LOT Polish Airlines Flight 5055

Aircraft

The aircraft was a 186-seat Ilyushin Il-62M built in 1983, registered SP-LBG and named after Tadeusz Kościuszko, a Polish military leader and national hero. It was one of seven Il-62Ms that LOT bought from the Soviet Union in 1983,^: 59 and it was used on international routes.^: 166 By the time of the accident, it had flown 6,971 hours and made 1,752 landings, against a service life of 30,000 hours and an overhaul interval of 10,000 hours.^{: 2 : 60 : 45} Other accounts give different flight-time totals, with the writer Aleksander Grobicki citing just over 5,000 hours and the journalist Jarosław Reszka just under 7,000 hours.^{: 166 : 59} It was powered by four Soloviev D-30KU turbofan engines mounted in pairs at the rear of the fuselage.^: 12–14 The two engines on the left side were numbered 1 (outer) and 2 (inner).^: 3 On 8 May 1987, the aircraft returned to Warsaw from a transatlantic flight from Chicago and underwent a routine six-hour check in preparation for its next transatlantic flight.^: 166

Crew

All of the crew members were Polish. The captain, Zygmunt Pawlaczyk, aged 59, had been a military pilot since 1951 and had joined LOT in 1955.^: 2 He had 19,745 flight hours, including 5,542 hours on the Il-62, of which 3,725 were as captain.^: 2 The first officer, Leopold Karcher, had been a military pilot since 1956 and had joined LOT in 1967.^: 2 He had 10,899 flight hours, of which 2,357 were on the Il-62.^: 2 The navigator was Lesław Łykowski, and the radio operator was Leszek Bogdan.^: 2 The flight engineer, Wojciech Kłossek, had been an instructor flight engineer on the Ilyushin Il-18 from 1985 and a flight engineer on the Il-62M since 1986.^: 2 He had 5,100 flight hours, of which 291 were on the Il-62M.^: 2 An instructor flight engineer, Ryszard Chmielewski, who had 10,571 flight hours, of which 6,695 were on the Il-62, was on board to monitor Kłossek's progress.^: 2 The cabin crew consisted of five flight attendants.^{: 2 : 3}

Departure and climb

The aircraft's take-off weight was 167 tonnes.^: 168 After receiving clearance at 10:17 CEST, it took off from runway 33 at Okęcie Airport at 10:18.^: 7–44 It climbed along airway R23 towards Grudziądz,^: 45 and it was due to leave Polish airspace near Darłowo.^: 7–44 Because the aircraft had not reached 18,000 ft (5,500 m) by the time it passed the TMN beacon near Płońsk, approach control instructed the crew to level off at 16,000 ft (4,900 m).^: 7–44 Military aircraft were operating at 17,000 ft (5,200 m), and civilian controllers had no radio contact with them to ensure separation.^: 7–44 Area control then took over the flight, which continued at 16,000 ft.^: 7–44 At 10:31, area control ordered an expedited climb to the cruising altitude of 31,000 ft (9,400 m), and the flight engineer set the engines to full take-off power for 30 seconds.^: 45 The flight continued normally until 10:41.^: 7–44

Engine failure

At 10:41, 23 minutes into the flight, the aircraft was passing over Warlubie, near Grudziądz, at an altitude of 8,200 m (26,900 ft) and a speed of 815 km/h (440 kn), when the low-pressure turbine of engine No. 2 disintegrated.^{: 45 : 3} Turbine fragments damaged engine No. 1 and set it on fire, punctured the rear fuselage and caused an explosive decompression, and severed electrical cables.^{: 238–242} The crew reported the decompression, the loss of two engines and a fire.^: 7–44 The cause of the failure was unknown to the crew, who initially thought that the aircraft had been struck by something, although one crew member said that there had been an explosion in an engine.^{: 7–44 : 63}

Pawlaczyk declared an emergency and decided to leave the planned route and turn back towards Warsaw.^: 7–44 Because of the decompression, he also began a rapid descent to 4,000 m (13,000 ft).^: 7–44 During the turn, the crew noticed that the flight controls were not working properly.^: 7–44 The elevator no longer responded, and the crew could control the aircraft's pitch only with the elevator trim tab, which is normally used to balance the aircraft aerodynamically.^: 16 At 10:44, the warning system indicated that the engine fire had been extinguished, and the crew began preparing to dump fuel.^: 7–44 The Il-62M's maximum landing weight was 107 tonnes, and only 6 tonnes of fuel had been used since take-off.^: 168 Fuel could be dumped only in straight flight, not while circling over a limited area.^: 16 The flight engineer found that only one of the aircraft's four electrical generators was working, and the crew switched off non-essential electrical equipment.^: 7–44 Because the fuel dump valves were electrically operated, power interruptions prevented them from working properly.^: 7–44 The crew briefly considered landing at Gdańsk, but Pawlaczyk decided to return to Warsaw.^: 7–44

Diversion and approach

With engines No. 1 and 2 shut down and the aircraft still heavy, Pawlaczyk could not maintain altitude, and the aircraft gradually descended.^: 16 As the situation worsened, he asked to divert to the military airfield at Modlin.^: 7–44 Warsaw air traffic control contacted military controllers to obtain permission, while the crew weighed the lack of information on Modlin's runway and weather conditions.^: 3 By then the aircraft had descended to about 3,000 m (9,800 ft), and the crew noticed sparks at the rear of the aircraft.^: 7–44 Permission to land at Modlin was granted at 10:54, and the crew received details of the runway's position, length and approach heading.^: 7–44

Information on the weather at Modlin, particularly the wind direction, was slow to arrive, and the crew reconsidered landing at Okęcie, which had full emergency cover for what was likely to be a crash landing.^{: 3 : 7–44 : 16} At 11:00, Pawlaczyk decided to continue to Okęcie.^: 7–44 Its rescue services were better equipped for the emergency landing of a large airliner than those at Modlin, although Modlin was also prepared.^: 47 At that point, the aircraft was about 90 km (56 mi) from Okęcie, flying at 495 km/h (267 kn) at an altitude of 2,050 m (6,730 ft).^: 47

Air traffic control directed the aircraft towards Piaseczno, and Pawlaczyk ordered the cabin crew to prepare the passengers for an emergency landing.^: 7–44 At 11:04, about 35 tonnes of fuel remained in the tanks, and the crew managed to reopen the dump valves and jettison fuel down to 32 tonnes before dumping stopped again.^: 7–44 Because of the fire, Pawlaczyk asked to land on runway 15, but the crew had difficulty establishing the aircraft's position relative to the runway.^: 7–44 He therefore decided to approach runway 33 from the direction of Piaseczno, circling Okęcie to the west over Raszyn, which allowed a landing into the wind at a lower ground speed and on a steeper approach path.^: 3 Near Józefosław, about 10 km (6.2 mi) from the runway, burnt parts of the structure and cabin fittings fell from the aircraft and started fires on the ground.^: 47

Crash

The final approach began at 11:08, when a warning indicated that the landing gear had not extended, which meant that the aircraft would have to make a belly landing.^: 7–44 The crew also reported a fire in the baggage hold.^: 7–44 Air traffic control proposed the shortest possible route to the runway, and Pawlaczyk, who was finding the aircraft increasingly difficult to control, flew a tighter turn. The fire, which was visible to witnesses on the ground, damaged the trim control system, and the aircraft began alternately to descend and climb.^: 3 Less than 6 km (3.7 mi) from the airport, the crew could not correct one of these oscillations, and the aircraft dived towards the Kabaty Woods.^: 3 About a minute before impact, Pawlaczyk radioed, "We are turning left. We will do all we can."^: 7–44

At 11:12:13, the aircraft struck the trees of the Kabaty Woods at about 470 km/h (250 kn), 5,700 m (3.5 mi) from the runway.^{: 45 : 3} The last words recorded from the cockpit were "Dobranoc, do widzenia! Cześć, giniemy!" ("Good night, goodbye! Bye, we're dying!").^: 7–44 The aircraft disintegrated on impact, and everyone on board was killed instantly.^: 2

Engine failure

The failed engine had run 2,793 hours of its 3,000-hour overhaul life.^: 12–14 The subcommission found that the roller bearing that separated and supported the coaxial shafts of the high-pressure and low-pressure turbines had been designed to contain 26 rollers but contained only 13, a change made during the engine's manufacture.^: 12–14 Three holes had also been drilled in the bearing's inner race to carry lubricant to the rollers.^: 12–14 The holes created a stress concentration that, combined with the greater load on each of the fewer rollers, initiated fatigue failure of the bearing.^: 12–14 The race and the rollers wore so badly that the bearing in effect became a plain bearing, and the shaft rotated eccentrically with a runout of about 1.3 mm (0.051 in).^: 12–14 The resulting friction heated the shafts to at least 1,000 °C (1,830 °F), until the low-pressure turbine shaft broke.^{: 12–14 : 3}

Freed from its load but still driven by the exhaust gases from the combustion chambers, the low-pressure turbine accelerated within a few milliseconds to a critical speed and disintegrated.^: 3 Part of the broken shaft and the first compressor stage fell out of the engine and were later found on the ground near the place where the failure occurred.^: 3 Turbine fragments ejected at about 160 m/s (520 ft/s) penetrated the rear fuselage and damaged engine No. 1, setting it on fire.^{: 238–242} Fragments heated to 500–700 °C (932–1,292 °F), together with short circuits in the severed electrical wiring, started a fire in baggage hold No. 4.^{: 238–242} Because the damage had disabled the aircraft's warning systems, including the fire warnings, the crew was unaware that the fire in the hold was spreading.^: 3 The reasons for the reduced number of rollers and the additional holes were not established.^: 12–14 A 2008 documentary attributed the missing rollers to workers at the Soviet engine factory, who were said to have made the decision on their own.

Conclusions

The commission concluded that the primary cause of the accident was design and manufacturing defects in the D-30KU engine.^: 12–14 It identified three contributing factors.^: 12–14 The pitch control system lacked survivability, since the severing of a single push rod left the crew able to control the elevator only with its trim tab.^: 12–14 Baggage hold No. 4, which lay in the plane of rotation of the engines' compressors and turbines, was inadequately protected against fire.^: 12–14 The rear fuselage also contained flammable materials.^: 12–14

The commission found that the flight time back to Warsaw roughly matched the time needed to dump enough fuel for a safe landing.^: 3 It also found that the crew's decision to continue to Okęcie rather than land at Modlin was based on Okęcie having the best firefighting and medical cover.^: 3 The commission judged that, in an extremely complicated situation, the crew had acted rationally and with the aim of saving the passengers' lives.^: 3 The prosecutor's office found that the crew's training and condition and the captain's decisions had been correct and had no causal connection with the accident.^{: 238–242} Maintenance, air traffic control and the weather were found to have played no part.^: 3 The commission's report was made available to the institutions concerned and to the aircraft's manufacturer.^: 3 The technical subcommission amended the Il-62M's operating instructions and issued 19 recommendations, 12 of which concerned the design of the engine and 6 the design of the airframe.^: 12–14

Soviet response

The Polish investigators encountered strong non-technical obstacles in their dealings with the Soviet side.^: 12–14 A 79-page Soviet study from August 1987 argued that the fatigue damage to the bearing was a result rather than a cause of the accident.^: 12–14 It justified the changes to the bearing by claiming that it had been poorly designed and could not work properly with the full number of rollers.^: 12–14 The study did not explain why the engine had not been submitted for recertification after such a significant change.^: 12–14 At Szałajda's initiative, two days of talks were held in the Kremlin, in which 39 Soviet representatives took part but were unable to refute the Polish evidence.^: 12–14 On 25 November 1987, the deputy prime ministers of Poland and the Soviet Union signed a document committing to the implementation of the recommendations.^: 12–14

Safety changes

Political conditions made it impossible for LOT to change its aircraft supplier, but the airline made technical and operational changes to its Il-62M fleet to improve safety.^: 12–14 These included duplicating the control system in the rear of the aircraft,^{: 12–14 : 14–16} installing a more sensitive engine shaft vibration monitoring system, the Swiss Vibro-Meter EVW-219, with individual gauges and warning lights for each engine in the cockpit,^: 12–14 using non-flammable materials in the baggage hold,^: 12–14 and adding smoke detectors and an automatic Freon fire-extinguishing system to baggage hold No. 4.^: 12–14 Engine oil was tested in a laboratory after every flight, and a small window was fitted in the door between the passenger cabin and the rear technical compartment, so that a fire could be fought if the door jammed.^: 14–16

On 5 October 1987, excessive shaft vibration led the crew of a LOT Tupolev Tu-154, which used the same engine type, to shut down an engine during a passenger flight from Warsaw to Milan. A similar incident occurred on 11 March 1990, on LOT Il-62 from Warsaw to Toronto. On 20 April 2008, a Cubana de Aviación Il-62M operating Flight 201 from Santo Domingo to Havana suffered an uncontained failure of its No. 2 engine at 25,000 ft (7,600 m). Debris damaged the No. 1 engine, causing a fire and a decompression, but the aircraft returned to Santo Domingo and landed safely with all 117 people on board unharmed.

Funerals and memorials

The Polish authorities expressed their condolences to the victims' families, and the Presidium of the Warsaw National Council declared 10 and 11 May 1987 days of mourning in the capital and in Warsaw Voivodeship.^{: 2 : 2} Condolences were sent by the leaders of many countries and by Pope John Paul II.^: 2 On the sixth anniversary of the assassination attempt on John Paul II, a mass for the victims was celebrated in Warsaw Cathedral.^: 2

On 23 May 1987, the 15 LOT employees who had died, including the crew, were given a state funeral with military honours at what is now the Powązki Military Cemetery, attended by thousands of people, including Deputy Prime Minister Szałajda and other officials.^{: 2 : 2} The Council of State posthumously awarded the Officer's Cross of the Order of Polonia Restituta to Pawlaczyk, the Knight's Cross of the order to the other five members of the flight deck crew, and the Gold Cross of Merit to the five flight attendants.^: 2 At his family's request, Pawlaczyk was buried in the family grave at Powązki Cemetery.^: 2 The other LOT employees were buried side by side near the crew of LOT Polish Airlines Flight 007, which crashed in 1980.^: 2 The passengers were buried in a common grave at the Northern Communal Cemetery in Warsaw, although some of the identified victims were buried by their families elsewhere, usually in their home towns. A street in Warsaw's Ursynów district is named after Pawlaczyk.^: 405