Thanks Randy. I'll redirect my message to Brad Marsh or anybody who has some real world time on the 737 NG 700 or 800 series..Regards,jack

>Kevin>>I believe your NG is exceeding 250 kts under 10 000' because>you are not following the pitch command on the flight>director. You probably need to increase your nose up attitude.>>>As Kris stated VNAV is a pitch mode, it still requires the>pilot to manually adjust pitch when not using autopilot. The>thrust does not vary to maintain 250 kts. >>Hope this helps, keep asking if it doesn't>>Hans>Hans, I can understand your arguement, but I have to dissagree with you. Kris clearly states "VNAV will maintain 250kt up to FL100 unless the restriction is deleted in the CLB page. VNAV will do this whether the A/P is engaged or not."I interpret this statement as VNAV will dictate the auto-thrust system to ensure 250kts is not exceeded until 10,000ft is reached, no matter whether you are spot on the F/D bars or not. VNAV knows that 250kts under 10,000 is a "Restriction", which it will try it's hardest to adhere to. The airplane doesn't just fly to 260kts (a small overshoot), but it will go straight to ECON CLB speed of around 300kts, which far exceeds any slight overshoot. In addition, I have been flying the F/D bars on the money with this same result.Kevin

"The way that this thread reads seems to me that the pilot in question (Kevin) simply expects the aircraft to fly itself once VNAV/LNAV are engaged, this is not the case if no A/P is engaged then YOU must drive the bus. I may have read this wrong but that is how it reads.The key is to see where the magenta speed bug is driven to when VNAV is engaged. It should drive straight to 250kt then passing FL100 drive to ECON climb speed (around 300 ish) then to ECON Mach then cruise mach! If it drives straight to the 300ish mark then it has ignored the FL100 restriction for some reason!" Well it "appears" to me the other is true Kevin. The magenta SPD BUG does infact give you 250/10000 without the A/P engaged but what it is not giving you is automatic pitch control, only F/D guidence for YOU to follow to maintain the VNAV profile. So far we have one classic driver but no NG pilots commenting on this little tibit so although I believe what I am stating I am still not convinced untill more proof is provided by a NG driver.... Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/Animation1.gifCaution! Not a real pilot, but do play one on TV ;-)AMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | Maxtor 6Y080M0 SATA 80 GIG | 512 DDR 400 | Windows Xp Pro | Windows Xp Pro 64 |

> So far we have one classic driver but no NG pilots commenting>on this little tibit so although I believe what I am stating I>am still not convinced untill more proof is provided by a NG>driver....I got to fly a -700 sim last month, thanks to a buddy at SWA - hope that counts. As I described earlier, in a VNAV climb mode, the autothrottles set fixed power as dictated by the N1 limit page. If flying by hand, the flight director indicates the required pitch to maintain the speed restriction.The key, as in all other instances, is to look at the flight mode annunciator. After takeoff, hit vnav, and look at the left (autothrottle) column. It will go to ARM for a second, then to N1, (or it may remain at N1). This indicates that power is fixed. Then look at the pitch column. It says VNAV SPD. This means that the VNAV pitch system goal is to maintain the airspeed. So if you fly the pitch bars on the flight director you'll maintain the correct airspeed.Here's a screenshot from the PMDG sim, showing the correct annunciations when a climb is flown by hand in VNAV.http://forums.avsim.net/user_files/89310.jpg

" got to fly a -700 sim last month, thanks to a buddy at SWA - hope that counts. " Sure it does, as long as that SWA sim had VNAV ;-) Good to see you back Tim...Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/Animation1.gifCaution! Not a real pilot, but do play one on TV ;-)AMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | Maxtor 6Y080M0 SATA 80 GIG | 512 DDR 400 | Windows Xp Pro | Windows Xp Pro 64 |

Ok talked to one of the NG pilots on the team who said it does what Tim has said.....Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/Animation1.gifCaution! Not a real pilot, but do play one on TV ;-)AMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | Maxtor 6Y080M0 SATA 80 GIG | 512 DDR 400 | Windows Xp Pro | Windows Xp Pro 64 |

Slightly off topic, but how do you get the nice dotted circle around the triangular symbol (on the ND) that represents your aircraft (as in Timothy M's screenshot above)?

"Thats true Randy, In the 744 you can ingage the LNAV and VNAC on the ground already. (LNAV is also possible in the NG, to arm on the ground)"You cannot engage LNAV or VNAV on the ground, Ramon... but you can ARM them. The LNAV and VNAV annunciations will appear in white on the PFD below TO/TO. LNAV will appear in green at 50' and VNAV will appear in green at 400, but they are still not considered to be engaged. You can only engage LNAV/VNAV if you select CMD.Hope this makes sense.Cheers.Ian.

turn the TCAS on :) (you need the 800/900)Luca

Look in the PMDG MENU and make sure TCAS RINGS are UNCHECKED then when you use TCAS you will see this option (Push the TFC button on the EFIS control panel)...Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/Animation1.gifCaution! Not a real pilot, but do play one on TV ;-)AMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | Maxtor 6Y080M0 SATA 80 GIG | 512 DDR 400 | Windows Xp Pro | Windows Xp Pro 64 |

Hi Gents,Sorry I have been away at work a bit and so missed most of this thread.Guys we haven't quite got things in order and I feel there is a fundamental misunderstanding about the AFDS - Auto Flight Director System.So lets have a quick recap of the tutorial I wrote to explain that there are 3 components to the system and they inter-relate as follows. Bear in mind we are talking about a highly complex and sophisticated system and the PMDG does an outstanding job of replicating what airlines pay millions of dollars for:So:First you must understand that there are FOUR pilots on the aeroplane. Two electronic ones (Autopilot A and Autopilot :( and two soft, squishy ones (Captain and First Officer). Any one of these pilots can manipulate the flight controls. They normally do so in such a manner as to follow the commands of the Flight Director. Only ONE pilot can fly the aeroplane at any time (except in the special case of an Autoland where both APs fly together for redundancy). An AP can ONLY fly the aeroplane if it is ENGAGED to the flight control system by pressing CMD A or CMD B and the fact that an AP is doing the donkey work of flying will be shown at the the top of the PFD by the word CMD in green.Second there is a Flight Director which will lead any of these FOUR pilots on the aircraft to where the crew want it to go. The Flight Director can be one of two types. Spilt Cue (the two MAGENTA bars shown on the PFD) or single cue (a small magenta trapezoid looking thing) and it provides command steering guidance in both PITCH and ROLL. There single cue system is just a variation but it works just the same - it guides us up and down and left and right.The FD will lead us around by the nose following different modes in ROLL and PITCH dependent on where you want to go.In ROLL you can follow either:1. The HDG Bug (Magenta cursor on ND)2. The VOR/LOC which is a ground based directional radio navigation aid providing guidance TO and FROM stations on the ground.3. The LNAV system which is a set of preprogrammed WAYPOINTS in the FMCIn PITCH you can follow either:1. LVL CHG in climb or descent2. VS = Vertical Speed3. VNAV PATH or VNAV SPEED - Both come from FMC4. GS = Glideslope - when flying an ILS approachSo how does the crew tell the Flight Director where to lead us? They use the Mode Control Panel - MCP.So first we decide where we want to go, tell the FD how to get there and then one of the four pilots on board follow it there.Easy Huh? Well I have not delved into just what these modes can do and what controls the commands they provide. Each mode could easily be the subject of quite a long post and if there is sufficient interest I will take a stab at each of them in turn.Anyhow, I hope this starts to clarify a little of the operation of the AFDS on the NG.Rgds,

"I interpret this statement as VNAV will dictate the auto-thrust system to ensure 250kts is not exceeded until 10,000ft is reached, no matter whether you are spot on the F/D bars or not. VNAV knows that 250kts under 10,000 is a "Restriction", which it will try it's hardest to adhere to. The airplane doesn't just fly to 260kts (a small overshoot), but it will go straight to ECON CLB speed of around 300kts, which far exceeds any slight overshoot. In addition, I have been flying the F/D bars on the money with this same result."Kevin,VNAV is a PITCH mode and does 2 things for the climb:Sets A/THR to CLB power in the N1 mode, ie the A/THR is commanded to set CLB N1 as dictated by the N1 limit page. VNAV will then pitch to maintain the speed restriction in the same way LVL CHG does. The exception is that it will level off at either the set MCP alt or any har heights set in the FMC whichever is lowest! So to put it in laymans terms VNAV tells the thrust to set climb power then pitches to maintain a set speed. In the case of being below FL100 this should be 250kt so you will tend to find the climb is pretty rapid.What you are saying is that VNAV pitches to a set attitude and then adjusts the thrust to give the desired speed, this is not correct and is only the case when using V/S mode as it is in a way dangerous. Consider that you set a V/S or pitch of 20 degrees nose up and you then expect the A/THR to adjust thrust to maintain speed, as you climb the air gets thinner and the required thrust becomes greater to maintain a given airspeed. Eventually the thrust reaches maximum and can go no further, your pitch or V/S remains as set so now the only thing that can change is your speed, it will get slower and slower until you stall. In the case of VNAV or LVL CHG the A/THR drives to a preset CLB setting and stays there. The aircraft then pitches to maintain the speed. So as the speed starts to reduce the pitch angle is lowered and if the speed rises the pitch angle increases thus you ensure you don't stall. Of course there is a little fiddling to be done as airspeed reduces due to air pressure but this is usually taken care of by the change over from constant Air speed to constant Mach. I'm just off to see if I can reproduce the VNAV issue on the 700 series and will report back.

Brad, I think your answer is better worded than mine but that is what I wanted to say. If you need any help putting together any help sheets just shout! Kris

Right guysI had a look at this and found the 700 VNAV operates just as I expected it to do using the same procedures we use on the 300. I have taken some screenies to walk through it and hopefully it will start to make some sense. This was a simple flight from Leeds Bradford (EGNM) to Edinburgh (EGPH) using a POL1W SID. Standard take off with flap 5 using full wing tanks bleeds on etc. I didn't use the A/P so this was all manually flown hence no CMD displayed on the EADI. This may take a few posts so read on and hopefully it will make sense. PIC 1Just after take off still flap 5 with VNAV and LNAV engaged. Note A/THR is in N1 mode slaved to the CLB N1 as shown on the engine display. Note the speed commanded is shown in magenta on the speed tape as 245kt, this is becuase I still have flap out! PIC 2I now have taken flap 1 and continue to accellerate, the magenta command speed is still shown as 245kt as I still have flap. Note I am following the Magenta flight director bars in order to maintain an accellerating climb.PIC 3 We are now clean and the new commanded speed is 250 kt as per the CLB restriction below FL100, I am maintaining the accellerating climb up to 250kt, note the pitch angle around 10 degrees nose up. This shallow angle allows the acclleration to 250kt but also reduces the climb rate to about 2500fpm.PIC 4 Now we have accllerated and show just below FL100, note that the pitch angle is similar but due to the extra speed we now have a climb rate of 4600fpm. Had I taken a screenie at the point when I reched 250kt you would have seen a higher pitch angle but my finger wasn't quick enough! Continued on next post! Kris

The last bit I assure you...PIC 5We are now through FL100 and the aircraft wants to accellerate to the commanded ECON Climb speed of 303kt. You can see the F/D is commanding a lower pitch than 10 degrees we had when 250kt was commanded and we had reached it, this is the aircraft's way of accellerating. It knows there is no more thrust and so lowers the nose and sacrifices climb rate for accelleration, note the climb rate is reduced from 4600fpm to 3600fpm and wil reduce further as we recuce the pitch angle and accllerate. The FMC should now show the SPD REST as dashes and the target speed will be highlighted as 303/0.693 or something along those lines. The commanded speed/mach varies according to altitude so it will change and your figures may not match mine! Hope that lot helps!