Last month, British authorities thwarted a plot to blow up an aircraft over the Atlantic. While it may have been a surprise to many, it was not the first time that terrorists have planned an attack using liquid explosives. Over a decade ago, Ramzi Yousef plotted to blow up a number of U.S. airplanes over the Pacific Ocean using explosive liquids with a detonator and timing device.

Since then, very little has been done at passenger checkpoints to screen passengers and carry-on baggage for the type of bomb used by Yousef.

The outmoded machines at airport checkpoints cannot easily detect plastic explosives and other threat objects, creating a major vulnerability in our aviation security system. Since 9/11, many of my colleagues and I have repeatedly warned FAA and TSA officials of the need to improve passenger and carry-on baggage screening for explosives. I specifically urged FAA and TSA officials to ban all liquids in carry-ons.

In order to effectively screen passengers and carry-on baggage, we either need a full complement of state of the art screening equipment and adequate personnel, or a larger number of screeners using existing technology. Unfortunately, we currently have neither. We should rescind the arbitrary limit on the number of screeners which was pushed by Congress and the administration, and immediately begin to acquire state-of-the-art bomb detection screening equipment.

Now that we've narrowly averted a re-play of the Yousef plot, I hope the administration will provide the funding necessary for bomb-detecting equipment at every airport in the country.