that is true, originally the subsystem architecture was prepared with the
suspend (
save/load) and
resume scenario in mind - however, this got crippled pretty quickly when all sorts of features were added that would no longer work with these application-level pre-defined "states" - moving that responsibility over to the aircraft domain does make sense for all the reasons previously mentioned. These days, that is probably the only reasonable way to deal with this. However, the more aircraft begin supporting such states, the more it would make sense to review what is needed (useful/helpful) at the application level in the form of infrastructure (or even just hooks) to support the corresponding "states".
We do have a number of more or less related systems and features that could greatly benefit from formalizing the data/systems modeling requirements, e.g. multiplayer, instant replay/flight recorder (fgtapes), dual-control, reset-reinit, checklists and, more recently, Emesary - the requirements here are very much overlapping. And a number of long term contributors have repeatedly tried to have the exact same discussion, including even Jon S. Berndt (JSBSim) - as a matter of fact, there is tons of related materials to be found in the devel list/forum archives - but if you don't want to do much reading, just make sure to look up Jon's original posting:
https://www.mail-archive.com/flightgear ... 20398.htmlThe idea itself is long-standing though, a number of related pointers are collected here:
http://wiki.flightgear.org/FDM_engine_f ... ardizationThe most recent summary is this, suggesting the use of aircraft-side "situations" represented in the form of different aircraft/system states (state vectors actually) using a combination of existing features like automated checklists and different startup situations to represent different aircraft configurations.
Unfortunately, this never got updated later on - however, it may make sense to review the corresponding discussions and see if this article (or a new one) can be updated to represent the latest "brainstorming".
PS: Originally, the save/load and resume functionality got broken when the "presets" feature got added a long time ago, see David Megginson's comments quoted at:
http://wiki.flightgear.org/Fixing_Presets