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JSACKS

Using VNAV below 10,000' (in descent)

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Today I was desc in VNAV PATH below 10,000' with a commanded SPD of 240 and the speed then bled off slowly to IAS 230 by about 9000'; it then slowly adjusted to 240 by about 7500'. If the speed bleeds off like this, can VNAV disconnect? How big a margin is there under 10,000'?Jonathan


Jonathan Sacks

Dell XPS Gen 4, Pentium IV Northwood extreme 3.8Ghz, 3Ghz RAM, eVGA 7900 GTO,

12 GoFlight modules plus MCP-PRO AP and EFIS, GF pedestal, CH rudder pedals,

CH throttle quadrant, 42" LG LED, 24" DELL LCD, Windows XP, FS2004, FSUIPC 3.96

FS Autostart 1.1 (Build 11), FS Navigator 4.6, UT, FE, GE, REX, PMDG, Level-D, PSS, etc.

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Jonathan,No, VNAV will usually not disconnect. When airpspeed gets more than 10 knot below the target speed of 240 knots, the auto throttle adds thrust as needed to get the airspeed back near the target speed. Floyd


John Floyd

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Guest Ross

VNAV will disconnect if you are in Speed managed descent ie, VNAV SPEED mode. It would not really allow a deviation of 10kts in the first place.

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In PATH, VNAV will disconnect 15 knots over target (in this case 255). This can happen OFTEN. If one's speed is high coming at the airport restriction (10000), then can can almost expect a VNAV disconnect. Manage your speed on the way down in PATH since PATH does not keep speed unless you get quite slow and it's only help too fast is AFDS reversion to LVL CH. In SPD, well it is on no path per se, only one that keeps the target so no it will not.Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/southparkcartmad.gif[h3]PMDG 747![/h3]Caution! Not a real pilot, but do play one on TV ;-)ASUS KV8 DLX | AMD 3200 64 | 1 GIG PC 3200 DDR | GIGABYTE 5700 ULTRA | ViewSonic VP192b 19" |


Randy J Smith

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Thanks for this reply Floyd. I only descend in VNAV PATH.JS


Jonathan Sacks

Dell XPS Gen 4, Pentium IV Northwood extreme 3.8Ghz, 3Ghz RAM, eVGA 7900 GTO,

12 GoFlight modules plus MCP-PRO AP and EFIS, GF pedestal, CH rudder pedals,

CH throttle quadrant, 42" LG LED, 24" DELL LCD, Windows XP, FS2004, FSUIPC 3.96

FS Autostart 1.1 (Build 11), FS Navigator 4.6, UT, FE, GE, REX, PMDG, Level-D, PSS, etc.

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Thanks, Randy.JS


Jonathan Sacks

Dell XPS Gen 4, Pentium IV Northwood extreme 3.8Ghz, 3Ghz RAM, eVGA 7900 GTO,

12 GoFlight modules plus MCP-PRO AP and EFIS, GF pedestal, CH rudder pedals,

CH throttle quadrant, 42" LG LED, 24" DELL LCD, Windows XP, FS2004, FSUIPC 3.96

FS Autostart 1.1 (Build 11), FS Navigator 4.6, UT, FE, GE, REX, PMDG, Level-D, PSS, etc.

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