11:12 AM EDT, 06/28/2024 (MT Newswires) -- Southwest Airlines ( LUV ) is under investigation by the National Transportation Safety Board and the Federal Aviation Administration for an incident where one of its planes allegedly took off from a closed runway at the Portland International Jetport in Portland, Maine, earlier this week.

"Southwest Airlines Flight 4805 departed from a temporarily closed runway at the Portland International Jetport on Tuesday, June 25. An airport vehicle exited the runway before the plane began its takeoff roll," an FAA spokesperson confirmed in an emailed response to MT Newswires. "The FAA and NTSB are investigating the event, which occurred around 5:45 a.m. local time."

The NTSB also confirmed it is investigating the incident and a preliminary report containing "factual information gathered during the initial phase of the investigation" will be available in 30 days. "A probable cause and any contributing factors will come in the final report in 12-24 months," the NTSB said.

A Southwest Airlines ( LUV ) spokesman said "Southwest Airlines ( LUV ) is engaged with the NTSB and FAA to understand the circumstances of an early morning Southwest ( LUV ) departure on Tuesday, June 25, of Flight 4805 from Portland International Jetport. After departure, the aircraft continued safely to its destination. Please contact the NTSB for additional details."

Shares of the airline were down nearly 0.3% in recent Friday trading.

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