Definition
A navigation system function that uses barometric altitude information from the aircraft's altimeter, combined with a published vertical path angle, to compute and display a continuous descent path on certain instrument approach procedures. Baro-VNAV provides vertical guidance to a Decision Altitude on approaches such as RNAV (GPS) approaches with LNAV/VNAV minimums, and its accuracy depends on the local altimeter setting and outside air temperature being within published limits.
Plain English
A system that uses the aircraft's altimeter (which measures air pressure) along with the planned approach path to show the pilot a smooth, steady glide down to the runway. Because it relies on air pressure, it only works correctly when the altimeter setting and temperature are within the limits printed on the chart.
Context Anchor
Seen on instrument approach charts and in aircraft equipment descriptions, especially when an approach allows vertical guidance based on the aircraft’s barometric altitude system.
Derivation
Baro is short for barometric, from the Greek baros meaning weight or pressure — the same root as in barometer. VNAV stands for Vertical Navigation. Together the term tells you the vertical guidance is being calculated from air pressure, not from a satellite-based or ground-based glideslope signal.
Why Pilots Care
It provides vertical guidance on approaches where ground-based glideslope or WAAS is unavailable, expanding the number of usable precision-like procedures.
Intuition Check
Do not assume Baro-VNAV is the same as a runway radio glidepath. It creates vertical guidance from the aircraft’s barometric altitude system, so the pressure setting and temperature limits matter.
Example Sentence 1
We briefed the RNAV approach using LNAV/VNAV minimums, since the temperature was within the Baro-VNAV limits printed on the chart.
Example Sentence 2
Before beginning the descent the crew verified the current altimeter setting so the Baro-VNAV path would remain accurate.