TruAirspeed vs CX

TruAirspeed is a True Airspeed Calculator for the iPhone and iPad. It's a bit different from other true airspeed calculators, in which the pressure altitude is an input. This requires resetting the altimeter to the standard sea level pressure of 29.92"Hg to read the pressure altitude. With TruAirspeed, you input the indicated altitude and the Kollsman window's pressure setting — the app then calculates the pressure altitude, density altitude, true airspeed and mach number for you. The calculations involved take full account of compressibility effects, but not shock waves, so it's limited to subsonic, non-transonic flight only. You have a choice of units for inputs and results, and you may choose either a calculator-style keypad (top row: 7-8-9) or a telephone-style keypad (top row: 1-2-3). You may also set a correction factor for your bird's airspeed indicator/pitot-static system, if you know it (mine is 0.95).

Based on the ASA CX-3® Flight Computer for pilots, this CX-3 app makes flight planning simple by taking confusion out of the equation. Fast, versatile and easy to use, the CX-3® delivers accurate results quickly and efficiently. Whether used for flight planning, ground school, or FAA Knowledge Exam preparation, the menu organization reflects the order in which a flight is normally planned and executed, resulting in a natural flow from one function to the next with a minimum of keystrokes. Multiple aviation functions can be performed on the CX-3® flight computer including those related to time, speed, distance, heading, wind, fuel, altitude, cloud base, standard atmosphere, glide, climb & descent, weight & balance, as well as a holding pattern function to help determine entry method and holding details. The CX-3® has 12 unit-conversions: Distance, Speed, Duration, Temperature, Pressure, Volume, Rate, Weight, Rate of Climb/Descent, Angle of Climb/Descent, Torque, and Angle. These 12 conversion categories contain 38 different conversion factors for over 100 functions. A calculator, clock, timer, and stopwatch are also built in along with multiple settings for lighting, backlighting, themes, time zones and more.