El Al Flight 402 was an international passenger flight from London to Tel Aviv via Vienna and Istanbul. On July 27, 1955, the flight, operated by a Lockheed Constellation registered as 4X-AKC, strayed into Bulgarian airspace and was shot down by two Bulgarian MiG-15 jet fighters and crashed near Petrich, Bulgaria. All 7 crew and 51 passengers on board the airliner were killed. The crash took place amid highly strained relations between the Eastern Bloc and the West and was the deadliest involving the Constellation at the time.
The Constellation originated its scheduled weekly flight from London, England, and departed Vienna's Wien-Schwechat International Airport (VIE) at 02:53, bound to Tel Aviv's Lod Airport (since renamed to Ben Gurion International Airport) via Istanbul. Why the plane veered off its intended route was never established, with highly conflicting opinions from Israeli and Bulgarian investigators. One possibility is that, using NDB navigation, thunderstorm activity in the area might have upset the navigational equipment so that the crew believed they were over the Skopje radio beacon, and turned to an outbound course of 142 degrees, but this version is not supported by any factual evidence of thunderstorms in the area. As a result, this version for the shooting are disputed by both Bulgarian military and by current historiographers of Bulgarian aviation. It is firmly established only that the El Al flight, flying at FL180 (an altitude of approximately 18,000 feet above mean sea level), strayed off the Amber 10 airway into Bulgarian territory. Bypassing the town of Tran, the El Al plane traveled a total of 200 km (120 mi) over Bulgarian territory at a 120 km (75 mi) distance from the border it crossed, before being shot down.
The aircraft's crossing of the Western Bulgarian border was registered by an observation post of the Bulgarian military near the town of Tran, and the Air Defence scrambled two MiG-15 jets with pilots Petrov (pair leader) and Sankiisky, by order of the Deputy Chief of Air Defense, Gen. Velitchko Georgiev. The MiGs took off the Dobroslavtsi airport, responsible for the defense of the capital city of Sofia. According to pilots Petrov and Sankiisky, Sankiisky first attempted to warn the El Al plane that it was in violation, by shooting signal rounds in front of the Constellation's nose; Petrov repeated the warning. In the meantime, the El Al plane neared the southern border of Bulgaria with Greece and the near-border city of Petrich, where it was shot down. According to Petrov and Sankiisky, the Constellation initially pretended to follow the instructions and deployed its flaps and landing gear, but then sharply retracted them and changed course to Greece, hoping to escape the fighters. The pilots' account has subsequently been disputed; the location of the crash near Petrich (a town several kilometers away from the border with Greece) suggests that the El Al flight had been followed without shooting until its very last minutes over Bulgarian territory. The final shoot-down order was given by Gen. Velitchko Georgiev, deputy commander-in-chief of Air Defense, who is quoted saying "If the plane is leaving our territory, disobeying orders, and there is no time left for more warnings, then shoot it down". The airliner was hit by the MiG-15's guns and then descended, breaking apart at 2,000 feet, and crashing in flames north of the town of Petrich, Bulgaria, near the Yugoslav and Greek borders, killing the 7 crew and 51 passengers on board.
At first, however, it was speculated that the aircraft was not brought down by fighters but by anti-aircraft guns from the ground. The next day, the Bulgarian government admitted to shooting down the airliner. They expressed regret and arranged an official inquiry (but would not allow a six-man investigative team from Israel to take part). This latter action has subsequently been criticized both by the Israelis and by Bulgarian sources within the investigation
The accident was investigated and the following probable cause statement was issued:
The aircraft sustained a hit or hits which caused loss of pressurization and a fire in the heater compartment. The aircraft broke up in mid-air due to explosion caused by bullets hitting the right wing and probably the left wing together with a projectile or projectiles of large calibre in the rear end of the fuselage.
As a followup/safety action, it was recommended that more VOR stations be used on airway Amber 10, instead of just one at the time of the accident.
Mail carried on this flight is known to have originated in Germany, the Netherlands, Romania and the USSR. A small amount of the mail was salvaged from the crash. As noted in Kibble, when the surviving mail arrived into Tel Aviv, Israel, it was stamped with a Hebrew instructional marking prior to being forwarded on to its final town destination within Israel. The boxed violet instructional marking reads (translated from the Hebrew):
"This piece of mail survived in El-Al airplane that was shot down over Bulgaria on 27.7.1955".
The Hebrew text is 2–3 mm (0.079–0.118 in) in size, while the outline of the boxed instructional marking is 19 mm × 36 mm (0.75 in × 1.42 in) in size.
The incident took place during one of the harshest standoffs of the Cold War, so it is hardly surprising that each side interpreted it as a serious provocation. The Bulgarian Communist government saw the accident primarily as a political negative in the détente in East/West relations that had been achieved in talks in Geneva earlier the same year, so after the incident both pilots were considered for demotion and threatened with prison terms by the minister of the interior Georgi Tzankov. Prison terms were not imposed, as the pilots were determined to have followed the orders given. Although the Bulgarian government at first refused to accept responsibility, blaming the Israeli airliner for penetrating its airspace without authorization, it eventually issued a formal apology, stating that the fighter pilots had been "too hasty" in shooting down the airliner, and agreed to pay compensation to the victims' families.