In the growing but highly competitive market of the airline industry, airliners have to differentiate themselves from their competitors while increasing or maintaining their profitability. They request innovations in aircraft interior design to increase aircraft capacity, reduce airplane turn time through fast boarding and unloading operations, improve passenger comfort and living space, lighten aircrafts and meet safety requirements. So many necessary yet conflicting expectations, which make aircraft interior and seat design very challenging. In this context, it is easier to only manage average standard passenger population in product development phase. But morphology of passengers is evolving, as our population ages and increases in size and weight. More and more elderly people travel, and the senior market cannot be neglected by airliners. Regulations prevent also discrimination and airliners must now cater to all types of passengers, whatever their age, weight or disability. While standard passengers can board an airplane, walk in the cabin and sit without difficulties, overweight, age and disability are usually associated with lower mobility, which raises difficulties and lowers the air travel experience. If seat access is one certain issue, seat comfort is somehow more important, especially for long range flight. The more severe is the impairment or the higher is the weight, the least is the satisfaction for the aircraft seat. That highlights the need for adapted design of aircraft seat for overweighted, senior passengers as well as the ones with severe mobility impairment, such as passengers that rely on permanent seating posture. Such design investigation, fitting to these populations, is not easy, request lots of difficult experimental tests with large group of volunteers. One alternative solution is the use of digital human model, more specifically finite element models, representing all these different populations, during the conception and development phases of aircraft seat. The present paper will describe the development methodology of new finite human models, adapted to non-standard population of passengers, such as elderly, overweighted and disabled people. These models have been developed starting from an existing human model representing standard aircraft population as reference 89 model, and based on literature review. These models have been then used in seating simulations for the evaluation of aircraft seat comfort and comparison for different postures. For severe mobility impairment passengers, there is a need of accurate figures for morphometric modification on the lower limb and lower trunk, as those segments may not be fully functional and are the most stressed segments during sitting. In order to identify morphometric modifications induced by permanent sitting posture, methodologies and methods of the reviewed process are presented and focused on permanent wheelchair users. Proposed modifications concern mainly bone, muscle, fat, and skin tissues. The most of those changes are applied to the reference finite element human model at pelvis region and lower extremities. That consists of the adaptation of muscle and fat distribution as well as the modification of radius of ischial apex curvature. Then, bony properties of these segments are updated. For the senior and overweighted human models, an equivalent modification process has been applied for the whole body, based on the available data and specificities of the reference model. It concerns the adaptation of morphology as well as muscle and fat distribution. For the senior model, bone properties are also modified. Seating simulations have been then performed with these dedicated models to evaluate their capabilities to highlight comfort problems encountered by these passenger population with respect to the reference standard passenger population. Three different postures, taxi, take-off and landing, inclined and relaxed ones, have been evaluated and compared.