Difficult to slow down

[gooo 0]

Hi all,it's just my impression or it's difficult to slow down during descend? In my opinion takes a lot of time to slow down. I tried 2day EIDW to EGBB ( rwy 15 ) and I found my self high and fast following the V-NAV profile. Any suggestions?Thanks

[nikita 241]

No particular suggestions.. Welcome to the slippery 737 :(

[Nathan Cupps 0]

If you feel that your losing grasp of the approach and the plane is trying to over correct where it puts you in a dive. You can always use flight detent to help you slow down. Also if your on approach use flaps a little earlier if you have to!

[Guest]

Maybe you should switch to LVL CHG or another mode and take over if VNAV isn't doing what you want? Maybe you should use the speedbrake? Do you have a lot of wind behind you? Depending on how close you are to the destination, you might lower flaps and/or gear a bit sooner (if speed permits it)? You could even switch to landing configuration just to slow down (including leveling off and then proceed the descent when you are on a more appropriate speed). Do you start the descent in time (set the lower alt some 5 miles before TOD)? Have you set everything up well enough in the FMC?Just some things I have read here and there when it comes to coming in too hard. :(

[gooo 0]

try this: EIDW to EGBB sid Liffy 4E UL975 MALUD star CHASE 1E trans CHASE for rwy 15. FL 270

Edited February 2, 2012 by gooo

[gooo 0]

Maybe you should switch to LVL CHG or another mode and take over if VNAV isn't doing what you want? Maybe you should use the speedbrake? Do you have a lot of wind behind you? Depending on how close you are to the destination, you might lower flaps and/or gear a bit sooner (if speed permits it)? You could even switch to landing configuration just to slow down (including leveling off and then proceed the descent when you are on a more appropriate speed). Do you start the descent in time (set the lower alt some 5 miles before TOD)? Have you set everything up well enough in the FMC?Just some things I have read here and there when it comes to coming in too hard. :(

Thank you for the tips, but my point was to compare the real one to the sim. I fly 737-8 NG and is much faster to slow down than the sim.....LVL CHG is grate if you are high on profile, so you can dive @ higher speed ( above FL100 ) It was nil wind condition. and yes I did descend on time :) and everything was well enough in the FMC

[martin-w 3,256]

It's accurate, its a slippery bird. Many real world NG pilots have confirmed this.Remember the old saying... You can slow down and you can go down, but you can't slow down and go down at the same time.Or at least not very well.You have speed brakes and you have the speed intervention button. You are the pilot, you are in control. Think ahead.You will find that with practice you will gain competence.It's on the numbers.

Edited February 2, 2012 by martin-w

[skyhawk8 0]

I had the same problem and was almost never able to reach any crossing alt. I used to fly with a CI value of eighty.I lowered that to about 20 to 25 and much to my amazment I hit all my alt's every time with very little to no speed brakes. I've also noticed that I don't fly over the TOD and dive to capture the descent path.I save fuel also. Not that saving fuel matters when I don't pay for it. Remember here it's "As Real as it Gets". Only drawback is that the flight is slightly longer.You can too fix that when your at FL by using the SPD INVT and select the speed you want. When you get within 20 miles or so of your TOD then just turn the SPD INTV off and let the FMC control the descent speed.This is the way I fly the NGX now and have never had a problem since.Steve Reinard

Edited February 2, 2012 by skyhawk8

[VLJ510 16]

Help the plane look ahead concerning winds aloft and use the DES Page - FORECAST Page to enter winds aloft and not just descend and let the plane take winds aloft as they come. Also high CI like 100 can make this happen too, use a more realistic CI value if not already.

Edited February 2, 2012 by VLJ510

[rocketfs 2]

I had the same problem and was almost never able to reach any crossing alt. I used to fly with a CI value of eighty.I lowered that to about 20 to 25 and much to my amazment I hit all my alt's every time with very little to no speed brakes. I've also noticed that I don't fly over the TOD and dive to capture the descent path.I save fuel also. Not that saving fuel matters when I don't pay for it. Remember here it's "As Real as it Gets". Only drawback is that the flight is slightly longer.You can too fix that when your at FL by using the SPD INVT and select the speed you want. When you get within 20 miles or so of your TOD then just turn the SPD INTV off and let the FMC control the descent speed.This is the way I fly the NGX now and have never had a problem since.Steve Reinard

As real as it gets: for the NGX, CI: 10 to 30http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_07/article_05_3.htmlBert Van Bulck

[vc10man 732]

@FrancoI too run with a CI of 40 and I check on the LEGS page for what speed/altitude I'll be before I reach LOC marker.If it is too high I manually input the speed/alt and sure enough I hit all the speed restrictions.Just out of curiosity as I'm sure you must do it, but do you prep your landing by setting your landing V_ref ?

[Tabs 2,790]

Thank you for the tips, but my point was to compare the real one to the sim. I fly 737-8 NG and is much faster to slow down than the sim.....LVL CHG is grate if you are high on profile, so you can dive @ higher speed ( above FL100 ) It was nil wind condition. and yes I did descend on time :) and everything was well enough in the FMC

Sorry, but I want to see proof of employment if you're going to make claims like this. A team of a dozen confirmed real world NG pilots were involved in the testing of this product and descent performance was something that was discussed to death. Not only does it match the Boeing performance data but we were told it felt right by the team too.

[davierosoft 13]

No particular suggestions.. Welcome to the slippery 737 :(

If VNAV is correct, all forecasts putted in, there will be no need of using speed brakes as they are a loss of efficiency and is something that the FMC don't want.The NG is slippery, but the NGX with few users suffers about an idle bug, this bug is present below 15500 fts and will lead in an higher idle around 40% of N1.Before someone speaks about the approach idle, I'm speaking of a bug where the idle changes with altitude only, with flaps and gears retracted.However, sometime most users experience that issue if cowl anti ice is on, this is normal as it increases the idle. If you want to use AI you must let the FMC knows in the des forecast so it will change the path to a soft one.

[davierosoft 13]

Franco,I'm curious about that idle problem, I really want to know if it is an issue or maybe all of them user related (I had it, but I'm almost sure I didn't anything wrong).On the next flight you do, it is possible to post screenshots about it if the problem is present?All you need to do is:-Make sure you have sp1b (wich solved a problem with not default G key)-Make sure your flight plan is right-Use clear skyes so you will eliminate possible wind errors-Use a CI around 30-Do not use cowl antiice-extend/retract gears using the G key.Take a screenshot before ToD,Save the flight for future referenceIf aircraft starts to accelerate too fast Make a screenshot.Pay attention at around FL150, maybe it is the altitude where the problem starts.-Check your idle above that altitude, and then below it.If N1 is above 38% make a screenshot making sure that gears, flaps, antiice are up and off-When DRAG REQUIRED stays long and speed brakes will not help too much, make another screenshot and save the flight.Post here the screenshots and be ready to send a ticket with the latest saved flight, maybe useful for pmdg.If doing the above, your idle will slowly decrease with altitude to 34% you have no problem and it is your fault, maybe related to the antiice not forecasted.Hope this help you, and, if you are one of the unlucky with the possible bug, I hope you will be the one who will help in troubleshoting it.

Edited February 3, 2012 by davierosoft

[davierosoft 13]

I've not said, but, MOST important, when descending, your AT mode will be mostly in ARM mode, this means that if you move the thrust levers, the engines will respond. Also a potentiometer noise can give wrong inputs and modify your thrust this increasing speed.Make sure, before ToD to retard your controller throttle to make sure it will not command the thrust levers.