BTS | Dictionary

Ice Action On Bridge Piers: The force required to break ice, transmitted to bridge piers and other structures in the river. Such a force could damage the structures. (TNDOT1)

Ice Clause: A standard clause in the chartering of ocean vessels. It dictates the course a vessel master may take if the ship is prevented from entering the loading or discharging port because of ice, or if the vessel is threatened by ice while in the port. The clause establishes right and obligations of both vessel owner and charterer if these events occur. (USTTA1)

Ice Gorge: A conglomeration of ice solidly packed from bank to bank which is obstructing the flow of the river and marine traffic. (TNDOT1)

Ice Pier: A heavily constructed cluster of piling or concrete behind which towboats moor or shelter from running ice. (TNDOT1)

Ice Shelf: Seaward extension of an ice sheet, floating but attached to the land on at least one side and bounded on the seaward side by a steep cliff rising 2 to 50 m or more above sea level. (DOI3)

Iceberg: A large mass of detached land ice in the sea or stranded in shallow water. (DOI4)

ICHCA: International Cargo Handling Coordination Association (USTTA1)

ICMTO: Independent Carrier Military Traffic Office (MTMC1)

ICT: Wichita Mid - Continent Airport (FAA11)

IDEAS: Innovations Deserving Exploratory Analysis Program (FHWA15)

Ident: (See also Identification) 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. (FAA4)

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. (FAA4)

Identification: See also Ident.

Identification: The official legends "For Official Use Only" and "US Government," and other legends showing either the full name of the department, establishment, corporation, or agency by which it is used, if such title readily identifies the department, establishment, corporation, or agency concerned. (GSA2)

Identification Lamps: Lamps used to identify certain types of commercial motor vehicles. (49CFR393)

IDL: Interfacility Data Link (FAA8)

Idle Thrust: The jet thrust obtained with the engine power control level set at the stop for the least thrust position at which it can be placed. (14CFR1)

IEEE: Institute of Electrical and Electronics Engineers, Inc. (USCG1)

IF: Intermediate Fix (FAA4)

If No Transmission Received For (Time): Used by Air Traffic Control (ATC) in radar approaches to prefix procedures which should be followed by the pilot in event of lost communications. (FAA4)

IFCN: Inter-Facility Flow Control Network (FAA17)

IFEA: In-Flight Emergency Assistance (FAA8)

IFMS: Interagency Fleet Management System (GSA1)

IFR: Instrument Flight Rules (FAA2) (FAA3) (FAA4) (FAA17) (FAA6) (FAA19) (FAA8) (FAA14) (FAA13)

IFR: Interim Final Rule (RSPA1)

IFS: Inflight Survey (USTTA1)

IFSS: International Flight Service Station (FAA2) (FAA19) (FAA14) (FAA13)

IFTA: International Fuel Tax Agreement (FHWA10)

IGOR: Interactive Guidance On Routes (FHWA15)

IIA: Independent Inspection Agency (RSPA1)

ILA: International Longshoremen's Association (MARAD4)

ILEV: Inherently Low Emission Vehicle (VDOT)

ILS: Instrument Landing System (FAA2) (FAA4) (FAA17) (FAA7) (FAA19) (FAA8)

ILWU: International Longshoremen's and Warehousemen's Union (MARAD4)

IM: Inner Marker (FAA4)

IMA: Individual Mobilization Augmentee (MTMC1)

IMC: Instrument Meteorological Conditions (FAA4) (FAA17) (FAA6) (FAA19)

IMCO: Intergovernmental Maritime Consultative Organization (MTMC1)

IMDGC: International Maritime Dangerous Goods Code (MTMC1)

IMG: International Maintenance Group (FAA7)

Immediately: Used by Air Traffic Control (ATC) when such action compliance is required to avoid an imminent situation. (FAA4)

IMO: International Maritime Organization (MARAD4) (RSPA1)

Imports: Receipts of goods into the 50 States and the District of Columbia from foreign countries and from Puerto Rico, the Virgin Islands, and other U.S. possessions and territories. (DOE3)

Impounding Space: A volume of space formed by dikes and floors which is designed to confine a spill of hazardous liquid. (49CFR193)

Impounding System: Includes an impounding space, including dikes and floors for conducting the flow of spilled hazardous liquids to an impounding space. (49CFR193)

Improper Loading: Loading, including weight shifting, of a vessel causing instability, limited maneuverability, or dangerously reduced freeboard. (USCG2)

Improper Lookout: No proper watch; the failure of the operator to perceive danger because no one was serving as lookout, or the person so serving failed in that regard. (USCG2)

IMS: Intermodal Management System (VDOT)

In Bulk: The transportation, as cargo, of property, except Class A and B explosives and poison gases, in containment systems with capacities in excess of 3,500 water gallons. (49CFR387)

In Draft: Current moving across the lock entrance toward the shore. (TNDOT1)

In Shape: Term used when a tow is properly aligned for entering a lock or passing through a narrow channel or opening between bridge piers. (TNDOT1)

In the Marks: Proceeding along the channel line as described in the channel report. Well on the line (imaginary) running from one mark to the other or from one light to the other. (TNDOT1)

In-Out Racks: Dry land boat storage on a vertical rack system. (BOC2)

In-Use Mile Per Gallon (MPG): A Miles Per Gallon (MPG) that was adjusted for seasonality and annual miles traveled. (DOE4) (DOE5)

Inactive Aircraft: All legally registered civil aircraft which flew zero hours. (FAA2) (FAA9)

Inboard-Outboard: Also referred to as inboard/outdrive. Regarded as inboard because the power unit is located inside the boat. (USCG2)

Incerfa (Uncertainty Phase): A situation wherein uncertainty exists as to the safety of an aircraft and its occupants. (FAA4)

Incident: See also, Accident, Casualty, Collision, Crash, Derailment, Event, Fatality, Injury, Truck Crash.

Incident: Collisions, derailments, personal casualties, fires, and property damage in excess of $1000, associated with transit agency revenue vehicles; all other facilities on the transit property; and service vehicles, maintenance areas and rights-of-way (ROW). (FTA1) (FTA2)

Incident Reporting Thresholds: For an incident to be reportable, it must involve a transit vehicle or occur on transit property, and result in death, injury, or property damage in excess of $1,000. (FTA1)

Incline Railway: Railway used to traverse steep slopes. (DOI3)

Inclined Plane: A railway operating over exclusive right-of-way on steep grades with unpowered vehicles propelled by moving cables attached to the vehicles and powered by engines or motors at a central location not on board the vehicle. (APTA1)

Inclined Plane Vehicles: Special type of passenger vehicles operating up and down slopes on rails via a cable mechanism. (FTA1)

Income Taxes For the Period: Provisions for Federal, State, local and foreign taxes, which are based upon net income. (BTS4)

IND: Indianapolis International Airport (FAA11)

Independent Surveillance: A system which requires no airborne compatible equipment. (FAA8)

Indicated Airspeed: The speed of an aircraft as shown on its pitot static airspeed indicator calibrated to reflect standard atmosphere adiabatic compressible flow at sea level uncorrected for airspeed system errors. (14CFR1)

Indication: The information conveyed by the aspect of a signal. (49CFR236)

Indication Locking: [with respect to rail operations] Electric locking which prevents manipulation of levers that would result in an unsafe condition for a train movement if a signal, switch, or other operative unit fails to make a movement corresponding to that of its controlling lever, or which directly prevents the operation of a signal, switch, or other operative unit, in case another unit which should operate first fails to make the required movement. (49CFR236)

Indirect Employment: In respect to waterways industry not necessarily engaged directly in river activities, but dependent upon the river. (TNDOT1)

Inductor: A track element consisting of a mass of iron, with or without a winding, that simulates the train control, train stop, or cab signal mechanisms on the rail vehicle. (TRB1)

Industrial Sector: Construction, manufacturing, agricultural and mining establishments. (DOE6)

Industrial Special: Any use of an aircraft for specialized work allied with industrial activity, excluding transportation and aerial application eg. pipeline patrol, survey, advertising, photography, helicopter hoist, etc. (FAA10)

Industrial Terminal: A specialized terminal whose primary purpose is manufacturing, not transportation services. (TNDOT1)

Industrial Track: A switching track serving industries, such as mines, mills smelters, and factories. (49CFR245)

Industry Briefing: Appearance of Coast Guard standards trained personnel before a gathering of boat and\or associated equipment manufacturers and/or dealers. (USCG1)

Industry Track: A switching track, or series of tracks, serving the needs of a commercial industry other than a railroad. (FRA2)

Inertial Navigation System: An Area Navigation (RNAV) system which is a form of self-contained navigation. (FAA4)

Inflight Survey (IFS): The Inflight Survey is administered to United States (U.S.) and foreign travelers departing the U.S. as a means of providing data on visitor characteristics, travel patterns and spending habits, and for supplying data on the U.S. international travel dollar accounts as well as to meet balance of payments estimation needs. The Inflight Survey (IFS) covers about 70% of U.S. carriers and 35% of foreign carriers who voluntarily choose to participate. (USTTA1)

Informal Factory Visit: A visit by Coast Guard personnel to a manufacturing facility to acquaint the manufacturer with the existence of the law, regulations, general administrative requirements affecting him, and possible penalties for violations. (USCG1)

Information Request: A request originated by an Flight Service Station (FSS) for information concerning an overdue Visual Flight Rules (VFR) aircraft. (FAA4)

Infrastructure: 1) In transit systems, all the fixed components of the transit system, such as rights-of-way, tracks, signal equipment, stations, park-and-ride lots, but stops, maintenance facilities. 2) In transportation planning, all the relevant elements of the environment in which a transportation system operates. (TRB1)

Initial Approach Fix: The fixes depicted on instrument approach procedure charts that identify the beginning of the initial approach segment(s). (FAA4)

Initial Approach Segment: 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. (FAA4)

Initial Impact Point: The first impact point that produced property damage or personal injury, regardless of First or Most Harmful Event. (NHTSA1) (NHTSA3)

Initial Terminal: The starting point of a locomotive for a trip. (49CFR236)

Injury: See also, Accident, Casualty, Collision, Crash, Derailment, Event, Fatality, Incident.

Injury: An injury involving lost time or other than on-site medical treatment. (AGA1)

Injury: 1) Bodily injury resulting from a motor vehicle accident. To qualify as an "injury," the injured person must require and receive medical treatment away from the accident scene. 2) Harm to a person resulting from a single event, activity, occurrence, or exposure of short duration. (FHWA2) (FHWA4) (FRA2)

Injury: Any physical damage or harm to a person requiring medical treatment, or any physical damage or harm to a person reported at the time and place of occurrence. For employees, an injury includes incidents resulting in time lost from duty or any definition consistent with a transit agency's current employee injury reporting practice. (FTA1)

Injury: Any physical damage or harm to a person. There are no thresholds. All injuries are reported. (FTA2)

Injury: Physical harm or damage to the body resulting from an exchange, usually acute, of mechanical, chemical, thermal, or other environmental energy that exceeds the body's tolerance. (NSC1)

Injury Accident: An accident for which at least one injury, but no fatalities, was reported. (FHWA2) (FHWA4)

Injury Crash: A police-reported crash that involves a motor vehicle in transport on a trafficway in which no one died but at least one person was reported to have: 1) An incapacitating injury; 2) A visible but not incapacitating injury; 3) A possible, not visible injury; or 4) An injury of unknown severity. (NHTSA3) (NHTSA4)

Injury Index: Refers to the highest degree of personal injury sustained as a result of the accident. (NTSB1) (NTSB2)

Injury Rate: The average number of nonfatal injuries per accident or per one hundred accidents. (FHWA4)

Injury Severity: The police-reported injury severity of the occupant, pedestrian, or pedalcyclist (e.g., severe or fatal; killed or incapacitating; minor or moderate; evident, but not incapacitating; complaint of injury; injured, severity unknown; no injury). (NHTSA1)

Inland: Means transit to and from inland ports connected by water routes made navigable by one or more lock structures. (SLSDC1)

Inland and Coastal Channels and Waterways: These terms include the Atlantic Coast Waterways, the Atlantic Intracoastal Waterway, the New York State Barge Canal System, the Gulf Coast Waterways, the Gulf Intracoastal Waterway, the, Mississippi River System (including the Illinois Waterway), Pacific Coast Waterways, the Great Lakes, and all other channels (waterways) of the United States, exclusive of Alaska, that are usable for commercial navigation. (TNDOT1)

Inland Area: The area shoreward of the boundary lines defined in 46 CFR 7, except that in the Gulf of Mexico, it means the area shoreward of the lines of demarcation (COLREG lines) defined in 33 CFR 80.740-80.850. The inland area does not include the Great Lakes. (49CFR194)

Inland Bill of Lading: A bill of lading used in transporting goods overland to the exporter's international carrier. Although a through bill of lading can sometimes be used, it is usually necessary to prepare both an inland bill of lading and an ocean bill of lading for export shipments. (USTTA1)

Inland Carrier: A transportation line that hauls export or import traffic between ports and inland points. (MARAD2)

Inland Navigation Facility: A navigation aid on a North American Route at which the common route and/or the noncommon route begins or ends. (FAA4)

Inland Waterway Convoy: One or more non-powered Inland Waterways Transport (IWT) vessels which are towed or pushed by one or more powered IWT vessels. (TNDOT1)

Inland Waterway Journey: Any movement of an Inland Waterways Transport (IWT) vessel from a specified point of origin to a specified point of destination. (TNDOT1)

Inland Waterway of the United States: Any improved waterway, the improvements to which are primarily for the use of vessels other than ocean going vessels. (TNDOT1)

Inland Waterway Transport (IWT): Any movement of goods and/or passengers using an IWT vessel on a given inland waterways network. (TNDOT1)

Inland Waterways Cabotage Transport: National Inland Waterways Transport (IWT) performed by an IWT vessel registered in another country. (TNDOT1)

Inland Waterways Fleet: Number of Inland Waterways Transport (IWT) vessels registered at a given date in a country and authorized to use inland waterways open for public navigation. (TNDOT1)

Inland Waterways On National Territory Traffic: Any movement of an Inland Waterways Transport (IWT) vessel within a national territory irrespective of the country in which the vessel is registered. (TNDOT1)

Inland Waterways Passenger: Any person who makes a journey on board of an Inland Waterways Transport (IWT) vessel. Service staff assigned to IWT vessels are not regarded as passengers. (TNDOT1)

Inland Waterways Passenger Transport Link: The combination of the place of embarkment and the place of disembarking of the passenger conveyed by inland waterways whichever itinerary is followed. (TNDOT1)

Inland Waterways Passenger-Kilometer: Unit of measure representing the transport of one passenger by inland waterway over one kilometer. (TNDOT1)

Inland Waterways Traffic: Any movement on an Inland Waterways Transport (IWT) vessel on a given network. (TNDOT1)

Inland Waterways Transit: Inland Waterways Transport (IWT) through a country between two places (a place of loading and a place of unloading) both located in another country or in other countries provided the total journey within the country is by an IWT vessel and that there is no loading and unloading in that country. (TNDOT1)

Inland Waterways Transport (IWT) Enterprise: Enterprise carrying out in one or more places activities for the production of IWT services using IWT vessels and whose main activities according to the value added is inland waterway transport and services allied to inland waterway transport. (TNDOT1)

Inland Waterways Transport (IWT) Freight Vessel: Vessel with a carrying capacity of not less than 20 tons designed for the carriage of freight by navigable inland waterways. (TNDOT1)

Inland Waterways Transport (IWT) Passenger Vessel: Vessel designed exclusively or primarily for the public carriage or passengers by navigable inland waterways. (TNDOT1)

Inland Waterways Transport (IWT) Vessel: Floating craft designed for the carriage of goods or public transport of passengers by navigable inland waterways. (TNDOT1)

Inland Zone: The environment inland of the coastal zone excluding the Great Lakes, Lake Champlain, and specified ports and harbors on inland rivers. The term inland zone delineates an area of federal responsibilities for response actions. Precise boundaries are determined by agreements between the Environmental Protection Agency (EPA) and the United States Coast Guard (USCG) and are identified in Federal Regional Contingency Plans. (49CFR194)

Inlet: An opening of the sea into the land or of a lake into its shore. (DOI4)

INMARSAT: International Maritime Satellite (FAA17) (USTTA1)

Inner Marker (IM): A marker beacon used with an Instrument Landing System (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 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. (FAA4)

Inner Packaging: A packaging for which an outer packaging is required for transport. It does not include the inner receptacle of a composite packaging. (49CFR171)

Inner Receptacle: A receptacle which requires an outer packaging in order to perform its containment function. The inner receptacle may be an inner packaging of a combination packaging or the inner receptacle of a composite packaging. (49CFR171)

Inner-Approach Obstacle Free Zone (OFZ): (See also Inner-Transitional Obstacle Free Zone, Obstacle Free Zone, Runway Obstacle Free Zone) The inner-approach Obstacle Free Zone (OFZ) 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. (FAA4) (FAA12)

Inner-Transitional Obstacle Free Zone (OFZ): (See also Inner-Approach Obstacle Free Zone, Obstacle Free Zone, Runway Obstacle Free Zone) The inner transitional surface Obstacle Free Zone (OFZ) 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. (FAA4) (FAA12)

INS: Immigration and Naturalization Service (BTS2)

INS: Inertial Navigation System (FAA4) (FAA8)

Inshore Traffic Zone: A designated area between the landward boundary of a traffic separation scheme and the adjacent coast, intended for local traffic. (DOI4)

Inspection and Weighing Services For Motor Vehicle Transport Facility: Establishments primarily engaged in the operation of fixed facilities for motor vehicle transportation, such as toll roads, highway bridges, and other fixed facilities, except terminals. (BOC1)

Instructional Flying: Any use of an aircraft for the purpose of formal instruction with the flying instructor aboard, or with the maneuvers on the particular flight(s) specified by the flight instructor; excludes proficiency flying. (FAA2) (FAA9) (FAA14)

Instructional Flying: Flying accompanied in supervised training under the direction of an accredited instructor. (NTSB2)

Instrument: A device using an internal mechanism to show visually or aurally the attitude, altitude, or operation of an aircraft or aircraft part. It includes electronic devices for automatically controlling an aircraft in flight. (14CFR1)

Instrument Approach: An approach to an airport, with intent to land, by an aircraft flying in accordance with an Instrument Flight Rules (IFR) flight plan, when the visibility is less than 3 miles and/or when the ceiling is at or below the minimum initial altitude. (FAA2)

Instrument Approach: 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. An instrument approach is prescribed and approved for a specific airport by competent authority Federal Aviation Regulation (FAR) Part 91. (FAA14)

Instrument Approach Procedure: (See also Cruise) 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. (FAA4)

Instrument Approach Procedures (IAP) Charts: Portrays 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 nondirectional beacon (NDB), tactical aircraft control and navigation (TACAN), very high frequency omnidirectional range (VOR), instrument landing system/microwave landing system (ILS/MLS), and area navigation (RNAV). These charts are identified by the type of navigational aid(s) which provide final approach guidance. (FAA4)

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. (FAA2) (FAA4) (FAA6) (FAA13) (FAA14)

Instrument Flight Rules (IFR) Aircraft: An aircraft conducting flight in accordance with instrument flight rules (IFR). (FAA8)

Instrument Flight Rules (IFR) Aircraft Handled: The number of Instrument Flight Rules (IFR) departures multiplied by two plus the number of IFR overs. This definition assumes that the number of departures (acceptances, extensions, and originations of IFR flight plans) is equal to the number of landings (IFR flight plans closed). (FAA2) (FAA13) (FAA14)

Instrument Flight Rules (IFR) Conditions: Weather conditions below the minimum for flight under visual flight rules (VFR). (14CFR1)

Instrument Flight Rules (IFR) Departure: An Instrument Flight Rules (IFR) departure includes IFR flights originating in center's area, accepted by the center under SOLE EN ROUTE clearance procedures, and extended by the center. (FAA2) (FAA13) (FAA14)

Instrument Flight Rules (IFR) Over: An Instrument Flight Rules (IFR) flight that originates outside the Air Route Traffic Control Center (ARTCC) area and passes through the area without landing. (FAA2) (FAA13) (FAA14)

Instrument Flight Rules (IFR) Over-The-Top: With respect to the operation of aircraft, means the operation of an aircraft over-the-top on an Instrument Flight Rules (IFR) flight plan when cleared by air traffic control to maintain "visual flight rules (VFR) conditions" or "VFR conditions on top." (14CFR1)

Instrument Flight Rules (IFR) Takeoff Minimums and Departure Procedure: Federal Aviation 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 National Airspace System (NAS)/Department of Defense (DOD) Instrument Approach Plate (IAP) Charts (W's) under a section entitled "IFR Takeoff Minimums and Departure Procedures." The IAP chart legend illustrates the symbol used to alert the pilot to nonstandard takeoff minimums and departure procedures. When departing Instrument Flight Rules (IFR) from such airports or from any airports where there are no departure procedures, standard instrument departures (SID's), or Air Traffic Control (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. (FAA4)

Instrument Flight Service Station (IFSS): A central operations facility in the flight advisory system, staffed and equipped to control aeronautical point-to-point telecommunications, and air-ground telecommunications with pilots operating over international territory or waters, which provides flight plan following, weather information, search and rescue action, and other flight assistance operations. (FAA2)

Instrument Landing System (ILS): (See also Glideslope, Localizer, Middle Marker, Outer Marker) A precision instrument approach system which normally consists of the following electronic and visual aids: 1) localizer-provides course guidance to the runway; 2) glide slope-provides vertical guidance during approach; 3) marker beacon-provides aural and/or visual identification of a specific position along an instrument approach landing. (FAA6)

Instrument Landing System Category: 1) Instrument Landing System (ILS) 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) ILS 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. 3) ILS 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. (FAA4)

Instrument Meteorological Conditions (IMC): Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling less than the minima specified for visual meteorological conditions. (FAA4)

Instrument Operation: Arrivals or departures of an aircraft in accordance with an Instrument Flight Rules (IFR) flight plan or Special Visual Flight Rules (SVFR) procedures or an operation where Instrument Flight Rules (IFR) separation between aircraft is provided by a terminal control facility. There are three kinds of instrument operations: 1) Primary Instrument Operations: arrivals and departures at the primary airport which is normally the airport at which the approach control facility is located. 2) Secondary Instrument Operations: arrivals and departures at all the secondary airports combined. 3) Overflights: operations in which an aircraft transits the area without intent to land. (FAA2) (FAA13) (FAA14)

Instrument Operations: Arrivals or departures of an aircraft in accordance with an IFR flight plan or special VFR procedures or an operation where IFR separation between aircraft is provided by a terminal control facility. (FAA3)

Instrument Practice Approach: An instrument approach procedure conducted by a Visual Flight Rules (VFR) or an Instrument Flight Rules (IFR) aircraft for the purpose of pilot training or proficiency demonstrations. (FAA4)

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. (FAA4)

Instruments of International Traffic: Lift vans, cargo vans, shipping tanks, skids, pallets, caul boards, and cores for textile fabrics, arriving (whether loaded or empty) in use or to be used in the shipment of merchandise in international traffic. (USTTA1)

Insulated Body: Truck or trailer designed for transportation of commodities at controlled temperatures. It may be equipped for refrigeration or heating. (ATA1)

Insulated Rail Joint: A joint in which electrical insulation is provided between adjoining rails. (49CFR236)

Insured and Principal: The motor carrier named in the policy of insurance, surety bond, endorsement, or notice of cancellation, and also the fiduciary of such motor carrier. (49CFR387)

Integrated Carriers: Carriers that have both air and ground fleets; or other combinations, such as sea, rail, and truck. Since they usually handle thousands of small parcels an hour, they are less expensive and offer more diverse services than regular carriers. (USTTA1)

Integrated Gas Company: A company that obtains a significant portion of its gas operating revenues from the operations of both a retail gas distribution system and gas transmission system. An integrated company obtains less than 90 percent but more than 10 percent of its gas operating revenues from either its retail or transmission operations or does not meet the classification of mains established for distribution. (AGA1)

Integrated Tow: Barges designed to fit together so the underwater configuration is the equivalent of a single hull of a motorized vessel. This eliminates water turbulence and increases efficiency. (TNDOT1)

Integrated Transportation: See Intermodalism Definition No. 3.

Interagency Fleet Management System (IFMS): The organizational title assigned to the General Services Administrations (GSA) interagency fleet operation which encompasses the Central Office, Regional Offices, and all Fleet Management Centers and Fleet Management Subcenters. (GSA2)

Intercept Glideslope Altitude: (See also Glideslope) The minimum altitude to intercept the glideslope/path on a precision approach. The intersection of the published intercept altitude with the glideslope/path, designated on Government charts by the lightning bolt symbol, is the precision Final Approach Fix (FAF). However, when Air Traffic Control (ATC) directs a lower altitude, the resultant lower intercept position is then the FAF. (FAA4)

Interchange: An area designated to provide traffic access between roadways of differing levels. (DOI3)

Intercity and Rural Bus Transportation: Establishments primarily engaged in furnishing bus transportation, over regular routes and on regular schedules, the operations of which are principally outside a single municipality and its suburban areas. (BOC1)

Intercity Bus: See also Bus, Motor Bus, Motorbus, School and Other Nonrevenue Bus, Transit Bus.

Intercity Bus: A bus with front doors only, high-backed seats, separate luggage compartments, and usually with restroom facilities for use in high-speed long-distance service. (APTA1)

Intercity Bus: A standard size bus equipped with front doors only, high backed seats, luggage compartments separate from the passenger compartment and usually with rest room facilities, for high-speed long distance service. (DOE6)

Intercity Passenger Mile: The distance generated by moving one passenger one mile on a trip between two cities. (TNDOT1)

Intercity Rail Passenger: A rail car, intended for use by revenue passengers, obtained by the National Railroad Passenger Corporation (currently AMTRAK) for use in intercity rail transportation. (49CFR37)

Intercity Rail Transportation: Transportation provided by Amtrak. (49CFR37)

Intercity Transportation: 1) Transportation between cities. 2) Transportation service provided between cities by certified carriers, usually on a fixed route with a fixed schedule. (TRB1)

Intercity Trucking: Trucking operations which carry freight beyond the local areas and commercial zones. (ATA2)

Interest Long Term Debt and Capital Leases: Interest on all classes of debt, both short-term and long-term, as well as the amortization of premium, discount and expense connected with the issuance of such debt and interest expense on capital leases. (BTS4)

Interfacility: Between adjacent facilities; between Air Control Facility (ACF) and ACF, or between ACF and Air Traffic Control Tower (ATCT), as contrasted with intrafacility. (FAA8)

Intergovernmental Revenue: Amounts received from other governments as fiscal aid in the form of shared revenues and grants-in-aid, as reimbursements for performance of general government functions and specific services for the paying government, or in lieu of taxes. This revenue excludes amounts received from other governments for sale of property, commodities and utility services. (BTS3)

Interior Compartment Door: Any door in the interior of the vehicle installed by the manufacturer as a cover for storage space normally used for personal effects. (49CFR571)

Interlocked Route: A route within interlocking limits. (49CFR236)

Interlocked Switch: A switch within the interlocking limits the control of which is interlocked with other functions of the interlocking. (49CFR236)

Interlocking Limits: The tracks between the opposing home signals of an interlocking. (49CFR218) (49CFR236)

Interlocking Machine: An assemblage of manually operated levers or other devices for the control of signals, switches or other units. (49CFR236)

Interlocking Signal: A roadway signal which governs movements into or within interlocking limits. (49CFR236)

Intermediate Approach Segment: 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. (FAA4)

Intermediate Fix (IF): 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 IF. (FAA4)

Intermediate Grade Gasoline: An increasingly common grade of unleaded gasoline with an octane rating intermediate between "regular" and "premium". Octane boosters are added to gasolines to control engine pre-ignition or "knocking" by slowing combustion rates. (DOE4) (DOE5)

Intermediate Landing: On the rare occasion that this option is requested, it should be approved. The departure center, however, must advise the Air Traffic Control Command Center (ATCCC) 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 ATCCC. (FAA4)

Intermediate Type Road Surface: Mixed bituminous and bituminous penetration (Surface/Pavement Type Codes 52 and 53). (FHWA2)

Intermittent, Casual, or Occasional Driver: A driver who in any period of 7 consecutive days is employed or used as a driver by more than a single motor carrier. The qualification of such a driver shall be determined and recorded in accordance with the provisions of 49 CFR 391.63 or 391.65 as applicable. (49CFR390)

Intermodal: (See also Landbridge, Minibridge, Multimodal Transportation, Piggyback, Trailer on a Flat Car/Container on a Flat Car, Trailer-on-Flatcar, Transshipment) Used to denote movements of cargo containers interchangeably between transport modes, i.e. motor, water and air carriers, and where the equipment is compatible within the multiple systems. (MARAD2)

Intermodal Container: A freight container designed and constructed to permit it to be used interchangeably in two or more modes of transport. (49CFR171)

Intermodal Passenger Terminal: An existing railroad passenger terminal which has been or may be modified as necessary to accommodate several modes of transportation, including intercity rail service and some or all of the following: intercity bus, commuter rail, intra-city rail transit and bus transportation, airport limousine service and airline ticket offices, rent-a-car facilities, taxis, private parking, and other transportation services. (49CFR256)

Intermodal Portable Tank: A specific class of portable tanks designed primarily for international intermodal use. (49CFR171)

Intermodal Transport: Enables cargo to be consolidated into economically large units (e.g., containers, bulk grain railcars) optimizing use of specialized intermodal handling equipment to effect high-speed cargo transfer between ships, barges, railcars, and truck chassis using a minimum of labor to increase logistic flexibility, reduce consignment delivery times, and minimize operating costs. (MARAD1)

Intermodal Transportation: Use of more than one type of transportation; e.g., transporting a commodity by barge to an intermediate point and by truck to destination. (TNDOT1)

Intermodalism: Typically used in three contexts: 1) most narrowly, it refers to containerization, piggyback service, or other technologies that provide the seamless movement of good and people by more than one mode of transport. 2) more broadly, intermodalism refers to the provision of connections between different modes, such as adequate highways to ports or bus feeder services to rail transit. 3) In its broadest interpretation, intermodalism refers to a holistic view of transportation in which individual modes work together or within their own niches to provide the user with the best choices of service, and in which the consequences on all modes of policies for a single mode are considered. This view has been called balanced, integrated, or comprehensive transportation in the past. (BTS2)

Internal Combustion Engine: An engine in which the power is developed through the expansive force of fuel that is fired or discharged within a closed chamber or cylinder. (TRB1)

Internal Traffic: See Internal Water Transportation.

Internal Water Transportation: Includes all local (intraport) traffic and traffic between ports or landings wherein the entire movement takes place on inland waterways. Also termed internal are movements involving carriage on both inland waterways and the water of the Great Lakes, and inland movements that cross short stretches of open water that link inland systems. (DOE6)

International: Traffic (passengers and freight) performed between the designated airport and an airport in another country or territory. (ACI1)

International Air Operator: Commercial air transportation outside the territory of the United States, including operations between the U.S. and foreign countries and between the U.S. and its territories and possessions. (DOE6)

International Air Transportation Association (IATA): Established in 1945, a trade association serving airlines, passengers, shippers, travel agents, and governments. The association promotes safety, standardization in forms (baggage checks, tickets, weight bills), and aids in establishing international airfares. International Air Transportation Association (IATA) headquarters are in Geneva, Switzerland. (USTTA1)

International Airport: 1) Any airport designated by the Contracting State in whose territory it is situated as an airport of entry and departure for international air traffic. 2) An airport of entry which has been designated by the Secretary of Treasury or Commissioner of Customs as an international airport for customs service. 3) A landing rights airport at which specific permission to land must be obtained from customs authorities in advance of contemplated use. 4) Airports designated under the Convention on International Civil Aviation as an airport for use by international commercial air transport and/or international general aviation. (FAA4)

International and Territorial Operations: The operation of aircraft flying between the 50 United States and foreign points, between the 50 United States and U.S. possessions and territories, and between two foreign points. Includes both the combination passenger/cargo and the all-cargo carriers engaged in international and territorial operations. (FAA14)

International Bunkers: Storage compartments, found on vessels and aircraft engaged in international commerce, where fuel to be used by the vessel or aircraft is stored. (DOE5)

International Cargo Handling Coordination Association (ICHCA): 1) Collects, edits and disseminates technical information relating to cargo handling by all modes of transport; 2) Maintains consultative status with the International Standards Organization for the development of standards relating to cargo handling equipment (such as hooks, containers, wire slings, spreaders and pallets); 3) Maintains a library for members' use and 4) Represents members' interests on an international basis. (USTTA1)

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. International Civil Aviation organization (ICAO) Regions include: (AFI) African Indian Ocean Region, (CAR) Caribbean Region, (EUR) European Region, (MID/ASIA) Middle East/Asia Region, (NAM) North American Region, (NAT) North Atlantic Region, (PAC) Pacific Region, (SAM) South American Region. (FAA4) (USTTA1)

International Civil Aviation Organization Broadcast: A transmission of information relating to air navigation that is not addressed to a specific station or stations. (FAA4)

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. (FAA4)

International Flight Service Station (IFSS): A central operations facility in the flight advisory system, manned and equipped to control aeronautical point-to-point telecommunications, and air/ground telecommunications with pilots operating over international territory or waters, providing flight plan filing, weather information, search and rescue action and other flight assistance operations. (FAA14)

International Freight Forwarder: A person, duly registered with the Federal Maritime Board, engaged in the business of dispatching shipments on behalf of other persons, for a consideration, by ocean going vessels in commerce from the United States, its territories, or possessions, and handling the formalities incident to such shipments. (TNDOT1)

International Inland Waterways Transport: Inland waterways transport between two places (a place of loading/embarkment and a place of unloading/disembarking) located in two different countries. It may involve transit through one or more additional countries. (TNDOT1)

International Maritime Organization (IMO): Established as a specialized agency of the United Nations in 1948. The International Maritime Organization (IMO) facilitates cooperation on technical matters affecting merchant shipping and traffic, including improved maritime safety and prevention of marine pollution. Headquarters are in London, England. (USTTA1)

International Maritime Satellite Organization (INMARSAT): An international partnership of signatories from 67 nations. The partnership provides mobile satellite capacity to its signatories, who, in turn, use the capacity to provide worldwide mobile satellite services to their maritime, aeronautical and land-mobile customersincluding shipping, cruise, fishing, research and offshore exploration industries, and airlines. INMARSAT began service in 1976. (USTTA1)

International Operations: In general, operations outside the territory of the U.S., including operations between the U.S. and foreign countries, and the U.S. and its territories or possessions. Includes both the combination passenger/cargo carrier and the all-cargo carriers engaged in international and territorial operations. (FAA2) (FAA15)

International Passenger: Any person traveling on a waterborne public conveyance between the United States and foreign countries and between Puerto Rico and the Virgin Islands and foreign countries. (TNDOT1)

International Transportation: Transportation between any place in the United States and any place in a foreign country; between places in the United States through a foreign country; or between places in one or more foreign countries through the United States. (49CFR171)

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 mote 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. (FAA4)

Intersecting Runway: Two or more runways which cross or meet within their lengths. (FAA4)

Intersection: 1) A point defined by any combination of courses, radials, or bearings of two or more navigational aids. 2). Used to describe the point where two runways, a runway and a taxiway, or two taxiways cross or meet. (FAA4)

Intersection Departure: A departure from any runway intersection except the end of the runway. (FAA4)

Interstate: Limited access divided facility of at least four lanes designated by the Federal Highway Administration as part of the Interstate System. (NHTSA3)

Interstate Air Commerce: The carriage by aircraft of persons or property for compensation or hire, or the carriage of mail by aircraft, or the operation or navigation of aircraft in the conduct or furtherance of a business or vocation, in commerce between a place in any State of the United States, or the District of Columbia, and a place in any other State of the United States, or the District of Columbia; or between places in the same State of the United States through the airspace over any place outside thereof; or between places in the same territory or possession of the United States, or the District of Columbia. (14CFR1)

Interstate Air Transportation: The carriage by aircraft of persons or property as a common carrier for compensation or hire, or the carriage of mail by aircraft in commerce: 1) Between a place in a State or the District of Columbia and another place in another State or the District of Columbia; 2) Between places in the same State through the airspace over any place outside that State; or 3) Between places in the same possession of the United States; whether that commerce moves wholly by aircraft or partly by aircraft and partly by other forms of transportation. (14CFR1)

Interstate Commerce: Trade, traffic, or transportation in the United States which is between a place in a State and a place outside of such State (including a place outside of the United States) or is between two places in a State through another State or a place outside of the United States. (49CFR390)

Interstate Commerce Commission (ICC): The federal body charged with enforcing Acts of Congress affecting interstate commerce. (ATA2)

Interstate Commerce Commission (ICC) Authorized Carrier: A for-hire motor carrier engaged in interstate or foreign commerce, subject to economic regulation by the ICC. (FHWA4)

Interstate Commerce Commission (ICC) Exempt Carrier: A for-hire motor carrier transporting commodities or conducting operations not subject to economic regulation by the ICC. (FHWA4)

Interstate Highway (Freeway or Expressway): (See also Expressway, Freeway, Freeways and Expressways, Highway) A divided arterial highway for through traffic with full or partial control of access and grade separations at major intersections. (FHWA3)

Interstate Highway System: This system is part of the Federal Aid Primary system. It is a system of freeways connecting and serving the principal cities of the continental United States. (FHWA5)

Interstate Pipeline: See also Intrastate Pipeline.

Interstate Pipeline: A pipeline or that part of a pipeline that is used in the transportation of hazardous liquids or carbon dioxide in interstate or foreign commerce. (49CFR195)

Interstate Pipeline: A natural gas pipeline company that is engaged in the transportation, by pipeline, of natural gas across state boundaries, and is subject to the jurisdiction of the Federal Energy Regulatory Commission (FERC) under the Natural Gas Act. (DOE1) (DOE5)

INTP: Interport Trucking (MTMC1)

Intrafacility: Within a single facility; for example: between two sectors within the same Area Control Facility (ACF), as contrasted with interfacility. (FAA8)

Intransit Deliveries: Redeliveries to a foreign country of foreign gas received for transportation across U.S. territory, and deliveries of U.S. gas to a foreign country for transportation across its territory and redelivery to the United States. (DOE5)

Intransit Passengers: Revenue passengers onboard international flights that transit an airport for non-traffic purposes in the 50 states. (FAA11)

Intransit Receipts: Receipts of foreign gas for transportation across United States (U.S.) territory and redelivery to a foreign country, and redeliveries to the U.S. of U.S. gas transported across foreign territory. (DOE5)

Intrastate: Travel within the same state. (BOC3)

Intrastate Air Transportation: The carriage of persons or property as a common carrier for compensation or hire, by turbojet powered aircraft capable of carrying thirty or more persons, wholly within the same state of the United States. (14CFR1)

Intrastate Commerce: Any trade, traffic, or transportation in any State which is not described in the term "interstate commerce." (49CFR390)

Intrastate Pipeline: See also Interstate Pipeline.

Intrastate Pipeline: A pipeline or that part of a pipeline to which 49 CFR 195.2 applies that is not an interstate pipeline. (49CFR195)

Intrastate Pipeline: A natural gas pipeline company engaged in the transportation, by pipeline, of natural gas not subject to the jurisdiction of the Federal Energy Regulatory Commission (FERC) under the Natural Gas Act. (DOE1) (DOE5)

Intraterritorial Traffic: Traffic between ports in Puerto Rico and the Virgin Islands, which are considered as a single unit. (TNDOT1)

Inundation Area: (See also Basin) An area of land subject to flooding. (DOI3)

Investments and Special Funds: Investments and advances to investor controlled and other associated companies, notes and receivables not due within one year, investment in securities issued by others, allowance for unrealized gain or loss on noncurrent marketable equity securities, funds not available for current operations, investments in leveraged leases, and net investments in direct financing and sales-type leases which are not reasonably expected to be amortized within one year. (BTS4)

IOAN: Inspect (and Repair) Only As Needed (MTMC1)

IPD: Implicit Price Deflector (BTS8)

IPDS: Integrated Product Development System (FAA7)

IRF: International Road Federation (ENO1)

IRI: International Roughness Index (BTS8) (FHWA8)

Iron: Old model truck. (ATA1)

Iron Lunger: The conventional 220 or 250 horsepower engine. (ATA1)

IRV: Improved Recovery Vehicle (MTMC1)

ISD: Interim Simulation Display (FAA7)

ISO: International Standards Organization (MARAD2)

ISP: Long Island Mac Arthur Airport (FAA11)

ISTEA: Intermodal Surface Transportation Efficiency Act (BTS2) (MTMC1) (NHTSA5) (NHTSA6)

ISU: Internal Airlift / Helicopter Slingable Container Unit (MTMC1)

ITA: International Taxicab Association (TRB1)

ITA: International Trade Association (BTS7)

ITAB: Intermodal Transportation Advisory Board (BTS8)

ITE: Institute of Transportation Engineers (TXDOT)

Itinerant Aircraft Operations: All aircraft operations other than local operations. (FAA13) (FAA14)

ITO: Hilo International Airport (FAA11)

ITO: Installation Transportation Officer (MTMC1)

ITRAM: International (Passenger) Traffic Management System (MTMC1)

ITS: Intelligent Transportation System (FTA4) (NHTSA6) (NHTSA5)

ITV: Improved Tow Vehicle (MTMC1)

ITWS: Integrated Terminal Weather System (FAA17) (FAA19)

IVHS: Intelligent Vehicle Highway Systems (MTMC1) (NHTSA5)

IVRG: In-Vehicle Route Guidance System (FHWA15)

IVSAWS: In-Vehicle Safety Advisory and Warning System (FHWA15)