Passengers at major airports such as Atlanta; Newark, N.J.; and Denver regularly wait in line 20 minutes or more, but screener staffing was cut at each of those airports last year.

Meanwhile, smaller airports such as Dayton, Ohio; Manchester, N.H.; and Houston's Hobby have had minimal waits since TSA started timing the lines two years ago. But they received more screeners last year and lines got even shorter.

3-MINUTE WAITS

The inconsistencies rankle both lawmakers and airport officials. Early in June, the U.S. House overwhelmingly approved a spending bill voicing concern that "screening wait times vary disproportionately by airport." The measure, which the Senate has not approved, orders the TSA to issue a report identifying airports with long lines.

"There can be lines, we all understand that, but when there's significant variation from airport to airport, we're concerned why," says Rep. Martin Olav Sabo, D-Minn.

At Kahului, passengers now race through the Indy Speedway of checkpoints. Not once did a passenger wait more than seven minutes from Jan. 1 to April 30, according to the TSA, which times lines every hour at every checkpoint in every commercial airport.

The lines at Kahului were three minutes or less 99.7 percent of the time — and 99.9 percent of the time during daylight hours. None of TSA's top 80 airports comes close to matching that speed record. Kahului handles about 16,200 passengers a day.

CHANGE PLANNED

In Orlando, with about 94,000 passengers a day, security lines ran 30 minutes or more 241 times in the first four months of the year. That prompted the airport to spend $1.8 million in April to hire a company to help passengers move through checkpoints faster.

The TSA recognizes shortcomings in the formula it has used to allocate screeners since shortly after taking over passenger screening in 2002. TSA chief Kip Hawley acknowledges the staffing model "is going to pop up answers that aren't intuitive." Hawley is changing the model and trying to fill screener vacancies that have plagued many airports.

Included is a more flexible system that gives local airport security directors greater control over staffing and evaluates the efficiency of an airport's security lines to determine whether it needs more screeners — or more efficiency. The agency is trying to reduce screener absences. And it is hiring more part-time screeners to work flexible schedules and be on the job only during peak hours.

LAYOUTS POOR

Some inconsistencies are inevitable. Some airports such as Los Angeles and Miami will always struggle with long lines because their layout limits the number of screening lanes, the TSA says.

In such cases, long lines are "outside the control of TSA," says Earl Morris, a TSA general manager who oversees the 43,000 screeners. "We can staff all the lanes that are available at an airport, but you can only get so many people through that funnel."

Variations in waiting times can be huge. From 6 to 7 on weekday mornings, one checkpoint at Miami International Airport missed the 10-minute goal 74 percent of the time during the recent 19-week period.

Philadelphia; Las Vegas; Orlando; San Diego; San Antonio; Tampa, Fla.; and Newark airports all have checkpoints that missed the 10-minute goal more than half the time from 6 to 7 a.m. weekdays, USA Today's analysis shows.

Hawley says lines are "improving" in their predictability but acknowledges that some airports either have too few screening lanes or not enough screeners. High absenteeism and injury rates and rapid turnover cause staff shortages.

"We have had an attrition problem at TSA over the last year," says Hawley, who took charge at TSA in July. "The folks that we bring in turn over at an unacceptably high rate in their first year."

Randy Walker, director of Las Vegas' McCarran International Airport, learned that last year after TSA announced it would increase the airport's screener staffing from 832 to 1,079.

HIRING WOES

Yet, morning lines in Las Vegas' two busiest checkpoints missed the 10-minute goal 54 percent of the time in the recent period USA Today studied. That's more than double the failure rate a year earlier.

Walker says the TSA boosted staffing to about 1,010 screeners when "recruitment just stopped. They weren't hiring anybody, and attrition kept catching up."

And when the TSA gave hiring authority to its airport security directors this year, Walker says, "They just handed it off to local people and said, 'You're in charge.' "

Hawley concedes, "For sure, there was a time as the centralized process was ramping down when the new process hadn't ramped up."

Hawley's top priority is avoiding excessive lines — 30 minutes or more — that infuriate passengers and "create large crowds" that can be a terrorist target.

By that measure, security lines are improving. USA Today's analysis shows a slight drop in the frequency of 30-minute-or-longer lines this year, and they are extremely rare. Passengers have about a 1-in-1,000 chance of waiting 30 minutes or more, though the odds are higher at more-congested airports such as Orlando, Los Angeles International, McCarran and Dulles near Washington, D.C.

A LITTLE BETTER

Eliminating 30-minute lines is more important to airports than meeting a 10-minute goal because the long waits "are the things passengers remember," says Ben DeCosta, manager of Atlanta's Hartsfield-Jackson International Airport, which handles more passengers than any airport in the world.

Although Hartsfield's lines are exceeding 10 minutes more frequently this year than last year, DeCosta praises the TSA because the hourlong waits that once plagued the airport are gone. The airport's longest line this year was 40 minutes.

"They are more vigilant in terms of making sure staffing occurs when it's needed," says DeCosta.