INSTRUMENT FLIGHT RULES [ICAO]- A set of rules governing the conduct of flight under instrument meteorological conditions.
INSTRUMENT LANDING SYSTEM- A precision instrument approach system which normally consists of the following electronic components and visual aids:

a..Localizer.
(See LOCALIZER.)
b..Glideslope.
(See GLIDESLOPE.)
c..Outer Marker.
(See OUTER MARKER.)
d..Middle Marker.
(See MIDDLE MARKER.)
e..Approach Lights.
(See AIRPORT LIGHTING.)
(Refer to 14 CFR Part 91.)
(Refer to AIM.)
INSTRUMENT METEOROLOGICAL CONDI-TIONS- Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling less than the minima specified for visual meteorolog-ical conditions.
(See INSTRUMENT FLIGHT RULES.)
(See VISUAL FLIGHT RULES.)
(See VISUAL METEOROLOGICAL
CONDITIONS.)
INSTRUMENT RUNWAY- A runway equipped with electronic and visual navigation aids for which a precision or nonprecision approach procedure having straight‐in landing minimums has been approved.
(See ICAO term INSTRUMENT RUNWAY.)
INSTRUMENT RUNWAY [ICAO]-One of the following types of runways intended for the operation of aircraft using instrument approach procedures:
a..
Nonprecision Approach Runway-An instru-ment runway served by visual aids and a nonvisual aid providing at least directional guidance adequate for a straight‐in approach.

b..
Precision Approach Runway, Category I-An instrument runway served by ILS and visual aids intended for operations down to 60 m (200 feet) decision height and down to an RVR of the order of 800 m.

c..
Precision Approach Runway, Category II-An instrument runway served by ILS and visual aids intended for operations down to 30 m (100 feet) decision height and down to an RVR of the order of 400 m.

d..Precision Approach Runway, Category III-An instrument runway served by ILS to and along the surface of the runway and:
1..
Intended for operations down to an RVR of the order of 200 m (no decision height being applicable) using visual aids during the final phase of landing;

2..
Intended for operations down to an RVR of the order of 50 m (no decision height being applicable) using visual aids for taxiing;

3..
Intended for operations without reliance on visual reference for landing or taxiing.

Note 1: See Annex 10 Volume I, Part I, Chapter 3, for related ILS specifications.
Note 2: Visual aids need not necessarily be matched to the scale of nonvisual aids provided. The criterion for the selection of visual aids is the conditions in which operations are intended to be conducted.
INTEGRITY-The ability of a system to provide timely warnings to users when the system should not be used for navigation.