We are planning an upgrade from 11.5.9/220.127.116.11 to 18.104.22.168/10.2.0.3 for one of our environments. While planning and documenting the steps for the upgrade, I discovered that the sequence of upgrade is different for OLTP and ASCP instances. For upgrades like this the general recommendation is to upgrade the DB first and then upgrade the Applications. This is for a simple reason that the new version of the Database is usually faster than the older one.
For OLTP instance we can upgrade DB first and Applications next.
However for ASCP, 11.5.9 ASCP is not certified to work with Oracle Database 10g. So we first need to upgrade the Applications first from 11.5.9 to 22.214.171.124 and then upgrade the DB to 10g.
Watch out this post for more updates on this upgrade.