From the press pool report on Melania Trump’s trip to Philadelphia:
The trip by First Lady Melania Trump to Philadelphia, where she is slated to visit a hospital, got off to a rocky start-about 15 minutes into what was supposed to be a 30 minute flight from Joint Base Andrews to Philadelphia, a small amount of smoke could be seen inside the plane and the interior filled with a burning smell.
A FLOTUS staffer came into our compartment and informed us that there was a “mechanical problem” and we would be returning to Joint Base Andrews and would re-evaluate on the tarmac.
A member of the flight crew passed out damp washcloths for passengers to hold over their faces for the smell. Plane landed again shortly after 9 am. We are being transported to the lounge area and are told we will be boarding a different aircraft soon.