This study establishes a foundation for evaluating hybrid electric aircraft (HEA) integration in commercial aviation, bridging the gap in the literature by addressing aircraft design, battery sizing, and operational aspects. The primary objective is to explore the feasibility and benefits of HEA in the context of airline operations, focusing on the regional market. A representative aircraft is identified through market analysis and historical flight data, and several HEA models are designed based on top-level aircraft requirements and design mission profiles. The performance of these HEA models is evaluated on actual, historical sequences flown by a commercial airline, comparing fuel burn benefits against a conventional aircraft. Key findings reveal that operating HEA at different levels of hybridization can achieve 1-5% fuel savings compared to conventional aircraft, contributing to energy efficiency and environmental sustainability goals. The most significant advantages emerge when HEA are operated on shorter range missions, indicating potential benefits for regional airlines. Some HEA configurations faced challenges in completing certain mission legs, but further optimization is possible. This paper serves as an essential stepping stone in the analysis and paves the way for a more extensive co-optimization problem, exploring the potential of HEA within commercial aviation.