Downtime is a dirty word at Delta Airline's primary parts distribution center in Atlanta. And that especially applies to the automated storage and retrieval system (AS/RS) used to store repair parts for its planes.

"If the AS/RS goes down, we risk missing a hot part for an aircraft," says Steve Kerns, manager of the stores area at the Atlanta facility. "If that happens, we have to cancel a flight at a considerable cost to Delta."

That's why Delta upgraded the controls and the positioning system on a ten-aisle mini-load system in Atlanta (HK Systems, 866-457-9783). The unit provides centralized storage for 100,000 of the 170,000 stock keeping units (SKU) maintained by Delta. It supports maintenance and repair operations around the world, filling about 60,000 orders per month.

In the 25 years since the original system was installed, maintenance—and downtime—were becoming an issue. "Six cranes had outlived their life expectancy," says Kerns. "And parts were increasingly difficult to locate for the other four."

The guidance system that directed the cranes to putaway areas was no longer reliable either. Misreads and system jams were common. "We used to have two full-time personnel just to maintain the AS/RS," says Kerns. As if maintenance wasn't enough, the old system wasn't compatible with a new SAP host system.

Delta solved those issues with new programmable logic controllers (PLCs), a warehouse control system (WCS) and a laser-guided positioning system. Today, orders are placed in the host enterprise resource planning system, regardless of where the repair facility is located. They are then entered into the WCS on a prioritized basis. Aircraft on the ground, for instance, get parts immediately. Parts are automatically retrieved and delivered to a station at the end of the aisle. There, the supply attendant confirms the part number and quantity. Once the attendant completes the transaction, the material is taken out of inventory.

The warehouse control system now provides a graphical representation of the system. That allows maintenance personnel to monitor the system and address issues before a breakdown.

The payoff: By eliminating system jams and down time, one maintenance person was freed up for use elsewhere in the facility. "But the biggest benefit has been reducing the risk of a down time and keeping planes in the air," says Kerns.