Editing Instrument landing system (section)

==Use==
At a controlled airport, [[air traffic control]] will direct aircraft to the localizer course via assigned headings, making sure aircraft do not get too close to each other (maintain separation), but also avoiding delay as much as possible. Several aircraft can be on the ILS at the same time, several miles apart. An aircraft that has turned onto the inbound heading and is within two and a half degrees of the localizer course (half scale deflection or less shown by the course deviation indicator) is said to be ''established'' on the approach. Typically, an aircraft is established by at least {{convert|2|nmi|km}} prior to the [[final approach fix]] (glideslope intercept at the specified altitude).

Aircraft deviation from the optimal path is indicated to the flight crew by means of a [[Course deviation indicator|display dial]] (a carryover from when an analog meter movement indicated deviation from the course line via voltages sent from the ILS receiver).

The output from the ILS receiver goes to the display system (head-down display and [[head-up display]] if installed) and may go to a [[Flight control computer|Flight Control Computer]]. An aircraft landing procedure can be either ''coupled'' where the autopilot or Flight Control Computer directly flies the aircraft and the flight crew monitor the operation, or ''uncoupled'' where the flight crew flies the aircraft manually to keep the localizer and glideslope indicators centered.