Thiruvananthapuram. Air India Flight 657 from Mumbai to Thiruvananthapuram has received a bomb threat. The plane had already reached Thiruvananthapuram. Then the pilot reported the bomb. There were 135 passengers on the flight. All were evacuated safely. Emergency has been declared at Thiruvananthapuram airport. The flight was taken to the isolation bay. Investigation is underway. In a statement issued by the airport authority, it has been said that after the emergency landing of the flight, all the passengers are safe and their luggage is being checked. The authority has also said that there is no cause for concern at the moment. This is the sixth case of bomb threat on a flight in the last 3 months. Earlier, bomb threats were given on three flights in June and two flights in May.