Which position is not valid for placing a colonel?

The role of a colonel typically encompasses positions that require significant leadership and command experience, as this rank is generally indicative of a senior officer with substantial responsibilities. Positions such as squadron commander, wing commander, and group commander are all roles that can legitimately be held by a colonel, as they involve leading large units and have elements of strategic oversight that align with the duties expected of a colonel.

The deputy commander position, however, is often filled by officers of varying ranks, but it's more common for this role to be assigned to officers ranked lower than colonel. In many organizations, the deputy commander serves as a support role to the commander, and while it's possible for a colonel to take on this role, it is less typical and does not align with the usual trajectory of a colonel's career path. Colonels are generally expected to command and lead at higher levels rather than serve as deputies, which contributes to the conclusion that placing a colonel in the deputy commander position would not be valid in many contexts.