Nomde's right.
You can actually do it anywhere while in the game. In the MA, TA, CT and offline.
You just take off in the plane you want a snap shot of and hit either f4 or f5 keys. Both take you outside of the plane and the f5 key can offer you different perspectives by using the zoom feature (hit "z" key then zoom using the [ and ] keys) and your view keys on the keyboard.
To get rid of the icon information just hold down the "alt" key and hit the "i" key until you toggle to "icons off". Now you will only see the plane with no type/name/distance information. When you're done toggle back to "normal icon mode".
Nomde already told you how to take the snapshot by
holding down the "alt" and hitting the "s" key.
The resulting snapshot can be found in your aces high folder and the path should look like this:
mycomputer/C:/program files/Htc/Aces High folder.
The pics will show up in the folder as ahss0.bmp (aceshighsnapshot1.bmp), ahss1.bmp, ahss2.bmp and so on. Easy to find and use.
Hope this helps.
