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Altimeter Setting
Altimeter setting is the value of the atmospheric pressure used to adjust the scale of a pressure altimeter so that it indicates the height of an aircraft above a known reference surface. This reference can be the mean sea level pressure ( QNH), the pressure at a nearby surface airport (QFE), or the " standard pressure level" of which gives pressure altitude and is used to maintain one of the standard flight levels. The setting of a sensitive pressure altimeter is shown in thKollsman window The QNH altimeter setting is one of the data included in METAR messages. An alternative setting is QFE or SPS/STD: *QNH - is the barometric altimeter setting that causes an altimeter to read aircraft elevation above mean sea level - ''altitude'' ( AMSL - above mean sea level) in ISA temperature conditions in the vicinity of the airfield that reported the QNH value. *QFE - is the barometric altimeter setting that causes an altimeter to read zero when at the reference datum of a particular a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure Altimeter
Altitude can be determined based on the measurement of atmospheric pressure. The greater the altitude, the lower the pressure. When a barometer is supplied with a nonlinear calibration so as to indicate altitude, the instrument is a type of altimeter called a pressure altimeter or barometric altimeter. A pressure altimeter is the altimeter found in most aircraft, and skydivers use wrist-mounted versions for similar purposes. Hikers and mountain climbers use wrist-mounted or hand-held altimeters, in addition to other navigational tools such as a map, magnetic compass, or GPS receiver. Calibration The calibration of an altimeter follows the equation :z=c\;T\;\log(P_o/P), where c is a constant, T is the absolute temperature, P is the pressure at altitude z, and Po is the pressure at sea level. The constant c depends on the acceleration of gravity and the molar mass of the air. However, one must be aware that this type of altimeter relies on "density altitude" and its readings can var ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World Meteorological Organization
The World Meteorological Organization (WMO) is a List of specialized agencies of the United Nations, specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. The WMO originated from the International Meteorological Organization (IMO), a nongovernmental organization founded in 1873 as a forum for exchanging weather data and research. Proposals to reform the status and structure of the IMO culminated in the World Meteorological Convention of 1947, which formally established the World Meteorological Organization. The Convention entered into force on 23 March 1950, and the following year the WMO began operations as an intergovernmental organization within the UN system. The WMO is made up of 193 countries and territories, and facilitates the "free and unrestricted" exchange of data, information, and research between the respective meteorological and hydrological institutions of its m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mean Sea Level
A mean is a quantity representing the "center" of a collection of numbers and is intermediate to the extreme values of the set of numbers. There are several kinds of means (or "measures of central tendency") in mathematics, especially in statistics. Each attempts to summarize or typify a given group of data, illustrating the magnitude and sign of the data set. Which of these measures is most illuminating depends on what is being measured, and on context and purpose. The ''arithmetic mean'', also known as "arithmetic average", is the sum of the values divided by the number of values. The arithmetic mean of a set of numbers ''x''1, ''x''2, ..., x''n'' is typically denoted using an overhead bar, \bar. If the numbers are from observing a sample of a larger group, the arithmetic mean is termed the '' sample mean'' (\bar) to distinguish it from the group mean (or expected value) of the underlying distribution, denoted \mu or \mu_x. Outside probability and statistics, a wide rang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard Pressure
Standard temperature and pressure (STP) or standard conditions for temperature and pressure are various standard sets of conditions for experimental measurements used to allow comparisons to be made between different sets of data. The most used standards are those of the International Union of Pure and Applied Chemistry (IUPAC) and the National Institute of Standards and Technology (NIST), although these are not universally accepted. Other organizations have established a variety of other definitions. In industry and commerce, the standard conditions for temperature and pressure are often necessary for expressing the volumes of gases and liquids and related quantities such as the rate of volumetric flow (the volumes of gases vary significantly with temperature and pressure): standard cubic meters per second (Sm3/s), and normal cubic meters per second (Nm3/s). Many technical publications (books, journals, advertisements for equipment and machinery) simply state "standard cond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure Altitude
Given an atmospheric pressure measurement, the pressure altitude is the imputed altitude that the International Standard Atmosphere (ISA) model predicts to have the same pressure as the observed value. The National Oceanic and Atmospheric Administration (NOAA) published the following formula for directly converting atmospheric pressure in millibars (mb) to pressure altitude in feet (ft): h = 145366.45 \left 1 - \left( \frac \right)^ \right In aviation, pressure altitude is the height above a standard datum plane (SDP), which is a theoretical level where the weight of the atmosphere is as measured by a barometer.Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25B), 2016, Chapter 4, p 4-4 It indicates altitude obtained when an altimeter is set to an agreed baseline pressure under certain circumstances in which the aircraft’s altimeter would be unable to give a useful altitude readout. Examples would be landing at a high altitude or near sea level under conditions of e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flight Level
In aviation, a flight level (FL) is an aircraft's altitude as determined by a pressure altimeter using the International Standard Atmosphere. It is expressed in hundreds of feet or metres. The altimeter setting used is the ISA sea level pressure of 1013 hPa or 29.92 inHg. The actual surface pressure will vary from this at different locations and times. Therefore, by using a standard pressure setting, every aircraft has the same altimeter setting, and vertical clearance can be maintained during cruise flight. Background Flight levels are used to ensure safe vertical separation between aircraft. Historically, altitude has been measured using an altimeter, essentially a calibrated barometer. An altimeter measures ambient air pressure, which decreases with increasing altitude following the barometric formula. It displays the corresponding altitude. If aircraft altimeters were not calibrated consistently, then two aircraft could be flying at the same altitude even thou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
METAR
METAR is a format for reporting weather information. A METAR weather report is predominantly used by aircraft pilots, and by meteorologists, who use aggregated METAR information to assist in weather forecasting. Raw METAR is highly standardized through the International Civil Aviation Organization (ICAO), which enables it to be understood throughout most of the world. Report names In its publication the '' Aeronautical Information Manual'' (''AIM''), the United States Federal Aviation Administration (FAA) describes the report as ''aviation routine weather report'', while the international authority for the code form, the World Meteorological Organization (WMO), describes it as the ''aerodrome routine meteorological report.'' The National Oceanic and Atmospheric Administration (part of the United States Department of Commerce) and the United Kingdom's Met Office both employ the definition used by the FAA. METAR is also known as ''Meteorological Terminal Aviation Routine Weathe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Height Above Mean Sea Level
Height above mean sea level is a measure of a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero level varies in different countries due to different reference points and historic measurement periods. Climate change and other forces can cause sea levels and elevations to vary over time. Uses Elevation or altitude above sea level is a standard measurement for: * Geographic locations such as towns, mountains and other landmarks. * The top of buildings and other structures. * Mining infrastructure, particularly underground. * Flying objects such as airplanes or helicopters below a Transition Altitude defined by local regulations. Units and abbreviations Elevation or altitude is generally expressed as "metres above mean sea level" in the metric system, or " feet above mean sea level" in United States customary and imperial units. Comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Q Codes
The Q-code is a standardised collection of three-letter codes that each start with the letter "Q". It is an operating signal initially developed for commercial radiotelegraph communication and later adopted by other radio services, especially amateur radio. To distinguish the use of a Q-code transmitted as a question from the same Q-code transmitted as a statement, operators either prefixed it with the military network question marker "" () or suffixed it with the standard Morse question mark (). Although Q-codes were created when radio used Morse code exclusively, they continued to be employed after the introduction of voice transmissions. To avoid confusion, transmitter call signs are restricted; countries can be issued unused Q-Codes as their ITU prefix e.g. Qatar is QAT. Codes in the range QAA–QNZ are reserved for aeronautical use; QOA–QQZ for maritime use and QRA–QUZ for all services. "Q" has no official meaning, but it is sometimes assigned a word with mnemonic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mnemonic
A mnemonic device ( ), memory trick or memory device is any learning technique that aids information retention or retrieval in the human memory, often by associating the information with something that is easier to remember. It makes use of elaborative encoding, retrieval cues and imagery as specific tools to encode information in a way that allows for efficient storage and retrieval. It aids original information in becoming associated with something more accessible or meaningful—which in turn provides better retention of the information. Commonly encountered mnemonics are often used for lists and in auditory system, auditory form such as Acrostic, short poems, acronyms, initialisms or memorable phrases. They can also be used for other types of information and in visual or kinesthetic forms. Their use is based on the observation that the human mind more easily remembers spatial, personal, surprising, physical, sexual, humorous and otherwise "relatable" information rather tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Altitude
In aviation, a flight level (FL) is an aircraft's altitude as determined by a pressure altimeter using the International Standard Atmosphere. It is expressed in hundreds of feet or metres. The altimeter setting used is the ISA sea level pressure of 1013 hPa or 29.92 inHg. The actual surface pressure will vary from this at different locations and times. Therefore, by using a standard pressure setting, every aircraft has the same altimeter setting, and vertical clearance can be maintained during cruise flight. Background Flight levels are used to ensure safe vertical separation between aircraft. Historically, altitude has been measured using an altimeter, essentially a calibrated barometer. An altimeter measures ambient air pressure, which decreases with increasing altitude following the barometric formula. It displays the corresponding altitude. If aircraft altimeters were not calibrated consistently, then two aircraft could be flying at the same altitude even thoug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Level
In aviation, a flight level (FL) is an aircraft's altitude as determined by a pressure altimeter using the International Standard Atmosphere. It is expressed in hundreds of foot (unit), feet or metres. The altimeter setting used is the International Standard Atmosphere, ISA sea level pressure of 1013 Pascal (unit), hPa or 29.92 Inch of mercury, inHg. The actual surface pressure will vary from this at different locations and times. Therefore, by using a standard pressure setting, every aircraft has the same altimeter setting, and vertical clearance can be maintained during cruise flight. Background Flight levels are used to ensure safe vertical separation between aircraft. Historically, altitude has been measured using an altimeter, essentially a calibrated barometer. An altimeter measures ambient air pressure, which decreases with increasing altitude following the barometric formula. It displays the corresponding altitude. If aircraft altimeters were not calibrated con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
