CHANDIGARH, May 24 — Night sorties over the rugged Himalayas may not be new to the IAF, with training and terrain familiarisation sorties by transport aircraft to airfields located in the Northern Sector being undertaken in the past. But Operation Vijay in the Kargil Sector last year has given an impetus to operational night flying for carrying out air maintenance to support Army formations deployed along the Line of Control.

The emphasis on night flying has resulted in another landmark achievement for the IAF, when the first night sortie to Thoise by an IL-76 was undertaken last week. This maiden night flight to Thoise, earlier virgin territory as far as night operations are concerned, was preceded by trial landing at night by the smaller AN-32 aircraft earlier. All trial flights were from the Chandigarh airbase.

Though Operation Vijay had required the IAF to carry out round-the-clock air maintenance, the sorties were to Leh, with flights to Thoise and other Advance Landing Grounds (ADG) being restricted to daytime. The IAF, had soon after started regular operational night sorties to Leh.

“Prior to Kargil, night sorties to Leh used to be for training purposes. One such sortie was carried out in about three or four months. It is now a regular task,” an officer here commented.

Both Leh and Thoise are high-altitude airfields situated at about 10,000 metres above sea level and at this altitude, the temperature is a major factor in the aircraft’s performance and load-bearing capacity. “At temperatures above 25 degrees Celsius, the AN-32 is forced to return without taking even a single person or any cargo on board,” an officer said. Even the much more capable IL -76 with its four jet engines and a load carrying capacity of up to 45,000 kg finds itself in the same predicament. “This is where the significance of night operations — when temperatures are low and consequently the load carrying capacity is at its maximum — lies,’’ the officer explained.

The IAF had been, in fact, exploring the possibility of night sorties to Thoise soon after the Kargil conflict had ended, but it required the installation of navigational aids on the approach leg to the airfield as well as prior sanction from Air Headquarters.

Night flying is done during the “moon phase”, when visibility is adequate for navigation, which means that sorties can be undertaken only during a few specific days in a month. Inclement weather conditions prevailing at Thoise even during the moon phase further put a spanner in the works.