No, they take off with whatever cargo is thrown at them, if for example they reposition aircraft to a neighboring airport you bet they will be flying very light.

Come on give me a break. Were talking about normal not a rare repositioning or a flight that was low on pax. I am talking about normal day to day ops. There is no way airlines are taking off with 20 pax in a 162 seat layout. If they are then thats why the idiots had to file bankruptcy in the first place. If they are taking a loss on certain routes you can bet they will start cutting back the number of flights so they can fill the planes more.

I am talking about day to day normal situations.

OK, then next time make sure your written language reflects wthat you think. If you say would never even occur to them to take off that light suggests there is some physical/regulatory barrier that prevents from from flying light.

OK, then next time make sure your written language reflects wthat you think. If you say would never even occur to them to take off that light suggests there is some physical/regulatory barrier that prevents from from flying light

Okay I see how you misunderstood that. What I was thinking about was real world pilots here flying the NGX. In the sim I just can't see them taking off in the NGX that light. That is probably why some of them stated they never saw 6000 fpm climbs or descents with the NGX. See what I mean now? To the OP, I finally found Ryan's post on this issue in another thread. Here it is.

Here's some facts folks - there is a lot misconception about how the plane's systems and physics in general really work going on in this thread:1. VNAV SPD is a "pitch for speed" mode - it is essentially the same thing as level change. Thrust is NOT modulated to control V/S in a VNAV SPD climb - EVER! The A/T sets the thrust at the climb N1 limit and then varies pitch to control the airspeed. If you use SPD INTV to slow down in a VNAV SPD climb, you are asking the airplane to pitch up - period. It will not reduce thrust and pitch to a lower angle, it keeps the N1 and pitches to whatever angle results in the selected airspeed.Reasons you could see "high" V/S in a VNAV SPD climb:a. The plane is extremely light - I see tons of people doing extremely short routes with the default payload and 1/3 fuel all the time. The thing is going to be a rocket even in the derated thrust modes at these weights. In real life, a super light NG is lost revenue for the airline. Try it closer to MTOW and see if the "high" climb rates aren't reduced.b. Derated/reduced climb not being used - if you put the plane in the unmodified CLB mode, that means the N1 limit the A/T shoots for is higher, requiring a higher pitch angle for the speed.(I believe these things explain why the real life controllers in the thread report seeing NGs doing ~2000FPM - they're heavy and they're derated)2. Regarding V/S - a lot of simmers have been led to believe by certain "passenger simulator" utilities that high V/S in a climb or descent is somehow bad or unrealistic. This is 100% untrue. One of our tech team pilots who flies the NG every week just told me that he saw over 7000fpm while reducing airspeed in the climb while light in a 700 the other day. (he's going to try to get video for me on his next trip)Bit of science/physics here - people *do not sense speeds*, we sense acceleration. Think about when you're up at cruise as a passenger on a plane in real life - you feel completely normal, you can get up and walk around etc. If you closed your eyes and put perfect earplugs in that blocked all the sound, you'd have no way of discerning whether you were sitting in your room at home or in a plane doing 600 knots over the ground. In fact, even when you're sitting at home in your room, the Earth your house is attached to is moving at a constant 67,000 mph around the Sun and in turn the Sun and our solar system as a whole is moving at an even higher rate of around 515,000 mph due to the rotation of our Milky Way galaxy. (You can thank Issac Newton and Albert Einstein for these insights into reality, seriously!) Motion at constant speeds do not matter in the SLIGHTEST and this applies to climb rates too - climbing at 500fpm feels exactly the same as climbing at 4000fpm as long as you're maintaining that constant vertical speed.3. Feet per minute in a climb does not = G forces. A 3000fpm climb does not mean you are pulling 3Gs. This is 100% an incorrect understanding. If you are ascending at a constant rate of 3000fpm, you're actually at around 1G. G forces are involved in the CHANGE between no climb and getting to 3000fpm. If you extremely violently pull up (like yank the yoke back completely in an instant), you will get that kind of G force. Gs are a measure of acceleration force - acceleration is a rate of change (think of it as change in speed per unit of time.) "G force" specifically is a measure of acceleration with respect to the normal pull of Earth's gravity. Standing on the surface, you're "pulling" 1G. 2Gs is two times that value, 3Gs is 3 times it and so on. I think a lot of simmers believe that G forces in an airliner are a lot higher than they really are - for comparison, an F-16C doing a max rate turn is going to pull somewhere in the vicinity of 9Gs max. No airliner can do anything even close to that even if you were completely manhandling the controls. Even 2Gs is unbelievably uncommon - I've done a 2G or so steep turn in a GA aircraft and if you haven't ever done it before, you're going "Holy crap!" - it is a HUGE change vs. what you would ever feel on an airliner in almost any situation.Now - taking into account all of this knowledge - is there still an assertion that something is wrong with our autopilot? If so, what exactly is it that does not violate any of the understanding above?Ryan Maziarz

That seems a bit weird though.. It should descend at the mach speed at a fairly normal,but likely brisk rate until it merges with the 330 knots. I'm not sure what the mach speedwould be at FL360 at 260 knots.. Mach .76-78 or so??I've flown a few flights with pretty high CI, and didn't really have any problems with itdiving like a rock. The descents were pretty normal, just fast speeds.If you are at FL360, the plane will be using mach speed, not IAS. And if you start adescent, it should act about the same as any other descent. Just faster.. It's notgoing to be running mach speed and suddenly decide to switch to IAS before it'stime.. Which at a high CI, will be in the mid to upper 20k ft range.Also, if the CI is that high, the mach speed will be pretty high too.. mach .79-80 range..It's gonna hold that mach speed until it see's the 330 knots, and then it will switch.Lately, I've quit running the high CI's, and have been using a more real world numberaround 35 or so.. 40 is about as high as I've been going lately.Anyway, I never saw anything really unusual using a high CI.. Just faster speeds.I get some pretty good climb rates with the 600 BBJ I run. It's loaded pretty lightand it's not unusual to climb out at 4000+ fpm in the earlier parts of the climb.But I don't see those high rates when running a loaded down Southwest flight.It's all in the weight as far as the high climb rates.I run the light 600 BBJ a lot at night when all the scheduled airline flights arekaput, and most of the big company pilots are in hotel rooms asleep. :/Even if I load a lot of furniture onto the plane, it's still pretty light withless than 30 people on board. Often I'll have less than 15 pax..Climbs like a scalded house cat. :)BTW.. Is that *the* Capt Billy Bob that is on u-toob?Your video's are a hoot.. :)

@ OP.If you are seeing ascents and descents as high as 6000 fpm, then YOU are doing something wrongOR it could have something to do with your control hardware setup.I very rarely see more than 3000 during climbs or 2000 during descents.This has nothing to do with cost index really.( better screenshots would be a big help !! )Fred.

Let us think about this again:VNAV descents are idle descents. If you have a lower CI, you'll have a lower IAS/mach and if you have a higher CI, a higher IAS/mach.So, if you're doing 250/.73 at idle, you'll be descending at a lower V/S than if I was at 300/.80.

Let us think about this again:VNAV descents are idle descents. If you have a lower CI, you'll have a lower IAS/mach and if you have a higher CI, a higher IAS/mach.So, if you're doing 250/.73 at idle, you'll be descending at a lower V/S than if I was at 300/.80.

Hi Matt.In the NGX, the only leg of a VNAV PATH descent that is full flight minimum idle, is from the T/D to the next waypoint.The rest of the descent will be a " Geometric Path Descent ".......changing between ARM and FMC SPEED.A lot of RW NG pilots hate the Geometric Path feature. They are hoping Boeing will give an option to turn it off.Fred.

As far as passengers not noticing steep descents is not true. I fly 4 to 5 times a month on commercial airliners and I can tell when we are in a steep decent even if I'm watching a movie or listing to music, you have the feeling of leaning forward like your diving into the earth and this usually never happens sure enough on my last flight from KJFK to KIAH It happened and it was uncomfortable the other passengers seemed to notice as well. Sure enough I got on flight aware after the flight and saw that we hit a 3,900 fpm descent for a minute or so but I definitely noticed. If you look at flight on flight aware for 737's the most VS they usually get is 2,800. But certainly not 6500!

Hi, I see you're a rw pilot.I have issues like the OP. I realize I must be doing something incorrectly. Just don't know what it is lol.Here's how I enter stuff in the FMS:Payload normally 4000 rear 3000 front. About 10-20 pax. Fuel 1/3 cause I do flights less than 300 miles normally. takeoff flaps 5, and I usually get really low V2, like 135-145. So in my speed window I enter v2+20, so anywhere from 155-165. For the autopilot, I "arm" VNAV and LNAV on the ground. When I takeoff I engage CMD A around 500 AGL and that's when the thing just rockets skyward. Eventually it slows as I retract my flaps (maybe I'm doing this too early??). I usually retract flaps as I pass the airspeeds on the tape. But then it skyrockets again (mainly between +4000 to +6000 fpm) until it reaches 10,000 ft, where the climb slow to gain airspeed, then the cycle repeats.

A simple guide would be, if you are not flying with a full load and full fuel, then use Thrust Reduction.(There is a very good example of this in the tutorial flight.)In your example I would put in much more passengers and use Derate 2 for the takeoff and Climb 2 for the initial climb. ( it will return to normal CLIMB at 15,000 ft )By doing this, I would be amazed if you see more than 3,600 - 3,900 fpm.The Assumed Temperature thrust reduction method is the best but you will need a good dispatch type program.I have looked at Topcat but not fully convinced as yet !!A cost index of between 20-40.Fred.

Hi Matt.In the NGX, the only part of a VNAV PATH descent that is idle, is from the T/D to the next waypoint.The rest of the descent will be a " Geometric Path Descent ".....usually with FMC SPEED active.A lot of RW NG pilots hate the Geometric Path feature. They are hoping Boeing will give an option to turn it off.Fred.

I didn't realize that was an option. I guess I'm accustomed to the way my company does it - VNAV PATH is idle until you're on the approach.

I didn't realize that was an option. I guess I'm accustomed to the way my company does it - VNAV PATH is idle until you're on the approach.

I wish it was that way too. It is what I was used to for years but things change.I guess Geometric Path is Boeing's way of introducing even more automation.The pilot can stay away from the throttles !Fred.

I didn't realize that was an option. I guess I'm accustomed to the way my company does it - VNAV PATH is idle until you're on the approach.

That would explain why the CI shouldn't interfere with step descents. If it was like you described ( within NGX ) I assume the VNAV PATH should use the gravity only to descend so that let me think that despite the CI, the FMC makes some mistakes somewhere and sometimes triggering 6000 fpm results.Is that correct ?

As far as passengers not noticing steep descents is not true. I fly 4 to 5 times a month on commercial airliners and I can tell when we are in a steep decent even if I'm watching a movie or listing to music, you have the feeling of leaning forward like your diving into the earth and this usually never happens sure enough on my last flight from KJFK to KIAH It happened and it was uncomfortable the other passengers seemed to notice as well. Sure enough I got on flight aware after the flight and saw that we hit a 3,900 fpm descent for a minute or so but I definitely noticed. If you look at flight on flight aware for 737's the most VS they usually get is 2,800. But certainly not 6500!

In the real world aircraft fly fully loaded whenever possible. Are the weights you are flying at in your NGX comparable to real world operations? A normally loaded 737 won't need to point itself so steeply at the ground to descend at the speed the FMC has calculated. If your aircraft weight is light that would explain the high rates of climb and descent you are seeing.To help identify the problem, please post the gross weight and cost index that go with the screenshots.Kevin Hall

Have a look

http://vimeo.com/27673259

http://vimeo.com/27688233

I wish it was that way too. It is what I was used to for years but things change.I guess Geometric Path is Boeing's way of introducing even more automation.The pilot can stay away from the throttles !Fred.

My company still has U10.7, so I guess we've opted out of the Full Geo Path for the App-only Geo Path.

Have a look

Don't see anything other than normal behaviour there. If in VNAV SPD the aircraft doesn't keep that closely to the computed path. If you increase the target airspeed for descent, rate of descent must increase. Once conditions stabilise rate of descent reduces to more "acceptable" levels. This is basic physics, nothing to do with a problem with the NGX.Kevin Hall

Don't see anything other than normal behaviour there. If in VNAV SPD the aircraft doesn't keep that closely to the computed path. If you increase the target airspeed for descent, rate of descent must increase. Once conditions stabilise rate of descent reduces to more "acceptable" levels. This is basic physics, nothing to do with a problem with the NGX.Kevin Hall

What it shows, is that the vertical speed does not jump as high as 5000-6000.So the problem with high vertical speed is weather. On those videos the weather is default.