Final answer:
The 80kt call-out is an aural alert used to confirm the aircraft has reached 80 knots during takeoff, ensuring airspeed indicators function correctly, and the aircraft is accelerating as expected before reaching the critical decision speed V1.
Step-by-step explanation:
The 80kt call-out is an aural speed alert heard in the cockpit of an aircraft during takeoff. This call-out is typically part of standard operating procedures (SOPs) to inform the crew that the aircraft has reached 80 knots during its takeoff roll. This speed is significant because it is often the final checkpoint before the aircraft reaches V1, which is the decision speed at which pilots must commit to taking off because there is insufficient runway remaining to stop safely.
The alert serves several purposes, including verification that the airspeed indicator is working properly, a cross-check for the pilots to ensure that the aircraft is accelerating normally, and validation that the takeoff can proceed safely. It is one of a series of critical speed call-outs made to enhance situational awareness and ensure the safety of flight operations.