Final answer:
In aviation’s F/MDS on the PFD, white text represents active modes or states currently in use, such as speed and altitude. Yellow text is used for cautionary information, warnings, or out-of-range values that require a pilot's immediate attention for safety.
Step-by-step explanation:
In the context of aviation and specifically the Flight Management/Guidance System (F/MGS) displayed on the Primary Flight Display (PFD), text color is used to convey specific information about the aircraft's status. White text typically represents the current active modes or states of the system that are engaged or in use. For example, the white text may indicate the current speed, altitude, heading, or other relevant information that the pilot is actively managing or monitoring.
In contrast, yellow text or amber text is usually indicative of cautionary information or a warning. This might represent out-of-range values, system cautions, alerts for the pilot's attention, or statuses that require immediate action to maintain the safety and stability of the flight. It is a color used across the cockpit for highlighting items that need immediate attention or are not functioning as expected. By standard cockpit color conventions, yellow is chosen for such warnings because it stands out against the normal blue and green hues typically used for other pieces of information.