Analytical Service Pty Ltd

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Report No. 456

SOME MECHANICAL AND STRUCTURAL ASPECTS OF THE SMOLENSK AIR CRASH

by Dr. Gregory Szuladzinski, MSME Independent Technical Advisor to Parliamentary Committee for Investigation of the Catastrophe of the TU-154 M on April 10, 2010

©Analytical Service Pty Ltd

This is a translation of the corresponding document in Polish

Version 6 May 2012

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Table of Contents Introduction...... 3 Summary of Results ...... 3 1. General Course of Events ...... 4 2. Anticipated and Real Structural Damage, Comparison ...... 6 3. What Happened near Point K? ...... 12 4. More about the fate of the left wing ...... 13 5. Kinetics of Last Phase of Flight ...... 15 6. Explosion in the Fuselage...... 18 7. Separation of the Tail Section of Fuselage ...... 24 8. Other Possible Considerations of this Accident ...... 25 9. Mortality in air accidents ...... 25 Appendix I. Collision of the Wing with a Tree (birch) ...... 25 Appendix II. Fragmentation ...... 26 Appendix III. Fuel in Special Circumstances...... 31 Appendix IV. Mechanics of HE Explosion and Aircraft Fire ...... 31 Appendix V. Aircraft Rotation around the Longitudinal Axis ...... 32 Appendix VI. Eyewitness Accounts ...... 33 Appendix VII. Other Incomprehensible Issues ...... 34 Conclusions ...... 34 Picture sources: ...... 35 Other Work of This Company...... 35 Technical questions related to this Report should be directed to the Parliamentary Group A. Macierewicza. After sorting (to avoid repetition) questions will be forwarded to the author to answer...... 35

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Introduction The incident took place in the Russian Federation on April 10, 2010, when the plane, a Tu-154M, owned by the Government of Poland attempted to land in Smolensk. On board there was the President of Poland, Dr. Lech Kaczynski, with his wife and many VIPs, a total of 96 people. Most of them were his closest staff, commanders of Polish armed forces, president of the central bank and leaders of Sejm, the Parliament of Poland. All of them including the flight crew died as a result of this accident. In view of the known facts the purpose of the following analysis is to determine the physical reasons that lead to the catastrophe. The available data are: The number and the size distribution of the fragments found after the crash along with some navigation data. Most of the information and photographs were made available by the Polish Parliamentary Committee for Investigation of the Crash and from Dr. Kazimierz Nowaczyk and Dr. Wieslaw Binienda, experts of the Committee. A substantial amount of data was provided by Marek Dabrowski, MSAE. A quantitative analysis of the spread of the debris is not undertaken in this report.

Summary of Results The destruction of the plane was initiated while it was still airborne, approaching landing. One explosion took place in left the wing, at about one-third length from the fuselage. This had a strong local effect on the wing, causing its split into two parts. A secondary effect was partial damage to other major structural connections. A second explosion took place inside the fuselage. It caused massive destruction and fragmentation of the fuselage into several major parts and hundreds of smaller pieces. The landing itself (or fall) in the wooded area, no matter how adverse, and at what angle, could not in any way result in fragmentation to the documented extent.

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1. General Course of Events Part of the left and right wing, a widened section adjacent to the fuselage and is often called the center wing. This section passes here through the cabin and is, in itself, very solidly built. In most air accidents, when the machine somehow hits the runway, this part is the least damaged in comparison with the tips of the wings or ends of the hull.

Fig. 1. The outline of the Soviet-made Tu-154M

Fig. 2. The aircraft trajectory, according to recent studies, is indicated by a black line. The upper graph shows it in a plan view, and lower in elevation. The TAWS point (later referred to as critical point, in short: the point K) is the place where the direction of the flight has significantly changed. The nearly vertical lanes on the upper photograph are: Gubienki Street (right) and Kutuzova Street (left).

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As per above, point TAWS (TAWS # 38 according to the NTSB report (Annex 4 to the report KBWL)) will be called a critical point, point K. (The plan view of the trajectory in Figure 2 is a simplification. The last section between point K and FMS really is an arc tangent to the previous segment. This means that the aircraft was turning). Point FMS indicates the location where the on-board computer (Flight Management System) memory suffered a power failure. Therefore, contact with the ground was lost. This aircraft has multiple protections against the power drop, so that the event leading to this had to be very serious. Barely visible small squares with the words "wing" and "stabilizer" are the places where the aircraft components were found. "Birch" refers to a tree, which was considered a direct cause of the crash. It has been hypothesized that hitting the birch tree resulted in the loss of the wing, and the general stability, which resulted in crashing to the ground. To investigate this issue, prof. Binienda of Acron University presented simulations employing FEA (Finite Element Analysis) and showed that, with appropriate speed, the wing was able to cut the birch, not vice versa. We must mention that in photos the birch looks like it was cut by a blunt object, but its relationship to the accident is difficult to determine. More detailed trajectory studies accomplished in the meantime show that any contact between an airplane and this tree was not possible. This, however, does not preclude the role of other trees in the whole event. The plane crashed into the ground near the point of FMS.

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2. Anticipated and Real Structural Damage, Comparison In the vicinity of point K a sudden event took place causing a change in course. (TAWS, Figure 2). The altitude was greater than 30 m and horizontal speed - about 270 km/h. Trees and forest undergrowth at the emergency landing area, had a tendency to reduce the horizontal velocity. ("Emergency landing" is used here as a loose term, meaning contact with the ground, no matter how undesirable the circumstances.) Elastic properties of the soil should act somewhat like a shock absorber, reducing the peak vertical acceleration of the fall. There were no obstacles in addition to trees, which could have significantly slowed down the machine. The effect should not be much larger, then then driving a car into the shrubbery of a grove at a speed of 150-250 km/h, which is the estimated speed at the time of impact. (At such a supposed grove, thin trees would need to be quite thin, as we compare the plane of a length of about 50 m to a car, less than 5 m). What should be expected in such a case? As for the plane, the skin would be broken at places and much crumpled sheet metal would result. The wings could be badly broken, but the fuselage should have only a limited breaks and locally damaged areas. Actual photos of the wreckage of the plane shown in Figure 3 and Figure 4 do not agree with such expectations.

Fig. 3a. A reassembled plane wreckage on the tarmac as seen from behind. The left wing is on the left.

Fig. 3b. It is an enlarged part of Figure 3a, showing the left edge of the torn fuselage, torn under passenger windows.

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Fig. 4. The wreckage on the tarmac as seen from the front. On the right one can see remnants of the left wing. It seems there is no clear connection with the rest of the center wing. Not only are the wings broken, but the hull is in pieces. The front part of the fuselage, in front of the wings, fell into normal position, while the rest of the hull fell "on the back". In other words, the rear part of the plane rotated in flight Figure 4 also suggests that the front ceiling of the fuselage has not been found or has been fragmented into pieces too small to combine them in the "outline". Figures 5 - 9 show the remains as they fell, shortly after their discovery. The devastation is much more thorough than an emergency landing would warrant, both in space and in the nature of the damage. There are tens of hundreds of large and small pieces. Mechanical impact to the ground, after a partial slowdown through the trees, does not justify such a fragmentation of structure. ("Emergency landing" is used here as a loose term, meaning the plane's contact with the ground, no matter how undesirable the way).

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Fig. 5. The remains of passenger cabin (parlor/lounge) in the correct position on the ground. Also, remnants of the chassis front, separated from base.

Fig. 6. Part of cockpit and front of main cabin in correct position on the ground

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Figure 7. Main, passenger part of the hull, torn and upside down. The left and right side of the blown passenger cabin can be seen open to outside. A part of the plane's ceiling on the right.

Fig. 8. Part of the rear segment of the fuselage, upside down

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Fig. 9. Rear part of the fuselage and wing, which landed up-side-down.

Fig. 10. The upper skin (No. 16) and lower (No. 2 according to Figure 11) removed from the left wing, on the tarmac. The lack of the wing's supporting structure (longerons) between skins, which must have been blown-out, is striking. In the crash scene both skin elements are spaced apart by more than 40 meters. The destruction shown in Figure 10 does not determine whether the break-out began in the interior of the wing, or from outside of the leading edge. It only shows the effects of a strong shock wave penetrating into the wing.

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Fig. 11. View of the left wing, as seen from the bottom. List of found parts.

1. Left center wing 2. Removable part of the left wing (bottom skin with Polish emblem - white/red chessboard) 3. End part of the wing 4. Deflector (end part) 5. Fragment 6. Fragment 7. Reducer 8. Fragment 9. Center slot, Section 2 (left fragment) 10. Center slot, Section 2 (middle fragment) 11. Center slot, Section 2 (right fragment) 12. Center slot, Section 2, (left fragment) 13. Interior slot 14. Broken away Longeron 1 of center wing with skin fragment 15. Broken away Air Conditioning block with skin fragment 16. Removable part of the left wing (upper skin over Polish emblem)

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3. What Happened near Point K? There is some evidence in the sound records of published by the MAK and by the Miller Commission and the transcription of the audio record prepared at the request of the prosecutor by the Polish Institute of Forensic Research, which together with other data suggests an explosion taking place in the wing. Sound recordings show that shortly before the point K one pilot swore and the passengers began to scream. This recording particularly matches the description of sounds in the cockpit, which in the last moments of the flight one passenger passed by telephone to his wife's voicemail. You cannot associate this with an explosion in the hull for the simple reason that, after such an event, passengers would no longer be able to scream. So, if this instant is considered as coinciding with the explosion in the wing, the passengers had reason to be fearful: a very strong shock and the beginning of the plane's tilt with perhaps the initial cracks in the fuselage. (Destruction shown in Figure 10 illustrates how powerful was the impulse of explosion). In the area of point K not only the direction of flight began to change, but there also occurred vertical acceleration, ca 0.27g upwards, as recorded by the instruments, Figure 20. (This does not nearly reflect the acceleration amplitude of the wing, because it was registered in the fuselage). The landing gear system reacted as if the plane was landing. There is a set of photos taken after the disaster from the point at Gubienki Street, where you can see the tip of the wing leaning against the tree. The surrounding trees bear the traces of which can be interpreted as the result of being bombed by debris. In one area, the smaller trees and branches are lying side - by - side, which could be due to the combined effects of the explosion and the blast of air passing from aircraft engines flying low above.

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4. More about the fate of the left wing Fig. 12. End segment of the left wing ( bottom surface). The location of the final segment of the wing in Figure 12 was marked with squares in Figure 2 and described as a "wing". Because everything takes time, even the system's reaction to the explosion, so the accident had to start a little before the point of K. Let's say, for simplicity, that it was more or less around the square marked "wing". What information does this carry about the trajectory of a falling item? If we take into account only the beginning and the end, the wing dropped down like a stone. But a stone flying horizontally along the plane has a speed of 270 km/h, or 75 m/s. To fall from a height of 30m, the stone needs less than 2.5s. Within this same time, the stone should cover about 190m in the horizontal direction. However, the wing is not a stone and if it flies with a main surface forward, it is subjected to a large drag. Still, despite the chaotic movements being possible, you can expect 90, or 60 meters, but not zero. Looking at the Figure 12, one can observe, especially with good digital magnification, fairly evenly distributed small wrinkles. Because they look tilted to the axis of the wing, they can be associated with high shear force, related to the separation of this segment of the wing. The jagged edges along a break line are not well seen on this photo. In Figure 3a, where the remains are assembled, one can see (in digital magnification), a large amount of debris between the edge of this segment and the rest of the wing. That remainder of the wing also suffered great damage, as shown in Figure 10 and 11. Everything points to the symptoms of an explosion. Where could be the center of such an event? One possible location is just before the leading edge of the wing. (Fig. 13a). The event, which pushes out and breaks up a short piece of the wing, applies shear force Q on both sides of the breakout. (Fig. 13b). (The force Q in the figure can be estimated as the product of the effective cross-section of the wing, and shear strength of its material).

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Fig. 13. a) The explosion just before the leading edge. The thin wavy line shows the extent of the torn fragment. (The width should not be taken literally); and b) The end piece of the torn wing flies back, turning/ spinning. This action on the end segment of the wing causes it to gain a reverse speed with respect to the aircraft movement. (Fig. 13b). An impulse applied by the shear force gives rise to a torque around the center of gravity, causing the wing section to spin around a vertical axis. Such a motion allows the wing segment to achieve a significant range of flight in the same way as a boomerang does. This hypothesis explains why the wing segment "returned" to the point of K. The strength of inertia pushed it forward, while the force of explosion pushed it back, spinning it simultaneously. The second force Q, applied to the remaining wing part, causes an additional resistance on the left side, and thus produces a tendency to turn to the left. A strong impulse in the middle of the wing causes a tendency to tear the wing base, as shown in Figure 11. Apart from this, the impulse could, to some extent, weaken the joints of the front part of the fuselage with the rest of the craft. Another possibility is an explosion inside the wing, caused by the load detonating between the longerons. It doesn't explain the kinetics too well, because the horizontal component of the pulse would be too small to send the tip in the direction opposite to the movement of the aircraft. To change the direction of the wing tip's flight, caused by an internal explosion, it is necessary for the shock wave to open the skin of the wing for the recoil effect to eventuate. During the destruction of the skin, the shock wave loses some of its intensity and it has less (net) strength than an external explosion. However, it is possible that an explosive going off in the front part of the profile resulted in only a somewhat smaller effect than an external explosion. The destruction shown in Figure 10 does not determine whether the event began in the interior of the wing or in front of its edge. It only shows what happened when a strong shock wave penetrated inside the wing.

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5. Kinetics of Last Phase of Flight

Fig. 14. Sketch of the undamaged Tu-154M.

Why assume an initial damage to the fuselage, as in Fig.15? It has much to do with the structure, where the strongly built center wing penetrates a fuselage. This means that the fuselage has a cutout, which weakens it. There is certainly a strong connection between the center wing and fuselage, quite sufficient for normal loads. However, such construction performs much worse in the case of impact loads that are associated with the explosion. This reasoning could be countered by saying that during landing such shock loads are present, and the designer was aware of that. However, we are dealing with a fundamental difference: The landing loads press the fuselage against the wing, while the impulse from the wing attempts to separate the two.

Fig. 15. The airplane after the explosion at the wing: the wing tip broken off, damaged base and pre-damaged front of the fuselage junction with the remainder.

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Fig. 16. More inclined plane is continuing its journey, leaving behind the wing tip.

The loss of leading edge at the fuselage and partial separation of the wing give two important aerodynamic effects: loss of lift on the left wing and an increase in aerodynamic drag. The first one causes rotation around the longitudinal axis, while the second forces the plane to turn left. Figure 16 shows the continuation of rotation and the wing segment left further behind. Figure 17 illustrates the fragmentation of the fuselage after the internal explosion, described below. The internal explosion in an already pre-damaged hull, in the presence of a still active torque causes the separation of the two parts. The front of the fuselage continued to rotate around the longitudinal axis, but only because of its inertia. The rear part is still "driven" by the uneven distribution of lift on the wings. This results in mutual rotation of these components so that the end of their relative position, as shown in the figure, is similar to what was found on the crash site.

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Figure 17. Relative position of the front of the fuselage and the rest of the plane after the internal explosion.

It is not important whether the angle of rotation of each of these two parts was exactly a multiple of 180⁰. It is enough if the rotation angle exceeds 90⁰, and as a result of inertia of the center wing, an upside down landing of rear portion is enabled. Speaking of the final location on the ground, the front part of the fuselage finally stopped at the approximately normal position. The rest of the machine was hitting the ground in the upside - down position and undergoing further fragmentation. Finally, parts of the center wing stopped near the cockpit after assuming an inverted position. A more detailed fragmentation pattern is shown in Figure 21, as created by Mr. Marek Dabrowski, MSA. Since this was created independently, not all of the details described here coincide with the above sketches.

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6. Explosion in the Fuselage. Within seconds of a hypothetical breaking of the wing, telecommunication contact with the plane was lost, and its monitoring and recording device stopped working. This event can be identified with the explosion in the hull, although the military prosecutor's office said: Recorders of the Tu-154 M stopped working at about 1.5 to 2 seconds before the plane's impact with the ground. The reason (according to experts) could be the damage to the electrical system. Recorders in the Tu-154M do not have emergency power supply. The prosecutor does not know what was the reason for a failure of electric system. This issue could not have been the subject of experts investigating the loggers, because this type of parameter cannot be registeredi. and then he tries to downplay the importance of this event. So, going back to Figure 2, an explosion took place on the wing around the point K, while the fuselage exploded near the FMS. The explosion inside the airplane, which was still in the air, is the only logical explanation of the effects, partially visible on the photographs, namely: airplane fragments scattered over a large area. (Figure 19), a very large number of very small fragments (most of them a few centimeters in diameter) that were found. (Appendix II, Figure 22), a segment of the hull with the characteristic opening and folding of edges (Figure 3b and Figure 7). The degree of opening of the hull skin is a measure of the energy of a material that exploded, the appearance of fragments of the hull as seen along its axis. The main parts of fuselage appear as though very little was left inside the cabin, besides the structure itself. The contents were "blown out" (Figure 7 and 10). (Lack of sufficient lighting makes it difficult to be more specific.) damage to the rear bulkhead area. (Chapter 7), number of burned and unburned debris. (Appendix IV - Aircraft Fire), rapid vertical acceleration, about 0.78 g, oriented down relative to the craft, as recorded by instruments. (Fig. 20), some passengers’ bodies torn to pieces. A great amount of human remains. Clothes sometimes torn off, sometimes forming characteristic tears. (Fig. 18). All these effects are observed when a HE explosion occurs next to a group of people. The last point deserves special attention because there is no other physical phenomenon, except for an explosion that could cause such effects. (Severe impact, in terms of speed occurring like here, can cause rupture of clothing, but not it's fraying to such an extent. Witnesses indicate that there is a range of degrees of destruction of clothing. Similarly, with the human bodies. Collision may result in loss of continuity, but not in dismemberment into many fragments). What could be the nature of the blast? The first thing you need to take into account are the substances present in the plane, oxygen and fuel vapor. The explosion in flight in partially emptied containers can only occur because of a spark, which is unlikely. (The tanks are constructed so as to exclude any possibility of arcing). The fuel vapor entering the cabin in such a quantity that a big explosion can eventuate is difficult to imagine. The amount of gas needed to achieve adequate concentration would be overwhelming to the passengers, who would first raise an alarm. In addition, explosions of this kind are relatively mild (with the same amount of energy involved). They produce splitting into a few pieces rather than smashing of the vessel wall. This is due to a more uniform distribution of the explosive energy within a container. More details about the behavior of fuel is given in Appendix III. The explosion could be caused by a solid material such as dynamite, or by another high-energy (HE) explosive. Such an event is associated with the propagation of shock waves, destroying everything in their path. The distance from the source of the explosion is a measure of a potential damage. This means that if the event took place in the central part of the hull, there are people in remote areas that have a greater chance of survival. (They could also be shielded to some extent by the chairs of other passengers). Either way, the nature of hull damage suggests the effect of the shock wave and a strong

18 - 35 Analytical Service Pty Ltd wind, which follows it. There are other possibilities, but the determination of how the explosives got into the airplane does not fall within the scope of the report. Can we determine any connection between the above and the explosion in the wing? It is difficult to accept such a relationship, because the locations of the explosions were far apart. A strong shock wave could not easily move from one place to another, even if it was supported by fuel. The center wing has many ribs, which are a serious obstacle. The wave may destroy some, and also get through the relief holes in the ribs, but then it would be severely weakened. The role of fuel in a disaster is best known in the following situation: a plane hits the ground, the tank cracks, fuel spills out, and often, a moment later, it may be followed by an ignition. What material was used, where it was at the time of the blast, and what was its total mass or energy, can be determined by performing a simulation using Finite Element Analysis (FEA). The results, compared with the actual damage to the structure, should lead an engineer to the correct conclusions. After conducting such a simulation one will know, for example, what transverse velocity of the disintegrating fuselage fragments was acquired. Only then one can closely associate that with the location of debris on the ground.

Figure 18a. Partially burned and torn clothes of the passenger from Lounge 3ii. The effect of the blast on the fragmentation of the fuselage also depends on the geometry of the latter. The status of human remains indicates that the source of explosion could be near Lounge No. 3, around the middle of the length of the passenger cabin. Apart from the opening of the ceiling, the shock wave also travelled along the hull. The component of it going towards the tail had few obstacles on its way to the back wall. It seems that the reflection from this wall was strong enough to make the perimeter of the hull crack, and the entire rear part of the aircraft to fly rearward. Having a clean aerodynamic shape, it could fly quite far. Owing to the compact shape it could survive the fall in good condition, as evidenced by pictures. The only exception was that the engines were torn off, along with the elevator and stabilizer. It was different for the wave component travelling toward the front of the aircraft. In the path there were a few partition walls, which reduced the impact, in spite of the open doors. The separation of the cockpit by the wave may be attributed to the fact that all the walls, with the exception of the last one, were destroyed. The graph in Figure 20 represents the history of acceleration. It shows two peaks of downward acceleration. One of them is a little weaker, but more extended. While the first can be associated with the beginning of an explosion in the hull (the first wave hitting the floor), the second may be a trace of splitting of the hull and the recoil, and then the subsequent detachment of the front and rear of the fuselage. At the first, a sharp peak of acceleration, we have the beginning of the degradation of the structure, but the

19 - 35 Analytical Service Pty Ltd recording still continued, because the sensors were still powered. Only after this second, longer lasting period, the record terminates, which means the power supply terminates and the structure is practically annihilated.

Fig. 18b. Torn and marginally burned uniform of the passenger of Lounge 3i.

There is an important question of direct influence of the blast on the movement of the aircraft. If the explosion took place only inside the fuselage, nothing would change the trajectory. When the explosion ripped the top of the hull, the gas escaped up at a high speed. The recoil effect pushed the hull down inducing the acceleration, as recorded during the flight. The disintegration of the hull as described previously, resulted in rapid changes in vertical velocity around the point of FMS. The breakup of the structure in the manner described also had to break the power wiring. There is also a marginal matter of the audibility of the explosion. If it took place completely inside the hull, the ground observers would have heard nothing. When the upper part of the hull was opened by the shock wave, the latter or whatever was left of it, went mostly up. Whatever reached the ground, was only due to the wave diffraction around the edges of torn fuselage. A terrestrial observer could hear only the gentle sound, compared to the passengers, which would have had their eardrums burst (autopsy would demonstrate this). Slightly better audibility would eventuate in the case of the plane flying upside down. However, the increased roar of engines would not help. Eyewitnesses present at that time near the scene confirmed that they heard the "thunder", "bangs", "bursts" or "explosions". (Appendix VI)

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Figure 19. Spread of larger pieces and debris of wreckage, based on satellite image of April 11, 2010. Resolution 50 cm per pixel.

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Fig. 20. The history of vertical acceleration at the critical time period. In normal flight, there is an overload of 1.0g. If the value is greater than 1.0g, the acceleration is directed upward. (maximum 0.27g). If less, to the bottom. (maximum 0.78g) The level of destruction is also affected by the final events, such as impacting of the trees or the ground, or even collisions between fragments. If the hull had previously disintegrated, the number of fragments would multiply. One of the aspects of the case that is difficult to understand is the duration of certain phenomena. In Figure 20, acceleration much higher than 1.0g takes a much longer time than a trace of the elastic wave pulse coming from the breaking wing. Similarly, the sounds that can be interpreted as the sound of cracking in the video mentioned in Sec. 3 last for a few seconds. A possible explanation that comes to mind may be a number of small, coordinated explosives, whose task is to pre-crack, rather than to break the structure. But this is only a preliminary idea, which is otherwise difficult to justify.

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Figure 21a. A reconstruction of last phase of the flight of Tu-154M.

Fig. 21a,b. A reconstruction of the airframe disintegration. After separation from the rest of the aircraft, the cockpit and the front lounge finally stopped in an upright position. The nature and degree of damage requires the use of advanced numerical methods to simulate the disintegration of the aircraft.

Figure 21c. A reconstruction of the in-flight airframe disintegration.

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7. Separation of the Tail Section of Fuselage Figure 23 is one of the pictures available that shows the tail segment at the place of fall. Construction drawings show that the bulkhead, around which there has been a rupture and separation from the rest of the hull, was strong, well built and had a concave (as viewed from the front of the plane) metal wall. If the fuselage fell at this spot in one piece and if the rear part hit the ground, the bulkhead would buckle, or even crack, but it would remain as a part of this section of the hull. To achieve this condition, the perimeter would have to ovalize. However, the profile, partly visible in the photographic documentation of the scene, is round, at least to the naked eye. The hull does not look distorted by a strong external impact. But the bulkhead itself appears damaged. Only high internal pressure can explain this. This state fits the hypothesis of an explosion. Apart from the above it should be noted that the left part of the beam connecting the two motors in Figure 23 is bent inside the tail section of the hull. This may be associated with hitting the ground, although it seems that in this case it should be bent in the opposite direction. Again, we face the question of fuel vapor explosion versus HE material. There is a difference between the nature of the shock wave in both cases. The latter gives a thinner, but more intense wave. When reflected from obstacles such as wall, suddenly the pressure increases near the wall. This causes the effect of the axial force to be combined with the local bending (axisymmetric) around the entire circumference of the affected area. (A simple example is the well-known configuration of a cylindrical pressure vessel wall near the closed end.) The formation of this secondary bending made it easier for the wall to break and the tail part to separate. In the case of fuel exploding, the wave is less intense, but wider and therefore not so much amplified by reflection. The secondary bending is weaker and the axial force plays a relatively larger role. In this situation, a better place for a separation may be the section through the last window in the hull. Although the cross-sectional area loss caused by the windows is not great, the windows induce stress concentrations, the effect of which is greater under dynamic loads than under the application static pressure. Could the separation of the tail section occur after the fall? Unfortunately, there is no discernible trace of the explosion on the ground.

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8. Other Possible Considerations of this Accident With this type of analysis there is always some uncertainty relating to the available information. Let us say that someone does not believe in time-space records, and asks: Why is it not possible that the explosion took place after hitting the ground? The answer is simple: the parts were scattered over a wide area with a width of about 40 m and a length of 130 m. A ground surface explosion can create such a result, but then the scene of the event would look different: the trees around would be mowed, and there would be a clear imprint in the ground, perhaps even a crater. Besides, we would not be able then to explain the rotation of the main part of the fuselage around its longitudinal axis. 9. Mortality in air accidents Most people imagine that when a jet crashes in one way or another, everyone on board is killed. This concept is caused by the media, which mainly describes the most tragic accidents. But the truth is different. Overall, the available statistics show that in most cases some of the passengers survive. There is a similarity of the crash near Smolensk with case of Airbus A320 falling during a 1988 air show. As a result of the confluence of several mistakes in setting the controls, the plane lost engine power and was forced to land in the forest It landed mowing many trees, but at the end there was a fuel explosion and huge fire. The ship was completely burned out. On board were 136 people, but only three (3) of them died. Perhaps the passengers were extremely lucky, but the incident confirmed that the landing in a wooded area does not always have tragic consequences. (On the web: ASN Aircraft accident Airbus A320-111iii). Another case took place in recent years with a different model of Tupolev aircraft. The machine was forced to land in the forest. During this event it cleared a path of several hundred meters. The aircraft suffered no damage visible from a distance. Appendix I. Collision of the Wing with a Tree (birch) The issue has somewhat wider aspect than was previously considered. Namely, the results of such collisions depends inter alia on the impact speed. If the speed is high, say 100 m/s or more, the wing would cut trees and other objects stronger than wood. If the speed is low, say 10 m/s, the wing will probably be broken by a tree. If the case is still of interest, it can be resolved quite accurately, using the Finite Element Method, as described below. The most important aspect of an aircraft wing colliding with a tree is a local phenomenon, namely, which of these two objects causes more damage to the other in the vicinity of the collision. It is therefore sufficient to build a small FEA model with a relatively short segment of the wing and a tree. Such a model should be inexpensive to prepare and execute, in terms of time needed for the task. In subsequent repeats of simulation, one must also reduce the impact speed, until a certain critical speed is reached when the wing is weaker than the tree. There is also something more important about such a collision. A typical "cross" collision of two slender objects end up breaking or shearing only one of them. There is a very little chance that the two objects become broken. This means that if the tree was cut, the wing survived (with superficial damage) and vice versa. This should close the discussion on the possible role of the birch in this case. Even if the MAK is right and contrary to recent research there was contact between the birch and the wing, neither the change of course was not noticeable, nor wing did not suffer much, so the role of the birch should be completely removed from consideration. Despite a protracted discussion about which was stronger, the birch or the wing, no one has done a simple calculation based on the nominal static strength. Both for the birch and the wing the strength is the product of the effective cross section and the shear strength of the material. The analysis should begin at this point, before using advanced methods. The difference in strength of these two elements may be so large that the dynamic approach may prove unnecessary. It should be noted that the velocity makes the cross section of the wing stronger.

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Appendix II. Fragmentation Imagine a container, such as a steel barrel, used for experimental purposes. The barrel is filled with water the internal pressure is growing. At some point the barrel breaks. If the pressure was growing slowly, the cracking is typically along one line. If the pressure rises rapidly, the barrel may disintegrate into several parts. If, instead of water, one puts an explosive into the barrel, then the more of this material that is used, the more fragments will result. With strong (or large) explosive charge, the barrel will disintegrate into an array of different size fragments. The smallest may have 2 cm2, and the largest will be a significant part of the barrel. These small pieces are often called shrapnel. They are a characteristic trace of the use of explosives against metal containers. The only other opportunity to produce fragments of aircraft structures is to strike a rigid barrier at high speed. There was no rigid obstacle in this case, whereas a speed of 270 km/h is insufficient to create a an abundance of shrapnel. The mechanism of creation of multiple cracks due to large and sudden loads and the related process of formation of fragments, is described in Chapter 15 of book published by the author of this report, Formulas for Structural and mechanical shock and impact (CRC Press 2009). Fig. 22a-g. Photographs of small fragments, found on 10 April 2010 around the streets Gubienki and Kutuzowa.iv In some debris (Fig. 22a, b) the rivet holes are visible, which makes it unlikely that they were caused by the forces tangential to the shell.

Fig. 22a.

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Fig. 22b

Fig. 22c

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Figure 22d

Fig. 22e

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Figure 22f

Fig. 22g

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Fig. 23. Tail section of the fuselage.

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Appendix III. Fuel in Special Circumstances The following applies to the behavior of aircraft fuel under accident conditions. The liquid fuel can be ignited but only the vapors are really flammable. A spark is needed to ignite, shock itself is not enough. Initially, degree of burning is fairly mild with a flame advancing at subsonic speeds (less than 340 m/s). It is called deflagration. Under favorable conditions, i.e. in sufficient concentration of vapor, the flame will accelerate, sometimes reaching very high speeds. It promotes detonation or the initiation of a blast. But in order for detonation to take place, one needs a complex set of conditions to fall into place. Fuel explosions typically have a more even distribution of energy in the volume of the vessel than HE materials, resulting in splitting of the container into a few parts rather than shattering it into many debris. Appendix IV. Mechanics of HE Explosion and Aircraft Fire Landing aircraft normally has a substantial fuel load. If, during an emergency landing the fuel ignites, it often results in a great fire which would burn, or at least scorch the whole craft. It is different scenario when a bomb detonates. (The word "bomb" is only a mental shortcut of 'explosive, which is subject to detonate.’) If a bomb is suspended in the air, for experimental purposes, there is a blast simultaneous with the appearing fireball. (If the weight of the charge is known one can calculate the size of the fireball). The surface of this fiery sphere is the shock wave. When the diameter of the sphere reaches a certain multiple of the diameter of the bomb, then the wave separates from the ball and continues its rapid outward movement, attacking all the obstacles on the road. In short, the fire is limited in its reach. If an explosion occurs inside the structure, the ball deforms according to the shape of the interior, unless the structure broken in some area. If the bomb separates the structure into parts, the flying fragments will be swept by fire. After contact with the ground, those parts will burn for some time. Elements located farther from the source or sheltered from the explosion remain unlit. The ripping of the hull in this case suggests an internal explosion. The “selectivity” of fire in this event was very well illustrated by the available video clips.Therefore, one should look to the nature of fire as supporting evidence for the explosion inside the airplane. An explosion of this nature leaves a signature that is difficult to remove. The surfaces are directly affected by persistent traces that can be detected by metallurgical analysis. People near the source of the blast may be affected by the shock wave and the fire, or just by the latter. The shock wave action is the more likely farther from the center of fire. But secondary fires are possible and that may complicate the investigation.

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Appendix V. Aircraft Rotation around the Longitudinal Axis The rolling began near critical point K and was due to loss of lift on the wing. The following calculation is approximate and simplified. The inertia data of the aircraft is assumed constant in spite of the accident, during which the lift force vanishes on the left wing together with the loss of part of that wing.

Takeoff mass: M0 = 110.5 t mass at point K: M = 78.6 t moment of inertia around the longitudinal axis, at startup: I0 = 1928 t-m2 moment of inertia around the longitudinal axis, point K: I = 1371 t-m2 (Assumed in proportion to the mass) estimated lift force on the wing P ≈ 0.4 Mg = 0.4x78, 600x9.81 = 308,400 N estimated distance of the center of aero of the wing from longitudinal axis: r = 8.2 m Wing moving upwards (right) will develop less lift than the same wing in normal flight, because it reduces the effective angle of attack. Here we assume a loss of 20%. torque M = 0.8Pr = 0.8x308,400x8.2 = 2.023 x106 Nm angular acceleration: ε = M / I = 1.476 rad/s2 the time t it takes the turn by the angle θ: θ = εt2 / 2, i.e. for θ = 90⁰:

Over time, the state of affairs will change and it is unlikely that such acceleration could be continued. Therefore, we assume that the angle of 90⁰ above the angular velocity is constant: ω = ε t =1.476x1.459 = 2.153 rad/s time to reach 120⁰ : (Δθ=30⁰), Δt = Δθ/ω = 0.243 s, t120 = 1.459 + 0.243 = 1.70 s time to reach 200⁰: (Δθ=110⁰), Δt = Δθ/ω = 0.892 s, t200 = 1.459 + 0.892 = 2.35 s One can obtain more precise results if, instead of the above intuitive assumptions, one uses more accurate data that can be obtained from the aerodynamic simulation. According to the MAK report, the time to reach the turn of 200⁰ was 6 s, but it is unclear whether this time was calculated in a manner consistent with this calculation. Of course, if not all of the lift on the wing has lost, turning was slower than the above shows and the calculated time would be longer.

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Appendix VI. Eyewitness Accounts Witness accounts present on 10 April, 2010 near the scene confirm that they heard the "thunder", "bangs", "detonations" or "explosions". Standing by my airplane I heard the sound of a Tu-154M engine approaching for landing. I recognized it by the sound of engines characteristic for this airplane. I emphasize, that I have not seen it, only heard it. It was a sound of engines characteristic when approaching to land. At one point I heard the engines begin to enter the starting range, as if the pilot wanted to increase the engine speed, and thus flatten out or change to increase altitude. At this time, I wondered what could have influenced them to do so. After the power increased, a few seconds later I heard a loud cracking sound, bangs and detonations. Then, came the sound of the dying engine, followed by silence. For me those were scary sounds, which I hope I never hear again in my life. These sounds were coming from the direction of the approaching zone of tarmac. (Lt. Arthur Wosztyl, Polish pilot of a military aircraft Yak-40, which landed in Smolensk 94 minutes prior the crash of Tu-154M and at the moment the disaster was 700-800 meters from the crash site) Suddenly I heard a roar, as if something exploded. (...) You know, like an explosion. (Anna-Nosarczuk Nikolayev, a resident of the house at. Kutuzov, whose windows are directed toward the crash site, was 300 meters from the site.) I heard only the blast. (Tatiana NN, a resident of the house at. Kutuzov, whose windows are directed toward the crash site, was 300 meters from the site.) I hear a strange sound, unusual for a landing, the wheezing. Aircraft could not be seen, only an outline. I saw only the tail. I felt that something would happen. And something tiny , as if from a comet, such a thing. (...) The fog was all around, and there was a flame behind the tail 5 meters long. (...) The tail was in a normal position. (NN Rustam, a hotel employee, "Novy" was 300 meters from the site.) I hear the sound of the motor, except that the sound was a little different, I look into the fog and see that the plane is moving low, the left wing almost down. (...) Through the window I heard such a terrible bang and two flashes of fire, but not a big explosion. (Slawomir Wisniewski, film editor, Polish public television TVP SA, stayed in the Hotel "Novy" was 300 meters from the site.) We stood on the edge of the garages (...) and the explosion was like a yolk, egg yolk, round and nothing more [shows with his hands an oval with a diameter of about 120 cm]. (Anatoly Zuev, stood by the garage 300 meters from the site.) I arrived maybe 15 minutes before the event. I saw an airplane that was flying very low. Clearly something was wrong. He began to cut the tops of trees and there in the distance we heard a loud bang - like a bomb. (Marif Ipatow, was near the garages 300 meters from the site) Aircraft often land here and we are accustomed to their sound. The plane was landing with a broken engine noise and loud cracks. (...) Was tilting from side to side, then fell down [gestures with his hand as the plane was tilting sideways]. (Dmitry Zakharkin aka Janis Ruskuł [in Russian edition of the speech to the state news agency RIA Novosti and introduced with the first of the names, then in the English version the second name was used], was to be near the garages, 300 meters from the site.) In the voice mail there was a recorded voice of my husband, who shouted [my name], "Asia Asia". In the background you could hear the crackling sounds, or perhaps my husband's voice was in the background, with the bangs and cracking dominating. We could hear the voices of people too, like the sound of the crowd. It was not clear. I did not recognize any words. It was the cry of the people. This recording took two or three seconds. Husband's voice was slurred. The cracks were short, sharp sounds. As if breaking the wafer or plastic plus a sound like wind noise in the telephone receiver. (Joanna D., wife of Mr Leszek D., who shortly before his death placed the phone call to his wife and recorded the farewell in voicemail. After listening to the recording the message was removed and the National Security Agency says that a copy of the recording was not kept). This day will be embedded in my memory for life. I saw the disaster with my own eyes. It happened in front of my own home. I live just 400 meters from the crash site. On Saturday morning I was outside the house. Suddenly I heard a terrible bang. A plane appeared on the hazy sky. Airplane as any other, I

33 - 35 Analytical Service Pty Ltd thought. Having lived a few hundred meters from the airport, you can get used to such views. One thing surprised me, though - at one point, the bang just froze. Literally, for a split second there hung dead silence over the forest. I turned my head and saw a falling plane. The legs buckled under me. After a while there was a terrible bang, and a glow of fire appeared in the trees. (...) I cannot believe what happened. Especially since this tragedy occurred in my own eyes, right in front of my house." (Sergei Wandierow, stood in the yard of his family house about 800 feet from the ground) (The word "explosion" and "detonation" as used in those relationships, and other direct witnesses describing events associated with the disaster, they may - but need not - describe the detonations of explosives.) Appendix VII. Other Incomprehensible Issues Since there is only a loose connection between common sense to the official investigation of the crash, the author takes liberty to ask the following, rhetorical questions: 1. Given that the prudent man is aware of the danger of air travel, how was it possible for one machine to carry the president, many members of government, state institutions and generals? The matter of disaster survival and continuity of power should be part of the strategy of any government. 2. Anyone interested in aviation accidents, who has access to the photographic material, would note, after some thought, that this fragmentation of the structure is not justified by landing in the woods, no matter how unfortunate. In neither of the two official reports is the explosion considered as a hypothetical cause of the crash, despite the testimony of witnesses. 3. A few of the Polish delegations traveled to see the wreckage. All were taking pictures only, as if there were no technically competent person among them, who would have an idea of taking samples with him, even some small shrapnel. Metallurgical analysis could clarify some of the guesswork. 4. The way the Russian Federation employees treated the remains of the aircraft. Heavy machinery were used to move debris, dragging them along the ground and then dropped onto trucks, one on top of another, as if it were scrap metal. (The film is available on YouTubev.) This procedure resulted in additional damage, which impedes the investigation. Knocking out windows with a crowbar by a Russian soldier in front of the television camera should not be treated as an individual act of vandalism.vi 5. For what purpose were the debris cleaned? After all, it is very difficult to diagnose causes of the disaster by removing traces of what happened.

Conclusions The front of the fuselage landed in a normal position, while the rest of the plane fell upside down. This means that the disintegration of the structure took place in the air. This report concludes that explosions were the cause. When a fuselage falls in its entirety, it may crack, although the rupture along the axis is rare. However, the opening of the hull to the outside can only be attributed to an internal explosion. Of all the traces the most important are: a huge amount of debris and dismemberment of human bodies. As long as there is no one with a better hypothesis consistent with the circumstances, it is the only explanation of the cause and sequence of the disaster.

Acknowledgement Thanks are due to Mr. V. Stanford, MSME, who reviewed this text and made many valuable suggestions that were implemented.

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Picture sources: Fig. 18a: http://www.se.pl/wydarzenia/kraj/to-jest-mundur-gen-blasika-szokujace-zdjecia-rzeczy- ofiar-smolenskiej-katastrofy-fragmenty-ksiazki-k_161590.html Fig. 18b: http://www.se.pl/multimedia/galeria/53445/98137/gen-basik-kona-kilka-minut-oto-jego- mundur-i-ubrania-innych-ofiar-katastrofy/ Fig. 22a-g: http://krohis.livejournal.com/238416.html http://www.flickr.com/photos/globovision/4507693591/ http://media.photobucket.com/image/smolensk/ciscazarmansyah/74-1.jpg?o=307 Other Work of This Company Analytical Service for many years now has been solving problems associated with fragmentation of structures, often involving explosives. Descriptions of some of the work can be found at: http://www.simulate-events.com/ The more you can watch live short films on YouTube: http://www.youtube.com/user/gs98765432 We recommend using headphones. Technical questions related to this Report should be directed to the Parliamentary Group A. Macierewicza.vii After sorting (to avoid repetition) questions will be forwarded to the author to answer. i Statement by Col. Irenaeusz Szeląg, the chief of the Military District Prosecutor's Office in Warsaw, leading the investigation, presented on 26 July 2011, at a press conference in Warsaw, discussed and cited, among others by the government-owned the Polish Press Agency in dispatched broadcasts at 13:39, 14:19, 16:33 and 19:34, the most extensive version of the PAP message was broadcast by the public television TVP1: http://tvp.info/informacje/polska/kolejny-polski-raport-w-sprawie-smolenska/4969091 and http://wiadomosci.gazeta.pl/wiadomosci/1,114873,10011320,Beda_zarzuty_w_sledztwie_prowadzonym_przez_NPW.html ii http://www.se.pl/wydarzenia/kraj/to-jest-mundur-gen-blasika-szokujace-zdjecia-rzeczy-ofiar-smolenskiej-katastrofy-fragmenty- ksiazki-k_161590.html iii http://www.bea.aero/docspa/1988/f-kc880626/pdf/f-kc880626.pdf (report committee to investigate the causes of the event on 26 July 1988 at Mulhouse-Habsheim with Airbus A 320; Journal Officiel de la République Française. Documents administratifs No 28/1990 of 24 April 1990) iv http://krohis.livejournal.com/238416.html http://www.flickr.com/photos/globovision/4507693591/ http://media.photobucket.com/image/smolensk/ciscazarmansyah/74-1. jpg of = 307 v http://www.youtube.com/watch?v=uWEPV_Zzf4E (the "Special Mission" by Anita Gargas given by public television TVP1 on 21 September 2010; approximately 2.05 min. recording) vi http://www.youtube.com/watch?v=uWEPV_Zzf4E (the "Special Mission" by Anita Gargas given by public television TVP1 on 21 September 2010; approximately 1.50 min. recording vii Mr Antoni Macierewicz, Chairman of the Parliamentary Committee investigate the crash of Tu-154M on 10 April 2010, the Sejm, ul. Wiejska 2/4/6, 00-902 Warsaw, [email protected]

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