The incident happened Sunday as passenger planes from Dubai-based Emirates and Abu Dhabi-based Etihad Airways were traveling in opposite directions between the Gulf federation and the island nation of Seychelles. Emirates, the Middle East's biggest carrier, said flight EK709 was returning to Dubai when what it called "an air traffic control incident" happened in airspace monitored by air traffic controllers in Mumbai, India. Etihad said a mid-air crash warning device known as a traffic collision avoidance system onboard the Airbus A320 from Abu Dhabi "ensured that safe vertical separation of both aircraft was maintained at all times."