ČSA Flight 540 was a regularly scheduled international flight from Prague, Czechoslovakia to Tehran, Iran via Damascus, Syria and Baghdad, Iraq. On 20 August 1975, the flight, operated by an Ilyushin Il-62, crashed 17 km (11 mi) from Damascus International Airport while descending in clear weather, breaking up and catching fire on impact. 126 of the 128 passengers and crew died in the accident, making it Syria's worst air disaster and the worst air disaster for the airline.

The aircraft involved was an Ilyushin Il-62 with the serial number 31502 and registration OK-DBF. It was produced in 1973 and delivered to the airline in the same year. The aircraft was named Brno Trade Fair.

At the time of the accident, the flight captain was Ján Gajdoš (54) with 19 000 flight hours (circa 3000 on Il-62), who led the crew consisting of co-pilot Stanislav Žižka (50) with 15 000 flight hours (circa 2500 on Il-62), navigator František Aulík (43), and flight engineers Karel Hasman (48) and Vladimír Hejduk, who was just off duty. The rest crew was also very experienced and had over 10,000 hours of flight time. 117 passengers were served by a team of six flight attendants.

Flight 540 departed Prague-Ruzyně International Airport on 19 August 1975 at 19:35. The flight proceeded normally for the next three and a half hours towards its scheduled stopover at Damascus International Airport. Shortly after midnight on 20 August 1975, the crew established a connection with the regional control center and a moment later with the airport tower in Damascus itself. At 00:10, the crew received a weather report, indicating clear conditions with a very light wind. The aircraft was being flown by co-pilot Žižka at this time. At approximately 01:15, the crew should have requested a final approach, but this did not happen. Shortly thereafter, rumors of a plane crash began to spread.

The plane crashed in the desert approximately 17 km from Damascus Airport. The front landing gear impacted first, followed by the left wing. The aircraft then began to slide on its belly, breaking apart and catching fire in the process. Only the tail section survived relatively intact. Debris was scattered over an area of 1 kilometer. The crash site was soon surrounded by Syrian soldiers from a nearby base. They helped the three surviving passengers to get out of the wreckage. A 30-year-old Syrian student, a girl and a boy survived, but the boy died on the way to the hospital. 125 people were dead on the spot.

The investigation took place almost immediately after the accident. However, there were complications for the Czechoslovak commission from the Institute for Professional Investigation of Air Accidents (ÚZPLN), which did not receive permission to investigate the crash site. After two days of negotiations, the commission received permission to inspect the site. The Syrian and Soviet commissions of inquiry also joined. They tried to find the black boxes, however the plane was not equipped with a cockpit voice recorder, which greatly complicated the investigation. The flight data recorder was found, but upon closer examination it was found that the tape with the data had burned, so it was unusable. The only point of reference was the footage from the control tower at the Damascus airport. However, there were no signs of trouble, except for one misunderstanding. However, communication from aircraft was performed by navigator Aulík.

Communication between crew and tower:

OK 540: Good evening, we are approaching Damascus VOR 5000 feet.

Tower: Good evening, please wait! (interruption) ….. 6315, take the first right!

OK 540: Turn right?

Tower: No, it's not for you. (interruption) ….. Flight 6315 take the first right!

OK 540: Thank you, first right.

Tower: OK 540, proceed to VOR approach, report runway final 23R, wind 230/12, QNH (altitude) 1010.

OK: Got it, runway 23 right, QNH 1010.

They also ruled out the possibility of an explosion in flight or being shot down, as the debris was scattered over a relatively small area. However, without a cockpit voice recorder and flight data recorder, they could only speculate. When interviewing eyewitnesses (two Czechoslovak ambassadors who were waiting for a flight and were supposed to travel to Tehran) the plane was turning towards the airport at the time of the accident, but was not ready to land, as the plane did not have its landing lights, and then they observed the explosion. Due to strict censorship in the Czechoslovakia, only little was written about the accident, and most of the material about it was top secret.

The investigative commission cooperated very sporadically with each other, especially the Syrian side, which refused to search the personal belongings of the victims, carried away the debris, and did not report whether they had found any important clues. Syrian citizens carried pieces of aircraft as well, due to lack of controlling of area. The official reason for the crash thus remains unknown.

Victim identification was recommended, where it was found that the flight captain had consumed a significant amount of alcohol during the flight, which was against company regulations. In the same way, he was supposed to provide communication with the airport tower, which was provided by the navigator instead. ČSA pilots who were colleagues of the killed crew were also questioned, who claimed that the crew of the given flight did not like each other and had disputes among themselves, which could have contributed to the accident. Although most of the instruments were destroyed in the accident, it was also concluded that the piloting co-pilot Žižka, out of habit, entered the wrong barometer value, due to which the plane could send wrong altitude information to the cockpit. There have also been theories about the pilot's suicide, a bomb or Mossad involvement.

There are two most likely theories: pilot error and being shot down by a Syrian missile.

The theory of being shot down by a Syrian surface-to-air missile was possible thanks to the ongoing war in Lebanon, due to opening official branch of Palestine Liberation Organization (PLO) in Prague few days earlier, so they might shot down this aircraft as a protest against this decision. There were also some minor missing pieces of wreckage, or month later the missing Malév Flight 240, which crashed near Beirut. Also one witness testified that plane was shot down by missile. The theory of the shooting down was further deepened thanks to the subsequent visit of the Syrian president to Czechoslovakia, allegedly to settle relations. However, the wreckage of the ČSA flight was searched and no traces of explosives or shrapnel were found. Most probable cause of Accident was pilot error.

• ČSA Flight 540 at PlaneCrashinfo.com

33°31′10″N 36°40′10″E / 33.5194°N 36.6694°E / 33.5194; 36.6694