Federal authorities are investigating a Southwest Airlines low-level flight over the Oklahoma City suburbs

DALLAS– Federal authorities are currently investigating a Southwest Airlines flight that triggered a low-altitude alert upon landing in Oklahoma City while still 9 miles (14.5 kilometers) from the airport.

The Federal Aviation Administration (FAA) said Thursday that an air traffic controller notified Southwest Airlines pilots after an automatic warning sounded at around 12:05 a.m. Wednesday morning.

According to data from Flightradar24, the plane descended to about 525 feet above the ground as it flew over the Oklahoma City suburbs en route to Will Rogers World Airport.

“Southwest 4069, low level alert. Is everything OK?” an air traffic controller asked the Southwest pilots.

“Yes, we are flying around 4069,” one of the pilots replied, as recorded by LiveATC.net. The air traffic controller told him to maintain 3000 feet.

The Dallas-based airline said the plane, a Boeing 737, landed safely shortly after midnight.

“Southwest follows its robust safety management system and is in contact with the Federal Aviation Administration to understand and resolve any irregularities as the aircraft approaches the airport,” a spokesperson said in a statement. “Nothing is more important to Southwest than the safety of our customers and employees.”