An Austrian Airlines flight carrying 57 people from Tel Aviv, Israel, to Vienna made an emergency landing in Bulgaria following a bomb threat.

According to a statement from Bulgaria’s Transport Ministry, the crew of Austrian Airlines flight OS82, an Airbus A320, reported receiving “a bomb threat” while flying near the Romanian border on Sunday.

Bulgarian MiG-29 fighter jets were scrambled to escort the aircraft to Vasil Levski Sofia Airport. All 51 passengers and six crew members disembarked safely.

Austrian Airlines spokeswoman Anita Kiefer said the passengers would be rebooked on alternative flights following a police search of the aircraft.

The incident follows two bomb threats involving Delta Air Lines flights between New York and Tel Aviv on October 13. One aircraft was evacuated and searched after landing at Ben Gurion Airport, while another was held at New York’s JFK Airport before departure. Both were cleared after security inspections found no explosives.

The latest scare also comes after an attempted terrorist attack aboard a Flydubai flight carrying mostly Israeli passengers from Dubai to Tel Aviv on September 30. A co-pilot attacked the captain with an emergency axe and attempted to seize control of the aircraft. Passengers and crew members overpowered the assailant, allowing the plane to make an emergency landing in Saudi Arabia. The pilot, Indian national Smit Machchhar, sustained serious injuries.

According to Emirati prosecutors, the suspect, an Omani national, had planned to crash the aircraft into the passenger terminal at Ben Gurion Airport to cause mass casualties.

Following the attempted hijacking, Israeli Prime Minister Benjamin Netanyahu ordered tighter security checks on foreign airline crews and a comprehensive review of aviation security procedures.