Terms and Definitions A - G
Terms and Definitions H - N
Terms and Definitions O - Z
H - N
Helicopter means a rotorcraft that, for its horizontal motion, depends
principally on its engine-driven rotors.
Heliport means an area of land, water, or structure used or intended to
be used for the landing and takeoff of helicopters.
HIGH OCCUPANCY VEHICLES (HOV) - Vehicles carrying a specified minimum
number of persons, usually three or more.
Freeways may have lanes designated for HOV use by car-poolers, vanpools
and buses.
HIRL means high-intensity runway light system.
Horizontal Dilution of Precision (HDOP). A measure of the satellite geometric
effects which degrade a user's horizontal position determination.
IAS means indicated airspeed.
ICAO means International Civil Aviation Organization.
Idle thrust means 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.
IFR conditions means weather conditions below the minimum for flight under
visual flight rules.
IFR means 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 IFR flight plan when cleared
by air traffic control to maintain "VFR conditions" or "VFR
conditions on top".
ILS means instrument landing system.
IM means ILS inner marker.
Incident with potential An incident that narrowly misses being an accident
and in which the circumstances indicate significant potential for substantial
damage or serious injury. Final classification will be determined by the
USFS Aviation Safety Manager.
Indicated airspeed means 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.
INSTRUMENT FLIGHT RULES (IFR) - Aircraft operation rules as pre-scribed
by Federal Aviation Regulations for flying by instruments.
Instrument means 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.
INT means intersection.
INTEGRATED NOISE MODEL (INM) – A computer program typically used
for FAR Part 150 noise compatibility planning and for FAA Order 1050 environmental
assessment and environmental impact statements.
Integrity. The probability that the system will provide accurate navigation
as specified or timely warnings to users when GPS data should not be used
for navigation.
INTELLIGENT TRANSPORTATION SYSTEMS (ITS) - Electronic, computer and communications
technology applied to surface transportation to increase safety, reduce
congestion, enhance mobility, minimize environmental impact, increase
energy efficiency and promote economic productivity for a healthier economy.
INTERMODAL - A transportation system connecting or including different
modes of transportation.
INTERMODAL SURFACE TRANSPORTATION EFFICIENCY ACT OF 1991 (ISTEA) - The
most recent legislation passed by the U.S. Congress that authorizes Federal
funding through 1997 for highway and transit purposes. The Act reinforces
MPO responsibilities and provides more flexibility in transportation planning
and programming decision making.
Interstate air commerce means 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.
Interstate air transportation (1) Between a place in a State or the District
of Columbia and another place in another State or the District of Columbia;
Interstate air transportation (2) Between places in the same State through
the airspace over any place outside that State; or
Interstate air transportation (3) Between places in the same possession
of the United States; Whether that commerce moves wholly by aircraft of
partly by aircraft and partly by other forms of transportation.
Interstate air transportation means 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:
Intrastate air transportation means 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.
ITINERANT OPERATIONS - All aircraft operations other than local operations.
Kite means a framework, covered with paper, cloth, metal, or other material,
intended to be flown at the end of a rope or cable, and having as its
only support the force of the wind moving past its surfaces.
LAND USE - The manner in which land or the structures on land are used
(i.e., commercial, residential, industrial, etc.).
Landing gear extended speed means the maximum speed at which an aircraft
can be safely flown with the landing gear extended.
Landing gear operating speed means the maximum speed at which the landing
gear can be safely extended or retracted.
LARGE AIRCRAFT - A large aircraft is an aircraft of more than 12,500 pounds
(5,700 kg) for its maximum certificated takeoff weight.
Large aircraft means aircraft of more than 12,500 pounds, maximum certificated
takeoff weight.
LDA means localizer-type directional aid.
Lease purchase agreement - Agreement providing that portions of lease
payment may be applied toward the purchase of the property under lease.
Leases - Contracts granting use of equipment (aircraft) for a specified
time in exchange for payment, usually in the form of rent. The owner of
the leased property is called the lessor, the user the lessee.
Length of hop - The average distance of a flight or stage length.
LEVEL OF SERVICE (LOS) - The quality of flow in the moving stream of people
or vehicles. Typically, ranges from LOS A (free flow traffic) to LOS F
(stop-and-go unacceptable conditions).
LFR means low-frequency radio range.
Lighter-than-air aircraft means aircraft that can rise and remain suspended
by using contained gas weighing less than the air that is displaced by
the gas.
LMM means compass locator at middle marker.
Load factor (LF) - The percentage of seats filled. Determined by dividing
RPMs by ASMs as a percentage (%).
Load factor means the ratio of a specified load to the total weight of
the aircraft. The specified load is expressed in terms of any of the following:
aerodynamic forces, inertia forces, or ground or water reactions.
LOC means ILS localizer.
LOCAL OPERATION - Operations performed by an aircraft that: (a) Operates
within the local traffic pattern or within sight of the airport; (b) Are
known to be departing for or arriving from an Airport within a 20-mile
radius of the Airport in question; or (c) Execute practice maneuvers such
as touch and goes or simulated instrument approaches at the airport.
LOM means compass locator at outer marker.
LONG RANGE TRANSPORTATION PLAN - A 15 to 20 year forecast plan which must
consider a wide range of social, environmental, energy and economic factors.
The plan addresses overall regional goals and how transportation can best
meet those goals within financial limits.
Long-range communication system (LRCS). A system that uses satellite relay,
data link, high frequency, or another approved communication system which
extends beyond line of sight.
Long-range navigation system (LRNS). An electronic navigation unit that
is approved for use under instrument flight rules as a primary means of
navigation, and has at least one source of navigational input, such as
inertial navigation system, global positioning system, Omega/very low
frequency, or Loran C.
M means mach number.
MAA means maximum authorized IFR altitude.
Mach number means the ratio of true airspeed to the speed of sound.
Main rotor means the rotor that supplies the principal lift to a rotorcraft.
Maintenance Deficiency An equipment defect or failure which affects or
could affect the safety of operations, or that causes an interruption
to the services being performed.
Maintenance means inspection, overhaul, repair, preservation, and the
replacement of parts, but excludes preventive maintenance.
Major alteration (1) That might appreciably affect weight, balance, structural
strength, performance, powerplant operation, flight characteristics, or
other qualities affecting airworthiness; or
Major alteration (2) That is not done according to accepted practices
or cannot be done by elementary operations.
Major alteration means an alteration not listed in the aircraft, aircraft
engine, or propeller specifications --
Major repair (1) That, if improperly done, might appreciably affect weight,
balance, structural strength, performance, powerplant operation, flight
characteristics, or other qualities affecting airworthiness; or
Major repair (2) That is not done according to accepted practices or cannot
be done by elementary operations.
MALS means medium intensity approach light system.
MALSR means medium intensity approach light system with runway alignment
indicator lights.
Manifold pressure means absolute pressure as measured at the appropriate
point in the induction system and usually expressed in inches of mercury.
Mask Angle. A fixed elevation angle referenced to the user's horizon below
which GPS satellites are ignored by the receiver software.
Maximum speed for stability characteristics, VFC/MFC means a speed that
may not be less than a speed midway between maximum operating limit speed
(VMO/MMO) and demonstrated flight diving speed (VDF/MDF), except that,
for altitudes where the Mach number is the limiting factor, MFC need not
exceed the Mach number at which effective speed warning occurs.
MCA means minimum crossing altitude.
MDA means minimum descent altitude.
MEA means minimum en route IFR altitude.
Medical Attention An injury, less than serious, for which a physician
prescribes medical treatment and makes a charge for this service.
Medical certificate means acceptable evidence of physical fitness on a
form prescribed by the Administrator.
METROPOLITAN PLANNING AREA - The region in which the MPO carries out its
transportation planning responsibilities and is designated as such by
the MPO and the Governor in accordance with ISTEA regulations.
METROPOLITAN PLANNING ORGANIZATION (MPO) - The agency designated by the
Governor to administer the federally required transportation decision-making
process in urbanized areas with over 50,000 population.
Military operations area. A military operations area (MOA) is airspace
established outside Class A airspace to separate or segregate certain
nonhazardous military activities from IFR Traffic and to identify for
VFR traffic where theses activities are conducted.
Minimum descent altitude means the lowest altitude, expressed in feet
above mean sea level, to which descent is authorized on final approach
or during circle-to-land maneuvering in execution of a standard instrument
approach procedure, where no electronic glide slope is provided.
Minor alteration means an alteration other than a major alteration.
Minor repair means a repair other than a major repair.
MM means ILS middle marker.
MOCA means minimum obstruction clearance altitude.
MODE - A particular form of travel, for example, walking or traveling
by automobile, transit or bicycle.
MODE SPLIT - The process by which the number of trips that will be made
by two or more modes of transportation is surveyed or estimated.
MOVEMENT AREA - The runways, taxiways, and other areas of an airport which
are used for taxiing, takeoff, and landing of aircraft, excluding loading
ramps and parking areas.
MRA means minimum reception altitude.
MSL means mean sea level.
Multilateral aviation greement - an agreement for air service among more
than two nations (see "Freedoms of the Air").
NATIONAL AIRSPACE SYSTEM (NAS) - The common system of air navigation and
air traffic control encompassing communications facilities, air navigation
facilities, airways, controlled airspace special use airspace, and flight
procedures authorized by FAR's for domestic and international aviation.
NATIONAL HIGHWAY SYSTEM (NHS) - A 155,000 mile system of roads, authorized
through ISTEA. Comprised of Interstate highways and roads designated as
most important to interstate travel, national defense, intermodal connections,
and international crossings. Congressional approval of the NHS system
was formalized by the National Highway System Act of 1995.
NAUTICAL MILE (NM) - The unit measure of distance in both nautical and
aeronautical context. A nautical mile equals 1.15 statute miles (6,080
feet). The measure of speed in regards to nautical miles is known as KNOTS
(nautical miles per hour).
Navigable airspace means airspace at and above the minimum flight altitudes
prescribed by or under this chapter, including airspace needed for safe
takeoff and landing.
NDB(ADF) means nondirectional beacon (automatic direction finder).
Network airline - An airline that operates a hub-and-spoke system.
Night means the time between the end of evening civil twilight and the
beginning of morning civil twilight, as published in the American Air
Almanac, converted to local time.
NON ATTAINMENT AREA - Any geographic region that has been designated as
non-attainment due to transportation related pollutant(s) that violates
the national ambient air quality standard. The Clean Air Act requires
that these areas perform air quality analyses and determinations to ensure
conformity.
Non-chargeable Accidents Those in which USFS was not exercising operation
control over the aircraft at the time of the accident but in which USFS
employees or USFS procured aircraft were involved.
Nonprecision Approach Operations. Those flight phases conducted on charted
Instrument Approach Procedures (IAPs) commencing at the initial approach
fix and concluding at the missed approach point or the missed approach
holding fix, as appropriate.
Nonprecision approach procedure means a standard instrument approach procedure
in which no electronic glide slope is provided.
NOPT means no procedure turn required.
NOTICE TO AIRMEN (NOTAM)- A notice identified either as a NOTAM or an
Airmen Advisory containing information concerning the establishment, condition,
or change in any component of, or hazard in, the National Airspace System,
the timely knowledge of which is essential to personnel concerned with
flight operations.
