On rare occasions. People with sickle cell trait under normal conditions (climate, altitude, normal life style) do not have any symptoms of sicle cell disease. Very occasionally individulas who had severe stressful conditions (boot camp under extreme heat and with dehydration), or worked under significanly reduced oxygen pressure (high altitude) did experieince vaso-occulsive crisis. Or had sudden death.
Sickle cell trait. Sickle cell trait shouldn't cause pain crises like someone with the disease. Sometimes patients are told they have trait but actually have sickle + thalassemia. Trait can cause problems however such as inability to concentrate the urine (isosthenuria), blood in the urine (renal papillary necrosis), kidney cancer, and sudden death if the patient gets dehydrated during vigorous physical exertion.