Recently I have seen many sites offering AIR installer files for their application only to find that thy are not being delivered using the correct MIME type. This means the browser thinks that the AIR file is a compressed ZIP file and on my Mac gives the .air a .zip extension as well.
To many new users to AIR this can be confusing and some are not sure why the AIR app is not auto installing. This can be a big drop out point for your new users well before they have even started the AIr application. So to make the users experience, it’s best to tell your webserver how to handle the .AIR file type. This can be done many ways but one of the easiest for those on Apache systems is to place the following line in the websites .htaccess file:
AddType application/vnd.adobe.air-application-installer-package+zip .air
This makes sure that the correct MIME type is assgned to the .air extension.