Why is it that Noach sent out the birds to see if the flood had subsided, and when he did find out he just waited for Hashem to tell him to leave? Why send the birds if you are going to wait for Hashem to leave the ark anyway? And why did he not just ask Og who was hanging on outside as described in Pirkei R' Eliezer (23)?
Rabbi Yonasan Grossman from Yeshiva Har Etzion explains as follows.
Although he may have been able to tell at Mount Ararat what the situation was, Noach also wanted to know what the situation was in locations that were further away.
Noach was waiting for Hashem to tell him to leave the Teivah, however he had to do something to show he was interested in leaving. Only after that did Hashem tell him to leave.
In addition, the world was as if created newly again. Just like when the world was originally created the birds were created before the people, the same here the birds went out before the people.