A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

. Independent parallel approaches - simultaneous approaches to parallel instrument runway where radar separation are not prescribed between aircraft using ILSs Indicated altitude - is the reading on the altimeter when it is set to the local QNH.

Instrument flight rules - IFR - Rules governing the procedures for conducting instrument flight. Also a term used by pilots and controllers to indicate type of flight plan.

ILS categories -

1. Category I - An ILS approach procedure which provides for approach to a height above touchdown of not less than 200 feet and with runway visual range of not less than 1,800 feet.

2. Special Authorization Category I. An ILS approach procedure which provides for approach to a height above touchdown of not less than 150 feet and with runway visual range of not less than 1,400 feet, HUD to DH.

3. Category II - An ILS approach procedure which provides for approach to a height above touchdown of not less than 100 feet and with runway visual range of not less than 1,200 feet (with autoland or HUD to touchdown and noted on authorization, RVR 1,000 feet).

4. Special Authorization Category II with Reduced Lighting.

An ILS approach procedure which provides for approach to a height above touchdown of not less than 100 feet and with runway visual range of not less than 1,200 feet with autoland or HUD to touchdown and noted on authorization (no touchdown zone and centerline lighting are required).-

5. Category III:

a. IIIA - An ILS approach procedure which provides for approach without a decision height minimum and with runway visual range of not

less than 700 feet.

b. IIIB - An ILS approach procedure which provides for approach without a decision height minimum and with runway visual range of not

less than 150 feet.

c. IIIC - An ILS approach procedure which provides for approach without a decision height minimum and without runway visual range minimum.

Instrument meteorological cinditions - IMC - Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling less than the minima specified for visual meteorological conditions.

Inner marker - IM - A marker beacon used with an ILS (CAT II) precision approach located between the middle marker and the end of the ILS runway, transmitting a radiation pattern keyed at six dots per second and indicating to the pilot, both aurally and visually, that he/she is at the designated decision height (DH), normally 100 feet above the touchdown zone elevation, on the ILS CAT II approach. It also marks progress during a CAT III approach.

Initial apptoach altitude -

INITIAL APPROACH SEGMENT - SEGMENTS OF AN INSTRUMENT APPROACH PROCEDURE - An instrument approach procedure may have as many as four separate segments depending on how the approach procedure is structured.

a. Initial Approach - The segment between the initial approach fix and the intermediate fix or the point where the aircraft is established on the intermediate course or final approach course.

b. Intermediate Approach - The segment between the intermediate fix or point and the final approach fix

c. Final Approach - The segment between the final approach fix or point and the runway, airport, or missed approach point.

d. Missed Approach - The segment between the missed approach point or the point of arrival at decision height and the missed approach fix at the prescribed altitude.

Instrument approach procedure - A series of predetermined manoeuvres by reference to flight instruments with specified protection from obstacles from the initial approach fix, or where applicable, from the beginning of a defined arrival route to a point from which a landing can be completed and thereafter, if a landing is not completed, to a position at which holding or en-route obstacle clearance criteria apply. Instrument approach procedures are classified as follows:

Non-precision approach (NPA) procedure. An instrument approach procedure which utilizes lateral guidance but does not utilize vertical guidance.

Approach procedure with vertical guidance (APV). An instrument approach procedure which utilizes lateral and vertical guidance but does not meet the requirements established for precision approach and landing operations.

Precision approach (PA) procedure. An instrument approach procedure using precision lateral and vertical guidance with minima as determined by the category of operation.

Note.— Lateral and vertical guidance refers to the guidance provided either by:

a) a ground-based navigation aid; or

b) computer-generated navigation data.

Instrument flight rules - IFR - A set of rules governing the conduct of flight under instrument meteorological conditions.

Instrument meyeorological conditions - IMC - Meteorological conditions expressed in terms of visibility, distance from cloud, and ceilingless than the minima specified for visual meteorological conditions.

Interpilot air-to-air communication - Two-way communication on the designated air-to-air channel to enable aircraft engaged in flights over remote and oceanic areas out of range of VHF ground stations to exchange necessary operational information and to facilitate the resolution of operational problems.