Here is an example of what people are talking about (its not my video):

Is that the I-fly? Does not look like the NGX to me. Also the guy is extremely light with 7,000 lbs Fuel and he is still climbing. In that case he is going to be like a Rocket.

Tab's hit in on the head: you're not playing with thrust in the climb - this applies to your bare-bones 150 just as much as your big 747. Pitch is adjusted for airspeed. That's how it works

Okay, so maybe the problem should be restated like this: Pitch should be adjusted to achieve the target speed, but not as much and as quickly as it does currently. That's the real problem. It's trying to achieve the target speed much more quickly than the RW counterpart. If a B738 80% loaded with 15Klbs of fuel at FL320 is told to reduce speed in the RW, they do not pull 1.4G climbs (as I observed again using the G readout) into 4500 fpm to bleed off speed as quickly as physically possible. It's much more gradual. Yes, autopilots in the real world can be aggressive, but not this aggressive. That's the core of the problem here, I think. And you can blame it on FSX winds or whatever, but the fact is PMDG could and should fix it to account for any FSX deficiencies, because at the end of the day people say "that PMDG isn't realistic in its behavior."And although I haven't jumpseated on a 738, I have on about 50 other airline flights, mostly other 737 variants. The 300 to 500 series is a better performer than the 800 anyway. And even they don't do these extreme changes like the PMDG. I always paid close attention to performance characteristics, how quickly they speed up, slow, typical climb rates etc over the different phases of flight. I've also probably spent 20,000 hours in my ATC career staring at speed and altitude readouts, calculating and recalculating climb rates, watching thousands upon thousands of climbs, descents, speed reductions and increases. And I'm telling you, this simulated 738 just does not behave this way vertically in the real world.Another problem with the autopilot (since someone asked above) is the PMDG will completely level off in a climb to increase its speed. Again, it should reduce its climb rate, but not to zero. You can't do that in the real world without first advising ATC and it just doesn't happen unless it's a super-rare pilot's discretion climb or they're near the max of their altitude. Certainly not suddenly level off at 15,000 feet like I've seen with this when "ATC" simply assigns a faster speed.This minimum climb rate requirement is probably in one of the FAR's but it's definitely listed in the AIM section 4-4-10 ( http://tfmlearning.f...p4/aim0404.html ).

If at anytime the pilot is unable to climb or descend at a rate of at least 500 feet a minute, advise ATC...Leveling off at any other time on climb or descent may seriously affect air traffic handling by ATC. Consequently, it is imperative that pilots make every effort to fulfill the above expected actions to aid ATC in safely handling and expediting traffic.

I just can't believe the r/w autopilot wouldn't have that minimum climb rate programmed in, because it could be a serious violation if a r/w aircraft suddenly leveled off in a climb without first notifying ATC (i.e. if it caused loss of separation the pilot could lose his license). Plus out of the thousands of 738's I've probably handled, I can't recall anybody asking to level off their climb to pick up speed, or observing it. I observed them all the time reducing their climb rate to speed up, down to about 1000 fpm, but they just don't completely level off like this PMDG does.Please PMDG I'm telling you these extreme changes in climb rates and leveling off in the climb at low altitudes (< FL300) just isn't realistic. Other stuff yes, this no! It's not meant to be criticism of your terrific product, just something in need of adjustment.

Fair enough, you bring up some really good points.

I have seen this behaviour during the climb with ASE when the TAT gets stuck. When TAT finally starts to fall, it falls very fast and causes a rapid shift in vertcial speed.Stephen Munn

Tabs,Here is an example of what people are talking about (its not my video):http://www.youtube.c...e&v=W1DdQhWdXwwThe climb issue is on 11.00The descent issue is on 21.20I flew many times in cockpit of 737. I am not a pilot yet, but know all things you told about in previous posts.I fully agree with you and I nearly agree with people, who says about fsx weather problem. BUT, If you look at the wind and temperature indicators on this video, you will see that from 0fpm to 5000fpm the wind was the same 280/15 and -3C.The change of vert speed is predicted of course! Because basically lvl change uses that 10knots overspeed to boost rate of climb. But the reason, everyone posting here is actully the acceleration between 0fpm to 5000fpm. I really jumps up! I know 737 not badly, and I can say that this deffenetly not how vert speed changes in 737s.

I do not see the problem here - the climb starts around 11:05 and it's around 11:30 by the time it reaches peak V/S. What exactly are you expecting here? 25 seconds to get a climb established does not seem excessively fast at all to me.Also, what are you doing with flaps still out 20 knots past clean maneuvering speed?

So was that the Ifly or PMDG? Reason I ask is because I never seen the NGX with Green Lights on the Buttons the way they are in that Video, plus I never saw those green rings before on approach showing the distances. How do you get those to show up?

So was that the Ifly or PMDG? Reason I ask is because I never seen the NGX with Green Lights on the Buttons the way they are in that Video, plus I never saw those green rings before on approach showing the distances. How do you get those to show up?

I had a look at that video. It's definitely the PMDG NGX.The green rings? Go to the FMC FIX page, put in any navaid or airport, and specify a distance without bearing (e. g. "EDDF" as fix, then e.g. enter "/10" to draw a 10 nm circle around Frankfurt Airport).

The green lights on the buttons is because it is the Honeywell MCP.

Well I thought it was the NGX but I never used the honeywell so that's why I was wondering cause I never seen that MCP before. Always use the Collins. As for the Fixes never used that yet either. So yeah I learned something new today.

I agree this should definitely be looked into. Just now I hit a little turbulence and hit overspeed (above 250kias) restriction while climbing out of flight level 7000ft. and it literally shot up to 7200 fpm climb , 25 degree nose up to slow the aircraft witch should never happen no matter what. If i were on this flight in real life i would have lost it.

After going through this thread it seems people are confusing their real-world 37 passenger experiences with no way to really correlate what the see/feel to what's actually happening up front.

Maybe some people are, please don't lump everyone in this thread under one heading. Some of us self loading cargo do know what we're talking about.

Tab's hit in on the head: you're not playing with thrust in the climb - this applies to your bare-bones 150 just as much as your big 747. Pitch is adjusted for airspeed. That's how it works.

I think only the OP thought otherwise.

Yes, autopilots can be aggressive some times. This goes for the RW too.... If you don't feel 'comfortable'...engage TCS and fly with that. There's all sorts of tips-and-tricks RW pilots use as well with the autopilot; it isn't just a VNAV/LNAV engage and let the thing do it. Playing around with heading select, bank angles, LVL CHG (which is used more then people think I believe) are all ways to help mitigate wonky autopilot behaviour. That's why they are there.

Actually autopilots generally don't do agressive things. Rapid responses tend to lead to over control and instability. Anyway the aircraft itself responds relatively slowly so the autopilot has to be designed to deal with that.. And I think simmers who've used several complex addons are aware of the various modes available and how they differ. However, even LVL CHG can be drastically different from one aircraft to another.

The NG's - the smaller variants at least - are rockets. That's how they are. These aren't huge airplanes gang.You got a -600 with only 75 people onboard and a light 7-8000 lbs fuel load for a rip up to Yellowknife and you'll scream up to altitude in no time. Couple WJA flight's I've been on we've haved no problem getting up to 410 on the southbound 1.5 hour leg. Fuel's not even worth tankering around any more nowadays

Any twin jet airliner is like that, not just the NG, and most people probably aren't flying the NGX that empty. It's more a question of thrust to weight ratio. The 757-200 has one of the highest.

It is a bummer that even with funky weather programs we all have the occasional temperature inversion or phantom thing that throws things out of wack. If you gave a RW autopilots a 5 degree temperature change and the sudden 50 or so knot IAS change it would probably freak out too....in fact it would probably just disconnect.

Here I agree, the problem is FSX's weather.

The Dr.'s put in some rediculous math into the autoflight system in this thing and I think it's all we can expect. Asking them to smoothen it out would only result in us whining later about unresponsive autopilot commands and such.

But this shouldn't be about personal preference it should be about representing reality as far as possible. I may be wrong but I suspect the autopilot is responding too much to fluctuating mach/speed inputs. If you filter out these high frequencies you could still have quick response to non fluctuating inputs.Kevin Hall

I do not see the problem here - the climb starts around 11:05 and it's around 11:30 by the time it reaches peak V/S. What exactly are you expecting here? 25 seconds to get a climb established does not seem excessively fast at all to me.Also, what are you doing with flaps still out 20 knots past clean maneuvering speed?

It's not my video

If you compare the time from lift off to level off at cruise level on real 737-800 and NGX, you will understand what we are talking about. The climb rates are really high. Its impossible to get 4000ft climb at FL250-300. It dereaces and comes to 1000-1500ft at 350 and higher. On classics sometimes you have to use vert speed to keep climb rate with pay of some speed until FL is reached.

Ussualy you will get 2500-3500 in climb, depending on weather and loadIn NGX you often get 4500-6000ft and when you approach assigned FL, the autopilot starts to decrease the vert speed. But because 5000fpm not a joke, so it does very hard moves with yoke and stabiliser and also overjumps by 100-200ft.

but not as much and as quickly as it does currently.

This I can agree with. I too have noticed, especially when new weather data is loaded in and winds shift significantly that the NGX can change pitch to react extremely quickly. If you want to test this, try dropping in a 100kt headwind while climbing. The amount of pitching the NGX does is entirely correct to get back to the proper, just way to quickly. Perhaps the VNAV speed mode needs to 'sample' over a second or so and react a second late instead of immediately.The other "issue" I have is relating to the decel's that are usually placed in between FL110 and FL100 on decent and the aforementioned minimum decent VS. These decels to get down below 250 should really be bigger so the VS can be maintained at a reasonable rate instead of near on levelling out. Quite often I'm seeing the bird go from a -1500 to -1800 VS to like -100 VS to reduce speed. Seems unrealistic, especially given that there's literally nothing stopping the aircraft beginning the decel at 11500 instead and flying 500VS instead or something like that.Note: I'm no pilot nor no boeing engineer. I'm just commenting on what I feel seems more appropriate.

Another problem with the autopilot (since someone asked above) is the PMDG will completely level off in a climb to increase its speed. Again, it should reduce its climb rate, but not to zero.

You must have a different add-on to me, mine does not do that.

In NGX you often get 4500-6000ft and when you approach assigned FL, the autopilot starts to decrease the vert speed. But because 5000fpm not a joke, so it does very hard moves with yoke and stabiliser and also overjumps by 100-200ft

.You also must have a different add-on to me, mine does not do that.