Inner pane or outer pane can make a big difference . I use a pen to determine whether the cracks are on the inside or outside . The back of your nails works just like you were buying marble . Ad Unguem .
Do not touch the glass with any soft parts of you hand as it might be on the inside and any glass slivers might not be healthy if they get in your blood .
If you are sitting behind a crack windscreen make sure you are well below the recommended speeds and ready for what may happen next , it would not be considered cowardice to lower your head out of the way of any possible flying glass until you get below the recommended speeds and cabin pressures.
