The fly mode can be changed in the Settings Panel
To use the helicopter mode you should have a three button mouse. If you only
have a two button mouse the third button can be simulated by pressing and
holding down Ctrl while using the left mouse button. The helicopter mode is nice
when you want to take a closer look at something. This mode is operated with only
the mouse. Holding down the left mouse button and moving the mouse forward or
backwards will make you fly forwards or backwards and by moving the mouse to the
left or right you will turn to the left or right. Holding down the middle mouse
button and moving the mouse forward or backward will make you move upwards or
downwards and by moving the mouse to the left or right you will move to the left
or right. Holding down the right mouse button and moving the mouse will make you
able to adjust your direction. You can't hold down more than one button at the
time.
Note: Sometimes you may lose functionality if you by accident hit the Ctrl key,
if this happens, try pushing the Ctrl key again.
In this mode you will need the left mouse button, <+> and <-> or <up arrow> and <down arrow>. Pressing <+> or <up arrow> will increase your speed. Pressing <-> or <down arrow> will decrease your speed. You fly by pressing and holding the left mouse button, and stop by releasing the left mouse button. By moving the mouse in different directions you will be able change your flying direction. Depending on you computer hardware you can experience lag and slow system response if you fly at tremendous speeds (e.g. 10000-15000 km/h or more) this is normal and you should decrease your speed to get back normal system response. In plane mode you can also perform rolls and spins by pressing the <R> key. This key toggles on/off the ability to spin around your own axis.
Locked mode is similar to helicopter mode but in this mode you can fly with constant altitude. You can change your altitude as you do in the helicopter mode, but while flying your pitch will not have an impact on the altitude. This mode is good for keeping a certain hight and pitch.
In this mode the camera will point straight down. You operate this mode with the left and middle mouse button (you can also use the right button as middle button in this mode). Use the left mouse button to navigate up, down, left and right. The middle button will as in helicopter mode change your altitude.