An instrument approach is a type of air navigation that allows an aircraft to land in weather restricting visibility, or to reach visual conditions permitting a landing. The principles of air navigation are the same for all aircraft, big or small. ... An aircraft is any machine capable of atmospheric flight. ... Landing is the last part of a flight, where a flying animal or aircraft returns to the ground. ... Instrument meteorological conditions (IMC) are weather conditions that require aircraft pilots to fly primarily by reference to instruments rather than outside visual references, as they could in Visual meteorological conditions (VMC). ... In aviation visual meteorological conditions are those in which visual flight rules (VFR) flight is permitted - that is, those in which pilots can see so far that they dont have to rely on their instruments to fly safely. ...
An approach is essentially classified as either precision or nonprecision, depending on the accuracy and capabilities of the navigational aids used. Precision approaches utilize both lateral and vertical information. Non-Precision approaches provide lateral and distance information. For non-precision approaches the pilot must use navigation radios (such as VORs, NDBs, GPS, DME, etc...) to figure azimuth and range from a station. Radio navigation is the application of radio frequencies to determining a position on the earth. ...
GPS (with vertical navigation) - Global Positioning System
Instrument Landing System, ILS is an air navigation system for landing. ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ...
Clearances authorizing instrumentapproaches are issued on the basis that, if visual contact with the ground is made before the approach is completed, the entire approach procedure will be followed unless the pilot receives approval for a contact approach, is cleared for a visual approach, or cancels their IFR flight plan.
When authorized by an instrumentapproach procedure, you may clear an aircraft for an approach to one runway and inform the aircraft that landing will be made on a parallel runway.
Except in the case of a VFR aircraft practicing an instrumentapproach, an approach clearance automatically authorizes the aircraft to execute the missed approach procedure depicted for the instrumentapproach being flown.