The worst mid-air crash in history occurred on 12 November 1996 when Saudi Arabian Airlines flight SV 763 crashed into incoming Kazakhstan Airlines flight KZ 1907 at Charkhi Dadri, a small town west of Delhi. All passengers and crew on both flights passed away in the crash.

The crash occurred when flight KZ 1907 and SV 763 collided mid-air, as the flights tried to land and take-off respectively. The crash happened at the height of 14,000 feet. It is calculated that the wing of the Kazakhstan Airlines flight hit the back engine of the Saudi Arabian Airlines flight on first impact. The flights came hurtling down on a town called Charkhi Dadri, 100kms away from Delhi. All 349 passengers passed away.

The crash shook up the global aviation industry and led to some important changes. These include: 

1. The implementation of an internal assessment for proficiency of English among pilots and aviation control centres. This was brought up by the Indian aviation board as a measure to maintain clear and understandable communication between pilots and the control centres. This is applicable on international routes only. 
2. The mandatory installation of Travel Collision Avoidance Systems (TCAS) in all aircrafts. This device alerts pilots if an aircraft is intruding into their airspace.