Exit seat armrests

Must armrests in exit seats must be fixed, or is it up to the operator to decide whether the armrests can be of the movable type?

In all my travels on airlines around the world, I’ve yet to see an exit seat with movable armrests. I’m not 100% sure if there is a regulation that requires it, however from a functional standpoint, all exit seat armrests are fixed because they contain the tray used by a passenger seated there. 

All other seats have a seat in front of it with a fold‐down tray attached, with the exception of bulkhead seats. I am not aware of any regulation or guidance that specifies whether it must be fixed in place or can be movable, but I have reason to believe it’s functionality coupled with safety. In my personal opinion, it would be unsafe to permit tray tables at exit seats when considering the interference a tray table down would cause during an evacuation. It would unquestionably interfere with someone trying to get out of the plane, and likely to interfere with many persons following behind. Passengers will only be thinking about getting out of the plane. Few passengers, if any, would stop to raise the tray table out of the way and lock it upright again. Additionally, being in the exit path, those seats will be banged repeatedly by passengers trying to get out of the plane. The tray table will be repeatedly knocked down, causing a delay in exiting that area. That is why, in my opinion, the best seats to install in an exit row are seats with fixed armrests and the tray table built into the armrest.