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The 1976 Zagreb mid-air collision took place on 10 September 1976, when
British Airways British Airways (BA) is the flag carrier airline of the United Kingdom. It is headquartered in London, England, near its main hub at Heathrow Airport. The airline is the second largest UK-based carrier, based on fleet size and passengers ...
Flight 476, a
Hawker Siddeley Trident The Hawker Siddeley HS-121 Trident (originally the de Havilland DH.121 and briefly the Airco DH.121) is a British airliner produced by Hawker Siddeley. In 1957, de Havilland proposed its DH.121 trijet design to a British European Airways (BEA ...
en route from
London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...
to
Istanbul ) , postal_code_type = Postal code , postal_code = 34000 to 34990 , area_code = +90 212 (European side) +90 216 (Asian side) , registration_plate = 34 , blank_name_sec2 = GeoTLD , blank_i ...
, collided mid-air with Inex-Adria Aviopromet Flight 550, a Douglas DC-9 en route from Split,
SFR Yugoslavia The Socialist Federal Republic of Yugoslavia, commonly referred to as SFR Yugoslavia or simply as Yugoslavia, was a country in Central and Southeast Europe. It emerged in 1945, following World War II, and lasted until 1992, with the breakup of Yu ...
, to
Cologne Cologne ( ; german: Köln ; ksh, Kölle ) is the largest city of the German western state of North Rhine-Westphalia (NRW) and the fourth-most populous city of Germany with 1.1 million inhabitants in the city proper and 3.6 millio ...
,
West Germany West Germany is the colloquial term used to indicate the Federal Republic of Germany (FRG; german: Bundesrepublik Deutschland , BRD) between its formation on 23 May 1949 and the German reunification through the accession of East Germany on 3 ...
, near
Zagreb Zagreb ( , , , ) is the capital (political), capital and List of cities and towns in Croatia#List of cities and towns, largest city of Croatia. It is in the Northern Croatia, northwest of the country, along the Sava river, at the southern slop ...
in modern-day Croatia. The collision was the result of a procedural error on the part of
air traffic controllers Air traffic control specialists, abbreviated ATCS, are personnel responsible for the safe, orderly, and expeditious flow of air traffic in the global air traffic control system. Usually stationed in air traffic control centers and control ...
in Zagreb. All 176 people aboard the two aircraft were killed, making it the world's deadliest mid-air collision at the time. It remains the deadliest aviation accident in Yugoslav and Croatian history.


Flights

British Airways British Airways (BA) is the flag carrier airline of the United Kingdom. It is headquartered in London, England, near its main hub at Heathrow Airport. The airline is the second largest UK-based carrier, based on fleet size and passengers ...
Flight 476 departed
London Heathrow Airport Heathrow Airport (), called ''London Airport'' until 1966 and now known as London Heathrow , is a major international airport in London, England. It is the largest of the six international airports in the London airport system (the others be ...
for
Istanbul Atatürk Airport ) , postal_code_type = Postal code , postal_code = 34000 to 34990 , area_code = +90 212 (European side) +90 216 (Asian side) , registration_plate = 34 , blank_name_sec2 = GeoTLD , blank_ ...
at 08:32 UTC as flight BA476, with fifty-four passengers on board and a crew of nine. At the controls of the
Hawker Siddeley Trident The Hawker Siddeley HS-121 Trident (originally the de Havilland DH.121 and briefly the Airco DH.121) is a British airliner produced by Hawker Siddeley. In 1957, de Havilland proposed its DH.121 trijet design to a British European Airways (BEA ...
was an experienced
captain Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police department, election precinct, e ...
, Dennis Tann (born 1932), who by the time of the accident had accumulated 10,781
flying hours Flight time or block time is an aviation term referring to the total amount of time spent piloting aircraft, and serves as the primary measure of a pilot's experience. Flight time is defined by International Civil Aviation Organization (ICAO) as ...
. He was assisted by First Officer Brian Helm and
Flight Engineer A flight engineer (FE), also sometimes called an air engineer, is the member of an aircraft's flight crew who monitors and operates its complex aircraft systems. In the early era of aviation, the position was sometimes referred to as the "air m ...
Martin Flint. Inex-Adria Flight 550 departed
Split Airport Split Airport ( hr, Zračna luka Split; ), also known as Resnik Airport ( hr, Zračna luka Resnik), is the international airport serving the city of Split, Croatia. It is located from Split, on the west side of Kaštela Bay, in the town of Kaš ...
at 09:48 UTC bound for
Cologne Bonn Airport Cologne Bonn Airport (german: Flughafen Köln/Bonn 'Konrad Adenauer') is the international airport of Germany's fourth-largest city Cologne, and also serves Bonn, former capital of West Germany. With around 12.4 million passengers passing thr ...
as flight JP550. It carried 108 passengers, mostly German holiday-makers returning home at the end of a holiday on the
Dalmatia Dalmatia (; hr, Dalmacija ; it, Dalmazia; see names in other languages) is one of the four historical regions of Croatia, alongside Croatia proper, Slavonia, and Istria. Dalmatia is a narrow belt of the east shore of the Adriatic Sea, str ...
n coast and a crew of five. At the controls sat Captain Jože Krumpak (born 1925), an experienced pilot with 10,157 flying hours, and First Officer Dušan Ivanuš. Inex-Adria was a
charter airline Air charter is the business of renting an entire aircraft (i.e., chartering) as opposed to individual aircraft seats (i.e., purchasing a ticket through a traditional airline). Regulation Charter – also called air taxi or ad hoc – flights ...
based in the
Socialist Republic of Slovenia The Socialist Republic of Slovenia ( sl, Socialistična republika Slovenija, sh-Latn-Cyrl, separator=" / ", Socijalistička Republika Slovenija, Социјалистичка Република Словенија), commonly referred to as Sociali ...
, the northernmost of the constituent republics making up
SFR Yugoslavia The Socialist Federal Republic of Yugoslavia, commonly referred to as SFR Yugoslavia or simply as Yugoslavia, was a country in Central and Southeast Europe. It emerged in 1945, following World War II, and lasted until 1992, with the breakup of Yu ...
. Both flights proceeded uneventfully until they approached the Zagreb
VOR VOR or vor may refer to: Organizations * Vale of Rheidol Railway in Wales * Voice of Russia, a radio broadcaster * Volvo Ocean Race, a yacht race Science, technology and medicine * VHF omnidirectional range, a radio navigation aid used in ...
.


Air traffic control

In the mid-1970s, the Zagreb
air traffic control Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled airsp ...
region was one of the busiest in Europe despite being seriously undermanned and poorly equipped. The Zagreb VOR was a reporting point for a number of congested airways between northern Europe and southeastern Europe, the Middle East, and beyond. The
airspace Airspace is the portion of the atmosphere controlled by a country above its territory, including its territorial waters or, more generally, any specific three-dimensional portion of the atmosphere. It is not the same as aerospace, which is th ...
was divided into three sectors by altitude: the lower sector below , the middle sector from , and the upper sector above .


Accident

On entering Yugoslav airspace from Austria, BA476 established radio contact with the Zagreb ACC upper-sector controller Gradimir Tasić at 10:04:12 UTC, informing him that they were at and expected to reach the Zagreb VOR at 10:14. The controller responded by instructing them to select transponder code 2312, and to call again on reaching the VOR: This was the last communication with the Trident aircraft before the accident, and the flight was uneventful until the very moment of the collision. At around the same time, JP550 contacted middle-sector controller Bojan Erjavec asking for a higher
flight level In aviation and aviation meteorology, a flight level (FL) is an aircraft's altitude at standard air pressure, expressed in hundreds of feet. The air pressure is computed assuming an International Standard Atmosphere pressure of 1013.25  ...
; the aircraft was at flight level 260 (approximately ). FL280 () and FL310 () were unavailable, so Erjavec informed JP550 of the situation and offered flight level 350 (approximately ), which the pilots accepted. To get clearance for a higher level, it was necessary to obtain the permission of the upper-sector controller. Erjavec waved his hand to get Tasić's attention, but Tasić (who was working the upper sector on his own, as co-worker Mladen Hochberger had gone to search for Nenad Tepeš, Tasić's replacement who was running late) was far too busy to be interrupted. Middle sector controller Gradimir Pelin was then instructed to co-ordinate the climbout for the DC-9 with Tasić. According to Pelin, he walked to the upper sector console holding JP550's flight progress strip. He asked Tasić if the DC-9 could climb to FL350. Tasić took the strip from Pelin and looked at it, then asked where the aircraft was at the moment. Pelin then pointed to a blip on the screen approaching Kostajnica. Tasić's response was 'yes, it could climb'. Pelin then noticed an aircraft on the screen coming from the direction of Metlika and asked Tasić about it, who said 'wait until they cross'. Pelin referred to the middle-sector screen to make sure that he had identified the DC-9 positively on the upper-sector screen. He then returned to Tasić and they both watched the targets pass each other, at which point Tasić authorised JP550 to climb. Pelin then called out to Erjavec and said 'yes, climb it'. Upon Erjavec receiving the OK from Pelin, he instructed the DC-9 to climb to FL350. That was at 10:07:40. At 10:12:03, JP550 called the Zagreb middle-sector controller to inform them that the aircraft was out of flight level 310. The last instructions given by Erjavec to JP550 were to call the upper-sector controller on 134.45 MHz and to stop squawking the assigned
squawk code A transponder (short for ''trans''mitter-res''ponder'' and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) is an electronic device that produces a response when it receives a radio-frequency interrogation. Aircraft have transponders to assist ...
. By instructing JP550 to squawk Standby, Erjavec simply released a code allocated for the middle sector. The data tag for the DC-9 would now disappear from his screen and the aircraft would become merely a point among many others. If everything about this handover had been normal, the DC-9 would have been given a new code on initial contact with the upper sector controller and would have been positively identified on the upper sector screen with its flight number and altitude readout. But this had not been a normal handover because of the ill-handled co-ordination for the climb. Also, Tasić was busy with other traffic and JP550 did not immediately contact the upper-sector controller. This could have been because the frequency was busy, but the pilots might also have delayed the call for some unknown reason. By the time JP550 contacted the upper-sector controller at 10:14:04 it had reached the Zagreb VOR and was already climbing through flight level 325 (approximately ). The controller immediately asked for confirmation of the aircraft's level: Realising the imminent danger of collision, Tasić instructed the JP550 to stop climbing. In doing so, he reverted to his native
Serbo-Croatian Serbo-Croatian () – also called Serbo-Croat (), Serbo-Croat-Bosnian (SCB), Bosnian-Croatian-Serbian (BCS), and Bosnian-Croatian-Montenegrin-Serbian (BCMS) – is a South Slavic language and the primary language of Serbia, Croatia, Bosnia an ...
language, contrary to the regulations. This meant that the British Airways plane, even if they overheard this conversation, would have very little chance of understanding their own imminent danger. The controller's last-ditch attempt to avert catastrophe turned what would have been a near miss into the collision he was trying to prevent. For, by the time JP550 had levelled off it was at flight level 330 (approximately ), exactly the same level as BA476: The mid-air collision occurred at 10:14:41. Half a minute later, Tasić attempted to call BA476 and instruct it to report passing the next waypoint at
Našice Našice () is a town in eastern Croatia, located on the northern slopes of the Krndija mountain in eastern Slavonia, 51 km southwest of regional hub Osijek. Administratively it belongs to Osijek-Baranja County. Geography Našice is located ...
, but was answered by a different flight: Tasić continued to call BA476 and JP550, ignoring calls from other aircraft, but to no avail: Meanwhile, a
Lufthansa Deutsche Lufthansa AG (), commonly shortened to Lufthansa, is the flag carrier of Germany. When combined with its subsidiaries, it is the second- largest airline in Europe in terms of passengers carried. Lufthansa is one of the five founding ...
Boeing 737 The Boeing 737 is a narrow-body aircraft produced by Boeing at its Renton Factory in Washington. Developed to supplement the Boeing 727 on short and thin routes, the twinjet retains the 707 fuselage width and six abreast seating with two u ...
was travelling eastbound on UB5 at flight level 290 (approximately ) towards Zagreb, only behind the Trident. The co-pilot saw the collision as a flash of lightning and afterwards, out of a ball of smoke, two aircraft falling towards the ground. The Lufthansa captain, Josef Kröse, reported the sighting to Erjavec, the middle-sector controller. This was spoken in such an agitated voice that Erjavec was unable to understand what was being said. (Later, on hearing the recording of this call, Captain Kröse had difficulty in understanding his own words.) The Lufthansa captain had to repeat his message several times. When the implications of what was being said dawned on Erjavec, he glanced across to the upper-sector controller. At his station sat a stunned Tasić, white-faced with shock. Slowly he lifted the headset from his ears and placed it on the console in front of him. The two aircraft had collided over the town of Vrbovec, northeast of Zagreb, the last five metres of the DC-9's left wing cutting through the Trident's cockpit section and forward passenger compartment. The
explosive decompression Uncontrolled decompression is an unplanned drop in the pressure of a sealed system, such as an aircraft cabin or hyperbaric chamber, and typically results from human error, material fatigue, engineering failure, or impact, causing a pressure vess ...
caused the forward part of the Trident's fuselage to disintegrate; the Trident fell, landing on its tail and sliding a short distance before its remains came to rest near village Gaj. The DC-9, now without over one-third of its left wing, went into an immediate nose-dive and slammed into the ground right-wing first, near village Dvorišće. In the end, everyone aboard both flights was killed.


Initial survivors

A police officer who was one of the first to arrive at the scene reported that a baby on the ground was "still giving feeble signs of life near the ritishplane, but even if the ambulances had arrived before me, it would have been too late to save it." Locals reported finding a boy, who was lying on a road near a field, and who displayed signs of life up to 15 minutes after the collision, but he eventually died.


Trial

By noon that day, all controllers were in custody for interrogation. Later, all were released except Tasić, who remained in custody until the trial. The trial opened on 11 April 1977 in Zagreb District Court. All the controllers were indicted under the Penal Code of Yugoslavia, Articles 271-72 as "persons who by endangering railway, sea or air traffic, threaten the lives of persons or property". Tasić was the only one to be found guilty; he was sentenced to seven years' imprisonment. After a petition by air traffic controllers, it was determined that Tasić had been used as a
scapegoat In the Bible, a scapegoat is one of a pair of kid goats that is released into the wilderness, taking with it all sins and impurities, while the other is sacrificed. The concept first appears in the Book of Leviticus, in which a goat is designate ...
, and he was released on 29 November 1978. He had served nearly two years and three months in prison.


In popular culture

A dramatised reconstruction of the events leading up to the accident, starring
Antony Sher Sir Antony Sher (14 June 1949 – 2 December 2021) was a British actor, writer and theatre director of South African origin. A two-time Laurence Olivier Award winner and a four-time nominee, he joined the Royal Shakespeare Company in 1982 a ...
and entitled ''Collision Course'', was made by
Granada Television ITV Granada, formerly known as Granada Television, is the ITV franchisee for the North West of England and Isle of Man. From 1956 to 1968 it broadcast to both the north west and Yorkshire but only on weekdays as ABC Weekend Television was its ...
in 1979. The events of the accident are also documented in a season 1 episode of ''Aircrash Confidential'' titled "Collisions", which was first aired on the
Discovery Channel Discovery Channel (known as The Discovery Channel from 1985 to 1995, and often referred to as simply Discovery) is an American cable channel owned by Warner Bros. Discovery, a publicly traded company run by CEO David Zaslav. , Discovery Chan ...
in 2011.


See also

''Similar accidents and incidents:'' * 1973 Nantes mid-air collision *
2002 Überlingen mid-air collision On the night of 1 July 2002, BAL Bashkirian Airlines Flight 2937, a Tupolev Tu-154 passenger jet, and DHL International Aviation ME Flight 611, a Boeing 757 cargo jet, collided in midair over Überlingen, a southern German town on Lake Const ...
*
2001 Japan Airlines mid-air incident On January 31, 2001, Japan Airlines Flight 907, a Boeing 747-400 en route from Haneda Airport, Japan, to Naha Airport, Okinawa, narrowly avoided a mid-air collision with Japan Airlines Flight 958, a McDonnell Douglas DC-10-40 en route from Gimhae ...


References

Cited texts * * *


External links


Final accident report 9/82Archive
Yugoslav Federal Committee for Transportation and Communications Second Commission of Inquiry, Published by the
Accidents Investigation Branch The Air Accidents Investigation Branch (AAIB) investigates civil aircraft accidents and serious incidents within the United Kingdom, its overseas territories and crown dependencies. It is also the Space Accident Investigation Authority (SAIA) ...
,
Department of Trade Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military * Department (administrative division), a geographical and administrative division within a country ...
*
AnnexesArchive

Accident report 5/77Archive
Yugoslav Federal Civil Aviation Administration Aircraft Accident Investigation Commission. Published by the Accidents Investigation Branch. *
AnnexesArchive
* ()
Pre-collision photos of Trident G-AWZT taken from Airliners.net

Pre-collision photo of DC-9 YU-AJR taken from Airliners.net

Crash site of the mid-air collision
from ''
Associated Press The Associated Press (AP) is an American non-profit news agency headquartered in New York City. Founded in 1846, it operates as a cooperative, unincorporated association. It produces news reports that are distributed to its members, U.S. new ...
Archive'' {{DEFAULTSORT:Zagreb Mid-Air Collision, 1976 Aviation accidents and incidents caused by air traffic controller error Aviation accidents and incidents in 1976 Aviation accidents and incidents in Croatia Adria Airways accidents and incidents Accidents and incidents involving the McDonnell Douglas DC-9 Accidents and incidents involving the Hawker Siddeley Trident 1970s in Zagreb 1976 in Croatia Mid-air collisions Mid-air collisions involving airliners British Airways accidents and incidents September 1976 events in Europe