Aeronautical Terms beginning with I
I Say Again
The message will be repeated.
IAF
Initial Approach Fix
IAP
Instrument Approach Procedure
IAWP
Initial Approach Waypoint
ICAO
ICAO Term International Civil Aviation Organization
Icing
The accumulation of airframe ice. Types of icing are: Rime Ice, Clear Ice, Mixed.
Icing Intensity
Trace, Light, Moderate, Severe.
Ident
A request for a pilot to activate the aircraft transponder identification feature. This will help the controller to confirm an aircraft identity or to identify an aircraft.
Ident Feature
The special feature in the Air Traffic Control Radar Beacon System (ATCRBS) equipment. It is used to immediately distinguish one displayed beacon target from other beacon targets.
IF
Intermediate Fix
If No Transmission Received For (Time)
Used by ATC in radar approaches to prefix procedures which should be followed by the pilot in event of lost communications.
IF/IAWP
Intermediate Fix/Initial Approach Waypoint. The Waypoint Where The Final Approach Course Of A T-Approach Meets The Crossbar Of The T. When Designated (In Conjunction With A TAA) This Waypoint Will Be Used As An IAWP When Approaching The Airport From Certain Directions, And As An IFWP When Beginning The Approach From Another IAWP
IFIM
International Flight Information Manual
IFR
Instrument Flight Rules
IFR Aircraft
An aircraft conducting flight in accordance with instrument flight rules.
IFR Conditions
Weather conditions below the minimum for flight under visual flight rules.
IFR Departure Procedure
IFR Takeoff Minimums And Departure Procedures.
IFR Flight
IFR Aircraft.
IFR Landing Minimums
Landing Minimums.
IFR Military Training Routes (IR)
Routes used by the Department of Defense and associated Reserve and Air Guard units for the purpose of conducting low-altitude navigation and tactical training in both IFR and VFR weather conditions below 10,000 feet MSL at airspeeds in excess of 250 knots IAS.
IFR Takeoff Minimums And Departure Procedures
Title 14 Code of Federal Regulations Part 91, prescribes standard takeoff rules for certain civil users. At some airports, obstructions or other factors require the establishment of nonstandard takeoff minimums, departure procedures, or both to assist pilots in avoiding obstacles during climb to the minimum en route altitude. Those airports are listed in FAA/DOD Instrument Approach Procedures (IAPs) Charts under a section entitled “IFR Takeoff Minimums and Departure Procedures.” The FAA/DOD IAP chart legend illustrates the symbol used to alert the pilot to nonstandard takeoff minimums and departure procedures. When departing IFR from such airports or from any airports where there are no departure procedures, DPs, or ATC facilities available, pilots should advise ATC of any departure limitations. Controllers may query a pilot to determine acceptable departure directions, turns, or headings after takeoff. Pilots should be familiar with the departure procedures and must assure that their aircraft can meet or exceed any specified climb gradients.
IFWP
Intermediate Fix Waypoint
ILS
Instrument Landing System
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.
ILS PRM Approach
An instrument landing system (ILS) approach conducted to parallel runways whose extended centerlines are separated by less than 4,300 feet and the parallel runways have a Precision Runway Monitoring (PRM) system that permits simultaneous independent ILS approaches.
IM
Inner Marker
IMC
Instrument Meteorological Conditions
Immediately
Used by ATC or pilots when such action compliance is required to avoid an imminent situation.
Incerfa (Uncertainty Phase) [ICAO]
A situation wherein uncertainty exists as to the safety of an aircraft and its occupants.
Increase Speed To (Speed)
Speed Adjustment.
Indicated Airspeed
The speed shown on the aircraft airspeed indicator. This is the speed used in pilot/controller communications under the general term “airspeed.”
Indicated Altitude
The altitude as shown by an altimeter. On a pressure or barometric altimeter it is altitude as shown uncorrected for instrument error and uncompensated for variation from standard atmospheric conditions.
Inertial Navigation System
An RNAV system which is a form of self-contained navigation.
Inflight Refueling
Aerial Refueling.
Inflight Weather Advisory
Weather Advisory.
Informal Runway Use Program
An approved noise abatement program which does not require a Letter of Understanding, and participation in the program is voluntary for aircraft operators/pilots.
Information Request
A request originated by an FSS for information concerning an overdue VFR aircraft.
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.
Initial Approach Fix
The fixes depicted on instrument approach procedure charts that identify the beginning of the initial approach segment(s).
Initial Approach Segment
Segments Of An Instrument Approach Procedure.
Initial Approach Segment [ICAO]
That segment of an instrument approach procedure between the initial approach fix and the intermediate approach fix or, where applicable, the final approach fix or point.
Inland Navigation Facility
A navigation aid on a North American Route at which the common route and/or the noncommon route begins or ends.
Inner Marker
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.
Inner Marker Beacon
Inner Marker.
Inner-Approach OFZ
The inner-approach OFZ (Obstacle Free Zone)is a defined volume of airspace centered on the approach area. The inner-approach OFZ applies only to runways with an approach lighting system. The inner-approach OFZ begins 200 feet from the runway threshold at the same elevation as the runway threshold and extends 200 feet beyond the last light unit in the approach lighting system. The width of the inner-approach OFZ is the same as the runway OFZ and rises at a slope of 50 (horizontal) to 1 (vertical) from the beginning.
Inner-Transitional OFZ
The inner transitional surface OFZ (Obstacle Free Zone) is a defined volume of airspace along the sides of the runway and inner-approach OFZ and applies only to precision instrument runways. The inner-transitional surface OFZ slopes 3 (horizontal) to 1 (vertical) out from the edges of the runway OFZ and inner-approach OFZ to a height of 150 feet above the established airport elevation.
INREQ
Information Request
INS
Inertial Navigation System
Instrument Approach
Instrument Approach Procedure.
Instrument Approach Procedure
A series of predetermined maneuvers for the orderly transfer of an aircraft under instrument flight conditions from the beginning of the initial approach to a landing or to a point from which a landing may be made visually. It is prescribed and approved for a specific airport by competent authority. a. U.S. civil standard instrument approach procedures are approved by the FAA as prescribed under 14 CFR Part 97 and are available for public use. b. U.S. military standard instrument approach procedures are approved and published by the Department of Defense. c. Special instrument approach procedures are approved by the FAA for individual operators but are not published in 14 CFR Part 97 for public use.
Instrument Approach Procedure [ICAO]
A series of predetermined maneuvers 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 (IAP) Charts
Portray the aeronautical data which is required to execute an instrument approach to an airport. These charts depict the procedures, including all related data, and the airport diagram. Each procedure is designated for use with a specific type of electronic navigation system including NDB, TACAN, VOR, ILS/MLS, and RNAV. These charts are identified by the type of navigational aid(s) which provide final approach guidance.
Instrument Departure Procedure (DP)
A preplanned instrument flight rule (IFR) departure procedure published for pilot use, in graphic or textual format, that provides obstruction clearance from the terminal area to the appropriate en route structure. There are two types of DP, Obstacle Departure Procedure (ODP), printed either textually or graphically, and, Standard Instrument Departure (SID), which is always printed graphically.
Instrument Departure Procedure (DP) Charts
Designed to expedite clearance delivery and to facilitate transition between takeoff and en route operations. Each DP is presented as a separate chart and may serve a single airport or more than one airport in a given geographical location.
Instrument Flight Rules
Rules governing the procedures for conducting instrument flight. Also a term used by pilots and controllers to indicate type of flight plan.
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. b. Glideslope. c. Outer Marker. d. Middle Marker. e. Approach Lights.
Instrument Meteorological Conditions
Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling less than the minima specified for 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.
Instrument Runway [ICAO]
One of the following types of runways intended for the operation of aircraft using instrument approach procedures: Nonprecision, Precision Category I, Precision Category II, Precision Category III.
Integrity
The ability of a system to provide timely warnings to users when the system should not be used for navigation.
Intermediate Approach
The segment between the intermediate fix or point and the final approach fix.
Intermediate Approach Segment
Segments Of An Instrument Approach Procedure.
Intermediate Approach Segment [ICAO]
That segment of an instrument approach procedure between either the intermediate approach fix and the final approach fix or point, or between the end of a reversal, race track or dead reckoning track procedure and the final approach fix or point, as appropriate.
Intermediate Fix
The fix that identifies the beginning of the intermediate approach segment of an instrument approach procedure. The fix is not normally identified on the instrument approach chart as an intermediate fix (IF).
Intermediate Landing
On the rare occasion that this option is requested, it should be approved. The departure center, however, must advise the ATCSCC so that the appropriate delay is carried over and assigned at the intermediate airport. An intermediate landing airport within the arrival center will not be accepted without coordination with and the approval of the ATCSCC.
International Airport
Relating to international flight, it means: a. An airport of entry which has been designated by the Secretary of Treasury or Commissioner of Customs as an international airport for customs service. b. A landing rights airport at which specific permission to land must be obtained from customs authorities in advance of contemplated use. c. Airports designated under the Convention on International Civil Aviation as an airport for use by international commercial air transport and/or international general aviation.
International Airport [ICAO]
Any airport designated by the Contracting State in whose territory it is situated as an airport of entry and departure for international air traffic, where the formalities incident to customs, immigration, public health, animal and plant quarantine and similar procedures are carried out.
International Civil Aviation Organization [ICAO]
A specialized agency of the United Nations whose objective is to develop the principles and techniques of international air navigation and to foster planning and development of international civil air transport. Regions include: 1. African-Indian Ocean Region 2. Caribbean Region 3. European Region 4. Middle East/Asia Region 5. North American Region 6. North Atlantic Region 7. Pacific Region 8. South American Region
International Flight Information Manual
A publication designed primarily as a pilot’s preflight planning guide for flights into foreign airspace and for flights returning to the U.S. from foreign locations.
Interrogator
The ground-based surveillance radar beacon transmitter-receiver, which normally scans in synchronism with a primary radar, transmitting discrete radio signals which repetitiously request all transponders on the mode being used to reply. The replies received are mixed with the primary radar returns and displayed on the same plan position indicator (radar scope). Also, applied to the airborne element of the TACAN/DME system.
Intersecting Runways
Two or more runways which cross or meet within their lengths.
Intersection
A. A point defined by any combination of courses, radials, or bearings of two or more navigational aids.
B. Used to describe the point where two runways, a runway and a taxiway, or two taxiways cross or meet.
Intersection Departure
A departure from any runway intersection except the end of the runway.
Intersection Takeoff
Intersection Departure.
Invalid Non-Alert
A situation in which the safety logic software did not issue an alert when an alert was required, based upon the design specifications.
IR
IFR Military Training Routes
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