Even the Beckhams of the world will still have to remove their (designer) footwear

Hobbling barefoot through airport security will remain the reality of American air travel for the foreseeable future, four different scanning devices failing to meet the Transportation Security Administration's (TSA) standards.

According to the TSA, the scanning devices (one of which is currently used in 18 countries) failed to adequately detect metal weapons and explosives in shoes, The New York Times reported.

"Over all, the machines we tested didn't detect all the materials we were looking for," a TSA spokesperson told the paper.

The United States government has spent millions of dollars testing the scanners with Homeland Security secretary Janet Napolitano last year admitting hope that research and development would lead to a solution that would ensure security without inconveniencing travelers.

TSA has admitted the removal of footwear "takes time, reduces the efficiency of the checkpoint, creates safety concerns with footwear removal and contributes to passenger dissatisfaction" but, as yet, the TSA has not found an adequate alternative - and travelers are not happy, the US Travel Association says.

"It's had enough of an impact that it has pushed people toward other forms of transportation," a spokesperson for the association said.