Enable the "Invincible Aircraft" control setting:

Then, enter one of the following codes during flight to activate the corresponding cheat function:

Cheat Codes:

[Ctrl] + [Tab] Add 500 feet to altitude
[Ctrl] + [Tab] + S Slow motion mode
[Ctrl] + [Tab]+ X Enable joystick

Move anywhere:

Activate cheat mode and the "Enable joystick"
code. Then, repeatedly press one of the following
keys to move your aircraft in the corresponding
direction.

Direction:
Key:

Forward
[Keypad 8]

Backwards
[Keypad 2]

Left
[Keypad 4]

Right
[Keypad 6]

Up
[Keypad 7]

Down
[Keypad 1]