The Federal Aviation Administration is investigating after a Southwest Airlines flight descended dangerously low while approaching Oklahoma Citys airport early Wednesday from Las Vegas.

Flight 4069 was still nine miles from Will Rogers World Airport when its low altitude triggered an automated warning to air traffic control around 12:05 a.m. local time. Air traffic control then alerted the flights crew, the FAA said in a statement shared with HuffPost.

Southwest 4069, low altitude alert. You good out there? the air traffic controller asked, according to an archived recording of the incident obtained by LiveATC.net .