparently missing" pages.
Note we're on page 26, not 25.

Published today:
24 minutes of radio silence?

BMKG: Weather Problem Did Not Disrupt Sukhoi’s Flight
Ezra Sihite | May 28, 2012

BMKG: Weather Problem Did Not Disrupt Sukhoi?s Flight | The Jakarta Globe

That weather man from BKMG is off the mark.

Salak and Pangarango have their own weather. It can be sunny and clear skies in Bogor where the weather station supposedly is and heavy cloud and rain in the hills.

Just walking on Salak one never takes it's weather for granted.

Be Careful on how to read this press reslease :

Apparently the aircraft was cleared to a specific reserved area to make a demo flight that included some orbits (360s) .once the instructions to enter the area and to perfom the first orbit were issued , it is normal for ATC anf the crew not to call each other .the next calls will be when the aircraft crew request to leave the area to go back to land , or if another aircraft would enter the area . So 24 min without calling each other is normal under the circumstances . This is not a radio comm problem .

In my experience, when an aircraft is cleared by an ATC for air-work in a designated location, it is usually also asked to "report on completion" of the air-work.
"If" this aircraft was cleared for only one orbit (as stated in the quoted recent press release and as reported previously) 24-minutes-long radio silence from both sides appears to me to be rather unusual....

Does not sounds right . You do not need to go to a special area to make a single 360.

The key to this is in the pre de briefing details. I have been involved in airshows organisations and the details of every and each flight presentation or demo flight is discussed and agreed upon in a large briefing between actual Pilots , Show organisers and ATC each day . How long this particular demo was planned for is therefore recorded somewhere.
Wait a bit more for the details.

Again , this "radio silence "as you call it , is not a cause of this accident