Reporters traveling with the first lady reported that 15 minutes after the plane took off smoke was spotted in the cabin and filled with a burning smell.
First lady Melania Trump's plane made an unplanned landing at Joint Base Andrews after the aircraft experienced a "minor mechanical issue".
The first report came from NBC's Peter Alexander. Secret Service agents headed toward the front of the plane.
The mechanical issue caused a strong smell of smoke.
The first lady also planned to tour a neonatal intensive care nursery and speak at a US Health Department conference on a new system that tracks infants suffering from opiate withdrawal.
Mrs Trump had been scheduled to visit a Philadelphia hospital and meet with families of children affected by exposure to opioids while in the womb.
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The plane landed safely about 9 a.m.
The First Lady of the President of the United States was aboard the flight to Philadelphia which was forced to returned to base in Maryland.
"Everything is fine and everyone is safe", said Stephanie Grisham, press secretary for the first lady.
Mrs. Trump's trip is being evaluated, but she is expected to continue her travels today.
Pool reporters said a "thin haze of smoke" was visible and smelled something burning.