Abstract: At approximately 10:56 a.m. on September 7, 1990, Employees #1 through #4 were helping to hoist and move a Titan AFT rocket motor segment from a test stand. A Lampson Crane, model LTL900, was seated on sheets of plywood that were placed on a 7 1/4 in. to 8 in. deep surface of pea-like gravel and road base aggregate that had been spread over the uneven fractured concrete surface. During a counterrotation of the crane's front crawler, the left track of the crawler sank into the pea-like gravel, resulting in the crane boom going too far out of horizontal level. The rocket motor then swung out beyond the crane's safe design limit, causing the main boom center pin to break loose. The main boom of the crane fell to the left, and the AFT rigging strut knocked off the left counterweights, which fell on Employee #1. He was crushed and killed. Employees #2 through #4 also sustained injuries; only Employee #2 was hospitalized.