A system and method for displaying medical information derived from a plurality of sources is described. The ground proximity warning system and method generally constructs alert envelopes and generates alerts if the upcoming terrain or other obstacles pierce the alert envelopes. In an illustrative embodiment, the balanced BST is built by identifying a central pointer at a midpoint of the pointer list, a left range of pointers before the midpoint, and a right range of pointers after the midpoint. The at least one product is stocked in a materials handling facility, and the defect history is associated with a specified time period. As a result, program execution speed is greatly improved.