A study investigated the relationship between avionics subsystem design characteristics and training time, training cost, and job performance. A list of design variables believed to affect training and job performance was established and supplemented with personnel variables, including aptitude test scores and the amount of training and experience. Thirty functional loops from ten avionics subsystems were selected as the units of equipment to be investigated. Ten students were observed performing each of the functional checkouts. Training time and training equipment cost data were collected for each loop. A factor analysis identified six factors which account for a major part of the variance in maintenance task performance: length of checkout procedure, equipment complexity, difficulty of checkout steps, nonautomatic checkout, diagnostic information, and clarity of information. The magnitude of the regression coeffients (.92 or better) establish this as a promising approach to deriving human resources data for systems under development. Additional research is needed to develop and quantify better hardware and personnel variables. (JK)