Deutschmark, thank you very much for your reply.
If we use only the keys, how can the constant pitch (climb, cruise or high-speed) be used?
You see, we choose the plane with this very parameter but at same time we do not define its meaning.
Certainly we may use the keys, but this is possible for the variable pitch.
And that is the contradiction, because in order to use the constant pitch we have to use the variable pitch!