Palair Macedonian Airlines Flight 301

Palair Macedonian Airlines Flight 301
The accident aircraft two weeks before the accident
Accident
Date 5 March 1993
Summary Atmospheric icing
Site near Skopje, Macedonia
Aircraft
Aircraft type Fokker 100
Operator Palair Macedonian
Registration PH-KXL
Flight origin Skopje Airport, Skopje, Former Yugoslav Republic of Macedonia
Destination Zurich-Kloten Airport, Zurich, Switzerland
Passengers 92
Crew 5
Fatalities 83
Injuries 14
Survivors 14

Palair Macedonian Airlines Flight 301 was a scheduled international passenger flight from Switzerland's Zurich-Kloten Airport to International Airport Skopje, Skopje, which crashed shortly after take off on March 5, 1993. The Fokker 100 was operated by Palair Macedonian Airlines, the national airline of Macedonia.

A total of 83 people, 79 passengers and 4 crew members, were killed in the crash while 14 people survived. At the time, it was the deadliest plane crash in Macedonia. It was surpassed a few months later on the same year when a Yakovlev Yak-42 slammed onto a mountain near Ohrid. It was the deadliest aviation accident involving a Fokker 100 at the time it took place, a record it maintained until TAM Flight 402 crashed on 31 October 1996. Flight 301 is still the second-deadliest Fokker 100 crash.[1]

The investigation of the disaster, which was assisted by the Dutch investigation team, concluded that the cause of the accident was due to the accumulation of ice on the wings of the aircraft. Also known as atmospheric icing, the ice accumulation caused the deterioration of lift force. Failure to adhere to the correct procedure for handling an atmospheric icing was also cited as one of the causes of the crash.

Aircraft

The aircraft involved in the accident was a Fokker 100 with a registration code of PH-KXL, with a serial number of 11393. The aircraft was new, built in 1992 and was sent to Palair Macedonian Airlines in 27 January 1993.[2] It had accrued a total of 188 flight hours and 136 flight cycles.[3]

Passengers and crews

Flight 301 carried 92 passengers and 5 crew members. Most of the passengers were Kosovo Albanians who were going to work in Switzerland.[3]

The pilot in command (pilot not flying, training captain) was identified as 49-year old Dutch Peter Bierdrager. He had his last medical check in 1992 and had accrued a total flying experience of 11,200 hours, of which 1,180 hours were in the Fokker 100. Other than the Fokker 100 license, he had also obtained licenses for Fokker F-27, Fokker 28 and Fokker 50. The acting captain (pilot flying) was identified as 34-year old Macedonian pilot. He had a total flying experience of 5,580 hours, of which 65 hours were in the Fokker. Before he joined AFT, he was a pilot at the Yugoslav's JAT.[3]

Flight

Flight 301 was an international scheduled passenger flight originating in Skopje, Macedonia with a final destination of Zurich, Switzerland. 92 passengers and 5 crew members were on board the aircraft. The Fokker 100, registered as PH-KXL, belonged to Palair Macedonian Airlines, the national airlines of Macedonia and the largest passenger airliner in Macedonia. The flight, however, was flown by members of the Aircraft Trading and Financing, a company based in the Netherlands, as based on a leased contract.[4][3]

Take off clearance was given at 11:11 local time. As Flight 301 took off, the local weather consisted of heavy snow and visibility was at 900 meters, Observation on the ground confirmed that the visibility was poor enough that the end of the runway could not be seen from Flight 301's position. 28 seconds after its take off clearance, Flight 301 became airborne.[3]

Just 2 seconds after taking off from Runway 34, the aircraft began to shake violently. While climbing through an approximate height of 50 ft and with an air speed of about 170 miles per hour, Flight 301 rolled severely to the left and then to the right, with a bank angle of 50 and 55 degree. The flight crew immediately applied ailerons and rudder input to correct the attitude of the aircraft. The autopilot cavalry chimed and the sink rate warning sounded.[3]

The aircraft's right wing tip struck the ground beyond the end of the runway with an angle of 90 degree. Flight 301 cartwheeled before crashing to the ground, with the fuselage breaking up into three pieces. The aircraft immediately exploded and burst into flames.[5][3]

First report of the crash was received from a United Nations Peacekeeper who heard the impact while he was walking towards the ramp. He then immediately flew to the crash site and rescued 7 survivors from the crash site. More emergency services from the airport and the United Nations then arrived at the crash site. As much as 20 survivors, of whom 5 were in critical condition, were transported to the hospital in Skopje. However, 4 survivors would later be pronounced dead on arrival. Several others succumbed to their injuries. [6][7][8]

Investigation

Weather

Weather data collected by investigators suggested that there was light to moderate snow prior and during the accident. Airport workers reported that the snow melted when it touched the ground. Prior to the accident, there was no visible snow on the runway, taxiway or apron. Investigators confirmed that it was a wet snow, that is, snow mixed with rain. Temperature at the airport was recorded to be at 0° Celsius. The aircraft was exposed to wet snow and the temperature was lower than the freezing dew point, a conducive condition for an atmospheric icing.[3]

Wing contamination

The aircraft had been checked for signs of snow and ice by ground crews prior to its take off. Statements collected by investigators suggest that the inspection concentrated on the right wing. Investigators noted that there was no evidence that the left wing had been inspected as comprehensive as the right one.[3]

Estimation conducted by investigators showed that the aircraft had been exposed with light precipitation, which later increased to moderate, for 1 hour and 15 minutes, with an unspecified amount of thickness. Due to the prevailing weather condition, investigators believed that the aircraft's wing upper surface had been covered with a thin layer of snow and possibly frozen to the skin.[3]

According to the ground crews, several people had touched the wing leading edge to detect ice. However, due to the height of the aircraft, only tall people were able to do this. They would also be only able to touch the leading edge near the wingtip, however they would not be able to reach the wing upper surface right behind the leading edge. Further examination revealed that the aircraft had arrived in Skopje with a relatively large amount of "very cold" fuel. This caused the wet snow, which was falling onto the surface of the wing, to freeze. This was later confirmed as inspection revealed that frosts had been detected under the fuel tanks.[3]

However, even though the aircraft had been covered by snow, the Flight Station Engineer and the ground crew had only reported "wet of melted snow". Investigators stated that they possibly had suffered an illusion. As per the final report, investigators stated[3]:

The wing upper surface temperature of the collector tank and main tank compartment 1 responded rapidly to the warmer fuel being added . In the test the maximum skin temperature remained below the temperature of the fuel in the fuel truck . But on Skopje airport the temperatures of the outside air, the aircraft and the fuel in the truck were not so far apart, only the residual fuel in the aircraft tanks was much colder. It is, therefore, conceivable that during and after refueling of Palair 301 the upper skin temperatures of the collector tank and main tank compartment 1 could have approached the fuel truck temperature closer than in the test[3] This warming effect due to the added fuel being well above 0° C could, according to the test result, remain during the time between the first and second refueling and again on the second refueling. For an observer this could create the impression that the snow was melting on the wing just like on the ground because of the nature of the snow and the (air) temperature and not because of some other effect. This would be an illusion, however, because the outer half of the wing tank could not benefit from this warming; effect and would thus collect snow. The warming effect causing the snow to melt on the inboard wing part would anyhow soon disappear after the boosterpumps were switched on prior to engine start.[3]

It was later confirmed that the ground crew had only checked the inner part of the wing and had not checked the outer part. As snow on the inner part of the wing melted, this would create an impression that there were no more snow left on the wing and that all snow had melted, including those on the outer wing, which is why investigators called this as an illusion.[3]

Lack of attention to icing

During the aircraft's previous flight to Skopje, which was operated by the same crew, the weather was not in a snowy condition. Light snow was only encountered when the aircraft's was approaching Skopje and reports stated that the snowflakes immediately melted when it contacted an object. Due to this, the crew didn't pay their attention to the weather, exposed themselves minimally to the weather and focused mainly on the cockpit instruments. Investigators stated that the crew might have thought that the weather wasn't a threat to the safety of the aircraft. The Flight Station Engineer also stated that the aircraft wouldn't require a de-icing, as the snow was regarded as "harmless".[3]

During the aircraft's inspection, the standard operating procedure of the company stated that the pilot of the aircraft must perform the outside preflight inspection. This was not done by the pilot. Instead, this duty was delegated to the Flight Station Engineer. The Flight Station Engineer was regarded as highly experienced, and thus the crew believed his words when he said that the aircraft didn't need a de-icing. Analysis from the weather data however suggest that the aircraft should've been de-iced.[3]

Recordings taken from the CVR showed that the crew didn't mention anything on the weather and that they never realized that the weather might have caused the aircraft's lost of control.[3]

Conclusion

The investigation board "determined that impact with the ground in a steep right bank shortly after liftoff was caused by loss of roll controllability due to contamination of the wings with ice. This situation resulted from an omission to carry out spraying of the aircraft with deicing or anti-icing fluid in meteorological conditions conducive to icing, due to a lack of ice-awareness of the flight crew and the Flying Station Engineer. Contributing factors were a lack of common background and procedures in a difficult multi-sources operational environment.[3]

See also

References

  1. ↑ Fokker 100 at Aviation Safety Network
  2. ↑ "Fokker 70/100 - MSN 11393 - PH-KXL". airfleets. Retrieved 10 September 2018.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 "Final Report PH-KXL" (PDF).
  4. ↑ Palair Macedonian Airlines Flight 301 at Planecrashinfo.com
  5. ↑ Gero, David (1996). Aviation Disasters Second Edition. Patrick Stephens Limited. p. 225.
  6. ↑ Plane carrying 97 crashes during snowstorm takeoff
  7. ↑ "Jet Crashes in Macedonia Storm". The New York Times. Retrieved 10 September 2018.
  8. ↑ "Macedonia air crash kills 79". The Independent. 6 March 1993. Retrieved 10 September 2018.

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