Corrected entry: When the President is firing his F-18's cannon he pulls the trigger. The trigger operates the radio. The same button that fires missiles fires the cannon, the pilot has to select which one first with the 'hat' switch in the top middle of the joystick.
Grumpy Scot
18th Oct 2009
Correction: The hat switch is for pitch and roll trimming, the castle switch is for sensor control. The upper left switch is weapon release (preps missiles for firing) and the trigger fires either the cannon or missile, depending on what's selected.