Hi,I found an unusual behaviour yesterday. I was at FL370 and decided to step climb to FL410. I got up there but then discovered that I was hard pressed to maintain mach 0.76 at FL410, so I decided to step back DOWN to FL370.The climb up to 410 went just fine. I entered 410 into the FMC CRZ page for altitude, selected 41000 on the MCP altitude window and re-engaged VNAV. The engines then spooled up to max CRZ thrust and I climbed fine. Stepping back DOWN was the problem. I entered 370 in the FMC CRZ page, selected 37000 in the MCP altitude window and re-engaged VNAV. Instead of the engines spooling down for the descent, they spooled all the way up to max CRZ thrust as if I were climbing. The plane did pitch over and descend, but at max thrust.I switched it out of VNAV and into LVL CHG soon and this spooled the engines down. Also, once I saw this I tried it out on several flights to make sure it wasn't just a fluke. It happens every time and doesn't seem to be dependant on the flight plan or anything, so it should be easy to reproduce.-Shaun

It's not a new VNAV bug.... It's a old one ;-)Cruize descents are implemented correctly in SU2....cheersanthonyAnthony MertonPrecision Manuals Developmenthttp://www.precisionmanuals.com

Oh, ok. Sorry, I had not seen this one posted so I thought I'd better post just to be on the safe side. :)-Shaun

Don't be sorry.It was not posted before (AFAIK)You did the right thing ;-)anthonyAnthony MertonPrecision Manuals Developmenthttp://www.precisionmanuals.com