According to the 09_AFDS_SYSTEM_737_678900_V14.pdf:Autothrottle: The autothrottle system uses the FMCs to directly control throttle input for maximum fuel conservation. The autothrottle is capable of providing for full flight throttle management from takeoff to rollout.. I must be doing something wrong as the auto-throttle won't reduce speed during approach...I always have to dial in the next flap extension speed, in the MCP, myself. Am I reading the above sentence incorrectly? I select the various flap speeds on the FMC's approach page but the FMC does not seem to reduce throttle? Victor Buck

According to the 09_AFDS_SYSTEM_737_678900_V14.pdf:Autothrottle: The autothrottle system uses the FMCs to directly control throttle input for maximum fuel conservation. The autothrottle is capable of providing for full flight throttle management from takeoff to rollout.. I must be doing something wrong as the auto-throttle won't reduce speed during approach...I always have to dial in the next flap extension speed, in the MCP, myself. Am I reading the above sentence incorrectly? I select the various flap speeds on the FMC's approach page but the FMC does not seem to reduce throttle? Victor Buck

I'm unsure about this one since I always control the speed by means of the MCP. But are you in both VNAV and LNAV?. That may be the problem if both are not selected. Just a thought.Jim D.

I select the various flap speeds on the FMC's approach page but the FMC does not seem to reduce throttle? Victor Buck

Ooops... You can only select ONE flap/speed config in the approach page, and that is the reference (Vref) speed for landing and the flaps position for landing.This selection will only transfer the green flap indications to the speedtape on the PFD, and nothing more.If you want the aircraft to follow an altitude/speed profile you have to use the LEGS page and program altitude and speed for every waypoint, and the fly in LNAV+VNAV.The NG is not an Airbus, and will not reduce speed everytime you select a lower flap position.

I always use MCP SPD on arrival and approach, rarely use VNAV below the flight levels. The MD11 is the first FMS I've used that will really fly her to the ground.

As others have noted, the landing speed you stick in the FMC on a bird such as the 737 is more about giving you a reference marker on the speed tape on the primary flight display (a little green flag normally), which will be your Vref landing speed (i.e the speed you should be at as you cross the runway threshold if there is no adverse wind factor).But it is worth noting that recommended landing speeds for aircraft are often not simply Vref itself, but Vref plus a certain extra speed margin of a few knots. This is to account for things such as gusty wind conditions, so you will see such stuff as Vref+10, noted as landing speeds in windy conditions, or Vref+5 or whatever (the normal formula to add, is 50 percent of the wind gust speed, beyond the average wind speed). This means that it is often better to either manually control the throttle, or enter a revised landing speed in the MCP and use the autothrottle that way.Since jet engines spool up slowly (and spool down slowly too), flying at exactly Vref can be a bit of a dodgy practice much of the time, and since your headwind component normally reduces as you get lower, where the interaction of ground friction tends to make a noticeable wind gradient in the last 200 feet or so, its one of the things that is not always best left to an automatic system.Al

Excellent gang...thanks for the replies. I DID read that paragraph wrong and DO need to do as I have in the past...use the Vspeeds/flaps as a reference, not expecting the AT to control it but doing it myself.<BASA> The NG is not an Airbus, and will not reduce speed everytime you select a lower flap position.. I am thankful that it is NOT an airbus. Recent RW events speak more to that than I can (not being anywhere near a "real" pilot!). I can only say that I operate a medium sized power generation facility...and I would NEVER allow that facility's control system to "allow" an override of my human input. I don't know about flight management...but I can tell you that 98% of our generating loss is due to control systems glitches. That is why I get paid the big bucks...to get the plant back into safe operation when the damn computer goes to crap. Sorry but, I will avoid Airbii products when flying in real life, in the future. I trust well trained pilots WAY more than I do any flight management system."If it ain't Boeing, I ain't going" Vic

According to the 09_AFDS_SYSTEM_737_678900_V14.pdf:Autothrottle: The autothrottle system uses the FMCs to directly control throttle input for maximum fuel conservation. The autothrottle is capable of providing for full flight throttle management from takeoff to rollout.. I must be doing something wrong as the auto-throttle won't reduce speed during approach...I always have to dial in the next flap extension speed, in the MCP, myself. Am I reading the above sentence incorrectly? I select the various flap speeds on the FMC's approach page but the FMC does not seem to reduce throttle? Victor Buck

Vic,Sounds like your'e at a fairly advanced level.As an NG rated pilot your quote with reference to the A/T is correct. The FMC should calculate it's TOPD point starting back from VREF+wind corr at the threshold all the way up to you cruise alt thus calculating all the decels along the way. I agree this machine is not an airbus, however, each time you select a flap setting on the final approach, the fmc should bug back to that flap speed using the A/T as required. Once landing flap is selected VREF+wind corr will be bugged (as selected on INIT REF). PMDG 747 manages this quite well I might add. Adding wind in FS just makes things worse I've found.I cannot replicate a full approach from cruise altitude all the way down without VNAV disconnecting but i have managed to conduct a few RNAV approaches in LNAV VNAV to 50ft. Most times I conduct an approach the aircraft stops descending and gets high on profile. Very frustrating.Hopefully better modelled in NGX.Ross F

I agree with Ross F. that the PMDG NG is difficult to make the VNAV work the way it does in real life."Vic, one of the first things they taught us in 737 ground school was that the 737 can "go down, or slow down, but it can't do both." Take a look at the fixes and note where the FMC thinks you should be slowing down. Maybe back those decelerations up a few miles. Remember that the landing gear is your friend if you get above the flap speeds.

Although not even in possession of a PPL, let alone a type rating for the NGs (my respect Ross and Matt, your input is worth its weight in gold, thank you),I have often read that the 737 is a slippery fish so to speak. I believe the PMDG, although it is now quite old in terms of FS, does this fairly well, as it tends to speed up fairly quickly if you push the nose down on descent...If I use the winds forecast on the descent page, I can generally get a more fitting descent profile with fewer deviations, though the winds forecast has to be close to be of any use... I am probably doing something wrong somewhere, but I am sometimes a little hot and high when vectoring to final, and sometimes need to hold over a some fix to lose a few feet in altitude. I tend to switch to MCP controlled speed and out of VNAV in the terminal area.She slows down at FL100/10000ft well enough generally, and it is shortly after that I tend to switch over... using the flaps reference speeds on the speed tape as a guideline. AP I tend to switch off at 1000RA when established and stable on the glide...My last trip last night, SWA698 into KPVD from KMDW, went generally well, though I seemed to have an autobrake disconnect (probably me hitting the brake pedals too early, I cannot remember exactly...) earlier than planned...I love checking in here and reading the typerated posters' experience, so thanks to you for that!Andrew

Although not even in possession of a PPL, let alone a type rating for the NGs (my respect Ross and Matt, your input is worth its weight in gold, thank you),I have often read that the 737 is a slippery fish so to speak. I believe the PMDG, although it is now quite old in terms of FS, does this fairly well, as it tends to speed up fairly quickly if you push the nose down on descent...If I use the winds forecast on the descent page, I can generally get a more fitting descent profile with fewer deviations, though the winds forecast has to be close to be of any use... I am probably doing something wrong somewhere, but I am sometimes a little hot and high when vectoring to final, and sometimes need to hold over a some fix to lose a few feet in altitude. I tend to switch to MCP controlled speed and out of VNAV in the terminal area.She slows down at FL100/10000ft well enough generally, and it is shortly after that I tend to switch over... using the flaps reference speeds on the speed tape as a guideline. AP I tend to switch off at 1000RA when established and stable on the glide...My last trip last night, SWA698 into KPVD from KMDW, went generally well, though I seemed to have an autobrake disconnect (probably me hitting the brake pedals too early, I cannot remember exactly...) earlier than planned...I love checking in here and reading the typerated posters' experience, so thanks to you for that!Andrew

Andrew,The FS B737 technology is fairly old (and the machine itself is a dinosaur). The PMDG model is simulated quite well in terms of slipperiness. I guess the point we were trying to get across was based on the original question in regards to the A/T and the use of VNAV/LNAV

There is also a few gates you need to meet when inside 50NM.10000' at 250kt 30NM5000' at 250kts 20NM (generally start slowing)3000' 180kts at 10NM

Now where's the fun in that? 250 til 10-12NM, thrust levers to idle & drop the gear, drop the flaps, spool up at 500'. Just tell the other guy first. ;)That may not work so well in a busy airport. . . .

The original NG's VNAV has some shortcomings (it was our first MSFS product and we've learned things along the way), the new NG 2.0 we're making will have it all including all the RNP approach, FMS calculated glidepath etc stuff. The 744 and MD-11 have much more robust vertical navigation modelling.

The original NG's VNAV has some shortcomings (it was our first MSFS product and we've learned things along the way), the new NG 2.0 we're making will have it all including all the RNP approach, FMS calculated glidepath etc stuff. The 744 and MD-11 have much more robust vertical navigation modelling.

Looking forward to it! PASI-PAJN, here I come. Let me know if you need another BETA tester. :)