In an RNAV approach to LNAV/VNAV minima, what is VNAV based on?

In an RNAV approach to LNAV/VNAV minima, the VNAV (Vertical Navigation) capability is primarily based on SBAS (Satellite-Based Augmentation System) or BaroVNAV (Barometric Vertical Navigation).

SBAS enhances the accuracy and integrity of GNSS signals by providing correction and augmentation data that enables more precise navigation information, which is crucial for vertical guidance during an approach. This system is particularly beneficial for achieving the required vertical performance, especially in a terminal environment where precision is essential.

BaroVNAV, on the other hand, utilizes the aircraft’s barometric altimeter to determine its vertical position relative to a predefined vertical profile. This method is capable of providing accurate altitude information as long as the altimeter settings are correctly managed throughout the flight, especially during the approach phase.

Together, these systems enable aircraft to utilize vertical navigation when approaching the runway, ensuring that they can adhere to the restrictions and guidance necessary for safe operation while maintaining compliance with the prescribed approach procedures. Thus, the integration of SBAS or BaroVNAV technologies fulfills the required vertical navigation criteria for RNAV approaches classified under LNAV/VNAV minima.