ATLANTA — The second American aid worker recently diagnosed with Ebola in west Africa is en route to Atlanta.

A chartered plane equipped to contain infectious diseases took off at 1:12 a.m. local time (9:12 p.m. EDT Monday) from Monrovia, Liberia. An Associated Press reporter saw the four-vehicle convoy arrive at the airport.

Although hospital officials haven’t released the patient’s identity, the aid group she was working with has identified her as 59-year-old Nancy Writebol. SIM said in a statement Tuesday morning that Writebol remains in serious but stable condition.

An official at Bangor International Airport in Maine says the plane landed there Tuesday morning to refuel and undergo a federal customs inspection before heading to Atlanta.

Writebol will be treated at an isolation unit at Emory University Hospital in Atlanta. Dr. Kent Brantly was taken there Saturday.