"His doctor's appointment is on which date?"
Translation:Aia kona hālāwai kauka ma ka lā ʻehia?
This question does not fit the ʻO equational pattern. @jdmcowan explains: Because it's indicating a location in time, not a time equivalence. In other words, the "is" here is not saying the two things are one in the same, but rather that you are indicating when or where something is happening.