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US aviation officials are investigating after a Southwest Airlines flight made a low approach, setting off an alarm.

The Federal Aviation Administration (FAA) said the alert sounded as a flight from Las Vegas came within nine miles (14.5km) of Will Rogers World Airport in Oklahoma City.

The incident happened just after midnight on Wednesday.

Data from aviation tracking website FlightRadar24 indicated that the plane came within about 500 feet (150 metres) of the ground.

An automated system called Minimum Safe Altitude Warning alerts air traffic controllers if a plane goes too low.

On an air traffic recording, a controller can be heard saying: “Southwest 4069, low altitude alert. You good out there?”

The FAA did not specify how close the plane came to the ground, and the pilot's response was not included on the audio recording, but FlightRadar24 used atmospheric and flight data to estimate that the craft came within about 525 feet of ground level.

The plane landed safely shortly afterwards.

In a statement Friday, Southwest said it is in contact with the FAA “to understand and address any irregularities with the aircraft’s approach to the airport.”

The FAA is also investigating a Southwest flight that came within about 400 feet of the ocean off of Hawaii during poor weather conditions in April.

The pilot of that plane bypassed a landing at Lihue airport and inadvertently caused a rapid decent, according to a company memo. The plane, a Boeing 737 Max 8, returned to Honolulu. Nobody was injured.

In May, a Southwest flight en route from Phoenix to Oakland experienced a “Dutch roll” – a potentially dangerous side-to-side movement across two axes.

Nobody was hurt but the plane, also a Boeing 737 Max 8, was damaged, and the National Transportation Safety Board is investigating.

The plane involved in the Oklahoma incident was a Boeing 737-800, not the Max 8 model.

Boeing has come under increasing scrutiny over its safety practices. Earlier this week families of victims in two crashes of the Boeing 737 Max asked for prosecutions and a fine of $24.8bn (£19.6bn).