Which is the correct list of flight director vertical modes?

The selection of the vertical modes in a flight director system is crucial for understanding how the aircraft manages altitude and vertical speed during different phases of flight. In this context, the correct choice identifies the typical vertical modes that define the system's capabilities.

The listed modes include vertical speed (VS), which allows for manual or automated control of the aircraft's vertical speed; altitude (ALT), which maintains a specific altitude; VNAV, or vertical navigation, which is used for managing vertical profiles according to the flight plan; PTCH, which often correlates to pitch control; FLC, or flight level change, which manages the climb or descent to reach a target altitude; and ALTS, which maintains a specific altitude with no change in vertical speed.

B is correct because it encompasses the essential vertical modes commonly used in flight director systems. This set accurately reflects the operational functionalities pilots rely on for managing altitude in various flight situations, ensuring that the aircraft operates safely and efficiently during climbs, descents, and level flight.

While other choices present combinations of terms that might be relevant to flight operations, they do not capture the complete and accurate set of vertical modes utilized by flight directors in a standardized manner, particularly with respect to VNAV and FLC, which are critical