If a child has sickle cell anemia, wouldn't both the parents need to have sickle cell trait?

Yes: In order to have sickle cell anemia, a child must have inherited 2 abnormal genes for hemoglobin (the part if the red blood cell that carries oxygen), one from each parent. There are many genetic types of "sickle cell disease", but usually at least one true sickle gene is involved.

No: There are varying forms of sickling diseases, however it is a recessive trait and so the parents may appear fine but carry the trait and yet have a child with the disease.