The U.S. airborne landings began with the arrival of pathfinders at 00:15. Navigation was difficult because of a bank of thick cloud, and as a result, only one of the five paratrooper drop zones was accurately marked with radar signals and Aldis lamps. Paratroopers of the 82nd and 101st Airborne Divisions, numbering over 13,000 men, were delivered by Douglas C-47 Skytrains of the IX Troop Carrier Command. To avoid flying over the invasion fleet, the planes arrived from the west over the Cotentin Peninsula and exited over Utah Beach.