Are there air stairs of some sort for FSX that are just independent bits you can use with any airplane?

The short answer is no. Technically, air stairs are part of the aircraft which is built in to the doorway, so I assume you actually meant the normal mobile passenger stairways of the kind often mounted on a truck or wheels of some sort, which are brought up to the plane.By default FSX can bring a few things up to your aircraft, but not stairs as far as I am aware. However, pressing Control and J when parked at a gate will extend the jetway from the terminal out to your aircraft if you are parked in the correct place. Additional default FSX scenery of that kind includes, pressing Shift and F to get a fuel truck coming out to you. Opening the cargo doors will get a baggage truck to you at some airports if your scenery settings are on high. But for stairs to be brought up to your aircraft, I think you'd be looking at an add-on aircraft that had them as part of the package.There are some add-on airliners that have such animated stairway scenery available, a few of them are: The CLS Boeing 747-200/300, which will bring everything from the honey wagon to cargo elevators LD3 containers and stairs up to your aircraft, via a little pop up menu, and it all looks pretty nice. The Wilco PIC 737 will get ground personnel around it and service vehicles in the Aviation and Mission add on. The Ariane 737 will do that sort of thing too, with stairs and a power cart for running without the APU and it also has the folding airstairs built into the forward passenger door which are animated and can be extended from the galley via the cabin crew's control panel, the FS9 version even has a pushback truck which you can drive to position the aircraft. The Supronov Designs Yak-40 also has the airstairs animated at the back of it which can be opened too. Both the Wilco and the Eaglesoft Citation X have some fancy animations when parked up, and some things such as a limo driving up to the aircraft at certain airports and a red carpet being rolled out. Some of these are currently only FS9 and not FSX though, notably the Yak-40 and the Eaglesoft Citation X, although they are coming to FSX.You could cheat and design scenery for stairs which only appeared at a certain detail preference level, then assign a shortcut to alter the scenery level to make the scenery appear, but it would require you to model the stairs yourself, and that seems like a lot of trouble to go to! Somebody might have had a go at doing that, but I don't know for sure, you could try looking int the AVSIM file library when it gets back up and running.Al

Yes, you're right, I meant the kind they drive up. The swarm of service vehicles is one of the things I get a kick out of with the CLS 747. I remember Jet City Aircraft had that sort of thing, too. Seems strange there is nothing like this for FSX. The stewardess in my CS 757 looks a little odd standing in front of an open door ten feet up without stairs. I fear for her safety.

Yes, you're right, I meant the kind they drive up. The swarm of service vehicles is one of the things I get a kick out of with the CLS 747. I remember Jet City Aircraft had that sort of thing, too. Seems strange there is nothing like this for FSX. The stewardess in my CS 757 looks a little odd standing in front of an open door ten feet up without stairs. I fear for her safety.

Do a search at FSdeveloper dot com for stairs. There is a GMAX vehicle with steps as a download for FS9. It can be made to compile in FSX. It is stationary but can be placed so when the plane stops the steps align to the door. These stairs should only be used if there is no FSX animated jetway.