I have sickle cell trait,i heard being at high altitudes could be dangerous,can taking a 16+hour flight harm me?

Possibly. : Great question. An airplane flight puts you at the equivalent of 8 to 10 thousand feet of elevation depending on the plane. That can cause sickling in patients with sickle cell trait. Ask your doctor whether you should wear oxygen for the flight. Stay very well-hydrated, and keep warm with blankets and layers! If you have trouble on the flight, oxygen is the key.