Difficult Access: The Impact of Recall Steps on Flight Management System Errors

This study examines flight management system (FMS) tasks and errors by C–130 pilots who were recently qualified on a newly introduced advanced FMS. Twenty flight tasks supported by the FMS were analyzed using a cognitive stage model (Sherry, Polson, Feary, & Palmer, 2002) to identify steps with the potential for errors. If a step was found not to have visual cues such as labels or prompts for the required action sequence it was identified as a recall step and a potential source of difficulty. If the action was supported by salient labels and prompts it was identified as a recognition step. Actual pilots using an FMS were observed and performance and errors categorized into the related task step. The greatest amount of observed difficulty was accessing the correct function, labeled as an access error. This process was found to be particularly vulnerable to recall problems. Pilots had the likelihood of .74 for committing an access error on tasks with 2 recalled access steps. This is compared to .13 for 1 recalled access step and .06 for no recalled access steps. Errors associated with formatting, inserting, or verifying entries were less common than access errors; however, these errors primarily occurred on tasks in which recall steps were required for the related step. A total of 93% of the format errors, 80% of the insert errors, and 81% of the verify errors occurred on the tasks that did not have good recognition support for each associated step. On a positive note, experience with the new FMS in the preceding 6 months was correlated with a decrease in overall errors, r(22) = –.42, p < .05, and a decrease in errors associated with inadequate knowledge to accomplish a required step, r(22) = –.61, p < . 01.