Aircraft Crash in Moscow
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That leaves less than 5000 feet before disaster. If the CCTV is accurate, that there were 30 seconds between TD and impact, that is an average velocity of approx. 115 mph. Allowing some velocity at the impact zone means there was little if any deceleration. Since the a/c obviously had residual velocity at the impact, the numbers suggest strongly the speed was higher than any survivable value. Assuming the impact speed was zero, post impact, (obviously) the average speed was far higher than 115 mph. Thanks to Doors to Automatic for the relative distances involved.
I am with vovachan in proposing uncommanded forward thrust. Unfortunately, there is the possibility also of commanded forward thrust. The Pitch of the a/c off runway did not follow the contour of the terrain. Rather, it suggested at least to me, there was a serious component of aerodynamic lift at the end of the runway.
Any low speed excursion would have the nose in the video lurch vertically. I did not pick that up. The "settling" I perceived could also be to the inertia of trajectory, so that wants a dash of salt.
I am with vovachan in proposing uncommanded forward thrust. Unfortunately, there is the possibility also of commanded forward thrust. The Pitch of the a/c off runway did not follow the contour of the terrain. Rather, it suggested at least to me, there was a serious component of aerodynamic lift at the end of the runway.
Any low speed excursion would have the nose in the video lurch vertically. I did not pick that up. The "settling" I perceived could also be to the inertia of trajectory, so that wants a dash of salt.
Last edited by Lyman; 2nd Jan 2013 at 17:10.
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the story of the 204 making 2 approaches
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Media allege that Vnukovo firefighting cars were on repair so the first emergency crews appeared on the scene no earlier than 50 minutes after the blaze broke out.
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For me, this a very strange accident/crash....
- a very light, modern jet didn't come to a halt on a +3 km runway, not snow covered, not icey
- no tech problems, at least not told to ATC
- between TD and impact, the AC lost only 20 kts (if true...)
- it is yet still not known, who was on the controles
- it is yet still not known who was in the cockpit and on which seat...
- a very light, modern jet didn't come to a halt on a +3 km runway, not snow covered, not icey
- no tech problems, at least not told to ATC
- between TD and impact, the AC lost only 20 kts (if true...)
- it is yet still not known, who was on the controles
- it is yet still not known who was in the cockpit and on which seat...
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Could I ask some of you Boeing and Airbus drivers something about a comment made previously in this thread criticizing the Tu-204's "Russianess" in that it's a "poorly" layed out cockpit with clunky nobs etc.
Is this really so? The cockpit looks like a nice place to be and doesn't look very cluttered to me. I am not an airline pilot (yet) so I can't judge the ergonomics of it all but I am curious to know the answer to this question.
Is this really so? The cockpit looks like a nice place to be and doesn't look very cluttered to me. I am not an airline pilot (yet) so I can't judge the ergonomics of it all but I am curious to know the answer to this question.
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hetfield
one question I can answer for you (info from VKO rescue team member):
Everybody was at their places in cabin and CC was at seats. CPT was at his seat which was completely destroyed by impact, 2P and F/E was at their seats BUT they buckle only lower belt, not the shoulder belts 
Same with CC - they were not on theit seats with shoulder belts. 
one question I can answer for you (info from VKO rescue team member):
- it is yet still not known, who was on the controles
- it is yet still not known who was in the cockpit and on which seat...
- it is yet still not known who was in the cockpit and on which seat...
Same with CC - they were not on theit seats with shoulder belts.
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BOAC, forget it. There was nor circling nor second attempt. I heard ATC recording (and posted link there) from radioscanner. Till touchdown there was not any hint of emergency situation. Also you can see track at flightradar24.
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If there had been a previous attempt to land, we would by now have had some information about it especially as it seems there was CCTV footage of the final attempt.
If there had been a failed attempt to land followed by circling to reduce the fuel load, it would then make no sense to try to land at an airport with no fire cover when there were three others so close.
If there had been a failed attempt to land followed by circling to reduce the fuel load, it would then make no sense to try to land at an airport with no fire cover when there were three others so close.
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Could I ask some of you Boeing and Airbus drivers something about a comment made previously in this thread criticizing the Tu-204's "Russianess" in that it's a "poorly" layed out cockpit with clunky nobs etc.
Is this really so? The cockpit looks like a nice place to be and doesn't look very cluttered to me. I am not an airline pilot (yet) so I can't judge the ergonomics of it all but I am curious to know the answer to this question.
Is this really so? The cockpit looks like a nice place to be and doesn't look very cluttered to me. I am not an airline pilot (yet) so I can't judge the ergonomics of it all but I am curious to know the answer to this question.
And I have to say, just as you, seems pretty organized, a well structured station. I have seen a few concepts in my life, and this doesn't turn me away like the pic of a 742, wher new developed screens (like TCAS) have been stuffed to whereever there was room to hold one.
Looks ok to me, even if somebody else might think the switches are "cluncky", they are still switches.
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I am probably wrong, but I thought Boeing has an iron in the 204 fire, and that it is basically a Russian version of the B-757....
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EMAS and Runway End Safety Area (RESA)
The role of the RESA and the use of EMAS has been raised by several people here – first by SGC. Thanks to the excellent diagrams/photos posted by Kulverstukas, I was able to look at what effect an EMAS would have had at Vnukovo Airport.
What an EMAS really does
Firstly let me clarify what an EMAS really does because there are sometimes misconceptions about what it can do. It is not a physical arrestor like the aircraft carrier arrestor cable, nor is it a barrier net or barricade like the military use.
It can be simplistically thought that an EMAS effectively adds 525 feet of runway with guaranteed maximum braking which is 160 metres.
Effectively because the deceleration in an EMAS varies due to several factors which can be correlated to aircraft weight – heavier aircraft do not slow down as quickly. EMAS design adjusts for this by providing longer EMAS beds for heavier aircraft to ensure it still effectively adds 525 feet of maximum braking.
guaranteed maximum braking because the EMAS does the braking for you. Regardless of brakes, tyres, systems, pilots, runway surface, or weather, EMAS gives you that guaranteed maximum braking. Staying with my simplistic 525 feet analogy, it gives a deceleration of 13 ft/s2 (which is 0.41g or a typical Boeing "Autobrake Setting MAX). The actual aircraft deceleration in the EMAS bed varies with weight and other factors from 0.38 g to 0.78 g for aircraft from the 747 to the CRJ-200.
Simplistic because there are many more factors at work, but there is a consistency in the results which suggests that simple works here.
Design EMAS for Vnukovo Airport
A standard EMAS design will stop the design aircraft at a runway exit speed of 70 knots; it has a paved 75-foot set-back, assumes no reverse thrust, and a 0.25 braking friction coefficient.
Assuming that the EMAS for Vnukovo Airport was designed with the Tu-204 as the design aircraft. Assume that the Tu-204-200 design aircraft has a MTOW of 244,115 lbs (110,750 kg). The designed EMAS structure would typically be a bed length of 375 feet (115 m) and a paved setback of 75 feet (23m); a total of 450 feet (137m) from the runway end which would easily be fitted at that end of the runway at Vnukovo.
If the aircraft left the runway at 70 knots, then it would be stopped at the end of this EMAS bed.
Performance of EMAS in actual accident
The performance of the EMAS in the actual accident would be very much affected by the speed at which the aircraft was travelling when it left the runway. The standard EMAS design assumes a runway exit speed of 70 knots, but for Vnukovo, Lyman has given us some reasoned estimation that the speed was 100 knots.
At 100 knots exit speed, a MTOW Tu-204 would leave the paved 75 feet area and enter the bed at 165.17 ft/sec (98 knots). It would leave the EMAS bed still travelling at a high 71 knots. From there it is about 123m to the first significant drop-off. Assuming very poor braking on the snowy ground, it would be travelling at 64 knots or more when it reached the first significant drop-off. The actual aircraft was light, so its deceleration in the EMAS bed would be slightly higher but the effect on speed would only be 5-6 knots lower. All this assumes no forward thrust, which would only have made matters worse.
So would the EMAS have saved the day or even mitigated the accident? Unfortunately in this case it appears not.
What an EMAS really does
Firstly let me clarify what an EMAS really does because there are sometimes misconceptions about what it can do. It is not a physical arrestor like the aircraft carrier arrestor cable, nor is it a barrier net or barricade like the military use.
It can be simplistically thought that an EMAS effectively adds 525 feet of runway with guaranteed maximum braking which is 160 metres.
Effectively because the deceleration in an EMAS varies due to several factors which can be correlated to aircraft weight – heavier aircraft do not slow down as quickly. EMAS design adjusts for this by providing longer EMAS beds for heavier aircraft to ensure it still effectively adds 525 feet of maximum braking.
guaranteed maximum braking because the EMAS does the braking for you. Regardless of brakes, tyres, systems, pilots, runway surface, or weather, EMAS gives you that guaranteed maximum braking. Staying with my simplistic 525 feet analogy, it gives a deceleration of 13 ft/s2 (which is 0.41g or a typical Boeing "Autobrake Setting MAX). The actual aircraft deceleration in the EMAS bed varies with weight and other factors from 0.38 g to 0.78 g for aircraft from the 747 to the CRJ-200.
Simplistic because there are many more factors at work, but there is a consistency in the results which suggests that simple works here.
Design EMAS for Vnukovo Airport
A standard EMAS design will stop the design aircraft at a runway exit speed of 70 knots; it has a paved 75-foot set-back, assumes no reverse thrust, and a 0.25 braking friction coefficient.
Assuming that the EMAS for Vnukovo Airport was designed with the Tu-204 as the design aircraft. Assume that the Tu-204-200 design aircraft has a MTOW of 244,115 lbs (110,750 kg). The designed EMAS structure would typically be a bed length of 375 feet (115 m) and a paved setback of 75 feet (23m); a total of 450 feet (137m) from the runway end which would easily be fitted at that end of the runway at Vnukovo.
If the aircraft left the runway at 70 knots, then it would be stopped at the end of this EMAS bed.
Performance of EMAS in actual accident
The performance of the EMAS in the actual accident would be very much affected by the speed at which the aircraft was travelling when it left the runway. The standard EMAS design assumes a runway exit speed of 70 knots, but for Vnukovo, Lyman has given us some reasoned estimation that the speed was 100 knots.
At 100 knots exit speed, a MTOW Tu-204 would leave the paved 75 feet area and enter the bed at 165.17 ft/sec (98 knots). It would leave the EMAS bed still travelling at a high 71 knots. From there it is about 123m to the first significant drop-off. Assuming very poor braking on the snowy ground, it would be travelling at 64 knots or more when it reached the first significant drop-off. The actual aircraft was light, so its deceleration in the EMAS bed would be slightly higher but the effect on speed would only be 5-6 knots lower. All this assumes no forward thrust, which would only have made matters worse.
So would the EMAS have saved the day or even mitigated the accident? Unfortunately in this case it appears not.
Last edited by OverRun; 3rd Jan 2013 at 04:04. Reason: Add light op weight effect
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So would the EMAS have saved the day or even mitigated the accident? Unfortunately in this case it appears not.
The assumption the aircraft left the runway at 100kts, is just that - an assumption at this stage. Might be faster, might be slower. Lets concentrate on what we know for sure.
If we go by known facts, I think that EMAS would most certainly have saved lives. Being that some of the injured died at hospital or after the crash, we can deduce that the impact speed was right around the threshold of survivability for these circumstances - regardless of what that actual speed was.
That is all that matters in a crash really - how quickly you come to a full stop. Speed is not the killer. If you hit the ground at 250kts but use up 3 miles to stop, then you will most likely survive the impact. But if you hit an unforgiving obstacle at 50kts and take only 1 foot to stop, then you will probably die or at least end up severely injured.
The overrun did not kill in this instance, it was the unforgiving obstacles that killed the occupants. EMAS would have certainly shaved 10 or 20kts of their speed, and that might have been enough to bring them within the threshold of the restraint devices and within the energy absorbing limits of the airframe. Remember that as speed increases, the chances of dying go up exponentially.
Either way, by FAA standards, this runway is illegal unless it has EMAS. The RSA is simply not long enough. And with obstacles so unforgiving like the dirt embankment they hit, IMHO, I would exceed the FAA limits and put EMAS all the way up to the highway shoulder (or even shorten the runway a bit to extend the EMAS strip). This time it was an empty repo flight, next time it might be a full IL96 with Russian vacationers.
Hopefully the Russian authorities, as tragic as this was, take this accident and look at it as a warning of how bad it could have been.
Unless there is a bit of M²/V² involved, I don't understand why if,
it would, assuming an entry of 100kts,
especially given that it was virtually empty.
Originally Posted by Overun
the aircraft left the runway at 70 knots, then it would be stopped at the end of this EMAS bed.
Originally Posted by Overun
leave the EMAS bed still travelling at a high 71 knots.
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I must be not understanding, overun. you suggest that EMAS' mechanism for energy dissipation is 'braking'. If a 125 meter bed 'effectively' provides 175m of 'additional runway braking', then the efficacy of its use is barely marginal.
The mechanism as I understand it has fibrous and frangible concrete installed as an 'arresting bed'; as the material decomposes with the passage of the landing gear, it provides greatly enhanced arrestment due friction and non uniform crumpling of the supporting material. My guess is that the landing gear is destroyed, the EMAS install is most definitely destroyed. But the sacrificial nature of the installation is a design consideration. Better to save lives than landing gear and lightweight frangible 'runway'?
Better than runway braking, surely?
I have to concur with Sqwak 7700, the EMAS system will attenuate velocity better than runway. It would have slowed the subject Tu204 markedly, perhaps saving everyone. The Runway is definitely non compliant per FAA, not that FAA regs should obtain here.
I would repeat my observation that 01 is "too long". Runway that should be overrun is not runway. It is overrun, and cannot (should not) be represented as usable runway for purposes of flight planning....
With great respect.
The mechanism as I understand it has fibrous and frangible concrete installed as an 'arresting bed'; as the material decomposes with the passage of the landing gear, it provides greatly enhanced arrestment due friction and non uniform crumpling of the supporting material. My guess is that the landing gear is destroyed, the EMAS install is most definitely destroyed. But the sacrificial nature of the installation is a design consideration. Better to save lives than landing gear and lightweight frangible 'runway'?
Better than runway braking, surely?
I have to concur with Sqwak 7700, the EMAS system will attenuate velocity better than runway. It would have slowed the subject Tu204 markedly, perhaps saving everyone. The Runway is definitely non compliant per FAA, not that FAA regs should obtain here.
I would repeat my observation that 01 is "too long". Runway that should be overrun is not runway. It is overrun, and cannot (should not) be represented as usable runway for purposes of flight planning....
With great respect.
Last edited by Lyman; 3rd Jan 2013 at 07:48.