Sustaining complex aerospace systems

Keith Button’s article in the March issue, “Wringing out the risks,” is a good read and I recommend it. However, I would like to add a bit of engineering philosophy rarely discussed: Long-lived complex systems are kept viable by detecting new, emerging failure modes with sufficient lead time ahead of the needed actions.

The sustainment phase of any complex system has several unique characteristics. For instance, the baseline shifts from “design” to “war-fighter expectations,” or sometimes called a “capabilities baseline.” Also, schedules shift from meeting initial operational capability or other critical milestones to determining the correct schedule to mitigate emerging risks lead time from impact. There are more, but the most important to this article is the shift from a FRACAS [failure reporting, analysis, and corrective action system] program in production, to a Closed Loop Failure Analysis contract with your repair depots.

Left to nominal, repair depots must focus on efficient production and speedy throughput. Important data about how your system is changing over time gets lost. A contract between the depot and the sustaining organization directs their efforts to discover emerging failure modes never dreamed of when the FMEAs [failure modes and effects analyses] were being written. The models discussed in the article can be updated with this new information. Aggressively going after this information was one way the U.S. Air Force and its contractors kept the Minuteman 3 meeting its mission for six decades despite only a few test flights per year. My role in the intercontinental ballistic missile team before I retired was defense contractor systems engineer.

If improving sustainment for all complex systems appeals to you, join our AIAA Complex Sustainment Community of Interest on AIAA’s Engage collaboration platform (

Charles T. Vono

Associate fellow

Ogden, Utah

Sustaining complex aerospace systems