vnav

[jc_150 3]

Hi all at pmdg and the forum. I have flown many successful flights with the 737-700,but 1 small detail is bugging my lack of knowledge at this moment in time, so hoping someone can enlighten me. What are the conditions of flight when VNAV passes control back to SPEED. ie one cannot press VNAV to let the FMC control the speed. On my last flight i seemed to be configured correctly from cruise and decent but the system would not allow me to press VNAV, it worked realy well with manual speed control from the autopilot panel, but just want to know what area i am not configuring correctly for VNAV to be able to take control..( on this flight I manually adjusted the speed and altitude acording to what was on the legs page and it was fine) thanks in advanceJohn Calleja

[crvm 0]

Below 10000 you must be with 15 knots of the target, above this altitude it should take well above that...[h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/betaimg.jpg

[Orlaam 306]

Hey Randy, how does this work? When I descend into an airport I get about 15 miles out and the VNAV disconnects, then the speed stays at 240 and the plane levels off way above what the target altitude is in the FMC and MCP. This always causes an overshoot, yet this never happened in SU1. What am I doing wrong? I put lower speeds into the FMC, but the plane stays at 240?Also, I tried the plane in 2004, however, the takeoff behavior was completely different. In 2002 it slowly follows my pitch via manual control and the speed slowly climbs per flap retraction. Then at about 4000 AGL I engage AP with V/LNAV, which seems to work as far as my knowledge of the NG goes. In 2004, during manual climb (no AP or CWS) the bird gained enough speed to retract to flaps 1 but suddenly lost power and speed. This was all different than its actions in 2002.Also, how do I set the fuel in 2004?? It reports overweight, yet my load manager is about 3/4 max weight. The fuel numbers aren't the same as 2002? This was confusing to me. I did however still have an empty center tank and know this wasn't the cause of my loss of speed during climb.ThanksChris

[crvm 0]

VNAV will DISconnect for a number of reasons, what does the CDU's SCRATCHPAD message tell you? AT G/S capture, VNAV will DISconnect, if you have a restriction that the FMC is unable to fly you will get a disconnect. Read the message and I can tell you exactly unless at G/S. I only fly 2004 so cannot help you there. I climb V2 +15-20. It's either 1500 or 3000 dependng on the noise abatement. Works just perfect for me. They set it so it would NOT be overweight, so you will have to review what you are loading. Screenshots help a lot *HINT HINT* ;)[h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/betaimg.jpg

[Orlaam 306]

I will try and gather some screenshots. I don't use LOC or APP when on approach. I usually fly AP V/LNAV until the altitude I select on the MCP is level and then disconnect everything to fly the final by hand. I will some other things and get some screens.Thanks,Chris

[crvm 0]

Ah ok, you CAN take VNAV down to the runway, make sure to set the MCP to 0 and reclick VNAV, elimniate all other restrictions on the LEGS page and create one for the threshold. This should work although I have not tried it myself..[h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/betaimg.jpg

[Orlaam 306]

Randy, here's some screens on a flight in FS9. One thing I noticed, was that unlike my 2002 install, the flaps display in zoom didn't show up on the engine CRT. I did, however, figure out my fuel issue in FS9, I didn't have weight checked :-rollI had to leave the h off of http, otherwise each picture was showing! So just add the h in-browser.My load out for FS9 (same as 2002):ttp://members.cox.net/orlaam/COF_Load.JPGRoute page 1 and 2:ttp://members.cox.net/orlaam/FMC_RTE1.JPGttp://members.cox.net/orlaam/FMC_RTE2.JPGPerformance Page:ttp://members.cox.net/orlaam/PERF_INIT.JPGTakeoff Reference:ttp://members.cox.net/orlaam/TAKEOFF_REF.JPGClimb Page:ttp://members.cox.net/orlaam/CLB_PAGE.JPGRoute with Hold (what do I enter in the blank spots, anything?):ttp://members.cox.net/orlaam/RTE_HOLD.JPGRoute modifications to speed (didn't do anything on descent):ttp://members.cox.net/orlaam/RTE_SPD_MOD.JPGPre-flight Overhead:ttp://members.cox.net/orlaam/OVHD.JPGTakeoff was perfect and so was Cruise:ttp://members.cox.net/orlaam/CRZ.JPGInitial Descent (all was perfect):ttp://members.cox.net/orlaam/DESCENT_1.JPGDescent where VNAV disconnects, however, I had 7700 in MCP. Then it levels off at 9780 and spools back up to 240 KIAS? I had to select a lower speed (130 in this case) and push V/S (ALT HOLD) to -2200 to descend enough to land manually. It was a steep descent.ttp://members.cox.net/orlaam/DESCENT_2.JPGWhat am I doing wrong? Is thing normal or how a real pilot would handle a late AP disconnect to manually land? I like to fly pretty close to the "5 mile final" before I disconnect AP and hand fly. I usually line my route up to the runway so I have time to lower flaps, gear, and arm autobrakes and spoilers. I'm trying to steer away from the AP autolands since I want to work towards longer hand-flown approaches. Any help is appreciated!!Chris

[crvm 0]

I cannot access your account to view the screenshots ;( Ok, let's tackle DEScent. 1] Why do you have the MCP set to 7700? Set this to the FAF (your final appproach fix altitude)altitude.2] What you are seeing is the aircraft slowing for the default airport restriction of 250/10000' (The FMC by default goes 240/ to give a 10 knot *buffer*). Notice 2 GREEN DONUTS on the ND (navigation Display) along the magenta path line. The first donut VNAV will start pitching to slow before reaching 10000', the second donut the aircraft will resume it's descent. If you might need to put out the boards to help slow before the second donut. 3] You can stay in VNAV all the way to G/S capture (if desired and ATC not giving you vectors etc, even then you might be able to keep VNAV if the worload is not bad otherwise you can go V/S).4] You want to be configured correctly by your 5 mile final. I leave the details up to you. Not all pilots disconnect the AP so soon. You can take it to 800 AGL or sooner depending.... It takes some time to peg this correctly, practice practice practice ;)[h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/betaimg.jpg

[Orlaam 306]

I'm gonna head off to bed, getting tired...lol.Can I post the screens here from my site like I started to without penalty. They just seemed large and there were so many, didn't know if this was okay in the forum. I'll post a couple for now, then if it's okay I can post more tomorrow..er..later today ;-)By the way, I set for 7700 so that I was well above the runway and ground, but low enough to descend without a steep pitch. Usually when I do this, the plane (SU1) gives me the altitude I want in the MCP, then I have time to disconnect AP altogether for a manual final. It's simply my way of getting used to finals off of APP/LOC before I try and hand fly longer approaches. I still use the ILS for reference visually and this method helps, as I'm within GS/LOC on the scale. I don't use vectors by ATC though.Speed mods didn't have any effect at waypoints per V/LNAV:http://members.cox.net/orlaam/RTE_SPD_MOD.JPGHere's where the VNAV Disconnect occurred:http://members.cox.net/orlaam/DESCENT_2.JPGMy load out was 100 Pax and about 12250 lbs. I didn't do any modifications in the FMC except on the LEGS page for slower speeds shown above. Takeoff wasn't derated or anything. All normal and no weather.Again, any ideas on what I SHOULD be doing would help. I'd like to know how to get the speed restrictions to work in the FMC if it's possible the way I'm doing it. And I don't understand holds if a go-around is necessary, but I can wait for Tim's tutorial on that.Chris

[Orlaam 306]

BUMP

[Orlaam 306]

Bump?Chris

[crvm 0]

Get rid of the 220/10000, there is a default restriction already for 240/10000 and I think it is having a hard time because you have MADE BIG the SPEED but not the ALTITUDE. Try making the restrictions both big i.e the SPD and ALT. If i recall correctly you must do it that way. Also, tell us your complete route and all restrictions listed. [h4]Best Wishes,Randy J. Smithhttp://www.precisionmanuals.com/images/betaimg.jpg

[Orlaam 306]

Thanks Randy, I have more screens if need be. My route is as follows:Direct --> AVONADirect --> FORPEJ18 --> CHEKRJ18 --> BOLICJ18 --> VERNOJ18 --> SJNJ74 --> DRYHTDirect --> BUREWDirect --> BIBQUThe other waypoints were entered when I selected my landing runway (3). The only restrictions I entered into the route were 220/ at BUREW and 180/ at BIBQU. I left the other setting as they were by default. I wasn't aware I had to also enter the altitude. I can try this next time.Sorry to be a pain Randy, just want to know what I'm doing wrong :)Chrishttp://members.cox.net/orlaam/RTE_HOLD.JPG