To install this sound you will have to decompress the file called "air.pbo"
It can seem complicated but if you follow my inscrutions everything will be ok.

1)Execute the file called cpbo.
It will ask you if you want to associate the *.pbo files to cpbo.
Clic yes.

2)Go to x:\Program Files\Bohemia Interactive\ArmA\addons and double clic on the file called "air.pbo" or "air" it will automatically extract the files contained in this archive in the addon folder.

3)Now place the file called "a10_eng22_1.wss" in the folloing folder : x:\Program Files\Bohemia Interactive\ArmA\addons\air\Data\sound, it will ask you if you want to eraze the existing one.
Clic yes.

4)Now right clic on the folder called "air" (x:\Program Files\Bohemia Interactive\ArmA\addons\air) ans select "create pbo.

Wait for the files to be compressed and that's it, you have your new harrier sound :)

P.S : Don't flame me because I explain everything, as I'm not able to make an install.bat I wanted to made this clear for everybody :)

Thanks to kegetys for his tools.