Learning Objective 062.07.05.05.05: Explain why an RNP APCH to LNAV/VNAV minima based on Baro-VNAV may only be conducted when the aerodrome temperature is within a promulgated range if the barometric input is not automatically temperature-compensated.

Effects of Cold Temperature on Baro-vertical Navigation (VNAV) Vertical Guidance

Non-standard temperatures can result in a change to effective vertical paths and actual descent rates when using aircraft baro-VNAV equipment for vertical guidance on final approach segments. A lower than standard temperature will result in a shallower descent angle and reduced descent rate. This is because a parcel of air loses pressure with height at a higher rate when cold, so set "pressure columns" are smaller in cold air and taller in warm air,

Conversely, a higher than standard temperature will result in a steeper angle and increased descent rate. Pilots should consider potential consequences of these effects on approach minima, power settings, sight picture, visual cues, etc., especially for high-altitude or terrain-challenged locations and during low-visibility conditions.