349: On November 12, 1996, the Charkhi Dadri mid-air collision took place between Saudia Flight 763 and Kazakhstan Airlines Flight 1907 over Charkhi Dadri, India. The collision was mainly the result of the Kazakh pilot flying lower than the assigned clearance altitude. All 349 passengers and crew on board the two aircraft died.[13] It remains the world's deadliest mid-air collision.[14] The Ramesh Chandra Lahoti Commission, empowered to study the causes, recommended the creation of the "semi-circular rule", to prevent aircraft from flying in opposite directions at the same altitude.[15] The Civil Aviation Authorities in India made it mandatory for all aircraft flying in and out of India to be equipped with a Traffic Collision Avoidance System (TCAS), setting a worldwide precedent for mandatory use of TCAS.