Commercial maintenance is under fairly constant economic pressure, and airline managers usually control the important productivity variables. Productivity gains thus tend to be incremental and steady. When airlines cannot boost productivity fast enough, the work goes outside to third-party shops. Then these independent vendors must shave, trim and innovate to make the goal. Third-party shops are more nimble than many airlines, but they must have scale and capital to maximize efficiency.

Military maintenance faces many of the same challenges, but under a different set of rules. Congress, not managers, controls some of the biggest decisions. And the U.S. Department of Defense tends to do things in big steps, whether it is introducing new aircraft, a revolutionary technology, or just a wave of reforms in maintenance practice.

The military also operates in a world of sudden changes, such as wars, that alter demands on its repair depots. Prolonged downtimes for overhauls that are tolerable in peace become intolerable during conflicts. U.S. defense officials have been pushing aviation depots to speed things up in recent years, and many depots have racked up impressive gains. The techniques used in military shops are adopted mostly from private models. Lean methods eliminate unnecessary tasks or unnecessary efforts for necessary tasks. Six Sigma approaches minimize the variation in common processes that throws work off-schedule. And a textbook method, the Theory of Constraints (TOC), looks for the blockages that slow things.

Southwest Continues To Trim

"Like most airlines, we use a scorecard to measure productivity," said Jim Sokol, vice president of maintenance at Southwest Airlines. The scorecard for internal work includes cost per available seat mile (ASM), span time, overtime hours, time required versus plan, and maintenance headcount per aircraft. Sokol reviews these measures in monthly meetings with his managers.

For outsourced work, Southwest first counts the cost of each assigned work package. To measure quality, the carrier looks at scheduled turntime, the vendor's ability to stay on schedule, missed inspection items and dispatch reliability.

In recent years, Southwest has reduced span times for the quarter- and half-D checks it does in-house, and for outsourced full Ds. Sokol attributes some gains to refined work programs, which have eliminated duplicate efforts. "But the biggest gains have come from the shift from MSG-2 to MSG-3, next-generation maintenance for next-generation aircraft." The MSG-3 program for new Boeing 737s aims for the right work at just the right intervals, exploiting improved reliability and better data on past performance. Sokol is looking at applying similar methods to Southwest's 737s-300s and -500s, but the required analysis of historical data on older jets makes the shift a major task.

Better data, better analysis of the data through better software and better communication tools also offer hope for the future. "Every airline is looking for the same thing," Sokol emphasized. "An adequate IT solution that can be successfully integrated."

In February, Southwest began converting its production control system from spreadsheets to software supplied by Sinex. The new system allows Southwest to match more closely employee shifts with scheduled workloads and to monitor progress against goals. Better control should reduce span time further and help Southwest gain perhaps 10% in efficiency.