I'm having trouble with VNAV descent. I'll be in cruise at, say, FL320. Just before TOD I enter a lower alt. in the MCP, but when I cross TOD the aircraft fails to descend and I get a message "PTH DES UNAVAILABLE" in the FMC scratch pad. Any idea what I'm doing wrong. On the -400 I use the same method and the aircraft will descend, following the alt. and speed restrictions.Dave F.

Do you have an END OF DESCENT POINT? What is your route? What that message means is a computed PATH is not availible. Solution is to select a SPD DESCnet OR construct an acceptable PATH...[h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/betaimg.jpg

Yup, you need to place at least one altitude restriction otherwise what path is it going to follow?

I had a STAR programed with altitude restrictions showing on the legs page. I must be doing something wrong. I'll scan the manuals again.Thank's anyway,Dave F.

That is not an E/D, choose a runway and all should be well ;)...[h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/betaimg.jpg