The September 11, 2001, attacks served as a wakeup call to governments and motivated officials to ramp up spending on security measures in many different ways. But one surge in security spending—to better protect airports—has gone too far, researchers say.

It’s questionable whether spending to shield terminals and other airport facilities from attack, as opposed to the mission of keeping terrorists off airplanes, makes sense from a cost-benefit perspective, the study shows.

“Compared with many other places of congregation, people are more dispersed in airports, and therefore a terrorist attack is likely to kill far fewer than if, for example, a crowded stadium is targeted,” John Mueller and Mark Stewart wrote in their paper, published in the Journal of Air Transport Management.

Mueller, a political science professor and security studies expert at Ohio State University, and Stewart, a civil engineering professor at Australia’s University of Newcastle, cited information from the Global Terrorism Database that showed there were 20 attacks on airports in the U.S. and Europe between 1998 and 2011, killing 64 people.

During this same time period, 31 attacks were recorded on aircraft, including the 9/11 attacks.

“This experience has led the 2007 U.S. National Strategy for Aviation Security to conclude that ‘reported threats to aviation infrastructure, including airports and air navigation facilities are relatively few,’” the authors said.

Mueller and Stewart also reported that among 53 cases since 9/11 in which Muslim terrorists planned or “vaguely imagined, doing damage in the United States,” only two plots involved airports.

It would take enormous sums of money to beef up security at leading airports.

A report prepared by the RAND Corporation in 2004 for Los Angeles International Airport (LAX) evaluated various risk reduction measures. If all the measures were adopted, they would cost $124 million annually for a large airport.  Mueller and Stewart completed their paper prior to last November’s shooting at LAX that killed a TSA agent.

“Assessed security measures [at airports around the world] would only begin to be cost-effective if the current rate of attacks at airports in the United States, Europe, and the Asia-Pacific increases by a factor of 10 to 20,” they wrote.

-Noel Brinkerhoff

To Learn More:

Cost-Benefit Analysis of Airport Security: Are Airports Too Safe? (by Mark Stewart and John Mueller, Journal of Air Transport Management) (pdf)

Academic Paper Suggests Additional Airport Security Not 'Sensible' (by Megan Gates, Security Management)

Are We Spending Too Much Money on Airport Security? (interview with John Mueller by Larry Mantle, KPCC) (start at 6:10)