Federal officials are investigating a Southwest Airlines low flight over Oklahoma City suburbs

DALLAS (AP) — Federal officials are investigating a Southwest Airlines jet that triggered a low-altitude alert as it prepared to land in Oklahoma City but was still nine miles from the airport.

The Federal Aviation Administration said Thursday that an air traffic controller notified the Southwest pilots after an automated warning sounded around 12:05 a.m. Wednesday morning.

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

“Southwest 4069, low altitude alert. You doing OK?” an air traffic controller asked the Southwest pilots.

“Yeah, we’re going around, 4069,” one of the pilots responded, as captured 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 just after midnight.

“Southwest is following its robust safety management system and is in contact with the Federal Aviation Administration to understand and address any irregularities with the aircraft’s approach to the airport," a spokesperson said in a statement. "Nothing is more important to Southwest than the safety of our customers and employees.”