Wessex helicopters, were lost. The lone surviving Chinook landed on Hermes. It spent the night there, arrived at San Carlos the next day, and was made available for missions on 29 May. The Chinook arrived with two aircrews, and a maintenance detachment, but they had no tools, spare parts or documentation, all of which were lost with Atlantic Conveyor. Somehow, it went on to fly 109 hours without servicing, carrying 1,500 troops, 95 casualties, 650 Argentine prisoners of war (POWs) and of cargo. At one point it carried 81 paratroops in a single load, and then returned to fetch another 75, and it survived being accidentally flown into the sea one night during a snowstorm. In addition to the helicopters, Atlantic Conveyor took with her four tent camps, complete with field kitchens and sanitary facilities, which would have accommodated 4,500 personnel. Another serious loss was a portable fuelling system and six fuel tanks. Material for building an airstrip at Port San Carlos also went down, but 59 Independent Commando Squadron Royal Engineers managed to build it anyway, using matting earmarked for repairing Port Stanley Airport. All ships were unloaded by 27 May, leaving only the two damaged LSLs at San Carlos. Over the mountains 3rd Commando Brigade North east of the Total Exclusion Zone (TEZ) that the British government had declared around the Falkland Islands, the Royal Navy designated a Tug, Repair and Logistics Area (TRALA) where ships could receive and transfer supplies, and conduct repairs of battle damage under the protection of the carrier battle group. Hercules airdrops were made to ships there. Ships were now held in the TRALA, from whence it took about 20 hours to reach San Carlos. Their captains preferred to navigate Falkland Sound by night, allowing them to be unloaded by day, which suited the Commando Logistic Regiment. Working around the clock was inadvisable, for there were no relief crews for the landing craft or helicopters. Only four Sea Kings had night vision equipment, allowing them to operate at night. These were reserved for night operations; to allow the crews to rest, and necessary aircraft maintenance to be performed, they were not employed during the day. One Sea King was permanently assigned to support of the Rapier battery. This left six Sea King, five Wessex and the Chinook helicopter available for logistical and tactical missions. Requested supplies took at least two days to fetch