One improtant thing to keep in mind is that Accessibility support doesn’t happen automatically. You have to tell flex you want Accessibility support in your app, and you need to implement it accordingly. Here are all the relevant links regarding Accessibility.
Enabling Application Accessibility
There are multiple ways to enabling application accessibility. See here for details. If you are using flex builder 2 to compile your app, from Flex builder, go to project—>properties —> flex compiler, check the box “generate accessible SWF file”.
Flex Accessibility Best Practices
Flex includes 22 components with built-in accessibility support. But this does not mean you can simply compile you app with accessibility enabled, and your app will meet all the requirement. You need to make sure you have taking care of Controlling Reading Order, Providing Instructions , Ensuring Keyboard Access, Providing Captions, Providing Text Equivalents, and Using Color Wisely.
Using Flex with JAWS
In order to most effectively use the JAWS screen reader with an Adobe Flex application, users must download and install scripts.