Precision Approach Path Indicator
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Precision Approach Path Indicator
A precision approach path indicator (PAPI) is a visual aid that provides guidance information to help a pilot to acquire and maintain the correct approach (in the vertical plane) to an airport or an aerodrome. It is generally located on the left-hand side of the runway approximately 300 meters beyond the landing threshold of the runway. Development The precision approach path indicator system was first devised in 1974 by Tony Smith and David Johnson at the Royal Aircraft Establishment in Bedford, England. It took them a further two years to fully develop the technology. Smith and Johnson's work was honoured by a commendation from the RAE, a Fellowship from the Aeronautical Society, an award from the American Flight Safety Foundation, and a Gold Medal from the British Guild of Air Pilots. Engineering firm Research Engineers (RE) were also heavily involved in the project, having produced and supplied PAPI units for the first trials that were conducted. The same design is still in ...
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Final Approach (aviation)
In aeronautics, the final approach (also called the final leg and final approach leg) is the last leg in an aircraft's approach to landing, when the aircraft is lined up with the runway and descending for landing.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 213 and 241. Aviation Supplies & Academics, 1997. In aviation radio terminology, it is often shortened to "final". In a standard airport landing pattern, which is usually used under visual meteorological conditions (VMC), aircraft turn from base leg to final within one-half to two miles of the airport. For instrument approaches, as well as approaches into a controlled airfield under visual flight rules (VFR), often a "straight-in" final approach is used, where all the other legs are dispensed with. Straight-in approaches are discouraged at non-towered airports in the United States. Approach slope An approach slope is the path that an airplane follows on its final approach to land on a runway. I ...
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Leading Lights
Leading lights (also known as range lights in the United States) are a pair of light beacons used in navigation to indicate a safe passage for vessels entering a shallow or dangerous channel; they may also be used for position fixing. At night, the lights are a form of leading line that can be used for safe navigation. The beacons consist of two lights that are separated in distance and elevation, so that when they are aligned, with one above the other, they provide a bearing. Range lights are often illuminated day and night. In some cases the two beacons are unlighted, in which case they are known as a range in the United States or a transit in the UK. The beacons may be artificial or natural. Operation Two lights are positioned near one another. One, called the front light, is lower than the one behind, which is called the rear light. At night when viewed from a ship, the two lights only become aligned vertically when a vessel is positioned on the correct bearing. During t ...
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Optical Landing System
An optical landing system (OLS) (nicknamed "meatball" or simply "ball") is used to give glidepath information to pilots in the terminal phase of landing on an aircraft carrier. From the beginning of aircraft landing on ships in the 1920s to the introduction of OLSs, pilots relied solely on their visual perception of the landing area and the aid of the Landing Signal Officer (LSO in the U.S. Navy, or "batsman" in the Commonwealth navies). LSOs used coloured flags, cloth paddles and lighted wands. The OLS was developed after World War II by the British and was deployed on U.S. Navy carriers from 1955. In its developed form, the OLS consists of a horizontal row of green lights, used as a reference, and a column of vertical lights. The vertical lights signal whether the aircraft is too high, too low, or at the correct altitude as the pilot descends the glide slope towards the carrier's deck. Other lights give various commands and can be used to require the pilot to abort the landing an ...
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Runway Edge Lights
Runway edge lighting are used to outline the edges of runways during periods of darkness or restricted visibility conditions. These light systems are classified according to the intensity they are capable of producing: * High intensity runway lights (HIRL) * Medium intensity runway lights (MIRL) * Low intensity runway lights (LIRL) Many HIRL and MIRL systems have variable intensity controls, whereas the LIRLs normally have one intensity setting. At airports where there is a control tower, the tower will manage the lights to account for visibility and pilot preference, but some airports do not have control towers. These airports will have Pilot Controlled Lighting, or PCL, where pilots can adjust the lighting themselves by keying a microphone button a certain number of times. The majority of runway edge lights are clear or white, but there are some exceptions to provide additional information to pilots in certain circumstances. When an instrument runway lighting is designed, t ...
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Runway End Identifier Lights
Runway end identifier lights (REIL) (ICAO identifies these as Runway Threshold Identification Lights) are installed at many airports to provide rapid and positive identification of the approach end of a particular runway. The system consists of a pair of synchronized flashing lights located laterally on each side of the runway threshold. REILs may be either omnidirectional or unidirectional facing the approach area.FAA Aeronautical Information Manual, Chapter 2 (Aeronautical Lighting and Other Airport Visual Aids), Section 1 (Airport Lighting Aids)
They are effective for: * Identification of a runway surrounded by a preponderance of other ...
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Instrument Landing System
In aviation, the instrument landing system (ILS) is a precision radio navigation system that provides short-range guidance to aircraft to allow them to approach a runway at night or in bad weather. In its original form, it allows an aircraft to approach until it is over the ground, within a of the runway. At that point the runway should be visible to the pilot; if it is not, they perform a missed approach. Bringing the aircraft this close to the runway dramatically increases the range of weather conditions in which a safe landing can be made. Other versions of the system, or "categories", have further reduced the minimum altitudes, runway visual ranges (RVRs), and transmitter and monitoring configurations designed depending on the normal expected weather patterns and airport safety requirements. ILS uses two directional radio signals, the ''localizer'' (108 to 112 MHz frequency), which provides horizontal guidance, and the ''glideslope'' (329.15 to 335 MHz frequency ...
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Visual Approach Slope Indicator
The visual approach slope indicator (VASI) is a system of lights on the side of an airport runway threshold that provides visual descent guidance information during approach. These lights may be visible from up to during the day and up to or more at night. Basic visual approach slope indicators consist of one set of lights set up some from the start of the runway. Each light is designed so that it appears as either white or red, depending on the angle at which it is viewed. When the pilot is approaching the lights at the proper angle, meaning the pilot is on the glide slope, the first set of lights appears white and the second set appears red. When both sets appear white, the aircraft is too high, and when both appear red it is too low. This used to be the most common type of visual approach slope indicator system; however, it is being phased out and replaced by precision approach path indicators (PAPIs), which are closer together and therefore more efficient to sight and ma ...
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Pilot Controlled Lighting
Pilot-controlled lighting (PCL), also known as aircraft radio control of aerodrome lighting (ARCAL) or pilot-activated lighting (PAL), is a system that allows aircraft pilots to control the lighting of an airport or airfield's approach lights, runway edge lights, and taxiways via radio. Technical details At some airfields, the airport/aerodrome beacon may also be ARCAL controlled. ARCAL is most common at non-towered airports or little-used airfields where it is neither economical to light the runways all night, nor to provide staff to turn the runway lighting on and off. It enables pilots to control the lighting only when required, saving electricity and reducing light pollution. The ARCAL frequency for most aerodromes is usually the same as the UNICOM/CTAF frequency, although in some rare cases, a second ARCAL frequency may be designated to control the lighting for a second runway separately. An example of the latter is runway 18/36 at the airport in Sydney, Nova Scotia. To ...
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Approach Lighting System
An approach lighting system (ALS) is a lighting system installed on the approach end of an airport runway and consisting of a series of lightbars, strobe lights, or a combination of the two that extends outward from the runway end. ALS usually serves a runway that has an instrument approach procedure (IAP) associated with it and allows the pilot to visually identify the runway environment and align the aircraft with the runway upon arriving at a prescribed point on an approach. Modern approach lighting systems are highly complex in their design and significantly enhance the safety of aircraft operations, particularly in conditions of reduced visibility. Operation The required minimum visibilities for instrument approaches is influenced by the presence and type of approach lighting system. In the U.S., a CAT I Instrument landing system, ILS approach without approach lights will have a minimum required visibility of 3/4 mile, or 4000 foot runway visual range. With a 1400-foot o ...
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Go-around
In aviation, a go-around is an aborted landing of an aircraft that is on final approach or has already touched down. A go-around can either be initiated by the pilot flying or requested by air traffic control for various reasons, such as an unstabilized approach or an obstruction on the runway. Etymology The term arises from the traditional use of traffic patterns at airfields. A landing aircraft will first join the traffic pattern/circuit and prepare for landing. If for some reason, the pilot decides not to land, the pilot can simply fly back up to traffic pattern altitude/circuit height, and complete another circuit. The term "go-around" is still used even for modern airliners, though they may not use traditional traffic patterns/circuits for landing. Reasons for use Initiation of a go-around may be either ordered by air traffic control (normally the local or tower controller in a controlled field) or initiated by the pilot in command of the aircraft. In naval aviation, t ...
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Air Traffic Controller
Air traffic control specialists, abbreviated ATCS, are personnel responsible for the safe, orderly, and expeditious flow of air traffic in the global air traffic control system. Usually stationed in air traffic control centers and control towers on the ground, they monitor the position, speed, and altitude of aircraft in their assigned airspace visually and by radar, and give directions to the pilots by radio. The position of air traffic controller is one that requires highly specialized knowledge, skills, and abilities. Controllers apply separation rules to keep aircraft at a safe distance from each other in their area of responsibility and move all aircraft safely and efficiently through their assigned sector of airspace, as well as on the ground. Because controllers have an incredibly large responsibility while on duty (often in aviation, "on position") and make countless real-time decisions on a daily basis, the ATC profession is consistently regarded around the worl ...
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