Presisjonsinnflyging

Presisjonsinnflyging is a Norwegian term that translates to "precision approach" in English. It refers to an instrument flight procedure that allows an aircraft to descend and land on a runway under instrument meteorological conditions (IMC), meaning when visibility is significantly reduced. This is achieved through the use of specialized navigation equipment in both the aircraft and on the ground.

The core of a presisjonsinnflyging system is the Instrument Landing System (ILS). An ILS provides pilots with both lateral and vertical guidance to the runway. The lateral guidance is provided by a localizer transmitter, which projects a radio beam along the extended centerline of the runway. The vertical guidance is provided by a glide path transmitter, which projects a radio beam at a precise angle down towards the runway threshold.

During a presisjonsinnflyging, the pilot monitors instruments that display the aircraft's position relative to these radio beams. By keeping the needles on the instruments centered, the pilot can maintain the correct track along the runway centerline and descend at the appropriate rate to intercept the runway. This allows for safe landings even in fog, heavy rain, or snow.

The decision height (DH) or decision altitude (DA) is a critical component of a presisjonsinnflyging. This is the altitude at which the pilot must be able to see the runway environment and make the decision to land or initiate a go-around. If visual contact with the runway is not established by the DH/DA, the pilot must abort the landing. Different categories of precision approaches (CAT I, CAT II, CAT III) define varying minima for visibility and DH/DA, allowing for landings in increasingly adverse weather conditions.