Anyone who has spent time waiting shoeless on an airport check-in line — in fact, anyone who flies — should pay serious attention to the recent revelation that an airline baggage handler was allegedly able to smuggle 153 firearms in an accomplice’s carry-on bag on 17 Delta flights from Atlanta to New York during a seven-month period. The reason, shocking in its simplicity, is that most backroom airport workers are not required to pass through metal detectors on the way to the job.

As Brooklyn’s district attorney, Kenneth Thompson, discovered in arresting five men for gun smuggling last month, this turns out to be a security defect at most airports in the nation.

U.S. Sen. Charles Schumer, D-N.Y., is now sensibly calling on the Transportation Security Administration (TSA) to mandate physical screening for all airport workers.

Agency officials responded that they would look into whether new safeguards were needed. Now, each airport works out separate security requirements; very few, if any, require physical screening of the full array of workers such as airplane cleaners, mechanics and baggage handlers, according to Schumer.

The Atlanta scheme is particularly alarming because it operated for an estimated five years in various airports. “They could have easily put a bomb on one of those planes,” Thompson noted.

The district attorney described how Georgia’s “lax gun laws” allowed the baggage handler to buy weapons online without a background check.

The handler carried the guns to work, free from any detector, and used his airport ID to take them through an employee entrance into the secure passenger area. There he would meet his accomplice in a men’s room and exchange guns for cash.

The accomplice, previously cleared through check-in, would load up his carry-on and take weapons aboard, even as the pilots and flight crews had to go through detectors.

TSA officials conducted a special inspection this week in Atlanta. But in the past they have said that cost and the potential disruption of airline operations have argued against the use of metal detectors for all workers.

The agency insisted that it was alert to insiders’ threats and that it required regular background and criminal checks on employees.

This hardly seemed enough after the backdoor path blazed by the Atlanta gun runners.