Some additional from AP (edited to remove duplication with original post):
"Federal Aviation Administration officials said Monday the planes came no closer than 300 feet vertically and no more than a half-mile horizontally. But air traffic controllers said the planes came within 100 feet vertically and there was no observable distance horizontally between them, sending the controllers scrambling to put the planes on divergent headings.
“Tower controllers intervened to attempt to resolve the conflict, assigning both aircraft diverging headings,” NTSB said. “The closest proximity of the two aircraft has not yet been determined.”
A spokesman for Cayman Airways said the company is disputing the classification of the incident as a near airborne collision.
“We’re treating it as a non-issue,” said Olson Anderson, the airline’s vice president of flight operations.
According to Anderson, the pilot of Flight 792 said the plane’s Traffic Alert and Collision Avoidance System, or TCAS, did not issue a warning. TCAS analyzes the projected flight path of approaching aircraft to alert pilots to potential collisions.
But Doug Church, a spokesman for the National Air Traffic Controllers Association, said the three controllers in Westbury, N.Y., who observed the incident told him they saw the two planes converge from two blips to a single blip on their radar.
The planes “passed on top of each other ... There was nothing discernible in terms of any space,” Church said. “It sank the hearts of every one of them. It was something they had never seen in 70 combined years of experience.”