Has anyone noticed a anomoly that occurs when climbing with the AP engaged (CMD) and in FLCH (MCP SPD) without the autothrottles engaged such that if thrust is reduced, the F/D does not lower the pitch attitude to track the set MCP speed? In situation, when I reduce thrust, the F/D command bars maintain pitch attitude and the airspeed decays and if left uncheck, will decay into the stall.This is contary to my understanding of FLCH/MCP SPD mode. If thrust is reduced, pitch attitude should reduce to maintain MCP set speed down to about 100 FPM vertical speed at which point speed when the decay if insufficient thrust is applied.The situation occurs when I'm holding a set MCP SPD in FLCH using thrust to control my ROC/ROD. As I approach target altitude, I'll reduce thrust to lover V/S, assuming of course I want to maintain set speed at level off. It appears the autothrottles handles the thrust reduction and leveloff with problem. But FLCH/MCP SPD does not track speed is thrust is reduced in a climb.Any observations or thoughts?Thanks,Rich BollWichita Kansas

>Any observations or thoughts?>I believe that FLCH requires the autothrottles, and uses either N1 (for climbs) or ARM (for descents) and doesn't care a fig for what the vertical speed is.Since what you want is a mode where pitch is used to maintain a constant airspeed, and thrust is used to vary vertical speed, try using the SPD button with the autothrottles disengaged. That may give the result you want.It may not.I don't have my Bulfer handy to see if would shed any light.

Tim,Thanks for the reply. FLCH should be "speed on elevators" and should operate regardless of whether A/T engaged or not. SPD is A/T speed intervention. Using SPD engages "speed on thrust" with an approprate vertical mode like VNAV or V/S. At least that's my understanding, but I could be mistaken.Rich

So your question is why do you not see correct F/D guidence for a manually set MCP speed with the A/T off? I am not sure what you mean by FLCH in this situation though, when you say FLCH I think LVL CH. Anyways, F/D guidence should display with or without the A/P-A/T for the selected MCP speed. Maybe provide a screenshot of the panel, it very well could be incorrect here but I am not sure... Best Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/southparkcartmad.gif[h3]I WANT MY 747![/h3]Caution! Not a real pilot, but do play one on TV ;-)

LVL CH is correct. Too many simulators and too many real airplanes. Active pitch mode is MCP SPD. I'll shoot a screen shot of what I'm seeing. and upload it. Right now I have to solve the FSUPIC 3.41 issue that effecting NG737.Thanks,Rich

>LVL CH is correct. Too many simulators and too many real>airplanes. Active pitch mode is MCP SPD. I'll shoot a screen>shot of what I'm seeing. and upload it. >>Right now I have to solve the FSUPIC 3.41 issue that effecting>NG737.>>Thanks,>>RichOK, so we're agreed that if we have the autothrottles off, and the MCP in LVL CHG, and CMD A or B active, with MCP SPD as the pitch mode in the PFD, then as we're climbing or descending to an altitude set on the MCP, manually adding or reducing thrust should result in a change in VS, with the autoflight system adjusting pitch to maintain the MCP speed.Now, let's go fly and see what happens, and get some screenshots. Back in a few.

>OK, so we're agreed that if we have the autothrottles off, and>the MCP in LVL CHG, and CMD A or B active, with MCP SPD as>the pitch mode in the PFD, then as we're climbing or>descending to an altitude set on the MCP, manually adding or>reducing thrust should result in a change in VS, with the>autoflight system adjusting pitch to maintain the MCP speed.>>Now, let's go fly and see what happens, and get some>screenshots. Back in a few.>>I'll have to edit the screenshots to keep them small, but here's the data:Start in level flight at 10000, altitude hold mode autopilot engaged and throttles set at 70% N1.Then I set the mcp speed to 220, the altitude to 25000 hit LVL CHG, and advance the throttles to the stops. The airplane climbs and gradually decelerates and maintains 220 knots in the climb.Now I pull the throttles back to 85% N1, and instead of lowering the nose, the autopilot RAISES the nose... and keeps raising it until a stall occurs. Then and only then does it lower the nose. once the stall is recovered, the nose again goes up and the cycle repeats.So, it appears to me there's definitely a bug here - the autoflight system is NOT deriving pitch from airspeed, at least not in climb. Now let's try a descent!level at 25000 in ALT HOLD, 80% N1 yielding 250 KIAS, set the mcp speed window to 270 knots, the altitude to 10000, press LVL CHG and pull the throttles to idle.Nose goes down, speed comes up to 270, and the autopilot maintains 270 KIAS.push the throttles forward to 50% N1, and the nose comes up and maintains 270. pull it back and the nose drops.So it appears to be only in CLIMB that the Autoflight system doesn't behave.

Thanks for the verification, Tim.I've seen this problem in climb phase with MCP SPD active without A/T quite often. I usually don't fly with A/T active unless I'm leaving the sim on it's own for awhile. I don't know that I've seen it act the same way during the descent phase. It's almost like it's in an altitude capture mode.Looking at CO's NG737 AOM, LVL CHG and other F/D modes should work with or without the AP and AT engaged. So, in a climb, I should be able to disengage A/T, retard the thrust and shallow the rate of climb. In the descent phase, I should be able to add thrust and shallow the descent rate with the A/T off or A/T in the ARM mode (I'm assuming ARM is equivilent to Clamp or Hold mode in other aircraft, but I could be mistaken on this one).Rich

aaa - This conversation explains a lot. I have also been experiencing the above problems. Will this be addressed in a fix? Would someone from the PMDG team look into it? Thanks.Kerin

Most Boeings I'm familiar with will pitch down in this situation, Rich, as you say.On aircraft which you can engage F/D modes on the ground you can even see this at the gate with the A/T and engines off. If you select a higher altitude on the MCP and hit the FLCH button, the F/D will go from the standard TOGA pitch up command to a pitch down command in an attempt to achieve the MCP selected speed.Something for the 744 ;-)Cheers.Ian.

Well no need for offical word, I can tell you 100% it is not going to be fixed anytime soon with the 747 going strong. There exists the possibilty of another update if PMDG choses to go with the BBJ. But if they don't do that I am not sure of the status of another patch, something for PMDG to answer but I would be pleased ifsome items left hanging were addressed before the product is put out to pasture ;DBest Wishes,[h4]Randy J. Smith[/h4]http://www.rawbw.com/~bdoolin/shinault/southparkcartmad.gif[h3]I WANT MY 747![/h3]Caution! Not a real pilot, but do play one on TV ;-)

Problem acknowledged --- thanks ! As an interim may I suggest the real world proper procedure of using VS as the pitch mode in cases where the vertical speed rate is the target ? Best,Vangelis===================================== E. M. Vaos Precision Manuals Development Group www.precisionmanuals.com=====================================

>Problem acknowledged --- thanks ! As an interim may I suggest>the real world proper procedure of using VS as the pitch mode>in cases where the vertical speed rate is the target ? >Thanks, Vangelis!

Thanks Vangelis,You folks really did a great job with NG737! I enjoy flying it.Take care,Rich BollWichita Kansas

Hi Ian,We cross paths quite a bit, don't we!Take care,Rich Boll