[redhead]

What is Avion? A struct? A class? Your mothers birthdaypressent ?
The compiler claims to be in need of a constructor for the class, and since you didn't show what it is, I'm assuming you need just that ie:

class Avion{
  private:
    // something hush hush
  public:
    Avion(void) {};   // this is a default constructor for class Avion
                      // Usualy called when using new()
    ~Avion(void) {};  // this is a default destructor for class Avion
                      // Usualy called when using delete()
    ...
};

I belive the default constructor/destructor is described in just about any C++ book describing how to use classes.
But since you didn't provide more than a few lines of code, I could be telling you something which you allready know and are using, and as a result this is just pissing you of.