"She was in the same room that the nose of the plane hit," said Dr Marc Benhuri, the brother-in-law of Ilana Benhuri, 50.
"I'm telling you it's an absolute miracle that she's alive. I honestly believe that God was sitting on her shoulder."
Ms Benhuri was doing paperwork at her desk when she heard the small plane outside her 40th-floor apartment, Marc Benhuri said.
The housekeeper saw the plane coming toward her and rushed into the other room to get her.
He said the plane crashed into the apartment as they were trying to make their way out, with the flames scorching her back and legs.
The women closed the door of the room where the plane hit, then closed the front door and ran down a fire escape to safety, he said.
Closing the front door of the fiery apartment probably saved their lives, the woman's brother-in-law said.
"She ran fast. That was a miracle. I don't know how she made it," said Dr Parviz Benhuri, Ilana's husband.
He said his wife, hospitalised in fair condition today, "has very good spirits".
"She has a burn from her lower back all the way to the ankles,"
Marc Benhuri said.
"She's in a lot of pain. She has a very big neck brace."
The Benhuris' housekeeper, Eveline Reategue, escaped serious injury.