A ProPublica/Frontline analysis of every cell tower-related fatality since 2003 found that tower climbing has a death rate roughly 10 times that of construction, making it one of the most dangerous jobs in America. AT&T, in particular, had the worst track record with more fatalities on its subcontracted jobs than its three closest competitors combined. Yet cell-phone carriers' connection to tower-climbing deaths has remained largely invisible, because climbers do not work directly for the communications giants whose wireless networks they enable. They are subcontractors - and a microcosm of a larger trend in American labor, in which companies increasingly outsource their riskiest jobs, avoiding scrutiny and accountability when workers die. Our reporting team penetrated deeply into the world of climbing, examining each of the 50 cell-tower deaths since 2003. Our reporters found climbers were often shoddily equipped, poorly trained and compelled to meet tight deadlines, sometimes by working through perilous conditions. And our investigation also revealed OSHA's struggles to improve safety in tower climbing and fields like it. Labor experts and even former OSHA chiefs described the agency as woefully ill-equipped to handle enforcement issues that have come with the growth of subcontracting.