Interesting paper: Paul J. Freitas (2012), “Passenger aviation security, risk management, and simple physics,” Journal of Transportation Security.

Abstract: Since the September 11, 2001 suicide hijacking attacks on the United States, preventing similar attacks from recurring has been perhaps the most important goal of aviation security. In addition to other measures, the US government has increased passenger screening requirements to unprecedented levels. This has raised a number of concerns regarding passenger safety from radiation risks associated with airport body scanners, psychological trauma associated with pat-down searches, and general cost/benefit analysis concerns regarding security measures. Screening changes, however, may not be the best way to address the safety and security issues exposed by the September 11 attacks. Here we use simple physics concepts (kinetic energy and chemical potential energy) to evaluate the relative risks from crash damage for various aircraft types. A worst-case jumbo jet crash can result in an energy release comparable to that of a small nuclear weapon, but other aircraft types are considerably less dangerous. Understanding these risks suggests that aircraft with lower fuel capacities, speeds, and weights pose substantially reduced risk over other aircraft types. Lower-risk aircraft may not warrant invasive screening as they pose less risk than other risks commonly accepted in American society, like tanker truck accidents. Allowing passengers to avoid invasive screening for lower-risk aircraft would introduce competition into passenger aviation that might lead to better overall improvements in security and general safety than passenger screening alone is capable of achieving.