Serious incident to the Airbus A320 registered VT-IEH and operated by IndiGo and to the Boeing 777 registered A6-EPJ and operated by Emirates on 28/01/2018 en route [Investigation led by AIB / India]

Preliminary data based on the notification from the Indian authorities:
Indigo aircraft was maintaining FL330 and was given descent to FL250 through the level of UAE353, (Singapore to Dubai) maintaining FL300. Both the aircraft reported receiving TCAS RA and there was infringement of separation minima. The longitudinal and vertical separation in area control was reported to be 1 Nm and 700 feet respectively. Both the aircrafts were observed to follow RA. The UAE353 was observed to report the TCAS RA thrice. The radar controller was also observed to give the descent to IGO334 to FL305 contrary to the TCAS instruction.