There are two primary contexts for the "Sierra" terminology in A320 operations:
A. Procedure Nomenclature (SID/STAR): In certain airports, procedures may be labeled with the suffix "S" (Sierra). For example, a "DEPARTURE 1S" or "ARRIVAL 1S." sierra pattern a320
B. The "Dive and Drive" / High-Energy Approach (Colloquial): Anecdotally, a "Sierra pattern" may refer to a non-precision or visual approach executed with excessive airspeed and altitude (High and Fast). There are two primary contexts for the "Sierra"
The pattern activates instantly when the pilot pushes either Thrust Lever from the CL (Climb) or IDLE detent to the TO/GA (Takeoff/Go-Around) detent, provided: Critical Note: On the A320, pushing the levers
Critical Note: On the A320, pushing the levers to TO/GA does NOT require pressing the takeoff/go-around button on the thrust levers (if equipped). Moving the levers physically into the detent is sufficient.
The most famous unpowered glider event was Air Canada Flight 143 (the Gimli Glider), a Boeing 767. The 767 has a superior glide ratio (12:1) and manual reversion (cable controls). The A320 has no manual reversion. Lose all hydraulics (impossible unless RAT fails), and you lose control.
The A320's closest near-miss occurred in 1994 over Afghanistan. A Ariana Afghan Airlines A320 ran a tank dry, then the crossfeed failed. The crew descended from FL 330, and the captain manually pumped the fuel by cycling the boost pumps—an ad-hoc Sierra Pattern. They restarted at 12,000 feet.