Question 1582Navigation General

You are correct, the answer is A) inaccuracies in the reference level. When correcting apparent altitude to observed altitude, you do not apply a correction for inaccuracies in the reference level. This is because the reference level, typically the visible horizon, is used as the starting point for the altitude measurement. Any errors or inaccuracies in the reference level are already accounted for in the apparent altitude. The other options are incorrect because you do need to apply corrections for the bending of light (option C), the equivalent reading to the center of the body (option D), and the equivalent reading from the center of the Earth (option B) when correcting apparent altitude to observed altitude.