REMEMBER Farid Seif? Mr Seif is the Houston Iranian-American businessman who mistakenly carried a Glock handgun through security, onto a plane, all the way from Houston to Indianapolis. When he got to his destination and realised his mistake, he alerted security officials. There was reportedly "nothing else" in Mr Seif's carry-on besides the weapon. Yet the security screeners at George Bush International, America's eighth-busiest airport, missed it entirely. The scariest part of that story was that Transportation Security Administration officials told reporters that this type of incident was "not uncommon."

Now another Texas airport, Dallas-Fort Worth, is proving the point. This week, a high-level TSA source told the local NBC affiliate that "An undercover TSA agent was able to get through security at Dallas/Fort Worth International Airport with a handgun during testing of the enhanced-imaging body scanners." Really:

The TSA insider who blew the whistle on the test also said that none of the TSA agents who failed to spot the gun on the scanned image were disciplined. The source said the agents continue to work the body scanners today.

This is not confidence-inspiring. It's actually infuriating. If TSA screeners can't even stop guns getting through security, why are they taking away our bottled water? Incidents like this only lend ammunition to TSA critics who say the whole airport security apparatus is an enormous waste of time and money. The TSA's attitude towards the reporting of these sorts of screw-ups isn't helpful, either. They only provided NBC with a brief statement claiming that they don't reveal the results of cover testing for "security reasons" and arguing that " advanced imaging technology is an effective tool to detect both metallic and nonmetallic items hidden on passengers." That's pretty much the public affairs equivalent of sticking their fingers in their ears and saying "lalalalala we can't hear you!"

As Gulliver has argued before, it is really hard to have an accountable TSA without greater transparency about the results of covert testing. The TSA continues to try to have it both ways on testing. Instead of leaking hints to the press that failure rates have decreased since the last public reports, the TSA should back up its whispering with actual data. If it won't, some enterprising congressional committee should subpoena it. "Trust us that this works" just isn't cutting it anymore.