yes PDA also have and (OS) operation system any hand held computer has an OS

A Personal Data Assistant phone has way more functions than a regular one.You can use them to make Microsoft compatible documents and spreadsheets, play music, play games, use timers and stopwatches, make a calender and much more. Remember, to do many of these functions you need to install apps (prc). Many PDA apps are free.

what is a pda in an aircraft

If you asked what a file on a PDA is, my answer is everything. anything you see on a desktop computer can also be a file on a PDA.

If you asked what a .pda file (having an extension of PDA), sorry, no idea. :)

PDA's can be connected to a computer. Files can be transferred from the PDA to the computer and from the computer to the PDA. Data such as phone numbers, addresses and appointments can be synchronized between PDA's and computers so the information can be the updated.