When would the TAS=IAS/CAS? When at sea level, pressure 29.92, and 15 degrees of temperature? What other realistic scenario both of these airspeeds are equal? Because it would be extremely rare to at any given altitude have a pressure of 29.92 and have a standard temp for that altitude I guess right?
Thank you!
True airspeed equals calibrated airspeed whenever the density altitude is zero. This occurs at sea level on a standard day, but can also occur at higher altitudes if it's cooler, or lower altitudes if it's warmer. For example, the density altitude is about 0 at a pressure altitude of 1000 feet when the temperature is $5^\circ\rm C$.
The relationship between indicated airspeed and calibrated airspeed depends on the aircraft. Commonly CAS and IAS are quite close at cruise but quite different in slow flight.
