***Link*** :: [91.173 ATC clearance and flight plan required.](https://www.ecfr.gov/current/title-14/section-91.173) ***Description*** :: `= this.link` ***Author*** :: [[FAA]] #### Key Quotes * No person may operate an aircraft in controlled airspace under IFR unless that person has— * Filed an IFR flight plan; and * Received an appropriate ATC clearance. #source #far