Final answer:
The red arrow in the SIDE STICK PRIORITY light indicates which pilot has control priority in aircraft with fly-by-wire systems.
Step-by-step explanation:
The Red Arrow in the SIDE STICK PRIORITY Light
The red arrow in the SIDE STICK PRIORITY light is a feature found in modern aircraft with fly-by-wire systems, such as Airbus aircraft. It indicates that the captain or the first officer's side stick has priority over the other. When one pilot is making an input on their side stick, the red arrow will appear to remind the other pilot not to make conflicting inputs.
For example, if the captain is making a control input to pitch the aircraft up, the red arrow will appear on the first officer's instrument panel, signaling that the first officer should not make any control inputs that oppose or conflict with the captain's command. This ensures that both pilots are not trying to fly the aircraft in different directions simultaneously, which could lead to confusion and potential safety issues.