Which situation requires a pilot to report changes in true airspeed?

Reporting changes in true airspeed is crucial for maintaining safety and effective communication between pilots and air traffic control. The requirement to report a change of 5% or 10 knots in average true airspeed is based on standard procedures aimed at ensuring that flight operations remain predictable and manageable for all aircraft in the vicinity.

When true airspeed changes significantly, it can impact the aircraft's performance, fuel efficiency, and overall flight profile. Such changes may also affect separation distances between aircraft, particularly in busy airspace where accurate positional information is vital. By adhering to the 5% or 10 knots threshold, pilots provide important data that helps ATC adjust their traffic management and maintain safe distances between aircraft. This requirement ensures that both the pilot and air traffic control have a clear understanding of the aircraft's status during the flight, contributing to overall flight safety.

In contrast, the other situations listed do not prescribe a specific requirement for pilots to report changes in true airspeed. For instance, an ATC request may or may not pertain to airspeed changes specifically, turbulence does not inherently necessitate a speed report unless it directly impacts the specified thresholds, and flying through restricted airspace is more focused on compliance with airspace entry and exit protocols rather than airspeed