The 80-year-old woman was not in zero gravity because gravity was accelerating her downward all the time she was weightless (80-year-old woman sets record as oldest to experience zero gravity, Jan. 14 issue).
Objects in orbit are weightless because centrifugal force of rotation is equal and opposite the force of gravity. Physicists don’t want to use the word “centrifugal” and have caused much confusion.
The woman could be weightless for only a short time because the airplane had to change its parabolic path and did not keep out of her downward path of travel.
NASA should realize that it is gravity that holds anything in orbit and it is the opposite centrifugal force that makes things weightless in orbit.
James F. Jackson
Carlisle, Ind.