The incident took place on last Sunday, shortly after the Spirit Airlines plane arrived at Portland International Airport.
Police said the incident escalated following landing: "she was upset Ms. Hernandez's children kicked the back of her seat, and stated she told Ms. Hernandez 'to tell her kids to stop it.'"
After landing Walker-Williams reportedly attacked the mother while removing her luggage from the overhead locker.
The two children, aged seven and three years old, were witness to the event.
Neither passenger raised the incident with cabin crew during the flight operated by Spirit Airlines.
The defendant claims Hernandez struck her "on the shoulder" mid-flight, after asking her to control her children.
Walker-Williams said she did not approach flight attendants because her "first reaction was to fight," telling officers: "You do what you got to do."
The Multnomah County District Attorney's Office charged Walker-Williams with assault and harassment.