June 28 (Reuters) - The National Transportation Safety

Board and Federal Aviation Administration said on Friday it will

investigate a Southwest Airlines ( LUV ) flight that departed

from a temporarily closed runway in Maine earlier this week.

The FAA said on Tuesday an airport vehicle exited the runway

before Southwest Flight 4805, a Boeing 737, began its

takeoff roll and departed around 5:45 a.m. local time (0945

GMT).

Southwest ( LUV ) said it is engaged with the NTSB and FAA to

understand the circumstances of the departure. After the

incident the plane continued safely to Baltimore, Southwest ( LUV )

said.

Several other incidents involving Southwest ( LUV ) flights in

recent months have raised concerns.

Last week, the FAA said it was investigating a Southwest ( LUV )

flight that descended to a low altitude of around 500 feet

(152.4 m) about 9 miles (14.5 km) from the Oklahoma City

airport.

After the automated Minimum Safe Altitude Warning sounded,

an air traffic controller alerted the flight crew of Southwest

Airlines Flight 4069, which had departed from Las Vegas.

Earlier this month, the FAA and NTSB said they were

investigating a May 25 Southwest ( LUV ) flight of a Boeing 737 MAX. The

NTSB said the plane experienced a "Dutch roll" at 34,000 feet

while en route from Phoenix, to Oakland, California. Such

lateral asymmetric movements are named after a Dutch ice-skating

technique and can pose serious safety risks.

The FAA said this month it was also investigating a

Southwest ( LUV ) 737 MAX 8 flight in April that came within about 400

feet of the ocean off the coast of Hawaii after bad weather

conditions prompted pilots to bypass a landing attempt at Lihue

airport.

During the go-around, the first officer "inadvertently

pushed forward on the control column while following thrust

lever movement commanded by the autothrottle," according to a

June 7 airline memo, and the plane began to descend rapidly,

hitting a maximum descent rate of about 4,400 feet per minute.

The pilots in a post-debrief said seeing the severity of the

flight "through the animations was a significant, emotional

event," Southwest ( LUV ) said, adding the incident prompted the airline

to review data and trends related to its procedures, training,

standards, and performance.