Chicago Transit Authority union president Robert Kelly says the operator of a Blue Line train that derailed at O'Hare early Monday may have dozed off.

Kelly says early indications show this may explain why the eight-car train jumped the tracks and landed on the stairs and escalators leading to the airport terminals just before 3 a.m.

According to Kelly, the female train operator had 17 hours off between her shifts, which was ample time to get the necessary rest.

At a news conference Monday, National Transportation Safety Board signal specialist Tim Depaepe said the motorman started her shift at about 8:40 p.m. Sunday.

Kelly said the operator, who has been employed with the CTA for about a year, will be interviewed by the NTSB on Tuesday.

The train operator was walking, talking and answering questions afterward, fire officials said. She was taken to the hospital with injuries to her leg and later released.

The incident left 32 others injured. Luckily there were no fatalities.