Airport screenings should keep us safe in the air by preventing people with dangerous motives from smuggling weapons on board, but apparently, the TSA is failing to catch those weapons most of the time.

The Department of Homeland Security revealed to Congress results of covert testing at airport security checkpoints. They found that security screeners and their procedures failed to uncover undercover mock explosives, guns and knives more than 70 percent of the time.

What’s worse, this comes two years after inspectors found the TSA failed 95 percent of the time to identify hidden explosives and weapons and TSA agents failed 67 out of 70 times to identify hidden weapons and explosives.

On top of that, in 2013, DHS conducted a similar series of tests and an undercover agent managed to smuggle a fake hidden bomb through New Jersey’s Newark Liberty Airport.

A member of the House Committee on Homeland Security summed up this week's classified briefing:

"Quite frankly, I think I speak for all of us when I say that we found that briefing disturbing," Committee Chairman Rep. Michael McCaul, R-Texas, said at a hearing following the briefing.

Disturbing doesn’t scratch the surface of the concern that Americans have when they read that two years after a scathing report of the security lapses, we learn that the TSA is still struggling to capture hidden weapons.

And let’s not forget what’s at stake. Terrorists only need to get it right one time to inflict chaos and take American lives. Sixteen years after September 11, the TSA can’t afford to be wrong at such a high rate, otherwise the results could be dangerous.

We hope the TSA is taking these continual failures seriously and addressing the problems with their internal systems. In a statement, they claim to be making improvements:

TSA is pursuing technology investments to include credential authentication technology, automated screening lanes and computed tomography as well as increased investment in training. The screening capabilities are complemented by additional layers, including vetting, Federal Air Marshals (FAMs) on flights, and the use of canines.

There are many problems with the TSA as we’ve tracked over the years, but perhaps complacency is the biggest one. Allowing American lives to be at risk could have grave consequences.