Which factor influences the relationship between CAS, TAS, and Mach while climbing?

The relationship between Calibrated Airspeed (CAS), True Airspeed (TAS), and Mach number during a climb is significantly influenced by environmental temperature. As altitude increases, the temperature typically decreases, affecting the air density and subsequently impacting the true airspeed.

In essence, true airspeed is the actual speed of the aircraft relative to the surrounding air mass, and it is directly influenced by temperature. Warmer air at a given altitude results in a higher density and thus affects the TAS for the same CAS and Mach number.

As the environmental temperature decreases at higher altitudes, the density of the air also decreases, leading to an increase in TAS for a given CAS. Similarly, the Mach number, which is the ratio of the aircraft's speed to the speed of sound, is also impacted by ambient temperature because the speed of sound changes with temperature.

Factors like pressure altitude and indicated airspeed do play roles in understanding aircraft performance and speed but do not have the direct impact on the relationship between CAS, TAS, and Mach in the same way that temperature does. Engine thrust is more related to the performance and power available rather than directly influencing these airspeed relationships.