TABSO Flight 101 was a scheduled service of the Bulgarian national airline from Sofia, Bulgaria, via Budapest, Hungary, and Prague, Czechoslovakia, to Berlin Schönefeld Airport in East Germany. The service was operated by the airline's 1960s' flagship equipment, the Ilyushin Il-18B airliner. On Thursday 24 November 1966, due to bad weather the aircraft was diverted to Bratislava airport, but when the flight resumed, the aircraft crashed into the surrounding hills shortly after takeoff, with the loss of 82 lives. The crash site is within modern-day Slovakia, and is considered that country's deadliest aviation disaster.

On the day of the accident, Flight 101 was operated by an Il-18B airliner registered LZ-BEN. It had been manufactured in January 1964 and had been accepted by TABSO on 22 January that year. By the time of the accident, it had not been involved in any incidents and had been maintained in accordance with the manufacturer's schedules.

The crew comprised Commander (captain) Lubomir Todorov Antonov, 41 years old, with 11,959 total flight hours. He was among TABSO's most senior Il-18 commanders, having gained command of the type in July 1962, a month or so after its inauguration into his airline's service. Antonov had passed a proficiency test two days earlier. He was very familiar with Bratislava Airport, having operated there on 11 prior occasions. Second Pilot (first officer) was Svetomir Dimitrov Shakadanov, 36, with 5975 flight hours. He had passed a proficiency check the previous day. Navigator Officer was First Class Specialist Navigator Slavi Stefanov Tomakov. Radio-Telegraphy Officer was Nikola Aleksandrov Tasev, 36 years old, with 3160 flight hours. On-Board Mechanical Officer was Stoyan Todorov Rangelov, 42, with 3602 flight hours. Cabin crew comprised stewardesses Maria Ivanova, Svetla Georgieva (also known as Svetla Marinova, married 18 days earlier to Ivan Slavkov) and Violina Stoichkova.

The 74 passengers on board Flight LZ101 were of 12 nationalities: Bulgarians, Argentinians, Britons, Chileans, Czechoslovaks, Germans, Hondurans, Hungarians, Japanese, Soviets, Swiss and Tunisians. Among them were four members of the Hungarian national judo team and their coach, Bulgarian opera soloist Katya Popova, Bulgaria's ambassador to the German Democratic Republic, General Ivan Buchvarov and famous Honduran writer and journalist Ramón Amaya Amador. The diversity of nationalities was partly explained by the recent Ninth Congress of the BKP Bulgarian Communist Party, many of them having been delegated to it by foreign communist parties.

Flight LZ101 departed Budapest at 11:46 hours CET. While it was en route, weather in Prague deteriorated. Commander Antonov elected to make a diversion to Bratislava Airport, landing there at 11:58. By 15:30, the weather in Prague had improved and Antonov decided to prepare to resume the flight. Bratislava Airport meteorologist Jan Popeleny briefed the Commander that medium to strong turbulence was expected above the Little Carpathians hills north-west of Bratislava.

By 16:10 the flight had boarded and at 16:20:30, Antonov was given clearance to taxi to Runway 04 or Runway 31 at his discretion. (He chose to use Runway 31 whose extended centreline crossed the Little Carpathians.) At the same time, he was cleared to take off, to turn right, to overfly the Nitra radio beacon and to proceed to overhead Brno and on to Prague at 5,100 metres (16,700 ft) Meanwhile, an Il-14 airliner of Czechoslovak Airlines (now as Czech Airlines) had taken off from Bratislava. In order to maintain separation between the slower Il-14 and his faster Il-18, Antonov was instructed to maintain a height of 300 metres (980 ft) until cleared to climb to his cruise altitude.

Flight LZ101 took off at 16:28 hrs in almost total darkness. Its departure was observed by air traffic controller Jaroslav Vadovic who reported that it had been normal. Shortly after reporting lift-off, LZ101 was instructed to turn right and contact the Bratislava Approach controller on a frequency of 120.9 MHz. The airliner failed to make the transition to Approach control. Some two minutes after departing Bratislava Airport, it crashed eight kilometres (5.0 mi; 4.3 nmi) from the airport into the Sakrakopec location in the foothills of the Little Carpathians, near Bratislava's borough of Rača. The area of impact was 288 metres (945 ft) above the elevation of the airport. The aircraft struck the snow-covered ground while flying without any bank angle, at a speed of some 250 knots (460 km/h; 290 mph) and while full take-off power was delivered by its engines. As it disintegrated over a period of 20 seconds, it left a swathe with a total length of 562 metres (1,844 ft; 615 yd) and a width of between 30 and 10 metres (98 and 33 ft; 33 and 11 yd), of which the main wreckage was located towards the end of a 265-metre-long (869 ft; 290 yd) strip. A fierce fuel fire broke out but burned out fairly rapidly, mostly because fragments and fuel had dispersed over a large area.

The location of the crash was close to built-up areas of Bratislava and very popular with hikers. The accident was observed and heard by many local residents, including an off-duty air traffic controller who immediately telephoned his colleagues at the airport. The approach controllers at the airport had not, however, observed the accident, visually or on radar.