5 C.F.R. § 842.405
Air traffic controllers, firefighters, law enforcement officers, and nuclear materials couriers
The annuity of an air traffic controller retiring under § 842.207 or a law enforcement officer, firefighter or nuclear materials courier retiring under § 842.208 is—
(a) One and seven-tenths percent of average pay multiplied by 20 years; plus
(b) One percent of average pay multiplied by the years of service exceeding 20 years.