The NTBS said in a Monday evening press conference that First Officer James Polehinke and not captain Jeffery Clay was in control of the plane Sunday morning.
Clay's wife told a Lexington newspaper that her husband was a "by-the-book" type of guy who wasn't tired when he got on the plane.
Debbie Hersman of the NTSB says the lights on Runway 26 hadn't been in use for years and weren't on when Flight 5191 made its way down the runway.
NTSB says evidence leads them to believe the plane was still grounded when it hit the end of the runway.
The safety board conducted a simulation of what might have happened but are also expected to conduct another one as early as Tuesday.
"There's also going to put together a similar exercise tomorrow morning or whenever the conditions are appropriate. We're trying to simulate the conditions as they were Sunday morning at 6 am," says Hersman.