Final answer:
SRS, or Speed Reference System, becomes active during the takeoff and initial climb phases of a flight for Airbus aircraft. It guides the aircraft to follow the best climb speed until reaching the acceleration altitude or when a different vertical mode is engaged.
Step-by-step explanation:
When we refer to SRS in the context of aviation, it generally stands for Speed Reference System, which is a part of the aircraft's Auto Flight System in Airbus aircraft. The SRS plays a crucial role during the takeoff and initial climb phases of a flight. It becomes active once the aircraft has been configured for takeoff (which involves settings such as flaps/slats position) and the takeoff phase is engaged by the crew.
Once active, the SRS provides guidance in pitch for the aircraft to follow the best climb speed, also known as V2, or another target speed set by the pilot. It remains in use until another vertical mode is selected or the aircraft reaches the acceleration altitude set before the flight, at which point the pilot typically switches to a different vertical mode such as climb or cruise. This is a critical system as it ensures the aircraft maintains a safe and efficient speed and trajectory during the critical phases of takeoff and initial climb.
Understanding the activation and operational parameters of SRS is a critical part of pilot training and cockpit resource management. It plays a significant role in ensuring the safety of the aircraft and its occupants right from the initial stage of flight.