This from the NTSB
quote
A check airman was on the flight deck along with the captain
and first officer. During cruise flight, the check airman
became ill and was relocated to the cabin for the remainder
of the flight. A medical emergency was declared and the
company was notified by the crew. A determination was made
to land at the scheduled destination of ATL.
The flight was cleared to land on runway 27R but instead
landed on taxiway M, which is situated immediately to the
north and parallel to runway 27R. The runway lights for 27R
were illuminated; the localizer and approach lights for 27R
were not turned on. Taxiway M was active but was clear of
aircraft and ground vehicles at the time the aircraft
landed. The wind was calm with 10 miles visibility.
Night/dark conditions prevailed; twilight conditions began
at about 7:20 a.m. EDT and the official sunrise was at 7:46
a.m. EDT. Unquote