Mid-Flight First impressions

[Guest adameke777]

PaulCan you do a quick experiment and change ICAO to 2000, see if that makes a difference.Adam

[baw716 0]

>Dave, welcome to the medication club first of all. It is>Vicodin for me, recovering from spinal surgery. C-scope, I>assume you are reffering to a camera where the sun don't>shine? I just had one done to look for internal bleeding from>top and bottom. Not fun, I wish you the best.--------------------------------------------------Thanks Paul and confirm your point for same reason. Outcome good. BTW, I have five blown discs (four in the C spine, one at L5/S1).Rx of choice Avinza (long acting MS) great stuff...long acting and no fog unlike the regular stuff. OK..now to the issue at hand: I think you hit the issue on the head. I was reading the 777 manual (the real one) under "climb constraints", and the books says the following:"Step ClimbFuel and ETA predictions assume the airplane climbs at each predicted step climb point as airplane weight decreases. FMC predicted step climb increments are based on the step size shown on the CRZ page. If a step size of zero is entered, the FMC assumes a constant altitude cruise. Flight crew entry of a planned step altitude on the CRZ or RTE LEGS page overrides the FMC step climb predictions before that point. Entry of a planned step altitude on the RTE LEGS pages overrides a "step to" entry made on the CRZ page.Predicted step altitudes are shown on the RTE LEGS page. The distance and ETA to the next step point (predicted or flight crew entered) are shown on the CRZ and PROGRESS pages. They are also shown on the ND map display with a green circle and S/C label".Of course, this explanation is clear as mud. :-rollerFrom what I gleen from your post below, you were making your altitude changes in the MCP based on the predicted OPT ALT. So, if I interpret the above correctly, if you were making a change in altitude based on the CRZ page, and the RTE LEGS page had a different altitude set for that waypoint leg, the RTE LEGS page would take priority over anything you change using the CRZ page.So my question is this: In your example, your step size was ICAO. As soon as OPT ALT 361 CDU commanded step to FL380, you initiated the climb, but the VNAV wouldn't accept it. What was the RTE LEGS alt at that position? If it was, say FL360, if I read the manual correctly, VNAV would not have commanded the climb to FL380. To do that you would have to use FLCH or IAS/MACH + VS.If your RTE LEGS altitude was FL380 at the point you initiated the climb, then there might be an argument for the possibility of a fault in the programming of the ICAO step climb profile on the CRZ page.Does this make any sense?It sounds like the proper procedure to change altitude when the RTE LEGS page is different than the OPT CRZ altitude is to change the altitude on the RTE LEGS page, then change it on the MCP, then hit VNAV. If you can confirm that information for me, then I think I will have this straight in my head...I think this is a procedural thing with the FMS (I am not a pilot, I would have to consult my brother in law who is a 747-400 F/O with about 10000PIC hours...he can give me the straight skinny...he knows both the PEGASUS and SMITH CDUs sideways). I admit to having a reasonable handle on the glass, but I am not an expert. I have the FMC Guide for the 777 as well as two 777 Operating Manuals and CBT training CDs...I suppose I could find the lesson for operating it and go through it myself to be sure.It doesn't sound to me to be a PSS FMS fault...Do you concur?ThanksDave LambB767 Captain British Airways Virtualbaw716------------------------------------------------------>Now for your question>I had step to 390 NOW in the CDU>OPT Alt was only 376 and Max was 404>It looks like the CDU logic was to not command 370 because I>was already beyond that for an OPT ALT but would not climb to>390 because OPT wasn't there yet.>Feel better,>-Paul>>EDIT: Just confirmed it. Initial crz alt was 340. Step size>was set to ICAO. As soon as Opt Alt hit 361 CDU commanded>step to 380. Max Alt was 397 and again VNAV disconnected when>I tried to initiate the climb. Entered 360 on the MCP and>initiated that instead and all was happy again.>>Liquid Cooled>AMD 4000 San Diego>2 Gigs Kingston Corsair XMS CL2>Dual 7800 GTX >24 inch widescreen dual 19 inch LCD>Raid-0>

[Brian Doney 127]

Just a little issue...ICAO doesn not allow for the use of even FL's above FL300, regardless of what OPT/MAX indicate.There seems to be a bigger issue at play here, but, that would be something to start with.

[baw716 0]

>Just a little issue...>>ICAO doesn not allow for the use of even FL's above FL300,>regardless of what OPT/MAX indicate.>>There seems to be a bigger issue at play here, but, that would>be something to start with.Ah, the game's afoot:I am looking at Bill Bulfer's FMC Guide for Big Boeings (incl PEGASUS on 777). STEP SIZE ICAO default value is 2000ft increments below FL290 and 4000ft increments above. A different STEP SIZE is allowed by entering the STEP SIZE in feet from 0 to 9000 in 1000ft increments. If NO step climbs will be made, it is "important" to enter zero so that the performance calculations will compute accurate fuel predictions.So, Brian, your statement above regarding STEP SIZE does not appear to be entirely correct. You can enter an even number flight level as your planned altitude based on the predictions on the PERF INIT page; however, the STEP SIZE at ICAO only references the increments of climb above FL290, not that you can't fly it. The default is ICAO; however, the value can be changed based on the particular conditions.What we need to try is flying with an even flight level as the programmed final altitude and program the STEP SIZE on the PERF INIT page with a) ICAO and see if the legs pages reflect the appropriate step sizes at the optimum points and :( with a value < or > an ICAO value, say 2000ft increments above FL300 and see if the FMS will recalculate the step climb profile accordingly.The question really comes down to a) if this particular aspect of the FMC is modelled in the 777 and :( if it is, what values other than the default ICAO can be entered either on the PERF INIT page or the CRZ page. We should test this to see if the step values can be manipulated in this form.Just as an aside, there is the zero step climb technique to consider. If no step climbs will be made, zero must be entered as stated above. This will blank TO STEP CLIMB header and field at 1R of CRZ and 4R of PROG 1/2. The step size zero technique eliminates all down path step climbs. Otherwise, performance calculations will assume the computed optimum steps will be made, possibly resulting in non-conservative predictions of fuel at destination. In cases where substantial headwinds exist at higher altitudes, FMC can show a savings by staying at a lower altitude.For example, you are planning a flight EWR-SFO and there are substantial headwinds at most levels along the most direct route (say FL340 and higher). If you don't enter ZERO in the STEP SIZE, the FMC will calculate fuel burn based on the "optimum altitude", which, if the proper average wind component for the route is not entered correctly can produce an incorrect fuel burn prediction. This is the purpose of the ability to override the ICAO in the STEP SIZE line of the PERF INIT page. You can change different values to achieve different fuel predictions based on various altitudes and wind conditions. In the case above, it might be more fuel efficient to do a straight climb to FL320 and stay there (on medium haul flights this is possible); in which case the STEP SIZE needs to be set to zero so it will calculate the correct fuel burn based on the altitude and winds you enter into the FMC. Note: Any entry made in STEP SIZE before the flight on the PERF INIT page propogates to the CRZ page.IMPORTANT NOTE: If you elect to change STEP SIZE during the flight, it can be done only on the CRZ page and not the PERF INIT page. Reference: Page 80 of FMC Guide for Big Boeings.Suggestion to pilots: Attempt to manipulate the STEP SIZE in the preflight setup and see what changes result on the LEGS pages and the CRZ page. You may find that you have different values for MIN/OPT/MAX altitudes predicated on a manual override of the default ICAO setting on the PERF INIT page.To PSS: Were these particular aspects of the FMC modeled in this release of the 777? Just curious, because if not, it might explain why some people are having some of these step climb issues. If not modelled, this would be an excellent add on, since it would give the ability to actually manipulate the fuel calculation on the ground based on the parameters fed into the FMC (especially winds and step climb variations) as well as provide improved fuel economy values for MIN/OPT/MAX altitudes under specific wind conditions.Also, side question for PSS, were pilot defined waypoints (pilot constructed) modeled in the FMC? Specifically:-Place-Bearing-Distance-Place-Bearing/Place-Bearing-Along Track Waypoint-Interval Lat or Long-Airway intersectionIf not, could you indicate which ones were not, so that we can build a work around for some of these pilot defined waypoints other than specific lat/log positions? If this information is in the user manual, then so indicate and I can look up the information and do the tests to see what can be manipulated, then I can report it back on the forum. In addition, if these are not included, these would be terrific improvements to have in the FMC and programming should not be terribly difficult (again ref. FMC Guide page 19-22).Final question-Conditional waypoints (waypoints not created by pilots) such as in SIDS/STARS...I presume these can be modeled based on how the specific SID/STAR is built and then loaded into the SID/STAR file. If this is not the case, can you also please advise and then possibly consider for future release?Many thanks,Dave LambCaptain, British Airways VirtualSenior Captain, United Airlines Virtual Cat IV

[psolk 3,040]

WOW,Dave,First off, glad to hear everything went well. I had 11 hours of surgery in September from the stomach and the back to have a titanium cage put in my back. I feel your pain. Agai, glad it worked out for you.I can not even begin to thank you. I was hoping for exactly this, people with more knowledge to come along and clear this up (or confuse me even more, I am not sure yet)If you look at my first post I actually asked if this was a PSS thing or a real world idiosynchracy. It is amazing how much we assume is a bug when in reality it works the same way on the real thing and not being a r/w pilot we have no clue. Based on your first post, If I command a step to 390 but my legs page still says 370 then I will only be able to climb under VNAV to 370 despite my PROG page saying CLIMB NOW.That makes a great deal of sense but the question would be does the r/w counterpart behave the same way as the sim or does it generate an unable crz alt message. Again, all I can do is assume but I would be very surprised if the r/w units just dropped the VNAV command altogether. You never know though..Similarly, I will try another long haul this afternoon. I took a long weekend in order to have ample testing time for my new T7 :)This time I will set the step to 2000 instead of ICAO and see how it handles it. Again, thank you so much for all of this information, I am doing my best to suck it up. Knowing the workaround to re-engage VNAV makes this more of an annoyance than an issue and if it proves to be r/w behaviour then kudos to PSS...Thanks again Dave, trying 2k feet step today Andy,-Paul Liquid CooledAMD 4000 San Diego2 Gigs Kingston Corsair XMS CL2Dual 7800 GTX 24 inch widescreen dual 19 inch LCDRaid-0

[Guest Davidoff]

Just an FYI, all pilots I have spoken to say that during step climbs they do not use VNAV because it gives you the max allowable engine thrust, which is not comfortable for the pax. They just use a v/s of about 500ft/min.

[psolk 3,040]

-Davidoff, you are 100% correct. If you watch the ITVV videos, they specifically mention that. The issue though is whether or not you will be able to re-engage VNAV at the Alt you climb to. If your initial CRZ AlT was 350 and step is set to ICAO then when the CDU says STEP NOW on the PROG page, if you go to VNAV it says step to 390. In reality your OPT ALT is 371 but because Step is ICAO and your OPT ALT is above 370 CDU tells you to step to 390. Because 390 is higher than the value in the legs page, VNAV will not accept it, you lose VNAV altogether, your econ spd on the PROG page and you have to fly the rest of the route via the MCP minus VNAV.So the question is not whether or not to use it for the climb but if VNAV is operating correctly and will be able to re-engage once the climb is complete.It does look like there (might) be an issue with the logic of the PSS CDU but we do have a workaround and some of those with a lot more knowledge than myself are researching this a bit as well.Thanks Davidoff, good point,-PaulLiquid CooledAMD 4000 San Diego2 Gigs Kingston Corsair XMS CL2Dual 7800 GTX 24 inch widescreen dual 19 inch LCDRaid-0

[FOD 23]

Just sterted my first flight witn V1.1 and inadvertantly selected Flap 1 at 5000 ft - well into a VNAV climb. On my system "Act Econ Climb" changed to "Act Econ Desc" and the aircraft entered a gradual descent at 1500 fpm - MDC alt was still set at 36000, the FD indicated a climb and LNAV continued as normal. Although I could continue the climb using VSFPA, I found that I could do nothing to restore the VNAV climb - I tried disconnecting and reconnecting the AP, changing the cruise level etc etc.I then saw your item #6 above and had a look at the take off and initial climb. I found that, if I selected flap up and then back to 5 at the time I changed from 15 flap to 5 flap - during the "Act Lim Spd Clb" phase, the VNAV profile remained ok; but if I did the same slightly later between the 5 and 1 flap speeds - during the "Act 250kt Clb" phase, VNAV changed to "Act Lim Spd Des" and the aircraft changed to the same 1500 fpm descent. Again, no way, I could revert to VNAV climb.To date I have not found out how to clear the FMC when an error like this occurs - very grateful if anyone has any ideas.John RooumBTW re your #8 - I have seen several in flight cockpit photos and this appears to be SOP once a route is "executed" in the CDU.

[psolk 3,040]

Hi John,I am enroute from KEWR-LLBG right now. ~10 hours to go LOL but I will try to replicate what you are saying ASAP. It might be tomorrow morning. Then Iwill figure out if we can get a workaround. Hopefully someone from the PSS team can look at it as well.As for my #8 I will watch the CP ITVV 777 video and see if it happens to show it... Maybe it is an operator option or like you said, just SOP.Thanks John,-PaulLiquid CooledAMD 4000 San Diego2 Gigs Kingston Corsair XMS CL2Dual 7800 GTX 24 inch widescreen dual 19 inch LCDRaid-0

[psolk 3,040]

Hi Adam, doing KEWR-LLBG right now and like you asked I set my step to 2000 during my pre-flight. Indeed, this time the legs page clearly depicts the steps as you scroll through. I see 330 (Initial crz) then 350 370 and 390 as I scroll through my 18 pages of legs :)I think that is the ticket. It is a much more realistic procedure I would imagine to climb at 2000 foot intervals opposed to 4000 foot intervals. I still wonder if this is realistic CDU behavior but perhaps Dave and his resources are better qualified to answer that. Anyone got a r/w T7 pilot handy :)-PaulLiquid CooledAMD 4000 San Diego2 Gigs Kingston Corsair XMS CL2Dual 7800 GTX 24 inch widescreen dual 19 inch LCDRaid-0

[FOD 23]

Thanks Paul - Appreciate that this is a "pilot error" function; for me the VNAV and indeed most of the FMC has worked perfectly when I follow SOP. But, now I have seen the flap inter-action, I would be interested in your findings when you have time. Looking forward to my first long haul in the V1.1 - unfortunately not until tomorrow.Have a Good FlightJohn R

[Brian Doney 127]

Dave,I'm afraid you've read further into my statement than you should have.I said nothing of the actual step size that is allowed for ICAO, only that even FL's are not considered valid above FL300 in ICAO. There's a big distinction there.Also, if you were flying eastbound across the US at FL350, this would also be invalid as far as ICAO, which is pre-RVSM, is concerned.I'm not sure just what exactly the problem is with the 777 here, and probably won't be investing too much time to find out, honestly, but I think a solid understanding of what ICAO actually is, that fact that it doesn't just stand for "4000ft", and what needs to be done to fly RVSM instead, is important.The fact that anyone was shooting for FL380 while ICAO steps were chosen in the FMC shows that there is some misunderstanding here.

[baw716 0]

Brian,I certainly hope that you are a real world pilot, as the tone and language of your post was quite provocative. Yes, I went far beyond what you stated in your post. I felt a more complete explanation of step size was needed, as many of us (myself included) don't necessarily have the complete knowledge necessary to master the nuances of this aspect of the use of the FMC...and this FMC is very different than the FMC on the 767.I did a significant amount of research for that post. I quoted straight from the flight manuals and the FMC Guide (updated for RVSM) published by Bill Bulfer. I also made it quite clear that I am not a real world pilot and was quoting from the manual. The information I provided seemed to help some people understand some of the unique issues involved in using step size, especially in the PERF INIT setup. I don't believe my information was inaccurate (at least to the extent I quoted it from the manual).After reading your reply to my post, I did substantially more research on you to determine if you are a real world pilot. Reasoning: I would never question any statement of a real world pilot regarding any aspect of flying. I did not find any information to lead me to conclude that you are a pilot; therefore, I feel compelled to state that I am a little irritated at being told, in effect, that I don't know what I am talking about.I would therefore appreciate you clarifying for us that you are a pilot (and forgive me for asking for a little proof--carrier will do) and if so, I would further appreciate you providing us a more in depth explanation of step size as it relates to RVSM flying. Perhaps then we can get closer to a concensus as to whether there is a even an issue with the 777 FMC as modeled in the PSS aircraft. My opinion is that the FMC is not 100% modeled and as such may create certain anomolies when attempting to use VNAV in RVSM flying if ICAO is the only step size profile available. I will be testing this extensively this weekend and will report my findings on the forum.As a closing thought, I believe the most productive thing we can do is to work together to improve the skills of all the virtual flying community. If you are a real pilot and I offended you by calling your statements into question, I apologize. If you aren't, then perhaps we are both better served paying attention to those individuals on this forum who are real pilots; more than any others, their advice will help us improve the quality of the virtual flying experience and the professionalism of those who operate within it. Regards,David LambCat IV Senior Captain-United Airlines VirtualA320/B767 Captain-British Airways Virtual

[Brian Doney 127]

David,Wow.I'll start by stating that I AM NOT a real-world pilot. I've said as much on about 50 different occasions in the various fora, here and elsewhere, so I guess, if that will be your qualifier as to the validity and accuracy of what I have posted, please, disregard my posts from this point forward."I certainly hope that you are a real world pilot, as the tone and language of your post was quite provocative."Well we've confirmed the first part of your statement, as once again, I AM NOT a pilot. As to the second part, ya know, the over-sensitivity of some in this community is actually quite amusing at times. I'm sorry that I don't conclude every post with a group hug at the end, but, that's just the way it is. I didn't insult you or anyone else here, nor did I belittle you or anyone else here. I stated that there is an obvious misunderstanding of what the ICAO rules actually are/were, becuase there IS an obvious misunderstanding of what ICAO rules are/were. No more, no less, so you can come down off of your soapbox now."Yes, I went far beyond what you stated in your post. I felt a more complete explanation of step size was needed, as many of us (myself included) don't necessarily have the complete knowledge necessary to master the nuances of this aspect of the use of the FMC...and this FMC is very different than the FMC on the 767."You still are not reading what I have posted. So now, for the third and last time, ICAO defines not only step size, but also valid levels, this is regardless of format, software revision, type, whatever. It is also now obsolete in most of the areas of the world we fly, as of last January, when North America and the Caribbean went RVSM.Before you say it, yes I am aware that Europe, NATS and WATRS went long before NA, that's not the point I'm making, and there's alot more to that whole story that need not be discussed here as most of it is irrelevant to the sim world.I drew NO conclusions of what the PSS FMC is or is not capable of, or that it is even itself in error, so your implied lesson on the differences between the 767 and 777 is not needed."After reading your reply to my post, I did substantially more research on you to determine if you are a real world pilot. Reasoning: I would never question any statement of a real world pilot regarding any aspect of flying. I did not find any information to lead me to conclude that you are a pilot; therefore, I feel compelled to state that I am a little irritated at being told, in effect, that I don't know what I am talking about."All ya had to do was ask, but hey, knock yourself out. Though I don't generally deal with people that conduct themselves in that manner, so, this will most definitely be my last willful communication with you, sir.As far as your hurt feelings, well, sorry, not really concerned with that, not even a little, since you, in effect, have done exactly the thing you take issue with, to me."I would therefore appreciate you clarifying for us that you are a pilot (and forgive me for asking for a little proof--carrier will do) and if so, I would further appreciate you providing us a more in depth explanation of step size as it relates to RVSM flying. Perhaps then we can get closer to a concensus as to whether there is a even an issue with the 777 FMC as modeled in the PSS aircraft. My opinion is that the FMC is not 100% modeled and as such may create certain anomolies when attempting to use VNAV in RVSM flying if ICAO is the only step size profile available. I will be testing this extensively this weekend and will report my findings on the forum."Well, I've done the first part, and since that seems to in your mind invalidate anything else I might offer, I won't bother with the rest. I will say that, this was all just gone through in another forum just down the hall from this one, if you truly are interested.A very simplified and short summary: - A valid RVSM FL must be chosen initially. - The STEP SIZE parameter must be modified to either a 2000 or 4000 ft step, and not left as ICAO."As a closing thought, I believe the most productive thing we can do is to work together to improve the skills of all the virtual flying community. If you are a real pilot and I offended you by calling your statements into question, I apologize. If you aren't, then perhaps we are both better served paying attention to those individuals on this forum who are real pilots; more than any others, their advice will help us improve the quality of the virtual flying experience and the professionalism of those who operate within it."I agree, but I'll also state, that getting on your soapbox to preach as you have, will not endear you to those on the flightdeck, or those close to them, and that those flying the line are not the only souls with access to the details which you seek. I've made no claims to be anything that I am not, and if that's not good enough for you, then good riddance.Good day sir.

[Brian Doney 127]

Paul,Just as an afterthought, and I'm sorry I didn't do this earler, I apologize to you for your thread veering off course as it has, and I won't contribute any further to that.Best to you, and good luck with your health issues. It's good to see you haven't let your physical afflictions bring you down.