Final answer:
The HDG reversionary key is applicable to an MFD (Multi-Function Display) gauge. The HDG reversionary key is used on an aircraft's Multifunction Display (MFD) to revert to the primary navigation mode, which shows the aircraft's heading on the Horizontal Situation Indicator (HSI) gauge.
Step-by-step explanation:
The HDG reversionary key is applicable to an MFD (Multi-Function Display) gauge. The HDG reversionary key is used on an aircraft's Multifunction Display (MFD) to revert to the primary navigation mode, which shows the aircraft's heading on the Horizontal Situation Indicator (HSI) gauge.
The HDG reversionary key is applicable to the Horizontal Situation Indicator (HSI) gauge on a Multifunction Display (MFD) in an aircraft's cockpit. The HDG key is used when a pilot needs to switch the MFD's display back to the primary navigation mode, which typically displays the aircraft's heading, among other navigational information. This functionality is important in situations where the primary navigational display fails, and the pilot must revert to the HSI display on the MFD to maintain situational awareness and control of the aircraft. It's a safety feature included in sophisticated avionics systems.
The High Definition Graphics (HDG) reversionary key is a feature commonly associated with Multi-Function Display (MFD) gauges in modern avionics systems. MFDs are advanced display units in aircraft that integrate and present various flight-related information on a single screen. The HDG reversionary key specifically pertains to the Heading mode or display on the MFD.
In avionics terminology, the Heading mode displays the aircraft's current heading, essentially the direction it is pointing. The HDG reversionary key allows pilots to toggle or revert to a particular mode or source of heading information in case of a system failure or when there is a need to cross-check and validate the data. This feature is critical for ensuring the availability of accurate heading information, which is fundamental for navigation and maintaining the desired flight path.
In essence, the HDG reversionary key enhances the reliability and redundancy of the avionics system by providing a quick and accessible means for the pilot to switch between different sources or modes of heading information displayed on the MFD. This functionality contributes to the overall safety and precision of aircraft navigation during various flight phases.