A approach of altitude measurement with high precision and reliability for unmanned aerial vehicle（UAV） is presented based on the air data computer

GPS and accelerometer.State equation and measuring equation of the system are established according to the model of kinematics and measuring principle of each sensor.Kalman filter is used to estimate altitude.A fault detection and isolation method is designed according as redundancy of measurement information.Simulation results show that altitude measurement of the system can give much more accurate estimation than other ones and has good reliability.