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jumboross

744 not descending?

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Hello AllI've been back to the 744 today after some time away. Have done two flights with properly programmed FMC with SIDs and STARs etc and have had the same problem twice, so I'm guessing it must be operator error?The aircraft takes off and climbs as it should with LNAV and VNAV engaged, then carries on to cruise as planned. The problem comes at the top of descent, or rather where the top of descent should be. As I reach and pass the little green 'TD' sign on the screen the aircraft just keeps flying at cruise altitude and speed (it does however keep to the correct LNAV profile, i.e. it continues following the purple line). On both occasions I made sure the MCP altitude was set to the next planned waypoint lower altitude. I presume I'm doing something wrong but can't seem to work it out? I've searched the forum and haven't found the same specific problem.Any help appreciated.Thanks,James.

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Hello AllI've been back to the 744 today after some time away. Have done two flights with properly programmed FMC with SIDs and STARs etc and have had the same problem twice, so I'm guessing it must be operator error?The aircraft takes off and climbs as it should with LNAV and VNAV engaged, then carries on to cruise as planned. The problem comes at the top of descent, or rather where the top of descent should be. As I reach and pass the little green 'TD' sign on the screen the aircraft just keeps flying at cruise altitude and speed (it does however keep to the correct LNAV profile, i.e. it continues following the purple line). On both occasions I made sure the MCP altitude was set to the next planned waypoint lower altitude. I presume I'm doing something wrong but can't seem to work it out? I've searched the forum and haven't found the same specific problem.Any help appreciated.Thanks,James.
Hi James!If you selected the next lower altitude on MCP as you said (before reaching T/D)....did you check in your CDU that, you also had a lower Altitude when passing that fix?I guess, you did, but can

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What is the FMA saying? The annuciator is the first place to look when you don't understand what the boxes are doing.

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pretty sure if you wait to ran out of fuel you will descent ... :( sorry cant resist ...

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This happened to me once, and I figured out that it was because I had a holding pattern programmed into the FMC. Once I deleted the holding pattern, the plane then recovered to capture the VNAV descent profile and everything operated as normal from there on out.

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