Landing at Kalapathar during Everest Base Camp Heli Tour is short timed because of temperature. Even during afternoon the temperature falls below 5 degree Celcius. Because of such cold weather , helicopter engine should continuously roll.  Once the engine is off , it is very hard to start again as combustion of gas is very hard due to cold weather and lack of sufficient oxygen. Another point for stopping only for short period of time at Kalapatthar is , travellers will have no time to acclimatize themselves on such high altitudes which may cause altitude sickess to them . To avoid such problems , the helicopter landing time is very short at Kalapatthar.