Pool - Planes available
Rate - Number of planes that will become available during a month
Used - Number of planes transfered from pool to active units so far (relacements)
Be aware that 'used' aircraft total includes all issues to air units.
So if aircraft are put back into the pool (e.g. after an upgrade) and issued later to another unit, the same aircraft will be counted twice. This may result in the 'used' aircraft total being larger than the number of aircraft you have in the game. (This isn't a problem but explains why you occasionally get funny numbers...)
Cheers,
Reg.
(One day I will learn to spell - or check before posting....)
Uh oh, Firefox has a spell checker!! What excuse can I use now!!!