A Convair CV-990 Coronado passenger plane, operated by Swissair, was destroyed when it crashed near Wrenlingen, Switzerland, killing all 47 on board. Swissair flight 330 took off from Zrich-Kloten Airport (ZRH), Switzerland at 13:14 on a scheduled flight to Tel Aviv (TLV), Israel. Seven minutes later an explosion occurred in the aft cargo hold. The airplane was flying at an altitude of 4300 m over Sattel-Hochstuckli, 41 km south of the airport. The flight crew reported a loss of cabin pressure and initiated a return to Zrich Airport. At 13:26 the crew radioed: “This is an emergency – we have fire on board and request immediate landing… our navigation is not OK… we request police investigation.” Smoke on the flight deck prevented the crew from seeing the instruments and about 13:33 electrical power was lost. The airplane entered a steep descent and impacted the wooded Unterwald area near Wrenlingen, Switzerland, about 24 km west-northwest of the airport. On the same day, a bomb exploded aboard a Vienna-bound Caravelle after takeoff from Frankfurt. The Caravelle, operated by Austrian Airlines landed safely. It was suspected that the Popular Front for the Liberation of Palestine (PFLP) was responsible for both attacks. However, the federal prosecutor’s office closed the criminal investigation into the perpetrators of the attack in November 2000 because the attackers could not be identified and arrested. Both bombings led to a UN treaty adopted in 1971, named Convention for the Suppression of Unlawful Acts against the Safety of Civil Aviation.