The Torah mandates that one rise when one’s father passes by as a sign of respect. The HIDA (LeDavid Emet) writes that so long as one’s father is standing, one is obligated to remain standing in his honor. Based on this, there developed a custom, especially in the Moroccan community, for a child to stand when his father receives an Aliya. A child should stand up from the time that the father goes up for the Aliya until he finishes the final blessing after reading. Furthermore, there are those who go up to the Teva after the father finishes the Aliya to kiss him, as a sign of respect.
Rabbi Avraham Amar (comments -Magen Avot OH) writes that in his city of Meknes, the custom was that one is only obligated to stand for one’s father as he passes by, but is not obligated to stand for one’s father’s the entire Aliya. He explains that as long as one’s father is not in one’s four Amot there is no obligation to stand. Furthermore, just as one stands for the Torah but then sits down when it is placed on the Teva, so too for one’s father, one can sit when he arrives at his place to read from the Torah. Nevertheless, this seems to contradict the conventional understanding of the Halacha which states that one must stand for one’s father so long as he is in one’s sight, even beyond four Amot.
Summary: One must stand for one’s father who is receiving an Aliya to the Torah. The common custom is to stand for the entire duration of the Aliya.