Recorded conversations between the airport and pilots show concern about runway conditions before a fatal accident last December.
A Southwest Airlines jet slid off a Midway Airport runway, crushing a vehicle and killing a six-year-old.
In the recording obtained by WFLD FOX Chicago News, air traffic controllers can be heard telling the Southwest Airlines pilots before they land that braking action on the runway is "fair to poor."
A short time later, there's a garbled sound and a flight controller says excitedly, "What was that?"
The Southwest flight 1248 pilot then says twice in a steady voice that the plane went off the runway and he requests assistance.
The plane went off the runway and into a street, crushing a vehicle and killing a six-year-old boy inside.
The accident remains under investigation.