Nov. 26--An annual test required of Transportation Security Administration (TSA) screeners has contributed to low morale and high turnover at the Minneapolis-St. Paul International Airport, longtime employees say.

Known as the annual proficiency review, the recertification test fails to assess a transportation security officer's ability to detect "real-world threats," said Celia Hahn, president of the unio that represents some 800 workers in Minnesota, North Dakota and South Dakota. Screeners who fail the test after two tries are automatically fired.

Since last summer, about 100 screeners who failed the test were fired nationwide, including 11 experienced officers at MSP, Hahn said, noting that others have retired early or quit, pointing to exam-related stress. The attrition rate of TSA employees locally is about 10 to 20 officers a month, she added.

The departures come as TSA attempts to hire hundreds of screeners across the country after last summer's long security lines infuriated travelers. TSA now employs about 44,000 screeners at 440 airports, but that's down from roughly 47,000 three years ago.

Nationally, TSA hired 373 workers to replac 4,644 who left the agency in 2014, according to the American Federation of Government Employees (AFGE). All of this has proved problematic as affordable airfares continue to attract more passengers.

TSA said in a statement that the recertification test is "fair and representative" of the screeners' work. "TSA strives to make the proficiency review as realistic as possible," said spokeswoman Lorie Dankers. MSP has 629 TSA screeners and expects to hire 30 to 40 more this fiscal year.

The recertification test calls for screeners to pat down co-workers, who are acting as travelers while supervisors watch -- an attempt to mimic real-life scenarios. Another part of the test requires a pat-down of a colleague posing as a passenger in a wheelchair.

unio officers say the most contentious portion of the test calls for screeners to view muddy X-ray images on a computer screen that bear no resemblance to images made by the actual equipment. At the airport, screeners view baggage with high-resolution machines, but the test images "look like a photo that's been xeroxed six times," said Neal Gosman, treasurer of AFGE Local 899 in St. Paul.

In addition, standard operating procedure calls for X-ray screeners to call for a supervisor if they see a questionable image in baggage. But that answer is not an option on the test. "They train for one thing and test for another," Gosman said.

Dankers said TSA strives to make the test as realistic as possible, noting "much of that review occurs in and around the screening locations wher people work each day."

Those failing the test can appeal, but Hahn says the Office of Professional Responsibility Appellate Board claims it has no authority to assess the validity of the exam. So far, all appeals lodged by fired MSP