Which condition indicates an increasing airspeed in a spiral?

The condition that indicates an increasing airspeed in a spiral is characterized by the airspeed increasing through 160 KIAS. When an aircraft is in a spiral descent, it typically experiences changes in both altitude and velocity due to the centrifugal forces acting on it. If the airspeed is increasing, it signifies that the aircraft is likely entering a more dynamic flight regime where the forces contributing to the spiral motion (such as bank angle and load factor) are causing the speed to climb.

In this scenario, as the aircraft's angle of descent sharpens, the increase in airspeed can be attributed to the combined effects of gravity acting on the aircraft as well as reduced drag at higher speeds, resulting in a continuous build-up of momentum. This understanding is crucial for pilots in recognizing the aircraft's behavior during such maneuvers and managing airspeed to maintain control and prevent undesired aircraft states.

Consequently, identifying airspeed increasing as it passes this specific threshold (160 KIAS) is essential for situational awareness and effective flight management.