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gbalean

FMC Quick Question

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Hi All,Well, it seemed my other question in relation to SquawkBox didn't reveal any answers for me, however I have just had this problem and need to get to sleep, so I thought asking you all might be a bit quicker and less effort than looking through the manuals (if it even is in there).On my flight yesterday I had a problem in that when I'd taken off I switched to LNAV at 400ft, however I received a radar vector and had to maintain altituded thereafter. When I was finally able to engage VNAV at much greater than 3000ft AGL (therefore off both lateral and vertical track), it would not engage, stating 'Unable cruise alt', although I got there easily when I had to regretfully use VSpeed instead. I believe it may have something to do with the estimated fuel at arrival being 0.0, although I did have plenty when I arrived (in a previous post I recall someone saying this was not all together uncommon in the NG series in the realworld also). I was unable to find any other problem, and N1 went into CRZ when we reached the FL390 cruise.Thankyou for any help :D,Geoffrey BaleanCanberra, AU (YSCB)http://www.hifisim.com/images/as2004proudsupporter.jpg http://www.vozvirtual.org/images/pmdgforumsignature.png"Today is the tomorrow you worried about yesterday. All is well!"Pentium 4 2.4GHZ, P4G8X Deluxe with Broadcom NetXtreme Gigabit Ethernet, 512MB RAM, LG Flatron L1710S 17" LCD, GeForce MX440 Millenium Silver, Creative Soundblaster Audigy, Logitech Speakers, CH Yoke & Rudder, Quantum Fireballp AS30.0 - Basically nothing crash hot :)MSFS 2004 acof, PMDG 737 6/7/8/900, Activesky 2004, Flight One Cessna 152, SquawkBox 2.3 w/ guage, ServInfo 2.2, FS AutoStart, FS Real Time, FSUIPC 3.212 (unreg.:()

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>Hi All,>>Well, it seemed my other question in relation to SquawkBox>didn't reveal any answers for me, however I have just had this>problem and need to get to sleep, so I thought asking you all>might be a bit quicker and less effort than looking through>the manuals (if it even is in there).>>On my flight yesterday I had a problem in that when I'd taken>off I switched to LNAV at 400ft, however I received a radar>vector and had to maintain altituded thereafter. When I was>finally able to engage VNAV at much greater than 3000ft AGL>(therefore off both lateral and vertical track), it would not>engage, stating 'Unable cruise alt', although I got there>easily when I had to regretfully use VSpeed instead.Possibly this could be caused from leveling off too long and the current Cruise Altitude in the FMC was now to high. Next time request a low cruise altitude and insert it in the FMC and try VNAV again. Or If the airplane is between the FMC target altitude on the RTE LEGS page for the active waypoint and the manually entered MCP target altitude, VNAV will not engage. To enable VNAV, adjust the FMC or MCP target altitude as appropriate. Floyd I believe>it may have something to do with the estimated fuel at arrival>being 0.0, although I did have plenty when I arrived (in a>previous post I recall someone saying this was not all>together uncommon in the NG series in the realworld also).This is totaly not true. You would not takeoff if the progress page was giving you a arrival fuel of 0.0 and your destination in real world. Floyd I>was unable to find any other problem, and N1 went into CRZ>when we reached the FL390 cruise.>>Thankyou for any help :D,>Geoffrey Balean>Canberra, AU (YSCB)>>http://www.hifisim.com/images/as2004proudsupporter.jpg>http://www.vozvirtual.org/images/pmdgforumsignature.png>>"Today is the tomorrow you worried about yesterday. All is>well!">>Pentium 4 2.4GHZ, P4G8X Deluxe with Broadcom NetXtreme Gigabit>Ethernet, 512MB RAM, LG Flatron L1710S 17" LCD, GeForce MX440>Millenium Silver, Creative Soundblaster Audigy, Logitech>Speakers, CH Yoke & Rudder, Quantum Fireballp AS30.0 ->Basically nothing crash hot :)>>MSFS 2004 acof, PMDG 737 6/7/8/900, Activesky 2004, Flight One>Cessna 152, SquawkBox 2.3 w/ guage, ServInfo 2.2, FS>AutoStart, FS Real Time, FSUIPC 3.212 (unreg.:()

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Hi Floyd!The altitude in the FMC was the same as the one I was at, and I cruised at FL390, the same as was in the FMC. Not sure if I understand your second bit clearly, however when I was and should have been in cruise according to the FMC, it also would not engage.In relation to the fuel, I set off with 5.6 thousand kilos as estimated even after a long taxi (expected) but as the flight progressed and the winds suddenly changed (Activesky w/ wind smoothing and winds aloft calculated in my fuel requirement sheets) the FMC estimated fuel went to 0.0, though I arrived with wings=2x2300kgs and 450kgs in the center, which was even above my expected max landing fuel of 3600 kilos all up. ;) I wouldn't set out with it displaying 0.0 fuel - that's just stupid :)Thankyou again!Geoffrey BaleanCanberra, AU (YSCB)http://www.hifisim.com/images/as2004proudsupporter.jpg http://www.vozvirtual.org/images/pmdgforumsignature.png"Today is the tomorrow you worried about yesterday. All is well!"Pentium 4 2.4GHZ, P4G8X Deluxe with Broadcom NetXtreme Gigabit Ethernet, 512MB RAM, LG Flatron L1710S 17" LCD, GeForce MX440 Millenium Silver, Creative Soundblaster Audigy, Logitech Speakers, CH Yoke & Rudder, Quantum Fireballp AS30.0 - Basically nothing crash hot :)MSFS 2004 acof, PMDG 737 6/7/8/900, Activesky 2004, Flight One Cessna 152, SquawkBox 2.3 w/ guage, ServInfo 2.2, FS AutoStart, FS Real Time, FSUIPC 3.212 (unreg.:()

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Maybe VNAV would not engage at FL390 because:You may have leveled off at FL390 past the TOD point. This can happen when you have an intermediate level off on short flights and fail to get to your planned cruise altitude before the TOD. If this is the problem, insert a lower cruise altitude in the FMC.Or, you may not have had a lower altitude specified on the LEGS page for the FMC to calculate a VNAV PTH descent.Or, maybe LNAV was not engaged.Floyd

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Thanks for the reply again!I was trying to get VNAV engaged right up from climb (after vectors), to cruise, and even when descending. I certainly got to the cruise altitude before the T/D, and the T/D point was still displaying. The legs page might be an issue - I just had the route inserted, not any STAR, however you would usually get that a bit before descent and it normally works fine. VNAV was engaged. Anyway, thankyou for your help Floyd, and I'll check out these things when I next fly, but hopefully the problem won't happen again ;)Geoffrey BaleanCanberra, AU (YSCB)http://www.hifisim.com/images/as2004proudsupporter.jpg http://www.vozvirtual.org/images/pmdgforumsignature.png"Today is the tomorrow you worried about yesterday. All is well!"Pentium 4 2.4GHZ, P4G8X Deluxe with Broadcom NetXtreme Gigabit Ethernet, 512MB RAM, LG Flatron L1710S 17" LCD, GeForce MX440 Millenium Silver, Creative Soundblaster Audigy, Logitech Speakers, CH Yoke & Rudder, Quantum Fireballp AS30.0 - Basically nothing crash hot :)MSFS 2004 acof, PMDG 737 6/7/8/900, Activesky 2004, Flight One Cessna 152, SquawkBox 2.3 w/ guage, ServInfo 2.2, FS AutoStart, FS Real Time, FSUIPC 3.212 (unreg.:()

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