For purposes of deciding whether to use the "simplified method" or the "general rule," is the annuity portion of Federal FERS retirement a "qualified plan"
Yes, FERS is a qualified retirement plan.
Refer to U. S. Office of Personnel Management FAQ Is my pension from OPM a "qualified" or "non-qualified plan"?
... and you would use the Simplified Method if the correct taxable amount is not shown in box 2a of the 1099-R.