There are numerous things in aviation that are not at all intuitive and, in fact, run counter to "common sense" as defined by our earth bound experiences. These things include the various ways of reckoning speed and altitude. So this section answers a number of common questions related to speed and altitude, and the effects that varying temperatures, air density and instrument errors affect the way we fly and flight plan.


• What are the various "speeds" used in aviation?

• What are the various "altitudes" used in aviation?

• What are Vx and Vy? Why are two different speeds given for climb?

• What is the difference between true airspeed and indicated airspeed?

• Why does my reciprocating (piston) engine aircraft struggle to climb at higher altitudes?

• Why is my manifold pressure so low at higher altitudes, especially when I have full throttle?

• How do I convert IAS into groundspeed?