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``MOD'' Program Analysis for Southwest Airlines

(Flint Craig, 1991)

Southwest Airlines (SWA) is required by the FAA to maintenance their fleets based on flight hours. There are five levels of checks that constitute the maintenance program; the service check, ``A'' check, ``B'' check, ``C'' check, and structural sampling. Currently, there are problems with variability in the time it takes to perform a ``C'' check because of structural corrosion or cracks often found in this check. These findings lead to excess work time and delays or cancellations of flights in the SWA routing schedule - a major economic drain. It has been proposed that a new ``MOD'' check be introduced to relieve the variability in the ``C'' check. A ``MOD'' check would constitute stripping the plane down and checking for structural faults such as corrosion, cracks, and other major problems. The proposal analysis first took the form of a simulation. The ``C'' check was simulated to determine delays in terms of minutes per day. After further consultation with SWA, it was decided that there is too much delay in the ``C'' check and that economic options on the ``MOD'' check were to be considered. These options are to either hire out for the ``MOD'' or perform the work in-house. This analysis was done on a spreadsheet because of the uncertainty involved in the ``MOD'' related variables. As ``MOD'' check data becomes available, the model can be updated with relative ease. Based on ``ballpark'' estimations by SWA Maintenance management, the least expensive of the two options is to perform the ``MOD'' check in-house.

Richard S. Barr
Fri Feb 17 16:09:51 CST 2006