1993 aviation accident
Palair Macedonian Airlines Flight 301 was a scheduled international passenger flight from Skopje to Zurich, operated by Palair Macedonian, the then-flag carrier of Macedonia, now called North Macedonia. On 5 March 1993, the aircraft operating the flight, a Fokker 100, crashed shortly after taking off from Skopje Airport in snowy conditions. Out of the 97 passengers and crew members on board, only 14 survived. At the time, it was the deadliest air disaster in North Macedonia.
The investigation of the disaster concluded that the accident was caused by ice accumulation on the wings. The aircraft had been parked in Skopje in snowy conditions. During the refueling, the ice around the wings' roots had melted due to the temperature of the fuel, while the ice on the tips hadn't. While conducting the pre-takeoff ground inspection, the crew opted not to de-ice the aircraft, thinking that most of the ice had melted and the remaining was safe enough for flying. The aircraft eventually encountered control problems during takeoff, which caused it to crash.
Aircraft.
The aircraft involved in the accident was a Fokker 100 with a registration code of PH-KXL and a serial number of 11393. The aircraft was new, built in 1992 and was sent to Palair on 27 January 1993. It was equipped with 2 Rolls Royce Tay 650-15 engines. It had accrued a total of 188 flight hours and 136 flight cycles.
The fuel storage system for the aircraft, according to Fokker, was divided into four distinct chambers. The collector tank (CT) was the compartment with the most inboard position, and the other three compartments—MT1, MT2, and MT3— were located, respectively, from inboard to outboard. The MT3 compartment was placed at the top of the slope-shaped sections and was the most outboard of the others. Each compartment, with the exception of the CT, had ribs to allow fuel to circulate. The CT would be fully fueled during refueling, and any extra fuel would be distributed among the compartments. Less fuel will be present the farther the compartment is from the airframe.
The most outboard fuel compartment, MT3, had the most room for extra fuel due to the way the aircraft was built because it was situated in the most outboard and highest position. As a result, the MT3 tank's fuel level would be lower than that of the other tanks during refueling, which prevented the upper wing skin from making contact with the fuel of the aircraft.
Passengers and crew.
Flight 301 carried 92 passengers and 5 crew members. Most of the passengers were Kosovars who were going to work in Switzerland. Dutch newspaper "Reformatorisch Dagblad" reported that there were also several Dutch and Swiss citizens on board the aircraft.
The flight was flown by members of Aircraft Financing and Trading (AFT), a company based in the Netherlands, based on a leased contract. Both pilots had the rank of captain. The pilot in command (pilot not flying (PNF), training captain) was 49-year-old Peter Bierdrager, a Dutch national. He had accrued a total flying experience of 11,200 hours, of which 1,180 hours were in the Fokker 100. The captain-under-training (pilot flying (PF) and acting captain) was an unnamed 34-year old pilot of Macedonian nationality. 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 Yugoslav's JAT.
Flight.
Pre-flight.
The aircraft arrived in Skopje at 10:40 a.m. after a flight from Frankfurt, Germany. It arrived late as the flight previously had been delayed due to a malfunction on the flap position indication. The aircraft was scheduled to fly to Zurich at 11:50 a.m. with the same crew members. However, due to fears of violating work and rest regulations, a crew switch was conducted and a new set of pilots were brought in. For the flight to Zurich, the aircraft would be piloted by Captain Peter Bierdrager and his Macedonian co-pilot who was undergoing training to transfer from Boeing 737 to Fokker 100.
While the crew from Frankfurt was staying in the hotel, the aircraft was parked in Skopje in snowy conditions. A flight station engineer (FSE) then came to inspect the aircraft. A brief check was conducted on the exterior of the aircraft. During the inspection, at 11:00 a.m. the aircraft was refueled with approximately of fuel. The replacement crew eventually arrived in Skopje approximately 30 minutes after the refueling and immediately boarded the aircraft. Upon arrival in Skopje, the company's dispatcher was requested by Captain Peter to get information regarding the weather. The dispatcher eventually came into the cockpit and briefed the crew about the incoming weather. In response to the information, Captain Peter decided to add an additional of fuel. The second refueling was commenced at around 11:40 a.m. and another exterior inspection was conducted.
Prior to the inspection, the dispatcher had briefly checked the aircraft for presence of ice and snow. After scraping his hand over the wing leading edges, he discovered that there was neither ice nor snow on the wings and it was particularly wet because all of the ice and snow had melted. This was eventually confirmed again during the second refueling when the FSE and Palair's ground crew members conducted a walk-around to check for the presence of ice and snow on the aircraft. Standing on a baggage cart, the FSE performed a "tactile check" by rubbing his hand over the wings. He noticed that there was some melted snow on the right wing and that the leading edge of the wing was clear of ice and snow. One of the ground crew then tried to confirm it and conducted a tactile check as well, collecting a stroke of snow from the inner flap of the right wing before showing it to the FSE. With the weather condition being taken into account, a discussion on whether the aircraft should be de-iced eventually ensued.
After a brief discussion with the ground crew, the FSE concluded that the aircraft did not need to be de-iced. He went back into the cockpit and told both pilots about his findings. The pilots immediately agreed and continued their routine checks.
Accident.
Flight 301 was an international scheduled passenger flight originating from the Macedonian capital of Skopje with a final destination of Zurich, Switzerland. The loadsheet that had been provided by the airport agent listed a total of 91 passengers and 5 crew members. The FSE was later added as one of the passengers.
After having been parked in the snow for more than one and a half hours, the crew contacted Skopje to request start-up clearance. Start-up was conducted soon after, and the aircraft was set for taxiing onto the runway. The engine anti-icing was set to on, the ignition went into automatic, and the flaps were set to 8 degrees. The crew was cleared to line up at Runway 34. Arriving on Runway 34, the crew decided to use the standard VR speed of .
At 11:11 a.m., the aircraft was cleared for take-off to Switzerland. At the time, there was moderate snow and visibility was limited to ; 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.
Flight 301 became airborne 28 seconds after its takeoff clearance and, according to the ATC who witnessed the take-off, vanished beyond the snow. Just two seconds after taking off from Runway 34, the aircraft began to shake violently. The aircraft was climbing at a rate of and the crew called out positive climb rate. As the crew was announcing, the aircraft suddenly rolled to the right at an angle of 11 degrees, surprising the crew. The first officer then tried to counteract this by applying a right wing-up aileron input at full force. The wings slowly returned to its previous position and the angle gradually decreased.
Intending to increase the climb, the first officer raised the nose to 10 degrees. The landing gear was retracted, and the aircraft was climbing. However, within a span of three seconds, Flight 301 rolled severely to the left with a bank angle of 50 degrees. Perturbed by the situation, Captain Bierdrager exclaimed "Ah shit!". The crew did not understand the anomalies they were facing at the time. Ailerons and rudder input were immediately applied to correct the attitude of the aircraft. The first officer tried hard to roll the aircraft to the right by making a full right aileron input.
Thinking that the autopilot was at fault, Captain Bierdrager exclaimed "Oh! Deselect!". They tried to turn it off, but then discovered that the autopilot had never been engaged. While applying the full right aileron input, the aircraft immediately rolled to the right at a dangerous angle of 63 degrees. The FSE who was sitting at the cockpit jump seat shouted "Nose up!" as the aircraft plunged towards the ground.
As the aircraft continued to dive, the crew pulled the elevator to almost at its maximum. The angle of attack increased, but the stall warning began to blare inside the cockpit. The aircraft eventually entered a sink rate of 2,000 ft/min and the alarm system warned the crew on the excessive sink rate.
The crew tried to recover the aircraft, and it appeared to be successful as the right angle started to decrease, down to as much as 15 degrees. However, as it approached the ground, the right wing dipped again, reaching 90 degrees. The tip eventually contacted the ground and grazed a road, cutting the airport's perimeter fence and detaching from the aircraft due to the collision. The aircraft, meanwhile, slammed into the ground with its right side and broke up. The cockpit, parts of the front cabin, and the tail surfaces separated from the airframe, while the front portion and the whole right side of the aircraft were immediately destroyed. The resulting collision caused the fuel to ignite and the aircraft burst into flames.
A substantial part of the aft fuselage remained intact after the crash. This was where most survivors were located. Despite this, the aft fuselage had been penetrated by the detached right engine during the crash, causing a fire that eventually destroyed the whole section.
Initial aftermath.
The sound of the crash was loud enough to be heard by a United Nations Peacekeeper Pilot who was walking on a ramp nearby. He immediately offered Skopje Tower via telephone to investigate the source of the noise. Using a Bell 212, the wreckage was immediately found nearly 0.5 km from the airport. The wreckage was spread over an area of 220 x 40 meters. After landing at the crash site, the personnel quickly notified other emergency services and nearby UNPROFOR army base about the accident and transported seven survivors from the area. The Bell 212 returned to the crash site two more times and evacuated more survivors. Shortly after, the Macedonian emergency services arrived at the site and commenced the search and rescue operation. As many as twenty survivors, of whom five were in critical condition, were transported to the hospital in Skopje. However, four survivors would later be pronounced dead on arrival. Several others succumbed to their injuries. Remarkably, the only surviving crew member, a flight attendant, suffered only minor injuries.
Investigation.
Following the crash, the Macedonian government immediately set up the State Accident Investigation Commission (SAIC), which was led by Yugoslavia's Ministry of Transport and Communications. Being the state of both manufacturer and registry, the Netherlands was involved in the investigation. Representatives from Rolls-Royce and Swissair were also invited to assist. The French BEA helped encode the FDR and CVR contents.
The result of the flight recorder readout would eventually be presented with a flight simulation, which would take months to complete, the Dutch government noted. The Macedonian government, however, wished to wrap up the investigation as quickly as possible. The final report on the crash was released by the SAIC in May 1993, just one month after the catastrophe. The Dutch government carried out additional investigations after being dissatisfied with the report's final draft. The Dutch government met with Swiss representatives after media reports that the Chairman of SAIC had declared the investigation to be finished and urged the Macedonian government to continue the investigation, which was agreed by the government, albeit reluctantly.
In January 1994, following a meeting that had been convened by representatives of the investigation team, parties involved in the investigation agreed to publish the summary of