The task definition for slow flight in the Airmen Certification Standards (ACS) is changing, again. When the private pilot ACS were finalized in June 2016, the FAA changed the definition of slow flight to maintenance of "an airspeed, approximately 5-10 knots above the 1G stall speed, at which the airplane is capable of maintaining controlled flight without activating a stall warning." This was a marked change from the definition long found in the now superseded Practical Test Standards (PTS). Pilots, for many years, had demonstrated slow flight by maintaining "an airspeed at which any further increase in angle of attack, increase in load factor, or reduction in power, would result in an immediate stall." The FAA said the reason for the change was to discourage teaching pilots to disregard a stall warning indication. Under the PTS standards, typically the entire maneuver was performed with the stall warning horn sounding.
This is a companion discussion topic for the original entry at https://www.avweb.com/news/faa-fiddles-with-slow-flight-phraseology