The lack of mobility in reclined sitting posture, the space limitations in seats in long distance flights along with the relief of pressure lead the passenger to scoop his hip forwards or to twist it. Consequent muscular and skeletal postural constraints may cause discomfort and pain on users. Searching for the reasons of constraints, human posture studies, ergonomics recommendations on chairs and aicraft priorities were seen. The study methods employed were a literature review on Ergonomics, Anatomies and Kinesiologists, aircraft interiors qualified informant and aircraft interiors specialized revues. A questionnaire was submitted to long flight passengers to search for body discomfort and inadequacies on seats. Data analysis (n=115) showed discomfort on neck region (63,3 percent), feet (59,1 percent) and low back (48,7 percent). Inadequacies on seats design such as width (58,3 percent), room for legs (50,4 percent), neck support (47,8 percent) and lumbar support (37,4 percent) were pointed by passengers. The hypothesis Lack of room in aircraft seats and the positions assumed during long distance flights cause postural constraints that lead to discomfort and pain on neck, low back and feet, numbness and irradiation on users was confirmed. Recommendations on lumbar support possibilities, height of seat and lower limbs positions were made. Suggestions like further observation of flying passengers, circulatory system and postural constraints on cervical and pelvic region were proposed.