Originally Posted by
cowpatz
Thanks for that. Is my interpretation of the VNAV logic correct in that if you are descending in VNAV SPD for an RNAV approach and your vertical track is approximating the calculated path and you then meet the "On approach" transition will the pitch mode automatically change from VNAV SPD to VNAV PTH or do you need to close the speed window and then open it again to get it out of VNAV SPD and into VNAV PTH?
The speed window closes when the pitch mode changes to VNAV from another pitch mode(such as having selected FLCH for descent where the speed window opened) which happens when you push the VNAV button. Happens as well at 400 feet on a typical departure when VNAV automatically engages from TO/GA pitch mode(because it was armed on the ground).