A Delta flight taking off the Atlanta Hartsfield/Jackson International Airport in Georgia reported smoke filling the cabin and cockpit in February, according to a preliminary report from The National Transportation Safety Board.

No oil was visible in the gauge on the right engine’s oil reservoir after a February Delta Air Lines flight filled with smoke during takeoff at Atlanta’s Hartsfield Jackson International Airport, a preliminary report from the National Transportation Safety Board said Wednesday.

A Delta Airlines flight from Atlanta that was forced to double back and make an emergency landing in February was filled with such thick smoke that pilots needed to wear oxygen masks, and flight attendants struggled to see passengers beyond the first row,