The problem with installing some type of screen is establishing the design criteria that provides sufficient protection but still provides necessary/desired visibility. What is the minimum weight & size of the shrapnel that one considers necessary to block? By installing a screen the organizers are accepting liability for anything that might harm a spectator who now assumes that the screen is "protecting" them. Also, since the races are held in different venues this screening system needs to be portable, and capable of being broken down for storage when it is not needed, right? Sorry, but this is an area where the spectator, like the pilots, assumes resposibility for their own well being. If you don't want to go, knowing that you could possibly be killed (47 year positive track record for spectator deaths at Reno until now) then you stay home. If you want to watch air races there is some inherent danger there, and you attend knowing that danger. Same with other high power race venues, you assess the risks, and attend if you want to be there first hand, and if you accept the inherent risks.