Polish Air Force Flight 101

Polish Air Force Flight 101 (also known as the Smolensk Air Disaster) crashed on 10 April 2010, when a Tupolev Tu-154 aircraft of the Polish Air Force crashed near the Russian city of Smolensk, killing all 96 people on board. Among the victims were the President of Poland Lech Kaczyński and his wife Maria, the former President of Poland in exile Ryszard Kaczorowski, the chief of the Polish General Staff and other senior Polish military officers, the president of the National Bank of Poland, Polish Government officials, 18 members of the Polish Parliament, senior members of the Polish clergy and relatives of victims of the Katyn massacre. The group was arriving from Warsaw to attend an event commemorating the 70th anniversary of the massacre, which took place not far from Smolensk.

The pilots were attempting to land at Smolensk North Airport—a former military airbase—in thick fog, with visibility reduced to about 500 metres (1,600 ft). The aircraft descended far below the normal approach path until it struck trees, rolled inverted and crashed into the ground, coming to rest in a wooded area a short distance from the runway.

Both the Russian and Polish official investigations found no technical faults with the aircraft, and concluded that the crew failed to conduct the approach in a safe manner in the given weather conditions. The Polish authorities found serious deficiencies in the organization and training of the Air Force unit involved, which was subsequently disbanded. Several high-ranking members of the Polish military resigned, under pressure from politicians and the media.

Various conspiracy theories about the crash have since been in circulation, and are promoted by Law and Justice's leaders Jarosław Kaczyński (twin brother to Polish President Lech Kaczyński) and his deputy, Antoni Macierewicz, who claim the crash was a political assassination. As of 2011, Polish and Russian investigations did not report any evidence supporting this claim.

Purpose of the flight
The flight's purpose was taking many high-ranking Polish officials to ceremonies marking the 70th anniversary of the Katyn massacre, a mass murder of Polish intellectuals, politicians, and military officers by the Soviets during World War II. The site of the massacre is approximately 19 km (12 mi) west of Smolensk. The area is fairly remote; Smolensk is the only city nearby and has the only two airports in the area: Smolensk North Airport, where the accident occurred, and Smolensk South Airport.

Destination airport
Smolensk North Airport is a former military airbase, presently in mixed military-civilian use. At the time of the crash, the airport was not equipped with an ICAO-compliant instrument landing system (ILS), the standard system used in most developed countries. The airport used to have a Russian-made landing system installed, which was decommissioned after civilian operations started. The Polish Tu-154 was modified to use western-style ILS.[citation needed] A non-directional beacon (NDB) was installed at the airport, but such a device is essentially a navigational aid, and can be used only for non-precision approaches, where it can guide the pilot to align with the runway, but offers no vertical guidance on how to descend towards the runway. The airport was equipped also with both a surveillance and landing radar. The lowest approved visibility conditions to land (approach minimums) were cloud base 100 meters (330 ft) and visibility 1,000 meters (3,300 ft).

The ground visual navigation aids on 10 April 2010 were not effective. According to the Polish report, the radar was unstable and swung within ±10%. From the photographic documentation of the Polish committee, it appears that the origin of components of the Smolensk North lighting system was unknown. This was not the Luch-2MU system as the Russians stated. The report from the inspection flight performed on 15 April 2010 stated that the approach lamps, depending on their location and on the altitude of an inbound aircraft, can be shaded by surrounding trees and shrubs when an aircraft is at a distance of 400, 700, and 800 metres from Runway 26. The lamps of the first group (900 m) had their light filters shattered and, of three bulbs installed, only one was serviceable.

Aircraft
The aircraft was a Tupolev Tu-154M of the 36th Special Aviation Regiment of the Polish Air Force (Siły Powietrzne), tail number 101. Built in 1990 at the Kuybyshev Aviation Plant as msn 90A837, it first flew on 29 June 1990. At the time of the accident, the airframe had accumulated more than 5,150 hours in 4,000 cycles. The service life of the Tu-154M is more than 25 years or 30,000 hours or 15,000 cycles (whichever comes first). All three Soloviev D-30KU-154 engines were within the service limits of 24,000 hours or 11,100 cycles.

"101" was one of two Tupolev Tu-154s that served as official government jets; the other with a tail number of 102 was a year younger and at the time of the accident it was being overhauled in the Aviakor aviation plant in Samara, Russia. The "101" aircraft had undergone a major overhaul in December 2009, and Alexey Gusev, the head of the maintenance plant that carried out the work, told Polish TV that it should not have had technical problems. The crash happened 138 flight hours after the most recent overhaul.

The aircraft operated as flight PLF101. PLF is the ICAO three-letter designator for the Polish Air Force used to identify the operator of an aircraft by air traffic control.

Crew
The cockpit crew consisted of pilot Captain Arkadiusz Protasiuk, co-pilot Major Robert Grzywna, navigator Lieutenant Artur Ziętek and flight engineer WO2 Andrzej Michalak. Protasiuk had landed at Smolensk three days earlier on 7 April in the same Tu-154; he served as first officer on that flight. Protasiuk had 3,531 flight hours, including 2,906 hours on the Tu-154. Co-pilot Grzywna had 1,909 hours, with 475 of them on the Tu-154. Ziętek had 1,050 hours, only 58 of them on the Tu-154. Michalak had only 329 hours, all on the Tu-154.

Take-off and cruise
Flight PLF101 took off from Warsaw at 9:27 Smolensk time after a delay of 27 minutes.

As the aircraft left Warsaw, weather conditions were rapidly deteriorating at Smolensk. A temperature inversion had developed, trapping moisture low in the atmosphere and causing a dense fog to develop. At 9:15 Smolensk time, about an hour and a half before the crash, a Yakovlev Yak-40 jet (flight PLF 031) also belonging to the Polish government and carrying Polish journalists from the President's press pool landed at the airbase without incident, though conditions were rapidly worsening at the time.[citation needed] Shortly thereafter, between 9:20 and 9:39 MSD, a Russian Ilyushin Il-76 (tail number 78817) made two attempts to land, but because of low visibility, it diverted to Vnukovo Airport near Moscow. Upon Flight 101 approach to the base, atmospheric conditions continued to worsen, and the fog continued to thicken, further reducing visibility to 400 metres (1,300 ft). The ground control personnel stated to Flight 101 that there were no conditions for landing. The captain then requested and was given permission to conduct a "trial" approach. The controllers instructed the captain as to the landing minimum of 100 metres (330 ft), to which the captain replied, "Yes, sir!"

Stress and workload factors
Meanwhile, the situation in the cockpit was one of very high stress. As the weather continued to worsen, the crew became increasingly aware of the extreme difficulty they would encounter in landing at Smolensk. The crew may have feared a negative reaction from their passengers should they have to divert to an alternative airfield. The protocol director was present in the cockpit from time to time, and the Commander-in-Chief of the Polish Air Force was present in the cockpit for the final approach phase of the flight, including the crash itself. At one point, the navigator is heard on the CVR saying "He'll go crazy", a possible reference to the President of Poland, had the crew chosen to divert. There may also have been some friction between the Air Force Commander and the captain, caused by an absence of the latter from condition training.

The captain and first officer's decision making may have also been affected by knowledge of a 2008 flight when the President of Poland ordered a change in destination right before departure and again while airborne. The captain and first officer had been the first officer and navigator, respectively, on that flight. Lacking charts or a flight plan for the new destination, the captain of that flight had decided he could not bring the aircraft to the new destination safely. Disobeying the President and a high-ranking Polish Air Force commander on board, the captain flew on to the originally planned destination. The Polish prosecutor's office would later clear that captain of any wrongdoing in relation to that flight, and he was even awarded a silver medal of merit for national defense. However, in the final report issued by MAK (The Interstate Aviation Committee; Russian: Межгосударственный авиационный комитет, МАК) – a supervising body overseeing the use and management of civil aviation in the Commonwealth of Independent States (CIS), it was stated he had not been assigned to fly the President again since that time, though Polish sources note he flew the President to New York in September 2008, despite objections from the President. The captain involved in the 2008 incident flew the Polish Prime Minister to Smolensk on 7 April without the President on board, but he was removed from the crew of the 10 April flight which carried the President. Knowledge of the 2008 incident and its repercussions may have weighed on the crew of Flight 101, potentially placing additional pressure on them to complete their flight to the original destination.

Complicating the situation was the increased workload on the captain. Normally, one pilot flies the airplane while another crew member handles radio communications. On Flight 101, the responsibility for communication usually rests with the navigator. At Smolensk however the situation was different. As the airport is not usually open for international flights and is not ICAO certified, the air traffic controllers were not required to be fluent in English, the ICAO standard language for ATC communication. As such, all communication between Smolensk ATC and PLF101 was carried out in Russian. Russian law requires international flights landing at military airports to have a Russian "Leaderman" (navigator; Russian lidirovshik) on board the flight, who is then responsible for all ATC communication, which is done in Russian. In the middle of March, as part of their request for permission to conduct the flight, Poland asked for "Leaderman" services and the latest airport data for Smolensk. At the end of March, after apparently receiving no reply to their first request, Poland tendered a second request for permission to fly, but did not request "Leaderman" services. As a spokesperson for the Air Force Command said: "The Russian side has not confirmed readiness to secure the flight leader". According to the Final Report, Russia did offer "Leaderman" services, but Poland refused, stating their crew had satisfactory knowledge of Russian and could conduct the flight without the Leaderman. In reality, the captain was the only member of the crew who could speak adequate Russian. Therefore, upon being handed off (transferred) to Smolensk ATC, the captain took over communication duties from the navigator. In a normal situation, this would dictate that the first officer be the pilot actually flying the airplane, but as the weather was bad the captain, as the most experienced member of the crew, elected to fly the airplane as well. Therefore, the captain was performing two tasks simultaneously which are usually split up, increasing his workload and requiring him to divide his attention.

Approach
Under these stresses, the crew continued their approach pattern and readied the aircraft for final descent. Radios were tuned to the two Non-Directional Beacons (NDBs) present at the field, and the autopilot was set up to use waypoints from the Flight Management System (FMS) units for navigation. The crew used their second radio to contact the Yak-40 which had landed earlier, inquiring as to the weather conditions. The Yak-40 crew replied, "Well, generally it's absolute shit here," and that, "(we) were lucky to land at the last moment." The Yak-40 crew estimated visibility was 200 metres (660 ft), but told Flight 101, "you might try...(to make an approach)." The crew of PLF101 acknowledged this information and continued their approach. As the aircraft approached the outer marker, the crew issued pitch commands (via the CLIMB-DESCEND wheel) to the autopilot. This is not recommended for the Tu-154, as the autopilot cannot maintain vertical speed accurately enough for the approach phase of flight; manual flight mode is instead recommended. Although the crew had not requested it, the radar controller began issuing reports to PLF 101 concerning their distance from the runway and whether or not they were on the glidepath. The Polish report noted that on multiple occasions the radar controller stated the airplane was on the glidepath when it was not.

The Terrain Awareness Warning System (TAWS) fired its first audible warning "terrain ahead!" at 10:40:06. This was because the Smolensk airport, as a former military airfield not open to international flights, was not in the system's database and therefore the system did not recognize that the airplane was approaching an airport. Six seconds later, someone (most likely the captain or navigator) pressed a button on the captain's FMS panel commanding standard barometric pressure be set on the captain's main electronic altimeter. This had the effect of increasing the altimeter's reading by 170 metres (560 ft); as the TAWS takes readings from this particular altimeter, this had the additional effect of silencing the warning. The captain's secondary (mechanical) and the copilot's main electronic pressure altimeters continued to read correctly. As the descent continued, the crew realized they had started descent too late. To compensate for this, they increased their vertical speed to 8 metres per second (26 ft/s), twice the prescribed rate for a normal approach. The aircraft did not have enough drag to maintain speed with this rate of descent, so even though the autothrottles commanded idle power from the engines, the speed of the aircraft increased to approximately 35 km/h (22 mph) higher than specified.

Approaching 300 metres (980 ft), the navigator began calling out the radar altimeter's reading. This is not standard practice for a non-precision approach, as the radar altimeter does not take into account the contour of the terrain around the airport. Standard practice would entail calling out the readings on the pressure altimeter, which is set according to atmospheric pressure and thereby references the elevation of the actual airport. The terrain on approach to Smolensk airport is uneven and locally much lower than the runway level.

Warning signs
At 200 metres (660 ft), the engines were still at idle power. Power settings for jet engines are expressed in instrument readings and flight data recorders as percentages labeled as "N1" and "N2". N1 and N2 refer to the spools, or shafts, of a jet engine on which the compressor and turbine blades are mounted; jet engine power is measured as a percentage of maximum N1 or N2 rpm. Although the shafts are not mechanically connected, the speed of one spool can be calculated based on the speed of the other spool and atmospheric conditions. The Tu-154 manual indicates that a go-around must be initiated at 200 m if the engines are running at or below 75% N2. This is because jet engine throttle response is not linear; jet engines have to "spool up" in order to produce more thrust. At power settings higher than 78%, this response is almost instantaneous; at idle power, it can take a full 8 seconds for a jet engine to "spool up" to full power. On Polish Air Force 101, the N2 values were not recorded by the flight data recorder (FDR). The N1 values were, and at 200 m they indicated 32–33% N1. 75% N2 equates to 51–52% N1 for the given conditions. As such, the engines were well below the 75% minimum N2 reading, and the crew should have initiated a go-around at this point, even though they were still above Decision Height (DH). However, they did not go around, and continued the descent. The Final Report would later determine that a go-around was technically possible from as low as 40 m, but that 200 m was the first of many times that the crew were required to go around, but did not.

At 180 metres (590 ft), the "terrain ahead!" warning again sounded on the flight deck. The crew continued the descent. According to MAK's report, at 100 metres (330 ft) (Decision Height) there was no "landing" or "go-around" call by the captain. If this happens, the first officer is supposed to overrule the captain, take control of the airplane, and initiate a go-around. Poland suggests that at this point the captain said "Go around", and 8 seconds later the first officer confirmed by saying "go around". (only the second of these two statements is recorded in the official transcripts by MAK; the first one may have been obscured by a simultaneous report by TAWS). Despite these calls, neither pilot initiated a go-around, and the descent continued. One second after the 100 m altitude was reached, the TAWS alert "PULL UP" activated and continued to sound for the remainder of the flight. "PULL UP" only activates when the TAWS computer believes a collision with terrain is imminent. Therefore, when "PULL UP" sounds, the crew is supposed to begin an immediate, maximum performance emergency climb (full power and angle of attack to the maximum permissible without stalling) and continue climbing until the warning stops. However, the crew continued the descent. In a typical situation with an airport in the TAWS database, the "PULL UP" warning might not have sounded at this point.[citation needed] There is a method of setting up the TAWS to prevent false warnings when flying into airports not in the database, known as "terrain inhibit" mode; however, the crew did not utilize it. Even if they had, an excessive rate of descent and excessive airspeed can cause the TAWS to issue a "SINK RATE" warning followed by a "PULL UP" warning. This point (10:40:40 local time, approximately 20 seconds before the collision with terrain) is also notable because this was the moment when the aircraft had crossed the minimum allowed approach slope for this airport (2°10'). Prior to this moment, the radar controller had no reason to think that the landing attempt was not proceeding normally. The behavior of the controller was later the subject of some criticism by the Polish media. The controller remained silent for about 12 seconds after the aircraft passed the 100 m mark, and, even at that point, he did not order a go-around, but, rather issued an instruction to transit from a descent to a horizontal flight. (The decision to go around was apparently reached in the cabin of the aircraft within a few seconds of that instruction.) In addition, according to some interpretations of the radio exchange between the ground and the aircraft, the crew was instructed by the ground control to descend to 120 metres (390 ft) and either to wait for clearance to land or request one explicitly, or to inform the ground control regarding their decision whether to land or to go around. (According to MAK's report, it meant that the crew was supposed to inform the ground control of their decision to land before passing the decision altitude, and that the ground control was supposed to allow the landing as long as the runway and the airspace were clear.) None of this ever happened, with the aircraft continuing the descent through the 120 m mark while the ground control remained silent. It is unknown whether the crew really understood the ground control instruction (literally, "landing additionally, 120, 3 m"), which was issued in Russian and used a relatively recent expression that was only codified in 2006.

For the next several seconds, the crew continued to call out "100 meters" as read from the radar altimeter. The aircraft was flying into a valley at this time and actually descended by 60–70 metres (200–230 ft). The crew began calling out radar altitude every 10 metres (33 ft). At 60 metres (200 ft) radar altitude (where the crew had set their radar altitude bugs), the First Officer called out "Go around" (this is the "confirmation" go around call referred to in the Polish comment above). Due to the terrain in the area, the aircraft was actually only 15 metres (49 ft) above runway level at the time. Simultaneously to this callout, the FDR recorded a brief pull on the control column, likely done by the first officer, as he instinctively started the go-around sequence of actions. According to the investigation, this attempt at a go-around was completely overridden by the auto-pilot, which was still active, and, in any event, it was not completed (protocol requires that the correct sequence of operations during a go-around attempt involves increasing thrust to takeoff mode and disengaging the autopilot, neither action was done at the time). Flight simulator testing by the investigation concluded that had the first officer completed a go-around at this point, the crash would likely have been avoided despite the violation of minimums and the excessive rate of descent. The investigation found that this was the last moment at which a go-around could have been successful.

Point of no return
As the crew called out "50 meters", the controller instructed "level 101", telling the aircraft to terminate descent. At 20 metres (66 ft), another controller instructed "Check altitude, level." Simultaneously with this final call, the control column was pulled full aft, commanding max pitch up from the aircraft, and the throttles were moved within one second from their flight idle positions to maximum power. The aircraft, due to the valley terrain, was actually 15 metres (49 ft) below the runway at this time. The Russian investigation surmised that at this moment the flight crew saw the trees through the fog, and instinctively reacted in an attempt to escape their grave predicament. The crew did not disengage the autopilot, but the action of commanding maximum pitch up on the control column overpowered it, causing the pitch channel to disengage. The control column briefly moved to neutral at this point, then moved full aft and remained there for the duration of the flight. According to the Polish report, the command "level" ordering a change to horizontal flight was issued at a time when the aircraft was at an altitude of about 14 metres (46 ft) above airfield level. Two seconds before the "level" command, the aircraft commander made the decision to go around. According to the Polish committee's findings, the command to level should have been issued 10 seconds sooner, when the aircraft was well below the glide path.

Soon after, the aircraft began hitting trees. One, a large birch with a trunk 30 to 40 cm (12 to 16 in) wide, ripped off about 6.5 metres (21 ft) of the left wing, including the left aileron. The resulting asymmetrical lift caused an uncommanded roll to the left. Within 5 seconds, the aircraft was inverted, hitting the ground with the left wing, followed very shortly after by the nose. The nose impact resulted in forces exceeding 100g, which killed everyone on board instantly. Even without the birch tree and subsequent roll, the excessive angle of attack would have led to an aerodynamic stall approximately two seconds after impact with that tree, which would also have led to a fatal accident. According to the Polish report, safety areas around every aerodrome are mandated by international regulations (including Polish and Russian law) to prevent situations where aircraft or aerodrome operation could be compromised by obstacles in the immediate vicinity. A thorough analysis of terrain reveals that obstacles were present in the safety area, with many trees exceeding the permitted height limit (mostly about 10–11 metres (33–36 ft)).

After the nose hit, the aircraft was violently torn apart by impact forces. The wreckage came to rest upside-down about 200 metres (660 ft) before the runway threshold and slightly left of its centreline. The largest pieces left were the wing roots (the strongest part of an airplane), the wingtips and the tail section. The tail section came to rest backwards, relative to the direction of flight. A small post-impact fire ensued, but was quickly brought under control by the emergency services and extinguished 18 minutes later.

The Governor of Smolensk Oblast, Sergey Antufyev, confirmed that there were no survivors of the crash. Pictures from the scene showed parts of the aircraft charred and strewn through a wooded area. The Russian Prime Minister, Vladimir Putin, said that the bodies of those killed in the crash would be brought to Moscow for identification. Kaczyński's body was identified in Smolensk and was flown directly to Warsaw on the afternoon of 11 April.

Investigation
As the accident occurred on Russian soil, Russia was tasked by ICAO procedure with primary responsibility for investigation, which it carried out with international cooperation. Poland also set up its own committee to investigate the crash, and prosecutors in both countries began criminal investigations.

Interstate Aviation Committee
In the Commonwealth of Independent States (CIS), the Interstate Aviation Committee (IAC) (Russian: Межгосударственный авиационный комитет (MAK)) oversees the use and management of civil aviation. The committee's Air Accident Investigation Commission is responsible for investigating civil aviation accidents occurring in commonwealth member nations. The committee is headquartered in Moscow, Russia.

Immediate actions
Within hours of the crash, the President of Russia, Dmitry Medvedev, announced the establishment of a special commission for the investigation of the accident. The commission was to be supervised by Prime Minister Vladimir Putin. An Investigation Committee of the Prosecutor General of Russia started a criminal case in accordance with a "violation of the safety rules" of the Russian Criminal Code.

Flight recorders
Two flight recorders, the cockpit voice recorder (CVR) and the flight data recorder (FDR), were recovered undamaged from the crash site during the afternoon/early evening of 10 April, as was confirmed by Sergey Shoygu, the Russian Minister of Emergency Situations. That evening, it was reported that the CVR recordings confirmed the crew attempted to land against the advice of air traffic controllers. A third flight recorder, a Quick Access Recorder (QAR) designed for maintenance diagnostics, was found on 12 April. The two Flight Management System (FMS) units were also recovered. The investigation was able to obtain information from the electronic memories of the Quick Access Recorder and one of the FMS units, despite the fact that they were not designed to withstand a crash. Since the FMS units are linked together, being able to read the memory of one meant the investigation was able to determine the actions performed by both units. It would later be discovered that the FDR was partially defective and had occasional gaps in its data, but as the QAR managed to survive the crash, by synchronizing the data from the two units, a complete picture of flight data emerged.

On the day after the crash, investigators said they had reviewed the flight recorders, and confirmed that there were no technical problems with the Soviet-built aeroplane, ruling out initial theories that the 20-year-old aircraft was at fault. Alexei Gusev, general director of the Aviakor factory, said that the aircraft's three engines had been repaired and technicians had upgraded the plane's avionics at a recent overhaul the previous year. He said that there were no doubts about the plane's airworthiness.

Search for human remains
Ewa Kopacz, former Polish Minister of Health, claimed before the Sejm that after the crash, ground was dug to a depth of one metre, and even if a tiny piece of human flesh was found, it was genetically tested. However, in the transcript released online by the Sejm, the meaning of her speech was changed: that when a small piece of flesh was found, the ground was dug to a depth of one metre. Moreover, in September 2010, one of the Polish pilgrims to Smolensk found a jaw with teeth and two other bones.

Russian cooperation
Russia offered full cooperation to Polish prosecutors during the investigation. According to the Interstate Aviation Committee (IAC) Polish investigators in Russia have been given access to all procedures of Russian investigators. However, Edmund Klich, the head of the Polish investigative commission, said that "Poland does not have a lot of things that (we) would like to have" and as an example gives lack of documentation of Smolensk airport and regulations about Air Control. Polish investigators do not have the authority to conduct investigative actions by themselves, but they participated on equal terms with their Russian counterparts in the interviews with people involved and other parts of the investigation. Polish officials were to secure all Polish state documents found in the wreckage, as well as electronic devices (portable computers and mobile telephones) belonging to government officials and military officers. In turn Russian investigators received from Poland materials secured after the crash, including those about the technical state of the aircraft and fitness of the pilot. The Polish investigation results were to be based in part on Russian findings, but they are not bound by the results of the Russian investigation. Preliminary results of the investigations were to be released on the Thursday after the crash (including the cockpit voice recordings), but this was postponed until after the weekend when the funeral of the Presidential couple was to take place, then postponed indefinitely until the full analysis was completed. The Flight Data Recorder and Cockpit Voice Recorder, both of Soviet design, were analyzed in Russia with the participation of Polish experts. The Quick Access Recorder, designed and produced in Poland, was sent to Poland and analysed there, with the participation of Russian experts. The Flight Management System units, manufactured in the United States, were analyzed there with the participation of the FAA, NTSB, Polish experts, and Russian experts.

Airport and pilot communication
The airport's traffic control communicated with the pilots in Russian, and one of the controllers claimed the Polish crew had problems communicating in this language. However, according to Tomasz Pietrzak, the former commander of the Polish 36th Special Aviation Regiment, the captain of PLF 101 was fluent in Russian and English. The Captain had landed in Smolensk three days before the crash, when he was part of the crew bringing Polish Prime Minister Donald Tusk to the 7 April ceremony, and at the time no communication problems with ground control were reported. However, while the captain knew Russian, the rest of the crew did not, in particular the navigator whose task it is to communicate with the ground, thus placing an additional workload on the captain. Previous flights to Smolensk had been accompanied by a Russian navigator, but none was provided for the April 2010 flights, with differing reasons for this given by Polish and Russian sides. The final accident report would later conclude that the captain's knowledge of Russian was "satisfactory."

The airport, which normally should have been closed due to the severe conditions, was not declared closed as its management feared that this could cause a diplomatic incident. According to the news agency Interfax, the pilot was told that Smolensk North Airport was enveloped in thick fog and strongly advised against landing, but still he decided to continue with the original flight plan and attempt a landing. According to an interview with a flight controller Pavel Plusnin it was suggested to the pilot that he land at an alternative airfield in Moscow or Minsk. According to Plusnin, the pilot said, that he would attempt one approach, and if landing was not possible, he would then divert to another airfield.

There was some concern in the press as to whether or not Russian military ATC had the authority to issue military orders to PLF 101, as the aircraft was a military flight. Under Russian law, military flights are under the control of Russian military ATC, and permission or denial for approach and landing must be given by the controller prior to these actions being undertaken by a flight crew. The final accident report determined that, as a foreign military aircraft, Russian controllers did not have the authority to issue military orders to PLF 101, and this had been communicated to the ATC personnel who handled the flight. The "trial" approach was conducted with the understanding by ATC that all risk for such an approach was to be undertaken by PLF101 and not ATC.

Theft from victims
On 6 June 2010, it was reported that payments worth €1,400 had been made from a credit card found on the body of historian Andrzej Przewoźnik, one of the victims of the crash. Credit cards belonging to the politician Aleksandra Natalli-Świat were also missing, but not used in transactions. On 8 June 2010, ITAR-TASS reported that four soldiers of Unit 06755 had been charged in connection with the theft, after being found in possession of three credit cards used to withdraw a total of 60,345 rubles. A Polish spokesperson said that the first withdrawals using the cards had been made around two hours after the crash. The Polish government admitted that the Russian soldiers involved in the theft were probably conscripts, and that earlier reports blaming members of Russia's OMON forces for the theft had been a mistake.

Initial reports
An initial report by CIS' Interstate Aviation Committee (Russian: Межгосударственный авиационный комитет (MAK)) revealed that all three engines were operating normally, and that there was no fire or explosion before the aircraft crashed. According to the newspaper Dziennik, Polish flight recorder ATM-QAR registered that precisely at 8:41:02.5 (Polish time) the tail of the aircraft separated. All systems of Tu-154 stopped working at 8:41:04. Fuel temperature was below 0 °C (32 °F). Engines when the aircraft was above the road were at 60% of their nominal power (Tu-154 needs about 10 seconds to get 100% of power from engines). They also determined that the aircraft was 40 metres (130 ft) lower than it should have been.

The discrepancy among the time of the crash registered by MARS flight recorders (10:41:05.4), ATM-QAR recorder (10:41:04), and when electricity lines were cut by the crashing aircraft a second or two before the final crash (10:39:35) was never explained.

On 19 May 2010, the preliminary report of the investigation into the crash was published. Alexei Morozov, the head of the technical commission of Russia's Interstate Aviation Committee, stated that the Tupolev Tu-154M had no mechanical faults, and that an air traffic control official at Smolensk North Airport had "warned twice that visibility was 400 metres (1,312ft) and that were no conditions for landing". The investigation ruled out a terrorist attack, explosion or fire on board the aircraft as the cause of the crash. It was also reported that the voices of two non-crew members were heard in the cockpit during the period leading up to the crash. One of the voices was identified by sources as the Polish Air Force Commander, Lieutenant General Andrzej Błasik. However, according to the findings of the Polish prosecutor's office in January 2013, General Błasik had not stayed in the cockpit and was a regular passenger. The other voice was later identified as the Director of Protocol.

According to the Interstate Aviation Committee report from 19 May 2010, the aircraft first hit an 11-metre (36 ft) tree approximately 1,100 metres (3,609 ft) from the runway. The aircraft was also off by 40 metres (130 ft) from the extended middle line of the runway. The TAWS alarm "Pull up!" was first sounded at 100 metres (328 ft) altitude and then repeated several times before the crash. It was first sounded 18 seconds before hitting the tree and the crew attempted to abort landing 13 seconds later. Due to geographical relief the aircraft was actually 15 metres (49 ft) below the runway at the time of the first impact.

On 26 May 2010, it was reported that pilot error had been identified as the reason for the crash.[citation needed] Edmund Klich, the head of the Polish investigative commission, stated in an interview "Pretty much everything is clear right now and nearly all evidence has been gathered". "The pilots ignored the plane's automatic warnings and attempted an incredibly risky landing," Klich said.[citation needed] According to the report, the crew of the Tupolev Tu-154M failed to respond for 13 seconds when the plane's "terrain approaching" alarm warned that the aircraft was less than 100 metres (330 ft) from the ground. The aircraft attempted to pull up after hitting a five-metre-tall (16 ft) birch tree, but part of the left wing had been sheared off in the impact. The aircraft then went into a roll before landing on its back and disintegrating five seconds later. Edmund Klich declined to speculate on whether the pilot had been placed under pressure to land, commenting, "Psychologists will have to assess the stress levels the pilots were subjected to."

On 1 June 2010, Poland's Interior Ministry published a transcript from the cockpit voice recorder of the crashed Tu-154M.[citation needed] The transcript confirmed earlier reports that the aircraft had attempted to land in bad weather against the advice of air traffic control and the plane's terrain awareness warning system. At one point in the recording, Mariusz Kazana, the Director of Diplomatic Protocol in the Ministry of Foreign Affairs, enters the cockpit and was told by the pilot "Sir, the fog is increasing. At the moment, under these conditions that we have now, we will not manage to land" to which Kazana replies "Well, then we have a problem."

Expert commentators have noted that the flight navigator, who was listing the altitude readings on the transcript, was referring to the radar altimeter (which gives height above ground) rather than the pressure altimeter (which would provide the height relative to the level of the runway). Because the terrain rises up to the runway, this could have had the effect of causing the pilot to fly far too low. The Final Report confirms this is exactly what happened.

The Russian report was published on 12 January 2011, and the Polish report was published on 29 July 2011. Both reports placed the majority of the blame for the accident on the pilots for descending too low without being able to see the ground. The Polish report also placed harsh criticism on the organization of Poland's special aviation regiment and its leaders, as well as finding deficiencies in the performance of the Russian air traffic controllers and in the airport's lighting and approach area. In Polish discourse, there remained wider questions and unease about the potential causes of the crash. This prompted a Warsaw court and a separate military investigation. Some of the unease subsequently fueled conspiracy theories revolving around aspects of the investigation, such as Russia's decision not to return the Polish plane wreckage to Poland. In the aftermath of the accident, Russia published a large number of restricted documents on the Katyn massacre, and declassified and published many more.[citation needed] Additionally, the Russian State Duma issued a declaration blaming Soviet leader Joseph Stalin and other leaders for ordering the Katyn massacre. Subsequent Katyn memorials have been joint Russian/Polish affairs attended by the leaders of both countries.

Russian final accident report
The MAK completed their investigation on 20 October 2010. A copy of the report was sent to the Polish authorities, who had 60 days to comment, after which the report was published on 12 January 2011.

After the Interstate Aviation Committee (IAC) report's publication, Poland stated that it was created in violation of Annex 13 to the Convention on International Civil Aviation because some requested documents or evidences were not provided by Russia and, according to a Polish lawyer, because Polish comments to the final report were not agreed to nor fully applied.

The final report noticed that the captain's electronic altimeter was set 170 metres (560 ft) higher than the actual position. This change was made after the aircraft began its final approach and soon after the first TAWS warning sounded. All other altimeters on board were set correctly. The investigation also determined that the controller's radar screen was not calibrated correctly and showed the airplane as being 90–150 metres (300–490 ft) closer to the runway than it actually was. Additionally, his radio calls to the crew regarding their distance to the runway were given in advance by an average of 500 metres (1,600 ft).

As part of their investigation, MAK conducted an experiment in a Tu-154M simulator to determine how late the crew could have gone around. "The experiment confirmed that during approaches in conditions similar to the flight conditions of the T-154M ... with a similar flight profile with vertical speed of descent of 7–8 m/s ... the aircraft characteristics guaranteed safe go around from the height of 40 m (without taking into consideration the possible obstacles and terrain along the flight path)." Taking into consideration the terrain at Smolensk, the investigation determined the last moment a go-around maneuver would have been successful was coincident with the first officer calling "Go around" and briefly pulling the control column at 60 metres (200 ft).

Polish comments on the draft of the final report
On the same day that the final report was published by MAK, Poland published its comments on the draft of the final report sent to MAK before. Poland stated that their comments were not taken into consideration. MAK did not include them in the report, but published this document on its website among other appendixes. Poland also published a final version of MAK report with changes performed by MAK in reaction for Polish comments highlighted (red color means changes of text, blue means text addition).

The main points of Polish comments are:


 * A list of documents, evidence, and other information requested by Poland but not received from the Russian side (First table in document "Lista Wystapien Strony Polskiej o Dokumentacje", List of requests from Poland about documentation. Entry "Nie otrzymano" means "Not received"). Sample of them: Standards of certification for usage of military airports on the Russian Federation territory, Instructions for flights in Smolensk area.
 * Poland notes that, according to international agreement between Poland and Russia from 1993, PLF 101 was classified in Poland as a military plane and should be treated as performing a military operation also on the territory of the Russian Federation, especially in non-classified airspace and during approaching a military airport without ICAO certification. During military operations the ATC can give orders to the crew about landing decisions as opposed to civilian flights where the ATC only gives recommendations, but where the final decision about landing is the pilots' responsibility.
 * Information that result of analysis of CVR (Cockpit Voice Recorder), performed by Polish Commission for the Investigation of National Aviation Accidents, says that first officer gives command "go around" at 100 m altitude This analysis has been ignored by MAK's final report.
 * Request for document confirmation that Commander of the Landing Zone was allowed to work in bad weather conditions. Documents confirm only admission for work at day and night in normal weather conditions. Poland notices also that Commander of the Landing Zone had never before worked at Smolensk and in last 12 months performed this function only 7 times. All that information is in his testimony. There is no documentation which certificate Commander of the Landing Zone on Smolensk airport which is required by Russian Law.
 * Polish position that ATC gives wrong information for PLF 101 ("on course, on glide slope") and "Level 101" was given too late. According to Final Report at this moment plane was up to 15–20 metres (49–66 ft) above runway level and 1,400 metres (4,600 ft) before runway begins.
 * Differences in approach card described by Final Report and approach card received by Poland before 10 April 2010 with information that Russia sent documents without information about reference system of coordinates in document. Poland assumed that coordinates are expressed using WGS-84 which is worldwide standard. Current standard for reference system used in Russia (according to its own law regulation) is PZ-90 which differ from WGS-84 by less than 40 cm (16 in) in any given direction.
 * Doubts about Smolensk compliance with Russian regulations because there were trees and other obstacles in an area 300 to 900 m long before the runway. The heights of these obstacles are 15m higher than allowed (according to both Russian and ICAO regulations). After the accident, trees in this area were cut. The structure of flight PLF 101 began to be destroyed in that area.
 * Polish explanation that there is no requirement in Military aviation for aircraft to have insurance (PLF 101 was owned and maintained by the Polish Military) and even civil regulations allows other financial protections besides insurance. In the case of PLF 101, the Polish National Treasury was financially responsible for the aircraft.
 * Polish explanation that, according to Polish law, Certificate of Airworthiness is required for civilian planes and is not obligatory for military machines — instead of this certificate, Polish military planes have to accomplish conditions regulated by "Instrukcja służby inżynieryjno-lotniczej Lotnictwa Sił Zbrojnych RP" (Instruction for engineering and aviation service of Aviation Forces in Republic of Poland). Poland also provides list of documents that confirm plane compliance with that document.
 * Information that Polish side had not received documentation of control flight over Smolensk nor documentation of RSP-6m2 radar system used in ATC.
 * Doubts about reliability of protocol after control flight which confirmed that light system (LUCZ-2MU) is working properly on Smolensk when MAK Final Report says it did not. Polish specialists were not allowed to be present during control flight.
 * Doubts about proper work of radar display according to protocol from control flight.
 * Request for source data to marker location on radar display described in Final Report. Information provided to Poland says that camera recorder in ATC was corrupted and there is no information about any other source data.
 * Request for information about 13 recorders mounted in ATC, and data recorded (even corrupted) for analysis. MAK states that camera, voice recorders and photo laboratory not worked properly and a lot of information was not saved.
 * Information that FCOM of Tu-154M in fact does not prescribe using the autopilot during non-precision approach, however this is also not forbidden.
 * Expressed lack of any document that confirms PLF101's status under Russian law.
 * Request for source data and method of calculation of Flight 101's weight. Poland says that original documentation about loading and weight measure was destroyed.
 * Allegations that documents certifying the medical examination of air controllers had manual corrections and are inconsistent with their testimonies where they confirmed that medical point was closed on 10 April 2010.
 * Correction of number of specialists—with list of their certifications—that performed technical support on Flight 101

Polish publication of ATC tapes
At an 18 January 2011 press conference, the Polish investigation made public the information contained in ATC recordings, and their analysis of such. They concluded that the "on course, on glide path" calls given to the pilots were made when the aircraft was actually off course, and furthermore the "Level!" call was given 11 seconds too late.

MAK publication of ATC tapes
In response to the Polish claims of publicity MAK published transcripts of ATC recordings on its website. The announcement made on MAK website states that the transcripts are based on a copy of recordings identical to the one which was given to the Polish side during the investigation.

The transcripts include: "Open microphone", phone calls and radio transmissions.[better source needed] The transcripts show that communication between the ATC and PLF101 was done mostly in Russian with only a few English phrases.

MAK report
The MAK report found the "immediate cause" of the accident was the failure of the crew to make a timely decision to proceed to an alternate airport despite being warned multiple times of the poor weather conditions at Smolensk. Another immediate cause was the descent below minimums without visual contact with the ground as well as ignoring numerous TAWS warnings. This led to controlled flight into terrain. Additionally, the MAK report found an "immediate cause" of the accident was the presence in the cockpit of the Commander-in-Chief of the Polish Air Force, which placed extreme stress and "psychological pressure" on the Captain to "continue descent in conditions of unjustified risk with a dominating aim of landing at any means."

A "contributing factor" to the accident was a long discussion with the Protocol director and the crew of the Yak-40 regarding the actual weather and the impossibility of landing at Smolensk in such weather conditions. The report found this discussion caused the Captain to experience "clash of motives." On one hand he knew that landing in the reported weather conditions was unsafe. On the other hand, he faced strong motivation to land at Smolensk anyway. He expected a strong negative reaction from the President if he chose to divert the airplane and land at an alternate airport.

Other "contributing factors" were a lack of compliance with standard operating procedures, a lack of crew resource management, and a significant gap in bad weather flights by the PIC (he had not flown in weather conditions similar to Smolensk that day in four months). Additional "contributing factors" were the Navigator calling out radar altitudes without considering the uneven terrain in the area, utilization of the autopilot and autothrottles much lower than minimum descent altitude which did not comply with the Flight Crew Operations Manual for the Tu-154, and the late start of the final descent which caused the crew to maintain a higher than normal vertical speed.

A "systemic cause" of the accident were "significant shortcomings in the organization of flight operations, flight crew preparation and arrangement of the VIP flight in the special air regiment."

Official Polish government report
The Polish Committee for Investigation of National Aviation Accidents (KBWLLP) published its report on 29 July 2011, also available in English and Russian. While the report stated that pilot error was the main cause of the accident, with the crew lacking adequate training in operating in adverse weather conditions, it differed from the Russian report in several aspects.

Chief among these differences was a conclusion that the pilots were not placed under pressure forcing them to land at Smolensk, and that the crew decided to abort landing when they reached 100m altitude (measured by radio altimeter) and had decided to go around using the autopilot. However, it was impossible for the autopilot installed in the aircraft to conduct an automatic go-around from a non-precision approach. The Polish investigation concluded this caused a delay in executing the go-around which contributed to the crash.[citation needed]

Another major difference was a conclusion that Russian air traffic control played a part in the accident by passing incorrect information to the crew regarding the plane's position. ATC gave distance callouts on average 500 metres (1,600 ft) in advance, and told the aircraft it was on the correct glidepath when it actually was not. Furthermore, the controllers gave the "Level 101" command ten seconds after the aircraft passed the 100 metres (330 ft) altitude where such call was supposed to be given.

The Polish report also found three deficiencies regarding the Smolensk airport which contributed to the crash. One was a large number of obstacles (mostly tall trees) in the area before the runway which should have been removed to keep the protected approach airspace clear of obstructions. The second deficiency was with the approach lighting system, which was charted incorrectly and not well maintained. Many bulbs were burned out, several others were missing their lenses, and others were obscured by shrubbery. The third concern was with the airport information received by Poland, which contained incorrect information. In addition to the lighting system not being depicted correctly, the airport's location was charted approximately 116 metres (381 ft) to the North of its actual position.

Due to numerous accusations raised by Law and Justice opposition party who rejected the official report's conclusions, a new commission was created in 2013, headed by Maciej Lasek. Its task was to publish and explain all the technical evidence used in the official report. Lasek commission's produced over a hundred very detailed technical reports, maps, transcripts, photos and videos which were originally published on www.faktysmolensk.gov.pl website.[citation needed] Shortly after the 2015 Polish parliamentary elections the website was shut down and all documents removed by the new government, but were subsequently restored on an independent mirror.[citation needed]

Cause of accident according to Polish report:


 * The immediate cause of the accident was the descent below the minimum descent altitude at an excessive rate of descent in weather conditions which prevented visual contact with the ground, as well as a delayed execution of the go-around procedure. Those circumstances led to an impact on a terrain obstacle resulting in separation of a part of the left wing with aileron and consequently to the loss of aircraft control and eventual ground impact.

Circumstances contributing to the accident:


 * 1) Failure to monitor altitude by means of a pressure altimeter during a non-precision approach;
 * 2) failure by the crew to respond to the PULL UP warning generated by the TAWS;
 * 3) attempt to execute the go-around maneuver under the control of ABSU (automatic go-around);
 * 4) Approach Control confirming to the crew the correct position of the airplane in relation to the RWY threshold, glide slope, and course which might have affirmed the crew's belief that the approach was proceeding correctly although the airplane was actually outside the permissible deviation margin;
 * 5) failure by LZC to inform the crew about descending below the glide slope and delayed issuance of the level-out command;
 * 6) incorrect training of the Tu-154M flight crews in the 36 Regiment.

Conducive circumstances:


 * 1) incorrect coordination of the crew's work, which placed an excessive burden on the aircraft commander in the final phase of the flight;
 * 2) insufficient flight preparation of the crew;
 * 3) the crew's insufficient knowledge of the airplane's systems and their limitations;
 * 4) inadequate cross-monitoring among the crew members and failure to respond to the mistakes committed;
 * 5) crew composition inadequate for the task;
 * 6) ineffective immediate supervision of the 36 Regiment's flight training process by the Air Force Command;
 * 7) failure by the 36 Regiment to develop procedures governing the crew's actions in the event of:
 * 8) * failure to meet the established approach criteria;
 * 9) * using radio altimeter for establishing alarm altitude values for various types of approach;
 * 10) * distribution of duties in a multi-crew flight.
 * 11) sporadic performance of flight support duties by LZC over the last 12 months, in particular under difficult WC, and lack of practical experience as LZC at the SMOLENSK NORTH airfield.