Helicopter pilots use helmets equipped with night vision goggle and counter weight. This increased load can lead to disc injury, so it is necessary to evaluate the load and moments applied to each cervical disc when pilot head is moving in different flight conditions. A 3D multi-body dynamic model of cervical spine is provided to investigate the effect of weight of the helmet in flexion, extension, lateral bending and axial rotation of the spine. The whole study was done in several steps: 1) to develop a non-linear dynamic model of spine. 2) to validate the model against the published data under flexion, extension, lateral bending and torsinal moments. 3) to solve three case studies to simulate a moving head in different direction. 4) to run the simulations again with consideration of adding a helmet into the model with different weight to find out the effects on the cervical discs loading. The results demonstrate that C2C3, C4C5 and C7T1 carry the highest loads depending on direction of imposed displacement on the head. Experts in the area of neck injury can study the results and locate the regions at risk of injury or they can feed this information into FEA model to get stress distribution in discs, bones or ligaments.