A few days ago I was tipped off by a friend in ATL that the start up date of JFK-IST would be moved from 24-MAY-13 to 27-APRIL-13. So it's now starting back up about a month earlier than planned which is always good news! it has been loaded in the timetables:
DL 72: Depart JFK @ 1705 and Arrive IST @ 1015 (+1)
DL 73: Depart IST @ 1215 and Arrive JFK @ 1650
Flights will operate with 767 aircraft.