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== Cause ==
== Cause ==


After the crash of Il-62 SP-LAA on [[LOT Polish Airlines Flight 007]] LOT Polish Airlines started replacing their Ilyushin Il-62s with the more modernized version, Ilyushin Il-62Ms. These had newer engines ([[Soloviev D-30]] instead of [[Kuznetsov NK-8]]), but both engines shared the same critical point - low pressure turbine and engine shaft design and construction.
After the crash of Il-62 SP-LAA on [[LOT Polish Airlines Flight 007]], LOT Polish Airlines started replacing their Ilyushin Il-62s with the more modernized version, Ilyushin Il-62Ms. These had newer engines ([[Soloviev D-30]] instead of [[Kuznetsov NK-8]]), but both engines shared the same critical point - low pressure turbine and engine shaft design and construction.


[[Image:Cylindrical-roller-bearing din5412-t1 type-n ex.png|thumb|100px|A roller bearing. The circular ring is the 'race' that the rollers run-in]]
[[Image:Cylindrical-roller-bearing din5412-t1 type-n ex.png|thumb|100px|A roller bearing. The circular ring is the 'race' that the rollers run-in]]

Revision as of 00:18, 29 September 2010

LOT Polish Airlines Flight 5055
Memorial to crash victims
Accident
DateMay 9, 1987
SummaryEngine failure, inflight fire, loss of flight controls
SiteWarsaw, Poland
Aircraft typeIlyushin Il-62M
OperatorLOT Polish Airlines
RegistrationSP-LBG
Flight originWarsaw Frederic Chopin Airport, Poland (WAW/EPWA)
DestinationJohn F. Kennedy International Airport, New York (JFK/KJFK)
Passengers172
Crew11
Fatalities183 (all)
Injuries0
Survivors0

LOT Polish Airlines Flight 5055 crashed in the Kabaty Woods nature reserve on the outskirts of Warsaw on May 9, 1987. The aircraft was an Ilyushin Il-62M bearing the name Tadeusz Kościuszko. (Two different Polish Il-62s bore that name; one was Il-62 SP-LAB (cn 21105), the second plane of this type purchased by LOT in 1971; the other, which crashed, was an Il-62M purchased in 1984.)

Cause

After the crash of Il-62 SP-LAA on LOT Polish Airlines Flight 007, LOT Polish Airlines started replacing their Ilyushin Il-62s with the more modernized version, Ilyushin Il-62Ms. These had newer engines (Soloviev D-30 instead of Kuznetsov NK-8), but both engines shared the same critical point - low pressure turbine and engine shaft design and construction.

A roller bearing. The circular ring is the 'race' that the rollers run-in

According to the Polish investigatory commission, the cause of the crash was the disintegration of an engine shaft due to faulty bearings inside the number 2 engine, which seized, causing extensive heat. This in turn caused the consequent damage to engine number 1 (and its fire), rapid decompression of the hull, a fire in the cargo hold (which was not detected due to a damaged fire alarm system sensor)[citation needed], as well as the loss of elevator controls and progressive electrical failure.

The bearings concerned were roller bearings; each was designed to have 26 rollers inside, but because the supply of the rollers to the factory was delayed - while the bearings had to be finished on time due to expiring contracts - each bearing had only 13 rollers[citation needed]. This reduced the rotational ability of the bearings; to correct for this, each bearing race had three holes drilled into it - strictly against technical recommendations - to allow the engine lubrication oil to get inside and increase its rotational ability. However, this greatly increased friction and, after several hours of operating, effectively turned the roller bearing into a sliding bearing[citation needed], or bushing. Slide bearings have the tendency to overheat during working[citation needed]; this contributed to the explosion and subsequent fire of the inner left engine on Flight 5055.

Flight and crew

The chartered plane to New York City took off from runway 33 at Okecie Airport at 10:18 am. The pilots were cleared to climb to 31,000 feet with a course set to Grudziadz VOR, which was reached at 26,500 feet.

The Captain was Zygmunt Pawlaczyk, 59, with 19745 hours in the air (5542 on Ilyushin-62s, and a captain from 11 May 1978). The first officer was Leopold Karcher, the flight engineer was Wojciech Kłossek, flight navigator was Lesław Łykowski, radio operator was Leszek Bogdan and Ryszard Chmielewski an instructor of flight engineers on a routine observation of the progress of Wojciech Kłossek. By a twist of fate, Chmielewski was scheduled as a flight engineer on LOT Polish Airlines Flight 007 seven years earlier, but he switched shifts with his colleague.

The purser was Maria Berger-Sanderska; other flight attendants were: Hanna Chęcińska (who was in the technical cabin-bay, next to the engines, and probably — after decompression — lost consciousness and burned in the fire or was sucked out of the plane; her body was never found despite extensive search), Małgorzata Ostrowska, Beata Płonka and Jolanta Potyra.

Emergency

Soon after Flight 5055 took off from Warsaw, the crew was instructed by the ATC to climb to an altitude 6000 m (18000 ft) as quickly as possible:

10:26 Flight 5055: Well, we go to New York, possibly we'll be able to get to flight level 180... (tongue-in-cheek)

10:26 Okęcie ATC: Gentlemen! You won't make it. You have about 5 kilometers to the TMN [Tango-Mike-November route]. I told you that clearance was set for 180 or higher. Military planes are training there, I have no communication with them to allow separation.

10:26 Flight 5055: Roger that. Roger that.

10:31:35 Okęcie: 5055, heading 310, immediately cut flight level 170.

10:31:39 Flight 5055: 5055, heading 310.

10:31:41 Okęcie: Climb immediately. I mean it, immediately.

At the moment, the crew applied maximum thrust on the engines to climb to 6000m. Supposedly, had they not applied thrust, the turbine disc in the inner left engine would have survived the entire flight. However, nine minutes after the thrust was applied, the faulty bearings inside the engine overheated enough to cause explosion (about 1000 degrees C.).

An engine exploded and started burning at 10.41 a.m., when the plane had just passed Lipniki village, near Warlubie (near Grudziądz, at 8,200 m and 810 km/h). The overheated bearings exploded, destroying the shaft; the turbine disc on the burning engine separated from the destroyed shaft; the freed disc spun to an enormous speed and, within seconds, explosively disintegrated, destroying engine two. Debris from the explosion violently spread around (with an estimated speed of 160 m/s), puncturing the hull, severing flight controls and electrical cables and causing damage to engine one - outer left one, which soon started also to burn. A piece of burning debris burst into cargo hold number 4 and caused a rapidly spreading fire; the inner left engine burned rapidly until impact.

Immediately, the crew noticed that the elevator control systems had failed — only vertical trim remained operative – and that two engines were disabled. The reasons for this were unknown to the crew; they initially suspected that the plane could have been hit by something. The pilots started an emergency descent to 13,200 ft. The closest airport where Il-62 might land was Gdańsk, but landing there was not possible because the crew could not dump enough fuel for the emergency landing attempt (takeoff weight of the plane on that day was 167 tons, until 10:41 approximately 6 tons of fuel were consumed; the maximum landing weight of Il-62M was 107 tons) so they turned their heading to Warsaw instead. Due to the damaged electrical system, the crew had problems with fuel dumping and they didn't realize that the fire had spread to the cargo holds in the back of the plane (cargo hold 4 and 6, and in final minutes probably reached into passenger cabin).

Initially, the crew intended to land at the military airport in Modlin, but at the final moment they decided to continue the flight to Okecie, where there was better fire and medical equipment. It was unclear at the time why the crew decided to continue the flight to Warsaw, given the rapidly spreading fire and lost flight controls, rather than land as quickly as possible at Modlin, where the fire and medical equipment was worse than Okęcie, but still good enough to deal with an emergency landing of an airliner with in-flight fire. Many at the time believed officials had decided the airliner must not land at a military airport and (contrary to official reports) denied the crew's request to land at Modlin. While this is somewhat plausible, no conclusive evidence supporting this theory was ever presented. The most probable hypothesis is that due to damage to the electrical systems, both the fire detector in the cargo hold and inside the engine did not work properly (on the CVR, an engine fire sound indicator was heard shortly after the explosion, but it latter faded out; the signal reappeared less than four minutes before the crash and continued until impact) and so Cpt. Pawlaczyk did not know about the magnitude of the fire in the hold and how quickly it was spreading, nor about the burning engine when he decided to fly to Warsaw.

About 10:53, an explosion in the cargo hold occurred; the reasons are unknown. It is supposed that some of the fuel tanks were damaged and fuel vapors drifted into burning cargo hold, causing an explosion.

The passengers were fully aware of the emergency; one of the passengers managed to write on the opening page of her copy of the New Testament: 9.05.1987 The plane's damaged... God, what will happen now... Halina Domeracka, R. Tagore St., Warsaw...

CVR fragment - the moment of engine explosion

10.41.28

Intermittent acoustic signal of autopilot disengage

10.41.30

Crew: Hey! Pressurization!

10.41.32

Acoustic ringing signal of cabin decompression

10.41.34

Crew: Is [there a] fire? What's going on?

10.41.35

Crew: Probably a fire.

10.41.37

Crew: Engine? Shut it down!

10.41.39

Crew: ...shut down. That first one is burning!

10.41.42

Crew: ...fire...

10.41.44

Crew: ...all small [referring to engines' throttles]

10.41.45

Crew: Warsaw?

10.41.46

Crew: ...all small. Decompression.

10.41.48

Crew: Two engines are gone!

10.41.49

Continuous acoustic signal of engine fire.

10.41.50

Crew: Two engines are gone!

Crew: Shut down...

Crew: We're turning around! Fire!

10.41.55

Crew: Danger!!! Warsaw radar LOT! Warsaw radar! [calling flight control]

Crash

The crew tried to land at Okęcie from the south (due to strong wind) and turned the plane 180 degrees to runway 33 but a rapidly spreading in-flight fire, which spread to the exterior of the plane (plane was trailing a huge flame and dense black smoke), caused a total failure of surviving flight controls, the plane trim. Also, the gear lowering was not functioning. The emergency fuel dumping pumps were also malfunctioning; supposedly because of damaged electrical systems, sometimes they stopped functioning at all, only to resume dumping fuel minutes later. At the moment of the crash, approximately 32 tons of fuel were still in tanks.

A very straight turn to the left was started at 11.09 at 4900 ft with an airspeed of 480 kph. At the moment, as plane passed the village of Józefosław, approximately 10 kilometers from the airport, several burnt-out elements of the plane's hull fell out, starting local fires on the ground. Supposedly, at this moment the fire destroyed the vertical trim controls. When the aircraft passed the town of Piaseczno, it went into sinusoid-shaped flight for the final seconds and nose-dived with a slight 11 degrees left bank and 12 degree pitch downwards, crashing into the ground at 480 kph (300 mph) and exploding into pieces in the forest 5700 meters from Warsaw airport runway. (As the nose dive started very shortly before the crash, one hypothesis states that in the final moments, fire from the cargo hold spread into the rear part of passenger cabin, causing mass hysteria; the passengers moved towards the nose of the plane, away from fire, destabilizing the plane and causing the dive. Another theory is that rapidly spreading fire misshaped the hull in its rear part, which - combined with strong forces acting on the empennage - altered the plane's angle of attack and contributed to the rapid dive.) The remains of the plane were scattered over a rectangular area, approx. 370 by 50 meters.

The last words recorded by the flight recorder inside the cockpit at 11:12:13 were: "Cześć! Giniemy!" (eng. Bye! We're dying!). All 172 passengers (including 1 infant; 17 were from the United States) and 11 crew died.

Nationality Passengers Crew Total
 Poland 155 11 166
 United States 17 0 17
Total 172 11 183

Last words

11.09.47 am

Okęcie Tower: From your current position you have about 15 kilometers to the runway.

Crew: Understood.

Crew: ...[turn] to the left! Engines to the left!

11.10.13 am

Tower: 5055, to the left, to the left zero-five-zero.

Crew: OK.

11.10.40 am

Tower: 5055, to the left, course 360.

Crew: We want to turn. That's just what we want. [implied meaning: "we're trying"]

Tower: Keep turning, turn to three-six-zero. Now you have about 12 kilometers to the runway.

Crew: OK.

11.11.02 am

Tower: 5055, to the left, course 330.

Crew: We are turning to the left.

Tower: Start final approach about 11 kilometers from the runway.

Crew: We will do all we can.

Tower: Understood.

Tower: [Turn] to the left, course 320.

Crew: Understood.

11.11.34 am

Tower: You've come to the right hand side of the runway centreline, continue left, course 300.

Tower: Wind is 290 degrees, 22 kilometers per hour. You are cleared for runway three-three.

Crew: OK.

11.12.10 am

The transmitter was turned on four times. Fragments of unintelligible utterances.

11.12.13 am

Crew: Goodnight!!! Goodbye!!! (scream) Bye!!! We perish!

Aftermath

The Okęcie Airport fire crew was aware of the emergency; when the plane crashed, they immediately drove towards the crash site, but they did not manage to reach it because the car was too wide and could not pass between the trees.

The day was warm and sunny, so many people rested in the vicinity of Kabaty Woods; after the crash many of them headed for the site. According to official reports, the site was quickly closed to the public, and no plundering of remains was officially registered. However, some unofficial reports about stealing money and valuable items surfaced later; Halina Domeracka's personal belongings, including her passport, New Testament, photos and glasses were recovered intact from the site, yet 400 U.S. dollars and 10000 Polish zlotys were missing.

Because some burning pieces of hull fell out, several local fires were initiated on the ground, propagated by the dumped fuel; all of them were extinguished by 12:00. A total of 195 firemen from 44 different units participated.

All victims' bodies were dismembered in the crash; from a total of 183 bodies, 62 were never identified.

The first TV and radio news about the crash initially reported that the crashed plane was Il-62M SP-LBD (cn 1138234) "Gen. Władysław Sikorski".

All crew members received posthumously high military and civil decorations: Cpt. Pawlaczyk was given the Officers' Cross of Polonia Restituta, other flight crew members received Knights' Cross of the same order, and the flight attendants received the Golden Cross Of Merit. The state funeral of the crew was conducted on 23 May 1987 at the Northern Communal Cemetery in Warsaw. The graves of the crew of LOT Polish Airlines Flight 007 are located a few hundred meters away.

Two days of national mourning were announced after the crash. Many officials from the entire world, including Pope John Paul II, expressed their condolences to the families of the victims.

The incident's cause was similar to that of LOT Polish Airlines Flight 007's crash seven years earlier. After the disaster of Flight 007, the Polish investigatory commission established that its engine shaft disintegration was the result of metal fatigue, improper alloy preparation resulting in a defective mechanism which was less resistant to fatigue, and a faulty design of the engine shaft. Detection of these faults was possible only after complete disassemblage of the engine and detailed analysis of all its elements, and as such was beyond capabilities of the ground servicing personnel. These concerns were addressed by the Polish Government's Special Disasters Commission in the 1980 inquiry, but the Russian designers, engineers and scientists disagreed with these findings, stating that the turbine disintegration was the result of engine failure, not its cause.

After Flight 5055's demise, a similar report was sent to Moscow; initially, it was denied (partially because the Russian engineers and politicians still held a grudge against Poles because LOT Polish Airlines, after purchasing Il-62s in the 1970s, replaced their radionavigational equipment with separately brought and more modern American equipment; it was at the time considered very inappropriate for political reasons), and the Russian engineers even made their own report, concluding that all damage to the engines were the consequence of the crash, which was caused by pilot error. However, despite pressure and threats from Russians, the Polish commission stood by their findings; finally, Russian engineers and politicians reluctantly accepted responsibility. Soon after the crash, LOT Polish Airlines, still being unable to purchase other planes than Russian ones, implemented several improvements in Il-62's construction:

  • doubling the flight controls (an issue raised in the 1980 report, but never addressed by Russian engineers)
  • installing an advanced system of engine shaft vibration detectors in every engine
  • installing more advanced smoke detectors in cargo holds (smoke detectors were found to be more reliable than the already used fire detectors) and advanced fire detectors in the engine nacelles
  • replacing all flammable cargo holds' components with unflammable ones
  • mandatory laboratory test of engine lubricating oil after every flight (the test, had it been conducted earlier, would have detected the damage to the bearings)

After the Revolutions of 1989, LOT Polish Airlines started purchasing Boeing 767s for their transatlantic destinations. The last Polish Il-62 was sold to Ukraine in late 1991.

Today

The crash site in 2009

After the crash, the place where the plane came down and exploded was — during three months of cleanup — ploughed and sown with new trees. As of 2009, the long mark in the forest is still perfectly visible from the sky.

On the north edge of that mark is a monument - high, black christian cross and a black stone with engraved names of 183 victims of that crash. In Ursynów district there is a Zygmunt Pawlaczyk street, and through Kabaty Forest run a Grove of "Kościuszko" Plane Crew.

Symbolic graves of the crew members lie in Powązki Military Cemetery, and a collective grave of unidentified victims lies in Wólka Węglowa Cemetery - the place where the victims were identified. Some identified victims were also buried there; others were buried in their hometowns.

The transatlantic route from Warsaw to destinations in the USA has not changed since 1987. Every time a plane departing from Warsaw passes Lipniki village, its crew honors the memory of their perished colleagues by a minute of silence.[citation needed]

See also

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