He and his father were going to the Grand Canyon, then would spend a week rafting down the Colorado River, and finally go on to Disneyland.
This is a fragment from a book. The narrator speaks in the past tense about future. The trip mentioned in the fragment was planned in advance. So I understand why author used "were going". But it is followed by "would spend".
Does that mean the narrator is uncertain about whether the actions "a week rafting down the Colorado River" and "go on to Disneyland" will happen? And if not why did he use the present conditional?