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ArannAvi8tor

777 Auto Step Climb

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So I think figured out what the issue is, and as I expected, I changed something.

 

I was reading through the manual (FCOM2 11.40.38) and came across where you can set the step climb size to 0 to stop the automatic calculation (I had some flights where it was overriding my planned step climbs). I just did a flight where I left the Step Size set to RVSM as is default and the auto step worked as expected and climbed to 310. I then changed the step size to 0 to test it and sure enough when I reached the next step climb the auto climb skipped over the step climb. When i changed it back to RVSM the step climb started immediately.

 

So it appears that for the auto step climb to work, the step size must be something other than zero. I am not sure if that is a bug or just me not reading the manual correctly.

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20 hours ago, ArannAvi8tor said:

So it appears that for the auto step climb to work, the step size must be something other than zero. I am not sure if that is a bug or just me not reading the manual correctly.

Step size 0 is how you turn off step climbs.  There is no need to do this when setting manual steps.  From current position up to where you set a manual step all automatic steps will be inhibited, and after your manual step the automatic step feature will continue based on step size.


Dan Downs KCRP

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22 hours ago, ArannAvi8tor said:

So it appears that for the auto step climb to work, the step size must be something other than zero. I am not sure if that is a bug or just me not reading the manual correctly.

Step size basically means that's the altitude you wish to climb when you perform a step climb. Having it at RVSM would default it to 2,000 feet between flight level 290 and 410, I believe. On the Boeing 747-400, for instance, the default step size shows as ICAO, which would have been 4,000 feet. I personally just drop it to 2,000 manually, so the FMC will plan the step climbs at 2,000 feet. By setting the step size to 0, you basically told the FMC that you don't want to perform a step climb, which is why it didn't give you one.


Captain Kevin

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Air Kevin 124 heavy, wind calm, runway 4 left, cleared for take-off.

Live streams of my flights here.

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2 hours ago, Captain Kevin said:

Step size basically means that's the altitude you wish to climb when you perform a step climb. Having it at RVSM would default it to 2,000 feet between flight level 290 and 410, I believe. On the Boeing 747-400, for instance, the default step size shows as ICAO, which would have been 4,000 feet. I personally just drop it to 2,000 manually, so the FMC will plan the step climbs at 2,000 feet. By setting the step size to 0, you basically told the FMC that you don't want to perform a step climb, which is why it didn't give you one.

It is interesting that you bring up the 747.

I just did a flight with the 747 and that is where I picked up this habit. My 747 will only allow manual step climbs if I set the step size to 0. With out setting the step size to 0 the calculated steps override even my initial climb altitude.

 

4 hours ago, downscc said:

Step size 0 is how you turn off step climbs.  There is no need to do this when setting manual steps.  From current position up to where you set a manual step all automatic steps will be inhibited, and after your manual step the automatic step feature will continue based on step size.

 

According to the documentation (and how the 747 operates) setting a step size of 0 does NOT turn off step climbs it simply turns off the calculated step climbs.

 

I just did a flight from FACT to EGLL with the 747-400 and I set the initial altitude to FL300 and the calculated step climbs started at FL310 and stepped to FL350 even though I wanted even Flight Levels. By setting the step size to 0, the calculated step climbs are removed and my manual step climbs worked beautifully FL300>FL320>FL340>FL360>FL380 even on auto step climb.

 

Now the auto step climb doesn't seem to work the same way 777 (I am not sure if that is a bug or not), which is fine, I just didn't realize it.

 

Also, while i understand that you all don't know me and it is easy to assume I don't know what I am talking about, this thread has never been about my lack of understanding how the 777 or 747 FMC work, I know how they work. This thread is simply about unexpected behavior of the auto step climb feature of the PMDG 777. I would kindly ask that we focus on that part of the thread.

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10 hours ago, ArannAvi8tor said:

According to the documentation (and how the 747 operates) setting a step size of 0 does NOT turn off step climbs it simply turns off the calculated step climbs.

Not sure what you mean here.

Setting Step 0 tells the FMC that you do not plan to step. Nothing in the aircraft prevents you from changing your cruise altitude when flying. That's for you and ATC to decide - not a computer. Computers are dumb. Never place your flight in the hands of the automation alone.

10 hours ago, ArannAvi8tor said:

I just did a flight from FACT to EGLL with the 747-400 and I set the initial altitude to FL300 and the calculated step climbs started at FL310 and stepped to FL350 even though I wanted even Flight Levels. By setting the step size to 0, the calculated step climbs are removed and my manual step climbs worked beautifully FL300>FL320>FL340>FL360>FL380 even on auto step climb.

Make sure you're using 2000 instead of RVSM. Sounds like you left ICAO in there. ICAO is non-RVSM (the 747-400 came out before RVSM, so instead of 2000' steps, you used 4000' steps, and cruised on alternate odds: 310, 350, 390, etc).

10 hours ago, ArannAvi8tor said:

Also, while i understand that you all don't know me and it is easy to assume I don't know what I am talking about, this thread has never been about my lack of understanding how the 777 or 747 FMC work, I know how they work. This thread is simply about unexpected behavior of the auto step climb feature of the PMDG 777. I would kindly ask that we focus on that part of the thread.

To be honest, in the land of troubleshooting, you MUST assume that everyone doesn't know anything. That sounds harsh, but to be honest, any time I've asked for support, it's usually been something dumb that I'd forgotten, or overlooked. Nobody is above simple errors, or forgetting the basics. See your post above as an example, honestly. Note how you assumed (based on prior experience) that it should've been 300 > 320 > 340 > 360, but the reality is that you left "ICAO" in the step size. Your assumption, based on the experience you're asserting makes you more knowledgeable (and understandably so), led you astray because you assumed knowledge of one plane transferred 1:1 to another. It didn't, and it caught you out.

The 777, for example, will auto-set your GEN source to the APU when you power that up after landing. You don't have to worry about the power source when you shut the engines down. Look back at the posts after the original 747 release and you'll see TONS of posts from our users who were absolutely baffled by the fact that the aircraft was dropping power, even though the APU was on. Simple thing: the 747 doesn't automatically transfer the source, people were used to the 777's automagic, and got bitten.


Kyle Rodgers

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10 hours ago, ArannAvi8tor said:

Also, while i understand that you all don't know me and it is easy to assume I don't know what I am talking about, this thread has never been about my lack of understanding how the 777 or 747 FMC work, I know how they work. This thread is simply about unexpected behavior of the auto step climb feature of the PMDG 777. I would kindly ask that we focus on that part of the thread.

But, it seems that you don’t know how it works.

If you set the step size to zero, you are telling the FMC to not calculate any step climbs down-route, so obviously the automatic step climb function (which does not exist in the real aircraft) will not work under those conditions.

Manual step climbs are not an FMC function. As pilot in command, you can initiate a climb to a higher level anywhere and any time you want, no matter what the step size may be - whether RVSM, ICAO or zero. The FMC will not prevent you from doing so, though you may bet a warning message if you command a climb to a higher altitude than the current calculated maximum altitude for your current weight.


Jim Barrett

Licensed Airframe & Powerplant Mechanic, Avionics, Electrical & Air Data Systems Specialist. Qualified on: Falcon 900, CRJ-200, Dornier 328-100, Hawker 850XP and 1000, Lear 35, 45, 55 and 60, Gulfstream IV and 550, Embraer 135, Beech Premiere and 400A, MD-80.

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16 hours ago, ArannAvi8tor said:

I just did a flight with the 747 and that is where I picked up this habit. My 747 will only allow manual step climbs if I set the step size to 0. With out setting the step size to 0 the calculated steps override even my initial climb altitude.

You can initiate a step climb anytime you'd like, regardless of step size. Step size only affects the FMC calculation.

16 hours ago, ArannAvi8tor said:

According to the documentation (and how the 747 operates) setting a step size of 0 does NOT turn off step climbs it simply turns off the calculated step climbs.

Yes, that's what it's supposed to do. The only way to "turn off" the actual step climb itself is by not initiating one in the first place (I'm leaving auto-step climb out of the equation here).

16 hours ago, ArannAvi8tor said:

Also, while i understand that you all don't know me and it is easy to assume I don't know what I am talking about, this thread has never been about my lack of understanding how the 777 or 747 FMC work, I know how they work. This thread is simply about unexpected behavior of the auto step climb feature of the PMDG 777. I would kindly ask that we focus on that part of the thread.

You're right, we don't know you. That's why we can't assume what you know. In any event, based on previous responded, as Kyle and Jim have both stated, it appears that there was, in fact, a lack of understanding in how it works with regards to the step size and step climbs.


Captain Kevin

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Air Kevin 124 heavy, wind calm, runway 4 left, cleared for take-off.

Live streams of my flights here.

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10 hours ago, scandinavian13 said:

To be honest, in the land of troubleshooting, you MUST assume that everyone doesn't know anything.

A bit off topic, but IT support in companies usually does very well assume you don't know anything about computers when you call them for any issue even when you explain them what is the problem and that you just don't have the admin rights to fix it! 🤣


Romain Roux

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Avec l'avion, nous avons inventé la ligne droite.

St Exupéry, Terre des hommes.

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13 hours ago, scandinavian13 said:

Not sure what you mean here.

Setting Step 0 tells the FMC that you do not plan to step. Nothing in the aircraft prevents you from changing your cruise altitude when flying. That's for you and ATC to decide - not a computer. Computers are dumb. Never place your flight in the hands of the automation alone.

So I don't know how else to say it, I encourage you to read the manual. Setting the step size of 0 simply removes the calculated step climbs, it does not prevent the Auto Step Climb feature from executing manually entered step climbs.

 

13 hours ago, scandinavian13 said:

Make sure you're using 2000 instead of RVSM. Sounds like you left ICAO in there. ICAO is non-RVSM (the 747-400 came out before RVSM, so instead of 2000' steps, you used 4000' steps, and cruised on alternate odds: 310, 350, 390, etc).

I don't want calculated step climbs, I use manually entered step climbs. This has worked for every flight I have done with the 747 there are no issues with that. What was unexpected behavior with the step size of ICAO was that when I entered a cruise altitude of FL300, I got calculated step climbs of FL310 > FL350 > FL390. By setting the step size to 0 and entering manual step climbs I was able to complete the flight with the steps FL300 > FL320 > FL340 > FL360. This is getting off topic though as this thread is about the Auto step climb feature of the 777.

13 hours ago, scandinavian13 said:

To be honest, in the land of troubleshooting, you MUST assume that everyone doesn't know anything. That sounds harsh, but to be honest, any time I've asked for support, it's usually been something dumb that I'd forgotten, or overlooked. Nobody is above simple errors, or forgetting the basics. See your post above as an example, honestly. Note how you assumed (based on prior experience) that it should've been 300 > 320 > 340 > 360, but the reality is that you left "ICAO" in the step size. Your assumption, based on the experience you're asserting makes you more knowledgeable (and understandably so), led you astray because you assumed knowledge of one plane transferred 1:1 to another. It didn't, and it caught you out.

I completely understand that mentality and even exhibit it myself, however my assumption was not that the step climb proceedure was the same, but that the auto step climb feature worked the same. My mistake. As this was a feature added by PMDG not boeing, it really isn't that unreasonable to assume that PMDG built them similarly.

 

12 hours ago, JRBarrett said:

But, it seems that you don’t know how it works.

If you set the step size to zero, you are telling the FMC to not calculate any step climbs down-route, so obviously the automatic step climb function (which does not exist in the real aircraft) will not work under those conditions.

Manual step climbs are not an FMC function. As pilot in command, you can initiate a climb to a higher level anywhere and any time you want, no matter what the step size may be - whether RVSM, ICAO or zero. The FMC will not prevent you from doing so, though you may bet a warning message if you command a climb to a higher altitude than the current calculated maximum altitude for your current weight.

Actually I do know what I am talking about as that is how the plane functions. When I say manual step climbs I am referring to entering an altitude in the legs page (e.g. FL360S). The step size is for the calculated step climbs that are calculated based on weight. I personally prefer to use the step climbs entered on the legs page instead of the calculated step climbs. The auto step climb, a feature added by PMDG, will initiate either type of step climb automatically. I am aware that I can change the altitude at any time as well, but this thread is related to the Auto Step Climb feature not actually executing step climbs.

 

7 hours ago, Captain Kevin said:

You can initiate a step climb anytime you'd like, regardless of step size. Step size only affects the FMC calculation.

Thank you for repeating what I was trying to explain.

 

7 hours ago, Captain Kevin said:

Yes, that's what it's supposed to do. The only way to "turn off" the actual step climb itself is by not initiating one in the first place (I'm leaving auto-step climb out of the equation here).

Once again exactly what I was saying. I think we are finally on the same page.

 

7 hours ago, Captain Kevin said:

You're right, we don't know you. That's why we can't assume what you know. In any event, based on previous responded, as Kyle and Jim have both stated, it appears that there was, in fact, a lack of understanding in how it works with regards to the step size and step climbs

And I lost you. I know how step size works, I don't know how else to explain it. There have been a lot of assumptions about my knowledge, but re-reading the post, I don't see where it comes from.

 

 

 

 

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I will try to explain this one more time.

 

In both the 777 and 747 documentation they refer to predicted step climbs on the PERF INIT page. To quote the documentation:

  • "0" to inhibit predicted step climbs, or
  • altitudes from 1000 to 9900 in 100 foot increments, or
  • "I" for ICAO, or
  • "R" for RVSM (Only on the 777)

As I prefer to use my own planned step climbs, I enter a "0" into the step size entry on the PERF INIT page. I then head over to the LEGS page and enter my planned step climbs by entering an altitude with an "S" after it (per the manual for planned step climbs).

When I reach my cruising altitude, I set the auto step climb feature in the AUTO CRUISE page from the FS ACTIONS area of the FMS.

Per the manual, the aircraft should begin a step climb at the planned fix of the flight plan. The 747 does this perfectly. The 777 does not. I know they are different planes, so this isn't entirely unexpected. The 777 does not initiate a step climb automatically unless the step size is set to something other than "0". Like I said, I don't know if this is a bug or a feature, just the behavior of my sim.


Now that I am aware of this diversion from the manual I can adjust my settings and continue enjoying these wonderful products.

 

Kyle, please feel free to close this topic if you feel that the situation has been resolved.

 

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16 minutes ago, ArannAvi8tor said:

There have been a lot of assumptions about my knowledge, but re-reading the post, I don't see where it comes from.

Here you go.

16 minutes ago, ArannAvi8tor said:

What was unexpected behavior with the step size of ICAO was that when I entered a cruise altitude of FL300, I got calculated step climbs of FL310 > FL350 > FL390.

And Kyle explained why it does this.

13 hours ago, scandinavian13 said:

Make sure you're using 2000 instead of RVSM. Sounds like you left ICAO in there. ICAO is non-RVSM (the 747-400 came out before RVSM, so instead of 2000' steps, you used 4000' steps, and cruised on alternate odds: 310, 350, 390, etc).

 

13 hours ago, scandinavian13 said:

Note how you assumed (based on prior experience) that it should've been 300 > 320 > 340 > 360, but the reality is that you left "ICAO" in the step size. Your assumption, based on the experience you're asserting makes you more knowledgeable (and understandably so), led you astray because you assumed knowledge of one plane transferred 1:1 to another. It didn't, and it caught you out.

 


Captain Kevin

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Air Kevin 124 heavy, wind calm, runway 4 left, cleared for take-off.

Live streams of my flights here.

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43 minutes ago, Captain Kevin said:

Here you go.

1 hour ago, ArannAvi8tor said:

What was unexpected behavior with the step size of ICAO was that when I entered a cruise altitude of FL300, I got calculated step climbs of FL310 > FL350 > FL390.

And Kyle explained why it does this.

14 hours ago, scandinavian13 said:

Make sure you're using 2000 instead of RVSM. Sounds like you left ICAO in there. ICAO is non-RVSM (the 747-400 came out before RVSM, so instead of 2000' steps, you used 4000' steps, and cruised on alternate odds: 310, 350, 390, etc).

 

14 hours ago, scandinavian13 said:

Note how you assumed (based on prior experience) that it should've been 300 > 320 > 340 > 360, but the reality is that you left "ICAO" in the step size. Your assumption, based on the experience you're asserting makes you more knowledgeable (and understandably so), led you astray because you assumed knowledge of one plane transferred 1:1 to another. It didn't, and it caught you out.

So you are quoting a section where Kyle didn't even understand what I said?

The ICAO step climb from an initial altitude of FL300 would be FL300 > FL340 > FL380 not the FL310 > FL350 that was calculated. The planned step climbs I entered was FL300 > FL320 > FL340 > FL360 but I never expected the 747 to calculate that as I don't use the calculated step climbs.

 

Like I said, I figured out what happened so it is only down to whether what happened was a bug or a "feature".

 

I am happy to continue to prove my knowledge of the step climb procedures of the 747 and 777.

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40 minutes ago, ArannAvi8tor said:

So you are quoting a section where Kyle didn't even understand what I said?

The ICAO step climb from an initial altitude of FL300 would be FL300 > FL340 > FL380 not the FL310 > FL350 that was calculated. The planned step climbs I entered was FL300 > FL320 > FL340 > FL360 but I never expected the 747 to calculate that as I don't use the calculated step climbs.

 

Like I said, I figured out what happened so it is only down to whether what happened was a bug or a "feature".

 

I am happy to continue to prove my knowledge of the step climb procedures of the 747 and 777.

Thanks for clarifying. I misunderstood your original statement, not realizing that you were speaking about manually entered step climbs (on the legs page), as opposed to manually initiated step climbs at a place and time of your choosing.

I normally use the FMC-calculated step climbs in both the 747 and 777, so have not seen the issue where the auto step function does not work with manual entries in the 777. It may well be a bug, especially since you have proven it does work that way in the 747.

Curious though, as to how you are determining the waypoints for your manual entries? I know that PFPX will calculate step climbs as part of the operational flight plan. Are you using that function, or a different method?


Jim Barrett

Licensed Airframe & Powerplant Mechanic, Avionics, Electrical & Air Data Systems Specialist. Qualified on: Falcon 900, CRJ-200, Dornier 328-100, Hawker 850XP and 1000, Lear 35, 45, 55 and 60, Gulfstream IV and 550, Embraer 135, Beech Premiere and 400A, MD-80.

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55 minutes ago, JRBarrett said:

Curious though, as to how you are determining the waypoints for your manual entries? I know that PFPX will calculate step climbs as part of the operational flight plan. Are you using that function, or a different method?

I use SimBrief (its free too, so give it a try) and in their flight plan they have the profile which outlines all of the altitudes for the flight including any airway maximum or minimum altitudes. I program them in manually more just for the hell of it. I don't use ATC or anything usually and I don't watch the long flights so why not follow the flight plan exactly.

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