Flying a SID with the FMC

[Guest Ray CYYZ]

Even derating beyond TO2 with a OAT setting gets me ballooning ... perhaps it is a combination FS9 - borderline machine that the ap calculations are just getting behind the plane due to slower rates.I do notice that tracking is sloppier in FS9 then in FS2002 but god, I just can't go back to those visuals out the window.I promise I'll buy a new machine as soon as I can ;) but I have just paid for all the 737NG manuals }(Ray

[Ray Proudfoot 8,964]

Hi Anthony,The world is simple, isn't it ?No it isn't and neither is programming the FMC. But if you're confused by the rules and which set to follow imagine the confusion for us poor end-users who don't have your level of expertise.I'm not asking that you follow rule A or rule B - all I ask is that having programmed the FMC we are then advised of which set of rules we should follow.I'm now setting my own rule. Don't set an altitude or speed constraint only - always set both. That way I know what I have to do and if the aircraft misbehaves I can blame myself and no-one else.Would this be a - sort of - satisfactory explanation on why things are the way they are ?I get the feeling that you think I'm having a dig at you. I'm not - not a personal dig anyway. The complaint was borne out of frustration at not knowing what the rules were under which VNav was disconnected. Following much dicussion this week I'm now a lot clearer as to what works and what doesn't.It may interest you to know that I went to a friends tonight who, so far, hasn't been able to fly this aircraft successfully. I showed him all the things I'd learned in the last 2-3 days and he really enjoyed completing two successful flights. We both agreed that although the product still has some rough edges these can be worked around and the base product is now solid and very enjoyable.I hope that goes some way to giving you a balanced view of the PMDG737.Keep up the good work!

[Guest amerton]

Ray,No problem ! I wasn't feeling bad about your post. What I was explaining is that the only rule I have seen written about this is the disconnect one. Sorry if I gave the impression I am confused.When and if I get other info, I'll see how it can apply. Until then... VNAV discon upon wpts with speed constraints only. ;-)anthony Anthony MertonPrecision Manuals Developmenthttp://www.precisionmanuals.com

[Ray Proudfoot 8,964]

Anthony,Thanks for the clarification and I hope the VNav rule is soon resolved.Whilst I have your ear (I bet you're regretting having jumped in now :D ) can you confirm what the current state-of-play is regarding the aircraft holding the optimum route as shown on the ND? I've found that it tends to understeer large turns and then having flown wide of the route then turns back in towards it attempting to get back on route asap. This has the undesirable effect of the aircraft making big turns one way then another before the ideal line is regained.I can't even begin to imagine the programming required to achieve this but I'm not sure if this is perceived as a bug or not. Perhaps you could confirm one way or another?Thanks,

[Guest amerton]

Ray,If this happens it is indeed regarded as a bug.How large is "large" ? Can you help us with a precise example, when you come at it again ? A screenie, showing the ND and PDF, a flight plan. Current weather, winds, speed alt etc... Everything needed so we can precisely reproduce it ? I must say it does not happen noticeably on my gear...Email me the stuff at amerton@precisionmanuals.comthanksanthonyAnthony MertonPrecision Manuals Developmenthttp://www.precisionmanuals.com

[Ray Proudfoot 8,964]

Hi Anthony,If this happens it is indeed regarded as a bug.Ah, good. That's what I suspected.How large is "large" ? Can you help us with a precise example, when you come at it again ? A screenie, showing the ND and PDF, a flight plan. Current weather, winds, speed alt etc... Everything needed so we can precisely reproduce it ? I can't be precise in saying what distance off the ideal route the aircraft deviates but it is significant and the fact that the aircraft then attempts to get back on course asap contributes to the problem. My flight up to Manchester from Gatwick is a perfect example of the problem. I'll send you the flight plan together with screen shots etc. Current weather really isn't a factor. In all three flights on this route the winds were light and wouldn't contribute to the problem. Obbviously if I was flying through a hurricane I'd make some allowances but conditions were benign.The problem is easily reproducable with any flight plan that has a SID with large changes in heading. The LAM4M SID out of 26L EGKK (London Gatwick) is such an example and I'll send you details later. I'm surprised you haven't experienced this problem on your own system but as you have much more space in America than the UK tight turns are perhaps a rarity ;-)Cheers,

[Guest amerton]

As a matter of fact I live in Geneva, Switzerland...:-)anthonyAnthony MertonPrecision Manuals Developmenthttp://www.precisionmanuals.com

[Ray Proudfoot 8,964]

Ah, lucky man! So you should be used to tight turns around those mountains! :7I've just put together my screen shots showing the overshoot problem and I'll send it to you together with the flight plan and FS2004 saved flight using a PMDG737-700 2D cockpit only.Weather was downloaded using the 15 minute option. Have fun!Cheers,