Missed approach point (MAP). A point prescribed in each instrument approach at which a missed approach procedure shall be executed if the required visual reference has not been established.
Mixed ice. A mixture of clear ice and rime ice.
MLS. See microwave landing system.
MM. Middle marker.
MOA. See military operations area.
MOCA. See minimum obstruction clearance altitude.
Mode C. Altitude reporting transponder mode.
Moment. The product of the weight of an item multiplied by its arm. Moments are expressed in pound-inches (lb-in). Total moment is the weight of the airplane multiplied by the distance between the datum and the CG.
Moment arm. The distance from a datum to the applied force.
Moment index (or index). A moment divided by a constant such as 100, 1,000, or 10,000. The purpose of using a moment index is to simplify weight and balance computations of airplanes where heavy items and long arms result in large, unmanageable numbers.
Monocoque. A shell-like fuselage design in which the stressed outer skin is used to support the majority of imposed stresses. Monocoque fuselage design may include bulkheads but not stringers.
Monoplanes. Airplanes with a single set of wings.
Movable slat. A movable auxiliary airfoil on the leading edge of a wing. It is closed in normal flight but extends at high angles of attack. This allows air to continue flowing over the top of the wing and delays airflow separation.
MRA. See minimum reception altitude.
MSA. See minimum safe altitude.
MSL. See mean sea level.
MTR. See military training route.
Multi-function display (MFD). Small screen (CRT or LCD) in an aircraft that can be used to display information to the pilot in numerous configurable ways. Often an MFD will be used in concert with a primary flight display.
MVA. See minimum vectoring altitude.
N
N1. Rotational speed of the low pressure compressor in a turbine engine.
N2. Rotational speed of the high pressure compressor in a turbine engine.
Nacelle. A streamlined enclosure on an aircraft in which an engine is mounted. On multiengine propeller-driven airplanes, the nacelle is normally mounted on the leading edge of the wing.
NACG. See National Aeronautical Charting Group.
NAS. See National Airspace System.
National Airspace System (NAS). The common network of United States airspace—air navigation facilities, equipment and services, airports or landing areas; aeronautical charts, information and services; rules, regulations and procedures, technical information; and manpower and material.
National Aeronautical Charting Group (NACG). A Federal agency operating under the FAA, responsible for publishing charts such as the terminal procedures and en route charts.
National Route Program (NRP). A set of rules and procedures designed to increase the flexibility of user flight planning within published guidelines.
National Security Area (NSA). Areas consisting of airspace of defined vertical and lateral dimensions established at locations where there is a requirement for increased security and safety of ground facilities. Pilots are requested to voluntarily avoid flying through the depicted NSA. When it is necessary to provide a greater level of security and safety, flight in NSAs may be temporarily prohibited. Regulatory prohibitions are disseminated via NOTAMs.
National Transportation Safety Board (NTSB). A United States Government independent organization responsible for investigations of accidents involving aviation, highways, waterways, pipelines, and railroads in the United States. NTSB is charged by congress to investigate every civil aviation accident in the United States.
NAVAID. Navigational aid.
NAV/COM. Navigation and communication radio.
NDB. See nondirectional radio beacon.
Negative static stability. The initial tendency of an aircraft to continue away from the original state of equilibrium after being disturbed.
Neutral static stability. The initial tendency of an aircraft to remain in a new condition after its equilibrium has been disturbed.
NM. Nautical mile.
NOAA. National Oceanic and Atmospheric Administration.
No-gyro approach. A radar approach that may be used in case of a malfunctioning gyro-compass or directional gyro. Instead of providing the pilot with headings to be flown, the controller observes the radar track and issues control instructions “turn right/left” or “stop turn,” as appropriate.
Nondirectional radio beacon (NDB). A ground-based radio transmitter that transmits radio energy in all directions.
Nonprecision approach. A standard instrument approach procedure in which only horizontal guidance is provided.
No procedure turn (NoPT). Term used with the appropriate course and altitude to denote that the procedure turn is not required.
NoPT. See no procedure turn.
NOTAM. See Notice to Airmen.
Notice to Airmen (NOTAM). A notice filed with an aviation authority to alert aircraft pilots of any hazards en route or at a specific location. The authority in turn provides means of disseminating relevant NOTAMs to pilots.
NRP. See National Route Program.
NSA. See National Security Area.
NTSB. See National Transportation Safety Board.
NWS. National Weather Service.
O
Obstacle departure procedures (ODP). A preplanned instrument flight rule (IFR) departure procedure printed for pilot use in textual or graphic form to provide obstruction clearance via the least onerous route from the terminal area to the appropriate en route structure. ODPs are recommended for obstruction clearance and may be flown without ATC clearance unless an alternate departure procedure (SID or radar vector) has been specifically assigned by ATC.
Obstruction lights. Lights that can be found both on and off an airport to identify obstructions.
Occluded front. A frontal occlusion occurs when a fast-moving cold front catches up with a slow moving warm front. The difference in temperature within each frontal system is a major factor in determining whether a cold or warm front occlusion occurs.
ODP. See obstacle departure procedures.
OM. Outer marker.
Omission error. The failure to anticipate significant instrument indications following attitude changes; for example, concentrating on pitch control while forgetting about heading or roll information, resulting in erratic control of heading and bank.
Optical illusion. A misleading visual image. For the purpose of this handbook, the term refers to the brain’s misinterpretation of features on the ground associated with landing, which causes a pilot to misread the spatial relationships between the aircraft and the runway.
Orientation. Awareness of the position of the aircraft and of oneself in relation to a specific reference point.
Otolith organ. An inner ear organ that detects linear acceleration and gravity orientation.
Outer marker. A marker beacon at or near the glideslope intercept altitude of an ILS approach. It is normally located four to seven miles from the runway threshold on the extended centerline of the runway.
Outside air temperature (OAT). The measured or indicated air temperature (IAT) corrected for compression and friction heating. Also referred to as true air temperature.
Overcontrolling. Using more movement in the control column than is necessary to achieve the desired pitch-and-bank condition.
Overboost. A condition in which a reciprocating engine has exceeded the maximum manifold pressure allowed by the manufacturer. Can cause damage to engine components.
Overpower. To use more power than required for the purpose of achieving a faster rate of airspeed change.
P
P-static. See precipitation static.
PAPI. See precision approach path indicator.
PAR. See precision approach radar.
Parallels. Lines of latitude.
&nb
sp; Parasite drag. Drag caused by the friction of air moving over the aircraft structure; its amount varies directly with the airspeed.
Payload (GAMA). The weight of occupants, cargo, and baggage.
Personality. The embodiment of personal traits and characteristics of an individual that are set at a very early age and extremely resistant to change.
P-factor. A tendency for an aircraft to yaw to the left due to the descending propeller blade on the right producing more thrust than the ascending blade on the left. This occurs when the aircraft’s longitudinal axis is in a climbing attitude in relation to the relative wind. The P-factor would be to the right if the aircraft had a counterclockwise rotating propeller.
PFD. See primary flight display.
Phugoid oscillations. Long-period oscillations of an aircraft around its lateral axis. It is a slow change in pitch accompanied by equally slow changes in airspeed. Angle of attack remains constant, and the pilot often corrects for phugoid oscillations without even being aware of them.
PIC. See pilot in command.
Pilotage. Navigation by visual reference to landmarks.
Pilot in command (PIC). The pilot responsible for the operation and safety of an aircraft.
Pilot report (PIREP). Report of meteorological phenomena encountered by aircraft.
Pilot’s Operating Handbook/Airplane Flight Manual (POH/AFM). FAA-approved documents published by the airframe manufacturer that list the operating conditions for a particular model of aircraft.
PIREP. See pilot report.
Pitot pressure. Ram air pressure used to measure airspeed.
Pitot-static head. A combination pickup used to sample pitot pressure and static air pressure.
Plan view. The overhead view of an approach procedure on an instrument approach chart. The plan view depicts the routes that guide the pilot from the en route segments to the IAF.
Planform. The shape or form of a wing as viewed from above. It may be long and tapered, short and rectangular, or various other shapes.
Pneumatic. Operation by the use of compressed air.
POH/AFM. See Pilot’s Operating Handbook/Airplane Flight Manual.
Point-in-space approach. A type of helicopter instrument approach procedure to a missed approach point more than 2,600 feet from an associated helicopter landing area.
Poor judgment chain. A series of mistakes that may lead to an accident or incident. Two basic principles generally associated with the creation of a poor judgment chain are: (1) one bad decision often leads to another; and (2) as a string of bad decisions grows, it reduces the number of subsequent alternatives for continued safe flight. ADM is intended to break the poor judgment chain before it can cause an accident or incident.
Position error. Error in the indication of the altimeter, ASI, and VSI caused by the air at the static system entrance not being absolutely still.
Position report. A report over a known location as transmitted by an aircraft to ATC.
Positive static stability. The initial tendency to return to a state of equilibrium when disturbed from that state.
Power. Implies work rate or units of work per unit of time, and as such, it is a function of the speed at which the force is developed. The term “power required” is generally associated with reciprocating engines.
Powerplant. A complete engine and propeller combination with accessories.
Precession. The characteristic of a gyroscope that causes an applied force to be felt, not at the point of application, but 90° from that point in the direction of rotation.
Precipitation. Any or all forms of water particles (rain, sleet, hail, or snow) that fall from the atmosphere and reach the surface.
Precipitation static (P-static). A form of radio interference caused by rain, snow, or dust particles hitting the antenna and inducing a small radio-frequency voltage into it.
Precision approach. A standard instrument approach procedure in which both vertical and horizontal guidance is provided.
Precision approach path indicator (PAPI). A system of lights similar to the VASI, but consisting of one row of lights in two- or four-light systems. A pilot on the correct glideslope will see two white lights and two red lights. See VASI.
Precision approach radar (PAR). A type of radar used at an airport to guide an aircraft through the final stages of landing, providing horizontal and vertical guidance. The radar operator directs the pilot to change heading or adjust the descent rate to keep the aircraft on a path that allows it to touch down at the correct spot on the runway.
Precision runway monitor (PRM). System allows simultaneous, independent instrument flight rules (IFR) approaches at airports with closely spaced parallel runways.
Preferred IFR routes. Routes established in the major terminal and en route environments to increase system efficiency and capacity. IFR clearances are issued based on these routes, listed in the Chart Supplement U.S. except when severe weather avoidance procedures or other factors dictate otherwise.
Preignition. Ignition occurring in the cylinder before the time of normal ignition. Preignition is often caused by a local hot spot in the combustion chamber igniting the fuel-air mixture.
Pressure altitude. Altitude above the standard 29.92 "Hg plane.
Pressure demand oxygen system. A demand oxygen system that supplies 100 percent oxygen at sufficient pressure above the altitude where normal breathing is adequate. Also referred to as a pressure breathing system.
Prevailing visibility. The greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle (which is not necessarily continuous).
Preventive maintenance. Simple or minor preservative operations and the replacement of small standard parts not involving complex assembly operation as listed in 14 CFR part 43, appendix A. Certificated pilots may perform preventive maintenance on any aircraft that is owned or operated by them provided that the aircraft is not used in air carrier service.
Primary and supporting. A method of attitude instrument flying using the instrument that provides the most direct indication of attitude and performance.
Primary flight display (PFD). A display that provides increased situational awareness to the pilot by replacing the traditional six instruments used for instrument flight with an easy-to-scan display that provides the horizon, airspeed, altitude, vertical speed, trend, trim, and rate of turn among other key relevant indications.
PRM. See precision runway monitor.
Procedure turn. A maneuver prescribed when it is necessary to reverse direction to establish an aircraft on the intermediate approach segment or final approach course.
Profile view. Side view of an IAP chart illustrating the vertical approach path altitudes, headings, distances, and fixes.
Prohibited area. Designated airspace within which flight of aircraft is prohibited.
Propeller. A device for propelling an aircraft that, when rotated, produces by its action on the air, a thrust approximately perpendicular to its plane of rotation. It includes the control components normally supplied by its manufacturer.
Propeller/rotor modulation error. Certain propeller rpm settings or helicopter rotor speeds can cause the VOR course deviation indicator (CDI) to fluctuate as much as ±6°. Slight changes to the rpm setting will normally smooth out this roughness.
R
Rabbit, the. High-intensity flasher system installed at many large airports. The flashers consist of a series of brilliant blue-white bursts of light flashing in sequence along the approach lights, giving the effect of a ball of light traveling toward the runway.
Radar. A system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, weather formations, and terrain. The term RADAR was coined in 1941 as an acronym for Radio Detection and Ranging. The term has since entered the English language as a standard word, radar, losing the capitalization in the process.
Radar approach. The controller provides vectors w
hile monitoring the progress of the flight with radar, guiding the pilot through the descent to the airport/heliport or to a specific runway.
Radar services. Radar is a method whereby radio waves are transmitted into the air and are then received when they have been reflected by an object in the path of the beam. Range is determined by measuring the time it takes (at the speed of light) for the radio wave to go out to the object and then return to the receiving antenna. The direction of a detected object from a radar site is determined by the position of the rotating antenna when the reflected portion of the radio wave is received.
Radar summary chart. A weather product derived from the national radar network that graphically displays a summary of radar weather reports.
Radar weather report (SD). A report issued by radar stations at 35 minutes after the hour, and special reports as needed. Provides information on the type, intensity, and location of the echo tops of the precipitation.
Radials. The courses oriented from a station.
Radio or radar altimeter. An electronic altimeter that determines the height of an aircraft above the terrain by measuring the time needed for a pulse of radio-frequency energy to travel from the aircraft to the ground and return.
Radio frequency (RF). A term that refers to alternating current (AC) having characteristics such that, if the current is input to antenna, an electromagnetic (EM) field is generated suitable for wireless broadcasting and/or communications.
Radio magnetic indicator (RMI). An electronic navigation instrument that combines a magnetic compass with an ADF or VOR. The card of the RMI acts as a gyro-stabilized magnetic compass, and shows the magnetic heading the aircraft is flying.
Radiosonde. A weather instrument that observes and reports meteorological conditions from the upper atmosphere. This instrument is typically carried into the atmosphere by some form of weather balloon.
Radio wave. An electromagnetic (EM) wave with frequency characteristics useful for radio transmission.
RAIM. See receiver autonomous integrity monitoring.
RAM recovery. The increase in thrust as a result of ram air pressures and density on the front of the engine caused by air velocity.
Pilot's Handbook of Aeronautical Knowledge (Federal Aviation Administration) Page 84