Ran scenario with blue as AI against red sub on surface at full speed radar and sonar on at 10km. Blue ships allocate only ASROC at target no harpoons. As Don stated player can launch both but is separate engagements.
Note to self and others: The existing missile guidance, eff100() errantly updates steering inertially guided missiles to the target location each game second as well as the 'intercept time'. effect4.c ln 6612, 6673, 7114