Optimizing employee assignment in inspection processes

Abstract

Our study focuses on employee assignment for component inspections at a majorDutch airline, where externally repaired components and consumables require inspection before release into stock. The problem features limited capacity, heterogeneous skills, component-workstation compatibility, and strict priority ordering. We formulate a binary integer program as a variant of Multiple Subset Sum Problem with Assignment Restrictions (MSSP-AR) extending the general formulation with with a strict priority constraint. Because strict priorities can block capacity, we introduce a phased procedure that iteratively re-optimizes after removing subsequent components in blocked categories, aligning with the logic of the IT system and improving utilization of employees. To keepmulti-run evaluation feasible under stochastic inspection times, we truncate the tail of priority level 3 components, which preserves optimal employee assignment solutions while reducing runtime substantially. Validation against operational data shows the average gap to the 90% target reduced from 65 percentage points to 15.3 percentage points under the model. On weekdays the effect is the highest as the average gap reduces from 57.9 percentage points to 2.4 percentage points. The approach delivers implementable employee assignment solutions under constraints applicable to the operation and provides a basis for future work on worker productivity heterogeneity, adaptive truncation, multi-day planning, tactical and strategic models, and broader applicability inMRO/logistics settings.