LOT airplane crash at Okecie

The aircraft

LOT initiated their transatlantic routes in the early 1970s, for which it decided to purchase the newly introduced Ilyushin Il-62. The aircraft which crashed was the first Il-62 LOT had purchased for this purpose, manufactured in 1971. As with all Ilyushins purchased, it was named after a famous Polish historical figure, in this case Nicolaus Copernicus ("Mikołaj Kopernik" in Polish).

Crash

On its final flight, the aircraft was piloted by Captain Paweł Lipowczan and First Officer Tadeusz Łochocki. Flight 007 was scheduled to depart from Kennedy International Airport at about 19:00 local time on 13 March 1980, but it was delayed because of a heavy snowstorm. It finally departed at 21:18, and after nine hours of an uneventful flight, it was approaching Okęcie Airport at 11:13 local time. During their final approach, about one minute before the landing, the crew reported to Okęcie Air Traffic Control that the landing gear indicator light was not operating, and that they would go-around and allow the flight engineer to check if it was caused by a burnt-out fuse or light bulb, or if there was actually some problem with the gears deploying.

(11:13:46) Okęcie Air Traffic Control: LOT 007, 5 degrees to the right.

(11:13:52) Okęcie ATC: LOT 007?

(11:13:54) LOT: Roger that... One moment, we have some problems with landing-gear-down-and-locked indicator, request a go-around.

(11:13:57) Okęcie ATC: Roger, runway heading and altitude 650 meters. [At that moment, "Kopernik" was at an altitude of 250 metres.]

(11:14:00) LOT: Runway heading and 650.

This was the last transmission from "Kopernik". Nine seconds later, the aircraft suddenly entered a steep dive. At 11:14:35, after 26 seconds of uncontrolled descent, the aircraft clipped a tree with its right wing and impacted the ice-covered moat of a 19th-century military fortress with the speed of about 380 km/h (238 mph) at a 20-degree down angle, 950 meters away from the runway threshold and 100 meters from a residential area. At the last moment Captain Paweł Lipowczan, using nothing but the plane’s ailerons, managed to avoid hitting a correctional facility for teenagers located at Rozwojowa street. On impact, the aircraft disintegrated; a large part of the main hull submerged in the moat, while the tail and parts of the main landing gear landed a few meters further, just before the entrance to the fort. On the scene, a diving team was later trying to recover parts of the aircraft (including some of the engines) from the moat, but it was far too murky; finally, the moat had to be dried to allow the air crash investigation team to recover parts of the disintegrated plane. The body of Captain Lipowczan was found lying on the street about sixty meters from the crash site; other bodies were scattered between the plane parts.

Among the 87 fatalities were Polish singer Anna Jantar, American ethnomusicologist Alan P. Merriam, six Polish students returning home from an AIESEC conference in New York and a contingent of the amateur U.S. boxing team. According to the doctors who arrived at the scene, many of the passengers were apparently asleep when the plane hit the ground, but some of them - including many of the boxers - were supposedly aware that they were about to crash, as they held to their seats so strongly that on impact, the muscles and tendons in their arms became severed. Some reports suggested that some of the boxers actually survived the crash and drowned in the moat, but no evidence for this was presented.

By ironic coincidence, at the time the "Kopernik" crashed, a conference on improvements in air travel safety was being held at Okęcie airport, less than a kilometer away.

In a twist of fate, Ryszard Chmielewski, the flight engineer, was scheduled to fly to Warsaw on that day; because he suffered from jet lag and insufficient rest after the previous flight, he switched shifts with one of his colleagues and flew out of New York one day later. Seven years later, as a flight engineer and instructor, monitoring the progress of flight engineer Wojciech Kłossek, he was on board of LOT Flight 5055, which crashed killing all 183 people on board.

In another twist of luck future Light Heavyweight World Champion Bobby Czyz was booked to be on the flight as part of the USA Amateur boxing program however due to a car accident the week before he was injured and did not make the trip. Additionally future boxing world contender Sal Cenicola injured his right shoulder in the weeks leading up the flight and he too did not make the fatal trip because of his injuries before the trip.

Nationality   Passengers Crew Total

 Poland               42    10     52

 United States     28      0     28

 Soviet Union        4      0       4

 East Germany     3      0       3

Total                         77    10     87

Investigation

The police quickly surrounded the site and removed any spectators; recovery of airplane pieces started soon afterwards. Both the cockpit voice recorder and flight data recorder were found quickly; unfortunately, the recording suddenly stopped nine seconds after the last transmission, 26 seconds before the crash.

While recovering the engines, the inner left engine - engine number 2 - was found to be cut in half, held together only by the fuel lines. When the engine was further examined, the disc of the low pressure turbine was found to be missing; despite an extensive search, it was not found at the crash site. Finally, the turbine disc was found about four kilometres (2.5 miles) from the site; it was broken into three similar-sized pieces.

After recovering the cockpit, the throttles of both engine 2 and 3 (inner right) were found to be set to shutdown mode, while on engine 4 (outer right) the thrust was set to maximum. The investigating commission asked the Russians if an Il-62 was able to reach the runway with one engine operating; no conclusive answer was received, but calculations based on the official technical data suggested that, while one engine thrust was insufficient for the aircraft to maintain altitude, it was enough to reach the runway and try to land. No explanation was found why the aircraft with one engine operating at maximum power suddenly entered a steep dive.

Detailed analysis of the pieces of the turbine disc found several metallic impurities on the edges of two of them; in one case, they were identified as coming from the engine nacelle, in another, the impurities came from the nacelle, the hull, control actuators and finally, electrical cables. Also, detailed examination of the surface of the broken disc showed significant evidence of material fatigue.

Sequence of events

Finally, when the control pushers were found to be cut in half, it was proven that the cut was not caused by the crash, and some traces of the metal alloy the turbine disc was made of was found on the surface of the cut, the sequence of events became clear. The disaster started when "Kopernik" was instructed to climb to a higher flight level. When the necessary thrust was applied to all four engines, the low-pressure turbine of the number 2 engine disintegrated after 9 seconds. One piece of the turbine disc got ejected upwards, not causing any significant damage; the second piece shot into the engine number 1, damaging it seriously; finally, the third piece of the disc shot into the hull, severed the rudder and elevator control rods and destroyed the number 3 engine, causing loss of control over the plane; it also severed power cables for both the flight data recorder and the cockpit voice recorder. This caused the last moments of "Kopernik" not to be recorded.

The cut control rods also explained the sudden steep dive. When they were cut, the horizontal stabilizer, under its own weight, dropped down, causing the nose also to go down. This could be counteracted by the vertical trim; in Il-62s, the switch setting the vertical trim to manual operation was secured by a thin, sharp wire. On Capt. Lipowczan's right hand, small wounds were found, and they were confirmed to be made while Lipowczan was still alive; supposedly, he ripped the security off and tried to control the vertical trim, but it was too late.

In an interview for Polish TV series The Black Series, Capt. Tomasz Smolicz, an experienced airline pilot who flew thousands of hours on transatlantic routes on Ilyushins Il-62 and Il-62M in the 1970s and 1980s (he flew "Kopernik" from Warsaw to New York on 13 March 1980), stated that the planes returning to Warsaw from America usually landed on runway course 155 (155 degrees, south-south-east), and if they landed at or before noon on a sunny day (such as on 14 March 1980), the sun was shining almost directly in their eyes, which were weary after several hours of night flight and constant monitoring of cockpit instruments; this sometimes caused disorientation and confusion if an indicator light actually was lit or not; so, on that day, the landing gear indicator could have actually been lit, but the crew members might have managed to see it incorrectly. During the recovery, the landing gear was found to be properly extended and locked.

Causes of disaster

According to the Polish government's Special Disaster Commission, the crash was caused by defects in materials, faults in the manufacturing process of the Kuznetsov NK-8 jet engine’s shaft, and weaknesses in the design of its turbine.

During the manufacturing of the low pressure shaft, at a location where its section diameter increases, a sharp, 90-degree step was made, resulting in a sudden diameter change over a very short linear length. In engineering terms, such sharp step instead of a radiused fillet causes a significant concentration of stress. This became a tragic, textbook example of stress concentration increase of a "stepped shaft", which in-turn initiated the formation of micro-cracks through the material core, a phenomenon known as material fatigue. Additionally, the metallurgical analysis found, that alloying impurities were present such as non-metallic inclusions in the alloy of the shaft, in addition to the incorrectly performed heat treatment process, which further reduced the shaft's ability to carry the torsional loads as designed. The improperly machined engine shaft, coupled with metallurgical alloy impurities, facilitated an accelerated fatigue of this key engine component via unmitigated formation of micro-cracks through the shaft's core, ultimately leading to its failure.

Over time, the magnitude of the structural defects in "Kopernik"'s shaft reached a critical point, and the shaft broke, resulting in the physical separation of the low pressure turbine from the low pressure compressor. As a result, the low pressure turbine explosively disintegrated. Ejected with enormous force, pieces of turbines damaged 3 of the plane's 4 engines and cut through the hull, causing the failure of the vertical and horizontal flight controls (rudder and elevator), and a massive failure of numerous systems of the airplane. The sudden loss of control of the flight control surfaces caused a steep, unrecoverable dive, and resulted in a crash, 26 seconds from the time of the original failure.

A press article, released in Poland in 2010 and based on the review of archival documentation kept in IPN claimed that PRL authorities contributed to the crash by demanding savings from PLL LOT and excessive exploitation of engines. The article also claimed that, when the engine that disintegrated on 14 March 1980 was earlier found to have an unusually high level of shaft vibrations, the only solution implemented by Polish ground personnel was switching the engine between different Il-62s; also, the turbine disc exhibited evidence of some crude attempts to repair it, against the producer's regulation. Part of the claims of the article was subsequently dismissed by the ground personnel and aviation experts: the mechanics claimed that they reported the high vibration level to the engines' manufacturer, but the only response they received was the paper stating that "the level of vibrations reported does not exceed the levels found by the manufacturers as ordinary." (The Polish TV documentary exhibits those documents in their original form.) Having no technical possibility of getting inside the engine and check it (this also contradicts the claims that the turbine disc was tampered with by the ground personnel), the mechanics decided to switch the suspicious engine between different aircraft, to ensure that it gets on the aircraft where the other three engines are in the best condition so, in case it fails, the aircraft could continue flight on three remaining engines - no one suspected such failure could lead to loss of flight controls and two of three other engines.

The engine shaft’s explosive disintegration

In the Kuznetsov NK-8 (in fact, in almost all Turbofan engines), air is sucked from the front of the engine by the low pressure compressor. After passing the compressor, air is divided into two channels, outside and inside. From the inside channel, air travels into the high pressure compressor, after which it enters the combustion chamber. Each step from the low to high pressure compressor increases air pressure. In the combustion chamber, air is mixed with fuel and then ignited. As combustion occurs, ultra high pressure gases exit the rear of the combustion chamber, pass both turbines, mix with air from the outside channel, then exits the engine’s rear — generating engine thrust for the aircraft. On their way, the ultra high pressure gases meet a high pressure turbine and a low pressure turbine, and the angle of their blades forces both turbines to spin. Since the turbines are connected by a common shaft to the compressors, as both turbines spin, both compressors are forced to spin also. The spinning of the compressors is needed for engine work, as their rotation sucks air into the engine, as well as further pressurizing it once it is inside (as air passes through each step of the compressors).

As the #2 engine's low pressure shaft failed in the engine due to metal fatigue, the low pressure turbine become suddenly physically separated from the low pressure compressor, freeing the turbine. Because the engine combustion chamber was still producing power, the suddenly freed turbine spun out of control with such enormous speed that within a fraction of a second, the centrifugal force caused the turbine to disintegrate explosively. Pieces of turbine were ejected tangentially with the speed of artillery shells.

Aftermath

The Polish government's Special Disaster Commission sent its findings on the cause of the accident to Moscow. In response, Russian engineers and scientists stated that the reasons given were implausible and that the turbine disintegrated because of engine failure, contrary to what was stated in the Polish report. (This could partially be attributed to a grudge Russian engineers held against Poles, who purchased their Ilyushins but replaced their radionavigational systems with separately purchased, more modern American ones.) Many years later it was revealed that after Flight 007's crash, all Il-62s used by Russian officials and VIPs had their engines discreetly replaced with newer ones. At one occasion, Polish governmental Il-62M had had specially installed newer engines for a joint Polish-Russian governmental trip to Beijing; after that, the engines were taken back to the USSR.

The Polish commission report also called for some modernizations in the Il-62 design, most notably doubling the flight controls, so that if one system failed the plane would still be controllable. At the time, redundant controls of this kind were in general use in American and European-made airliners. This issue was never addressed by the Russians; none of their Ilyushins of all types had installed alternate controls.

A small statue dedicated to the boxers who perished in the accident - a trigonal prism made of bronze, with a knocked-out boxer statue at the top, is located at the grounds of Warsaw sport club Skra Warszawa. An identical statue is located at the United States Olympic Training Center in Colorado Springs. The statues were funded by Thomas Kane of Printon Kane and Company and AIBA and designed by American sculptor Auldwin Thomas Schonberg.

The graves of the "Kopernik" crew are located at the Powązki Military Cemetery in Warsaw. One of the streets adjacent to the crash site bears the name of Captain Paweł Lipowczan.