I had a look at the/a DC-9 today.
The first time in a long time I've fully used any of our DC-9 simulations (since HJG/FS development, for me, has literally been 1 project after another since around 2008) .... beyond my needing to always remain "basically familiar" with its functions (along with those all of our other panels/simulations too) for support related reasons.
I selected "a DC-9 panel/simulation" .... the JT8D-7 powered SERIES 30 version for the benefit this test. This selection doesn't impose any difference/s, at all, though as "the like" of simulated Pressurization Systems is compiled to function identically for each DC-9 panel/base pack (it's other details that define significant differences between each of these DC-9 simulations .... and which applies similarly among most of our other simulations too).
I'll start by saying the DC-9 panels we offer here were originally compiled by Stellan HILMERBY (whom was, at the time, an SAS captain on the type). His intent was these panels be used primarily as "a home PC based familiarization tool" (not a training tool) for SAS DC-9 pilots .... those at least whom indulged in FS .... and later for "advanced FS enthusiasts" too. That's why these DC-9 panels are "relatively" complex (until one makes the effort to adapt to them) with a lot of systems functionality (notice I don't say fidelity) compiled into them ....
"in so far as what FS will permit" (key words). There's a lot of grey area within FS itself though and some aviation parameters simply can't be represented well, or at all, by "the game" .... and which needs to be appreciated of course. Thanks to the efforts of our George CARTY the original programing errors (not errors as such since these were essentially just a case of limitation of abilities on the part of the original developers) were all "FIXED" .... and we then added a number of other new features as well .... nothing though that implicated the Pressurization functions as simulated in the original DC-9 panels/simulations.
ANYWAY ....
I set up my DC-9 for a test. Flying from the default KSEA (airport altitude around 435 FT ASL) to KLMT (airport altitude around 4,022 ASL). 2 airports with reasonable altitude, and by implication, temperature/air pressure environment differences (at least that'd be the case "if" FS was totally authentic) .... a route I know well through it having become my standard pre-release FS flight testing track since 2006 and for every simulation we ever released here.
In my case .... I figured it was probably best to start by going into the "FS WEATHER/ADVANCED" options and setting up the like of AIRPORT ALTITUDE, AIR TEMPERATURE, and AIR PRESSURE parameters etc prior to loading my DC-9 into FS. FS does need to be told where it is, and what the situation is in regard to wherever it's set up for, otherwise it'll apply uniform values to everything right across the board (FS probably does this in regard to whatever scenarios are set up anyway).... or so is my understanding. I don't have, or use, addon WX related utilities and nor do I download RW WX related data either for anywhere I fly. I simply set up my own virtual weather in FS, manipulate certain selectable FS WX related parameters, and then accept whatever "the game" gives me".
Now .... and in order to try'n avoid what could otherwise have potential to become a prospectively, lengthy, and/or otherwise excessively technical response ....
The conclusion of my own DC-9 experience today, even applying the pre-loading WX related parameters I related above, was "pretty much in line with what you reported. The panels pressurization system seemed to indicate correctly from TO .... and all the way up to cruising altitude. I went to up FL310. The cabin pressurization system had been set up for 8,500 FT .... and the BARO settings were accordingly, and correctly (I think .... some of its features are small and hard to read though, so, I can only assume I'd set it up properly) .... and then adjusted passing through 17,500 FT both on the way "UP and coming back "DOWN" again too. The altitude for my destination airport was adjusted prior to arrival there also. Everything seemed to function correctly all the way "UP .... and "DOWN" .... but upon arrival at my destination the principal needle indicated at around + 10 FT whilst the secondary needle indicated around 200 FT. Again .... barely different from what you reported if different at all.
I can therefore only assume what we've got is how it all works .... "given the limitations of FS" .... and the fact I wasn't subjected to any bells, whistles, horns, lamps or any other warnings (of any description) throughout the entirety of my own DC-9 test suggests all was set up fine.
FS can simulate some operational parameters (but how well it does so is a matter open to conjecture) .... but .... whilst these panels feature a lot of systems that do work well we can't guarantee the integrity of some finer, and more complex, features represented among these panels once exposed to the dictates of FS .... other than to say if one's not (once again) subjected to any bells, whistles, horns, lamps or any other warnings, and if everything else is apparently working well too, and one doesn't end up dropping out of the virtual sky, then, all must be about as good an FS experience as one could ever wish for using these DC-9 simulations.
Can't really provide a better/more conclusive report than this given, despite the fact I've got a good technical head in regard to the functionality of everything we offer here, even my own understanding and knowledge of some features is limited.
Not really what you want to know I guess, but again, the best I can relate based on today's DC-9 test and my current knowledge of what we offer and how (I think) it should all be used and work .... amid some of the limitations and dictates of FS itself.
Mark C
AKL/NZ
