Instrument landing system

345:, with the 90 Hz output pulling the needle right and the other left. Along the centreline the two modulating tones of the sidebands will be cancelled out and both voltages will be zero, leaving the needle centered in the display. If the aircraft is far to the left, the 90 Hz signal will produce a strong DC voltage (predominates), and the 150 Hz signal is minimised, pulling the needle all the way to the right. This means the voltmeter directly displays both the direction and magnitude of the turn needed to bring the aircraft back to the runway centreline. As the measurement compares different parts of a single signal entirely in electronics, it provides angular resolution of less than a degree, and allows the construction of a 1314:

modernization and in all-weather operations capability at CATI/II and III airports, terminal area navigation, missed approach guidance and surface operations. GBAS provides the capability to service the entire airport with a single frequency (VHF transmission) whereas ILS requires a separate frequency for each runway end. GBAS CAT-I is seen as a necessary step towards the more stringent operations of CAT-II/III precision approach and landing. The technical risk of implementing GBAS delayed widespread acceptance of the technology. The FAA, along with industry, have fielded Provably Safe Prototype GBAS stations that mitigate the impact of satellite signal deformation, ionosphere differential error, ephemeris error, and multipath.

705: 691:). Most often, these are at larger airports but many small general aviation airports in the U.S. have approach lights to support their ILS installations and obtain low-visibility minimums. The ALS assists the pilot in transitioning from instrument to visual flight, and to align the aircraft visually with the runway centerline. Pilot observation of the approach lighting system at the Decision Altitude allows the pilot to continue descending towards the runway, even if the runway or runway lights cannot be seen, since the ALS counts as runway end environment. In the U.S., an ILS without approach lights may have CAT I ILS visibility minimums as low as 92: 325:, the antenna is normally placed centrally at the far end of the runway and consists of multiple antennas in an array normally about the width of the runway. Each individual antenna has a particular phase shift and power level applied only to the SBO signal such that the resulting signal is retarded 90 degrees on the left side of the runway and advanced 90 degrees on the right. Additionally, the 150 Hz signal is inverted on one side of the pattern, another 180 degree shift. Due to the way the signals mix in 672: 1039:(SMGCS) plan. Operations below 600 ft RVR require taxiway centerline lights and taxiway red stop bar lights. If the CAT IIIb RVR minimums on a runway end are 600 feet (180 m), which is a common figure in the U.S., ILS approaches to that runway end with RVR below 600 feet (180 m) qualify as CAT IIIc and require special taxi procedures, lighting, and approval conditions to permit the landings. FAA Order 8400.13D limits CAT III to 300 ft RVR or better. Order 8400.13D (2009) allows 386:

transmitted using lower carrier frequencies, using 40 selected channels between 108.10 MHz and 111.95 MHz, whereas the glideslope has a corresponding set of 40 channels between 328.6 and 335.4 MHz. The higher frequencies generally result in the glideslope radiating antennas being smaller. The channel pairs are not linear; localizer channel 1 is at 108.10 and paired with glideslope at 334.70, whereas channel two is 108.15 and 334.55. There are gaps and jumps through both bands.

287:, used a more complex system of signals and an antenna array to achieve higher accuracy. This requires significantly more complexity in the ground station and transmitters, with the advantage that the signals can be accurately decoded in the aircraft using simple electronics and displayed directly on analog instruments. The instruments can be placed in front of the pilot, eliminating the need for a radio operator to continually monitor the signals and relay the results to the pilot over the 390: 310:, secondary frequencies that are created when two different signals are mixed. For instance, if one takes a radio frequency signal at 10 MHz and mixes that with an audible tone at 2500 Hz, four signals will be produced, at the original signals' frequencies of 2500 and 10000000 hertz, and sidebands 9997500 and 10002500 hertz. The original 2500 Hz signal's frequency is too low to travel far from an antenna, but the other three signals are all 1047:

system is considered as fail-operational. A HUD allows the flight crew to fly the aircraft using the guidance cues from the ILS sensors such that if a safe landing is in doubt, the crew can respond in an appropriate and timely manner. HUD is becoming increasingly popular with "feeder" airlines and most manufacturers of regional jets are now offering HUDs as either standard or optional equipment. A HUD can provide capability to take off in low visibility.

370: 2352: 483: 596:. This lets aircraft land using the signal transmitted from the back of the localizer array. Highly directional antennas do not provide a sufficient signal to support a back course. In the United States, back course approaches are typically associated with Category I systems at smaller airports that do not have an ILS on both ends of the primary runway. Pilots flying a back course should disregard any glide slope indication. 444: 209: 38: 2609: 1145: 2619: 306:. In the earlier beam systems, the signal was turned on and off entirely, corresponding to a modulation index of 100%. The determination of angle within the beam is based on the comparison of the audible strength of the two signals. sa In ILS, a more complex system of signals and antennas varies the modulation of two signals across the entire width of the beam pattern. The system relies on the use of 515:

terrain is sloping or uneven, reflections can create an uneven glidepath, causing unwanted needle deflections. Additionally, since the ILS signals are pointed in one direction by the positioning of the arrays, glide slope supports only straight-line approaches with a constant angle of descent. Installation of an ILS can be costly because of siting criteria and the complexity of the antenna system.

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directional signals, which demanded that they be relatively narrow. The ILS pattern can be much wider. ILS installations are normally required to be usable within 10 degrees on either side of the runway centerline at 25 nautical miles (46 km; 29 mi), and 35 degrees on either side at 17 nautical miles (31 km; 20 mi). This allows for a wide variety of approach paths.

1011: 1373: 498: 1287:(GNSS) resulted in its not being adopted in civil aviation. At the time ILS and MLS were the only standardized systems in Civil Aviation that meet requirements for Category III automated landings. The first Category III MLS for civil aviation was commissioned at Heathrow airport in March 2009 and removed from service in 2017. 2076: 2013:

Sep 24, 1929: At Mitchel Field, N.Y., Army Lt. James H. Doolittle became the first pilot to use only instrument guidance to take off, fly a set course, and land. Doolittle received directional guidance from a radio range course aligned with the airport runway, while radio marker beacons indicated his

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For both automatic and HUD landing systems, the equipment requires special approval for its design and also for each individual installation. The design takes into consideration additional safety requirements for operating an aircraft close to the ground and the ability of the flight crew to react to

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In each case, a suitably equipped aircraft and appropriately qualified crew are required. For example, CAT IIIb requires a fail-operational system, along with a crew who are qualified and current, while CAT I does not. A HUD that allows the pilot to perform aircraft maneuvers rather than an automatic

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An ILS must shut down upon internal detection of a fault condition. Higher categories require shorter response times; therefore, ILS equipment is required to shut down more quickly. For example, a CAT I localizer must shut down within 10 seconds of detecting a fault, but a CAT III localizer must shut

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Smaller aircraft generally are equipped to fly only a CAT I ILS. On larger aircraft, these approaches typically are controlled by the flight control system with the flight crew providing supervision. CAT I relies only on altimeter indications for decision height, whereas CAT II and CAT III approaches

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mile (600 m) visibility 1,800-foot (550 m) visual range is possible if the runway has high-intensity edge lights, touchdown zone and centerline lights, and an ALS that is at least 2,400 feet (730 m) long (see Table 3-3-1 "Minimum visibility values" in FAA Order 8260.3C). In effect, ALS

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of 75 MHz are provided. When the transmission from a marker beacon is received it activates an indicator on the pilot's instrument panel and the tone of the beacon is audible to the pilot. The distance from the runway at which this indication should be received is published in the documentation

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Additionally, because it is the encoding of the signal within the beam that contains the angle information, not the strength of the beam, the signal does not have to be tightly focussed in space. In the older beam systems, the accuracy of the equisignal area was a function of the pattern of the two

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A receiver in front of the array will receive both of these signals mixed together. Using simple electronic filters, the original carrier and two sidebands can be separated and demodulated to extract the original amplitude-modulated 90 and 150 Hz signals. These are then averaged to produce two

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ILS starts by mixing two modulating signals to the carrier, one at 90 Hz and another at 150. This creates a signal with five radio frequencies in total, the carrier and four sidebands. This combined signal, known as the CSB for "carrier and sidebands", is sent out evenly from an antenna array.

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in the United States) is a safety-critical system that augments the GNSS Standard Positioning Service (SPS) and provides enhanced levels of service. It supports all phases of approach, landing, departure, and surface operations within the VHF coverage volume. GBAS is expected to play a key role in

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will direct aircraft to the localizer course via assigned headings, making sure aircraft do not get too close to each other (maintain separation), but also avoiding delay as much as possible. Several aircraft can be on the ILS at the same time, several miles apart. An aircraft that has turned onto

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In contrast to other operations, CAT III weather minima do not provide sufficient visual references to allow a manual landing to be made. CAT IIIb minima depend on roll-out control and redundancy of the autopilot, because they give only enough time for the pilot to decide whether the aircraft will

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Due to the complexity of ILS localizer and glide slope systems, there are some limitations. Localizer systems are sensitive to obstructions in the signal broadcast area, such as large buildings or hangars. Glide slope systems are also limited by the terrain in front of the glide slope antennas. If

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The pilot controls the aircraft so that the glide slope indicator remains centered on the display to ensure the aircraft is following the glide path of approximately 3° above horizontal (ground level) to remain above obstructions and reach the runway at the proper touchdown point (i.e. it provides

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Once established on an approach, the pilot follows the ILS approach path indicated by the localizer and descends along the glide path to the decision height. This is the height at which the pilot must have adequate visual reference to the landing environment (e.g. approach or runway lighting) to

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measurement of distance to the runway. DMEs are augmenting or replacing markers in many installations. The DME provides more accurate and continuous monitoring of correct progress on the ILS glide slope to the pilot, and does not require an installation outside the airport boundary. When used in

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Local Area Augmentation System (LAAS) is under development to provide for Category III minimums or lower. The FAA Ground-Based Augmentation System (GBAS) office is currently working with the industry in anticipation of the certification of the first GBAS ground stations in Memphis, TN; Sydney,

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It is essential that any failure of the ILS to provide safe guidance be detected immediately by the pilot. To achieve this, monitors continually assess the vital characteristics of the transmissions. If any significant deviation beyond strict limits is detected, either the ILS is automatically

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is mandatory to perform Category III operations. Its reliability must be sufficient to control the aircraft to touchdown in CAT IIIa operations and through rollout to a safe taxi speed in CAT IIIb (and CAT IIIc when authorized). However, special approval has been granted to some operators for

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Accuracy of the system was normally on the order of 3 degrees in azimuth. While this was useful for bringing the aircraft onto the direction of the runway, it was not accurate enough to safely bring the aircraft to visual range in bad weather; the radio course beams were used only for lateral

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To use the system an aircraft only needed a conventional radio receiver. As they approached the airport they would tune in the signal and listen to it in their headphones. They would hear dots and dashes (Morse code "A" or "N"), if they were to the side of the runway, or if they were properly

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In the United States, airports with CAT III approaches have listings for CAT IIIa and IIIb or just CAT III on the instrument approach plate (U.S. Terminal Procedures). CAT IIIb RVR minimums are limited by the runway/taxiway lighting and support facilities, and are consistent with the airport

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works in the same general fashion as the localizer and uses the same encoding, but is normally transmitted to produce a centerline at an angle of 3 degrees above horizontal from an antenna beside the runway instead of the end. The only difference between the signals is that the localizer is

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transmits IJFK to identify itself, while runway 4L is known as IHIQ. This lets users know the facility is operating normally and that they are tuned to the correct ILS. The glide slope station transmits no identification signal, so ILS equipment relies on the localizer for identification.

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the SBO signals destructively interfere with and almost eliminate each other along the centerline, leaving the CSB signal predominating. At any other location, on either side of the centerline, the SBO and CSB signals combine in different ways so that one modulating signal predominates.

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extends the runway environment out towards the landing aircraft and allows low-visibility operations. CAT II and III ILS approaches generally require complex high-intensity approach light systems, while medium-intensity systems are usually paired with CAT I ILS approaches. At some

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Many illustrations of the ILS concept often show the system operating more similarly to beam systems with the 90 Hz signal on one side and the 150 on the other. These illustrations are inaccurate; both signals are radiated across the entire beam pattern, it is their relative

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dots and dashes. The switch also controlled which of two directional antennae the signal was sent to. The resulting signal sent into the air consists of dots sent to one side of the runway and dashes to the other. The beams were wide enough so they overlapped in the center.

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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.

338:(DC) signals. Each of these signals represents not the strength of the original signal, but the strength of the modulation relative to the carrier, which varies across the beam pattern. This has the great advantage that the measurement of angle is independent of range. 1168:" after its inventor, the C. Lorenz AG company. The Civil Aeronautics Board (CAB) of the United States authorized installation of the system in 1941 at six locations. The first landing of a scheduled U.S. passenger airliner using ILS was on January 26, 1938, when a 2073: 521:

and ILS sensitive areas are established to avoid hazardous reflections that would affect the radiated signal. The location of these critical areas can prevent aircraft from using certain taxiways leading to delays in takeoffs, increased hold times, and increased

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procedure, then try the same approach again, try a different approach, or divert to another airport. Usually, the decision on whether or not the pilot continues with the approach relies on whether the runway is visible or not, or if the runway is clear or not.

1279:(MLS) allowed for curved approaches. It was introduced in the 1970s to replace ILS but fell out of favor because of the introduction of satellite based systems. In the 1980s, there was a major US and European effort to establish MLS. But a combination of 352:

Although the encoding scheme is complex, and requires a considerable amount of ground equipment, the resulting signal is both far more accurate than the older beam-based systems and is far more resistant to common forms of interference. For instance,

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based on infrared sensors, that provide a day-like visual environment and allow operations in conditions and at airports that would otherwise not be suitable for a landing. Commercial aircraft also frequently use such equipment for takeoffs when

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The Honeywell and FAA team obtained System Design Approval of the world's first non-federal U.S. approval for LAAS Category I at Newark Liberty International Airport, operations in September 2009 and Operational Approval on September 28, 2012.

1327:(GPS) provides an alternative source of approach guidance for aircraft. In the US, the Wide Area Augmentation System (WAAS) has been available in many regions to provide precision guidance to Category I standards since 2007. The equivalent 1331:(EGNOS) was certified for use in safety of life applications in March 2011. As such, the number of Cat I ILS installations may be reduced, however there are no plans in the United States to phase out any Cat II or Cat III systems. 2074:

https://www.marketwatch.com/press-release/instrument-landing-systemsils-market-share-size-global-regional-analysis-key-findings-growth-factors-industry-demand-key-players-profiles-future-prospects-and-forecasts-to-2025-2021-08-26

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signal to be broadcast from the airport, which is dramatically less expensive than the multiple, large and powerful transmitters required for a full ILS implementation. By 2015, the number of US airports supporting ILS-like

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effects due to the use of multiple frequencies, but because those effects are dependent on the terrain, they are generally fixed in location and can be accounted for through adjustments in the antenna or phase shifters.

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for that approach, together with the height at which the aircraft should be if correctly established on the ILS. This provides a check on the correct function of the glide slope. In modern ILS installations, a

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switched off or the navigation and identification components are removed from the carrier. Either of these actions will activate an indication ('failure flag') on the instruments of an aircraft using the ILS.

2319: 1697: 1031:(HUD) guidance that provides the pilot with an image viewed through the windshield with eyes focused at infinity, of necessary electronic guidance to land the airplane with no true outside visual references. 1191:

The instrument landing systems market revenue was US$ 1,215 million in 2019, and is expected to reach US$ 1,667 million in 2025, with a CAGR of 5.41% during 2020–2025 even with the negative effects of the

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The CSB is also sent into a circuit that suppresses the original carrier, leaving only the four sideband signals. This signal, known as SBO for "sidebands only", is also sent to the antenna array.

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in the signal will affect both sub-signals equally, so it will have no effect on the result. Similarly, changes in overall signal strength as the aircraft approaches the runway, or changes due to

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guidance, and the system was not enough on its own to perform landings in heavy rain or fog. Nevertheless, the final decision to land was made at only 300 metres (980 ft) from the airport.

191:(GNSSs) instead of requiring expensive airport infrastructure is leading to the replacement of ILS. Providing the required accuracy with GNSS normally requires only a low-power omnidirectional 2508: 271:. The accuracy of this measurement was highly dependent on the skill of the operator, who listened to the signal on earphones in a noisy aircraft, often while communicating with the tower. 1065:

Some commercial aircraft are equipped with automatic landing systems that allow the aircraft to land without transitioning from instruments to visual conditions for a normal landing. Such

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Instrument Landing Systems(Ils) Market Share, Size Global Regional Analysis, Key Findings, Growth Factors, Industry Demand, Key Players Profiles, Future Prospects and Forecasts to 2025 (

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mile (0.80 km) (runway visual range of 2,400 feet (730 m)) are possible with a CAT I ILS approach supported by a 1,400-to-3,000-foot-long (430 to 910 m) ALS, and

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Australia; Bremen, Germany; Spain; and Newark, NJ. All four countries have installed GBAS ground stations and are involved in technical and operational evaluation activities.

1303:(WAAS), LPV has similar minima to ILS for appropriately equipped aircraft. As of November 2008, the FAA has published more LPV approaches than Category I ILS procedures. 1940: 145:(DME). The ILS usually includes high-intensity lighting at the end of the runways to help the pilot locate the runway and transition from the approach to a visual landing. 746:; for example, the pilot can key the microphone seven times to turn on the lights on the high intensity, five times to medium intensity or three times for low intensity. 2504: 1328: 1069:

operations require specialized equipment, procedures and training, and involve the aircraft, airport, and the crew. Autoland is the only way some major airports such as

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to fly the approach automatically. An ILS consists of two independent sub-systems. The localizer provides lateral guidance; the glide slope provides vertical guidance.

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the inbound heading and is within two and a half degrees of the localizer course (half scale deflection or less shown by the course deviation indicator) is said to be

550: 2290:- Illustrates and describes how ILS navigation signals are displayed on board of an aircraft in various positions, which may occur during a safe approach for landing. 425:

An aircraft approaching a runway is guided by the ILS receivers in the aircraft by performing modulation depth comparisons. Many aircraft can route signals into the

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In addition to the previously mentioned navigational signals, the localizer provides for ILS facility identification by periodically transmitting a 1,020 Hz

2191: 2130: 1466: 1296: 197: 99:, which provides lateral guidance. The transmitter and antenna are on the centerline at the opposite end of the runway from the approach threshold. Photo of 1684: 2683: 2341: 2047: 1852: 2351: 649:

modified so that one unit can provide distance information to either runway threshold. For approaches where a DME is specified in lieu of marker beacons,

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approaches to runways without ALSF-2 approach lights and/or touchdown zone/centerline lights, which has expanded the number of potential CAT II runways.

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150 ft (46 m) allowed by FAA with RVR > 1,400 ft (430 m), CAT II aircraft and crew, CAT II/III HUD and CAT II/III missed approach.

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a system anomaly. The equipment also has additional maintenance requirements to ensure that it is capable of supporting reduced visibility operations.

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is noted on the instrument approach procedure and the aircraft must have at least one operating DME unit, or an IFR-approved system using a GNSS (an

2663: 1812: 2673: 1564: 539:(LDA) in the United States) – a modified ILS to accommodate a non-straight approach; the most famous example was for the approach to runway 13 at 468:

The localizer will allow the aircraft to turn and match the aircraft with the runway. After that, the pilots will activate approach phase (APP).

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is installed, co-located with the ILS, to augment or replace marker beacons. A DME continuously displays the aircraft's distance to the runway.

119:(329.15 to 335 MHz frequency) for vertical guidance. The relationship between the aircraft's position and these signals is displayed on an 1714: 1386: 1175:

D flew from Washington, D.C., to Pittsburgh, Pennsylvania, and landed in a snowstorm using only the Instrument Landing System. The first fully

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at night or in bad weather. In its original form, it allows an aircraft to approach until it is 200 feet (61 m) over the ground, within a

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mile (1.2 km) (runway visual range of 4,000 feet (1,200 m)) if the required obstacle clearance surfaces are clear of obstructions.

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systems of various types. These normally consisted of a radio transmitter that was connected to a motorized switch to produce a pattern of

233: 361:, will have little effect on the resulting measurement because they would normally affect both channels equally. The system is subject to 2283: 2552: 438: 188: 2014:

distance from the runway. He flew in a hooded cockpit, but was accompanied by a check pilot who could have intervened in an emergency.

1284: 709: 2653: 2025: 1754: 1548: 156:. The US-developed SCS-51 system was more accurate while also adding vertical guidance. Many sets were installed at airbases in the 1117:(a carryover from when an analog meter movement indicated deviation from the course line via voltages sent from the ILS receiver). 986:

ICAO/FAA only, not mentioned by the JAA(EASA), not used on airports by May 2017, a plane would have to be towed to clear the runway

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approaches exceeded the number of ILS installations, and this is expected to lead to the eventual removal of ILS at most airports.

1976: 1951: 1169: 523: 2528: 2496: 2334: 2144: 2480: 2448: 2396: 1460: 1310: 536: 2108: 1884: 91: 2259: 1518: 1300: 232:, using a combination of radio signals and, in many cases, high-intensity lighting arrays to enable a safe landing during 1218: 1132:

where the autopilot or Flight Control Computer directly flies the aircraft and the flight crew monitor the operation, or

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normally located beyond the departure end of the runway and generally consists of several pairs of directional antennas.

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land in the touchdown zone (basically CAT IIIa) and to ensure safety during rollout (basically CAT IIIb). Therefore, an

646: 637: 632: 620: 487: 142: 141:(MM), placed close to the position of the (CAT 1) decision height. Markers are largely being phased out and replaced by 83:. Bringing the aircraft this close to the runway dramatically increases the range of weather conditions in which a safe 79:

mile (800 m) of the runway. At that point the runway should be visible to the pilot; if it is not, they perform a

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Repository and Open Science Access Portal; National Transportation Library; United States Department of Transportation

127:. The pilot attempts to manoeuvre the aircraft to keep the indicators centered while they approach the runway to the 2648: 2524: 2492: 2476: 2460: 2388: 2327: 1500: 1426: 1363: 1290: 1114: 173: 31: 1910: 1208: 675: 645:

conjunction with an ILS, the DME is often sited midway between the reciprocal runway thresholds with the internal

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Nearly all of this pilot training and qualification work is done in simulators with various degrees of fidelity.

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on the approach. Typically, an aircraft is established by at least 2 nautical miles (3.7 km) prior to the

684: 666: 592:. However, usage of older, less directional antennas allows a runway to have a non-precision approach called a 177: 1243: 1160:

alone, without a view outside the cockpit. A basic system, fully operative, was introduced in 1932 at Berlin-

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where the flight crew flies the aircraft manually to keep the localizer and glideslope indicators centered.

1125: 518: 415: 2678: 2576: 2468: 1483: 1437: 1036: 671: 1779: 2516: 2360: 2293: 1809: 1641: 369: 362: 2234: 414:') is published for each ILS approach to provide the information needed to fly an ILS approach during 2588: 2500: 2472: 2456: 2404: 2400: 1975:

For example, Southwest Airlines flies HUD equipped Boeing 737 aircraft to fog-prone airports such as

299: 2001: 1718: 2436: 2432: 2424: 2384: 1506: 1098: 947: 782: 739: 589: 221: 180:(MLS), but few of these systems have been deployed. ILS remains a widespread standard to this day. 2618: 2572: 2444: 2420: 2412: 1228: 1157: 1107: 393:

Common type of illustration showing misleading examples of ILS localizer and glideslope emissions

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A number of radio-based landing systems were developed between the 1920s and 1940s, notably the

2300: 2658: 2580: 2280: 2209: 1544: 1306: 1193: 1144: 615: 303: 192: 1990: 2464: 1495: 1343: 1253: 448: 419: 389: 326: 295: 58: 2102:"Annex 10 – Aeronautical Telecommunications, Volume I (Radio Navigation Aids) Amendment 81" 2564: 2287: 2080: 1816: 1731: 1449: 1377: 1153: 1121: 1074: 1028: 995: 777: 756: 540: 459: 311: 237: 164:, which led to it being selected as the international standard after the formation of the 128: 80: 1747: 755:

decide whether to continue the descent to a landing; otherwise, the pilot must execute a

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localizer, taken at the runway 06L of the Montréal–Trudeau International Airport, Canada.

2026:"Planes Are Landing By Radio When Fog Hides The Field", February 1931, Popular Mechanics 968:

1,200 ft (370 m) RVR in Canada, 2,600 ft (790 m) RVR for single crew

482: 2584: 2380: 2376: 2127:"Worlds first low-visibility microwave landing system comes into operation at Heathrow" 1263: 1113:

Aircraft deviation from the optimal path is indicated to the flight crew by means of a

443: 411: 335: 157: 100: 37: 2637: 2560: 2536: 2392: 2356: 1832: 1014: 611: 605: 168:(ICAO) in 1947. Several competing landing systems have been developed, including the 133: 17: 2148: 1810:

FAA Order 8260.3C, United States Standard for Terminal Instrument Procedures (TERPS)

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The output from the ILS receiver goes to the display system (head-down display and

462: 284: 208: 161: 153: 108: 1979:(KSMF), allowing flights to take off when they would otherwise be unable to do so. 2101: 1991:"FAA Historical Chronology: Civil Aviation and the Federal Government, 1926–1996" 1073:

remain operational every day of the year. Some modern aircraft are equipped with

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operations. A chart includes the radio frequencies used by the ILS components or

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Microwave Landing System For Jets Is Demonstrated. New York Times. May 20, 1976.

2069: 1888: 1472: 1293:(TLS) can be used where a conventional ILS cannot work or is not cost-effective. 1213: 1180: 1165: 641: 354: 249: 149: 1050: 2568: 1172: 563: 259: 1941:"Acceptable Means of Compliance (AMC) and Guidance Material (GM) to Part-SPA" 115:(108 to 112 MHz frequency), which provides horizontal guidance, and the 1238: 1233: 1010: 544: 501:

Given this display, the pilot must correct to the left and a little upwards.

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Department of Transportation and Department of Defense (March 25, 2002).

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ICAO Annex 10 Volume 1, Radio Navigation Aids, Fifth Edition — July 1996

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Aeronautical Telecommunications, Volume 1 (Radio Navigation Aids) 2.1.1

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The top 10 manufacturers in the instrument landing systems market are:

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that changes dependent upon the position of the approaching aircraft.

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becoming the first pilot to take off, fly and land an airplane using

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provide distance information as the approach proceeds, including the

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system that provides precision lateral and vertical guidance to an

2532: 1421: 1143: 1049: 1009: 703: 670: 496: 481: 442: 388: 207: 169: 36: 1410: 654: 2323: 2301:"New Instrument System Proposed for Flight and Landing Safety" 1432: 769:

ICAO/FAA/JAA (EASA) precision instrument approach and landing

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system meeting TSO-C129/ -C145/-C146), to begin the approach.

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aligned, the two mixed together to produce a steady tone, the

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identification signal. For example, the ILS for runway 4R at

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Previous blind landing radio aids typically took the form of

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Satellite emergency position-indicating radiobeacon station

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A localizer (LOC, or LLZ until ICAO standardisation) is an

2145:"EGNOS navigation system begins serving Europe's aircraft" 1152:

Tests of the ILS began in 1929 in the United States, with

2000:. United States Federal Aviation Administration. p. 240:

or reduced visibility due to fog, rain, or blowing snow.

553:(ICLS) – a modified ILS for (aircraft) carrier landing. 1621:"An Introduction into the Signals of ILS, DME and VOR" 950:

has an unusually high glideslope angle of 5.5 degrees.

41:

Diagram of an instrument landing system (ILS) approach

2260:"Happy Landings In Fog", June 1933, Popular Mechanics 1361: 1017:

indicating the ILS category of a runway as CAT II/III

683:

Some installations include medium- or high-intensity

422:

and the prescribed minimum visibility requirements.

2367: 1833:"Getting to grips with CAT II / CAT III operations" 341:The two DC signals are then sent to a conventional 1110:(glideslope intercept at the specified altitude). 2505:Emergency position-indicating radiobeacon station 1329:European Geostationary Navigation Overlay Service 152:which saw relatively wide use in Europe prior to 1916:. Transport Canada. March 31, 2016. p. 282. 1847: 1845: 294:Key to its operation is a concept known as the 1827: 1825: 1128:. An aircraft landing procedure can be either 283:The ILS, developed just prior to the start of 95:View of the primary component of the ILS, the 2335: 2262:article on the early system setup in the USA. 1715:"Approach chart of Kai Tak Airport runway 13" 1663:"Localizer and Glide slope Frequency Pairing" 61:system that provides short-range guidance to 8: 1858:. IVAO training. 31 May 2017. Archived from 1586:"History of Radio Flight Navigation Systems" 1565:"Satellite Navigation - GPS/WAAS Approaches" 1467:Localizer performance with vertical guidance 1440:– the pilot who made first automated landing 1297:Localizer Performance with Vertical guidance 410:An instrument approach procedure chart (or ' 2276:Website dedicated to the description of ILS 1819:, effective 2016-03-14, accessed 2017-12-04 400:difference in the depth of modulation (DDM) 2513:Standard frequency and time signal station 2342: 2328: 2320: 2307:. Vol. 46, no. 1. pp. 86–88 1741: 1739: 234:instrument meteorological conditions (IMC) 977:No touchdown zone, no centerline lighting 166:International Civil Aviation Organization 1037:surface movement guidance control system 767: 447:The localizer station for runway 27R at 368: 90: 1950:. EASA. 25 October 2012. Archived from 1717:. flyingtigersgroup.org. Archived from 1531: 1368: 939: 2256:– U.S. Centennial of Flight Commission 2214:: CS1 maint: archived copy as title ( 2207: 1748:"2001 Federal Radionavigation Systems" 1700:ILS Glide Slope Critical Area Advisory 1636: 1634: 1580: 1578: 1576: 1574: 1387:Acronyms and abbreviations in avionics 1027:hand-flown CAT III approaches using a 946:The slope is selected by the airport, 486:Glide slope station for runway 09R at 2050:from the original on 20 February 2014 1614: 1612: 1610: 1608: 1606: 1604: 1602: 1543:(1st ed.). Osprey. p. 143. 1283:reluctance to invest and the rise of 1148:Luftwaffe AFN 2 indicator, built 1943 1006:Special CAT II and CAT III operations 588:Modern localizer antennas are highly 568:John F. Kennedy International Airport 7: 1179:using ILS occurred in March 1964 at 478:Instrument landing system glide path 373:Normal limits of localizer coverage. 314:and can be effectively transmitted. 2355: 2171:"2017 Federal Radionavigation Plan" 1887:. FAA. May 15, 2018. Archived from 1219:Advanced Navigation and Positioning 998:(RA) to determine decision height. 439:Instrument landing system localizer 321:For lateral guidance, known as the 189:global navigation satellite systems 123:, often additional pointers in the 27:Ground-based visual aid for landing 2684:Types of final approach (aviation) 2299:Jackson, Hagan L. (January 1947). 2040:"History of Aircraft Landing Aids" 1853:"Navigation instrumentation – ILS" 1760:from the original on June 14, 2011 1732:Kai Tak Airport#Runway 13 approach 1285:Global Navigation Satellite System 744:pilot controls the lighting system 710:Aurel Vlaicu International Airport 535:Instrument guidance system (IGS) ( 25: 2129:. atc-network.com. Archived from 1911:"Aeronautical Information Manual" 551:Instrument carrier landing system 2617: 2608: 2607: 2350: 2254:History of Aircraft Landing Aids 2114:from the original on 2008-10-15. 1687:from the original on 2014-02-23. 1371: 1307:Ground-Based Augmentation System 298:, a measure of how strongly the 30:For the Preston Reed album, see 2664:Navigational flight instruments 2549:Instrument landing system (ILS) 2497:Radio direction-finding station 2359:and systems in accordance with 2235:Aeronautical Information Manual 1948:Annex to ED Decision 2012-019-R 1792:from the original on 2017-02-11 1619:Balmus, Elena (16 April 2019). 2674:Radio stations and systems ITU 2481:Radionavigation mobile station 2449:On-board communication station 2397:High altitude platform station 1461:Local Area Augmentation System 1311:Local Area Augmentation System 1124:if installed) and may go to a 1075:enhanced flight vision systems 537:localizer type directional aid 1: 1704:: pg 4, ILS Course Distortion 1519:Wide Area Augmentation System 1346:based landing system, called 1301:Wide Area Augmentation System 1259:Other manufacturers include: 1170:Pennsylvania Central Airlines 1002:down in less than 2 seconds. 640:(DME) provides pilots with a 416:instrument flight rules (IFR) 228:approaching and landing on a 2529:Ship's emergency transmitter 2489:Radiolocation mobile station 2485:Radionavigation land station 1416:Distance measuring equipment 1405:Blind approach beacon system 1209:Airport Lighting Specialists 1057:view of a CAT IIIa landing ( 1041:special authorization CAT II 750:Decision altitude and height 708:Approach lighting system at 638:Distance measuring equipment 633:Distance measuring equipment 143:distance measuring equipment 65:to allow them to approach a 2241:Digital Terminal Procedures 1681:"ICAO DOC8400 Amendment 28" 1642:"Instrument Landing System" 524:separation between aircraft 220:operates as a ground-based 2700: 2525:Experimental radio station 2493:Radiolocation land station 2477:Radiodetermination station 2461:Aeronautical earth station 1501:Transponder landing system 1350:, is in operation on some 1291:Transponder Landing System 812:ft) or visibility > 800 664: 630: 603: 475: 436: 296:amplitude modulation index 247: 176:(GCA) and the more recent 174:ground-controlled approach 32:Instrument Landing (album) 29: 2603: 2429:Land mobile earth station 2237:, FAA – February 11, 2010 2169:Mattis, James N. (2017). 1513:VHF omnidirectional range 1444:Global Positioning System 1325:Global Positioning System 1162:Tempelhof Central Airport 1097:At a controlled airport, 1071:Charles de Gaulle Airport 678:approach lighting system. 218:instrument landing system 107:ILS uses two directional 51:instrument landing system 2654:Aircraft landing systems 2597:Emergency locator beacon 1977:Sacramento International 1541:A Dictionary of Aviation 1539:Wragg, David W. (1973). 1490:Precision approach radar 1478:Microwave landing system 1277:Microwave Landing System 1164:(Germany) named LFF or " 1024:automatic landing system 667:Approach lighting system 178:microwave landing system 2521:Radio astronomy station 2271:ILS Tutorial Animations 2125:NATS (March 26, 2009). 1989:Preston, Edmund (ed.). 1455:Instrument flight rules 1244:Liberty Airport Systems 1126:Flight Control Computer 717:Visibility minimums of 610:On some installations, 2469:Aircraft earth station 2389:Survival craft station 2281:ILS Tutorial Animation 2044:centennialofflight.net 1484:Non-directional beacon 1438:George Vernon Holloman 1299:(LPV) is based on the 1149: 1062: 1018: 713: 685:approach light systems 679: 502: 494: 455: 394: 374: 213: 204:Principle of operation 104: 42: 2361:ITU Radio Regulations 2294:Categories of the ILS 1930:(incomplete citation) 1352:short runway airports 1147: 1053: 1013: 707: 676:Odate-Noshiro Airport 674: 594:localizer back course 584:Localizer back course 500: 485: 446: 392: 372: 211: 94: 40: 18:Category III approach 2589:Multi-satellite link 2545:Radar beacon (racon) 2501:Radio beacon station 2473:Broadcasting station 2457:Aeronautical station 2405:Mobile earth station 2028:bottom-right of page 740:non-towered airports 506:vertical guidance). 363:multipath distortion 300:amplitude modulation 185:precision approaches 183:The introduction of 2437:Coast earth station 2425:Land mobile station 2377:Terrestrial station 1838:. Airbus. Oct 2001. 1507:Visual flight rules 1264:Indra (Normarc ILS) 1099:air traffic control 948:London City Airport 849:JAA(EASA): > 300 783:Runway visual range 770: 222:instrument approach 121:aircraft instrument 2445:Ship earth station 2421:Base earth station 2413:Land earth station 2286:2016-03-04 at the 2079:2021-09-21 at the 1815:2017-05-13 at the 1323:The advent of the 1229:Universal Avionics 1150: 1108:final approach fix 1063: 1019: 913:JAA(EASA): 250–700 839:ICAO/FAA: > 350 768: 714: 680: 519:ILS critical areas 503: 495: 456: 395: 375: 347:precision approach 302:is applied to the 214: 125:attitude indicator 105: 43: 2649:Navigational aids 2631: 2630: 2581:Satellite network 1891:on March 22, 2022 1194:COVID-19 pandemic 1177:automatic landing 936: 935: 903:ICAO/FAA: 150–700 661:Approach lighting 616:carrier frequency 472:Glide slope (G/S) 304:carrier frequency 57:) is a precision 16:(Redirected from 2691: 2669:Radio navigation 2644:1929 in aviation 2621: 2611: 2610: 2577:Satellite system 2465:Aircraft station 2372: 2354: 2344: 2337: 2330: 2321: 2316: 2314: 2312: 2243:, FAA – May 2010 2220: 2219: 2213: 2205: 2203: 2202: 2196: 2190:. Archived from 2189: 2181: 2175: 2174: 2166: 2160: 2159: 2157: 2156: 2147:. Archived from 2141: 2135: 2134: 2133:on July 7, 2011. 2122: 2116: 2115: 2113: 2106: 2098: 2092: 2089: 2083: 2066: 2060: 2059: 2057: 2055: 2035: 2029: 2023: 2017: 2016: 2010: 2008: 1995: 1986: 1980: 1973: 1967: 1966: 1964: 1962: 1956: 1945: 1937: 1931: 1924: 1918: 1917: 1915: 1907: 1901: 1900: 1898: 1896: 1885:"Order 8400.13D" 1881: 1875: 1874: 1872: 1870: 1864: 1857: 1849: 1840: 1839: 1837: 1829: 1820: 1807: 1801: 1800: 1798: 1797: 1791: 1784: 1776: 1770: 1769: 1767: 1765: 1759: 1752: 1743: 1734: 1729: 1723: 1722: 1711: 1705: 1695: 1689: 1688: 1677: 1671: 1670: 1659: 1653: 1652: 1646: 1638: 1629: 1628: 1616: 1597: 1596: 1590: 1582: 1569: 1568: 1561: 1555: 1554: 1536: 1496:Space modulation 1376: 1375: 1374: 1367: 1254:Rockwell Collins 987: 984: 978: 975: 969: 966: 960: 957: 951: 944: 920: 916: 910: 906: 899: 895: 883: 879: 872: 868: 856: 852: 846: 842: 835: 831: 819: 815: 811: 807: 800: 796: 771: 736: 735: 731: 726: 725: 721: 700: 699: 695: 627:DME substitution 488:Hannover Airport 449:Hannover Airport 134:marker beacon(s) 78: 77: 73: 59:radio navigation 21: 2699: 2698: 2694: 2693: 2692: 2690: 2689: 2688: 2634: 2633: 2632: 2627: 2599: 2565:Radio altimeter 2541:Secondary radar 2517:Amateur station 2370: 2368: 2363: 2348: 2310: 2308: 2298: 2288:Wayback Machine 2250: 2228: 2223: 2206: 2200: 2198: 2194: 2187: 2185:"Archived copy" 2183: 2182: 2178: 2168: 2167: 2163: 2154: 2152: 2143: 2142: 2138: 2124: 2123: 2119: 2111: 2104: 2100: 2099: 2095: 2090: 2086: 2081:Wayback Machine 2067: 2063: 2053: 2051: 2037: 2036: 2032: 2024: 2020: 2006: 2004: 1993: 1988: 1987: 1983: 1974: 1970: 1960: 1958: 1957:on 21 July 2018 1954: 1943: 1939: 1938: 1934: 1925: 1921: 1913: 1909: 1908: 1904: 1894: 1892: 1883: 1882: 1878: 1868: 1866: 1865:on 16 July 2017 1862: 1855: 1851: 1850: 1843: 1835: 1831: 1830: 1823: 1817:Wayback Machine 1808: 1804: 1795: 1793: 1789: 1782: 1778: 1777: 1773: 1763: 1761: 1757: 1750: 1745: 1744: 1737: 1730: 1726: 1713: 1712: 1708: 1696: 1692: 1679: 1678: 1674: 1661: 1660: 1656: 1644: 1640: 1639: 1632: 1618: 1617: 1600: 1595:. pp. 2–4. 1588: 1584: 1583: 1572: 1563: 1562: 1558: 1551: 1538: 1537: 1533: 1529: 1524: 1427:Flight director 1382: 1372: 1370: 1362: 1360: 1321: 1272: 1202: 1189: 1181:Bedford Airport 1154:Jimmy Doolittle 1142: 1122:head-up display 1095: 1029:head-up display 1008: 996:radio altimeter 991: 990: 985: 981: 976: 972: 967: 963: 958: 954: 945: 941: 918: 914: 912: 908: 904: 897: 893: 881: 877: 870: 866: 854: 850: 848: 844: 840: 833: 829: 817: 813: 809: 805: 798: 794: 778:Decision height 766: 757:missed approach 752: 733: 729: 728: 723: 719: 718: 716: 697: 693: 692: 682: 669: 663: 635: 629: 614:operating at a 608: 602: 586: 577: 560: 541:Kai Tak Airport 532: 512: 480: 474: 441: 435: 408: 312:radio frequency 281: 252: 246: 206: 129:decision height 101:Indra's Normarc 81:missed approach 75: 71: 70: 35: 28: 23: 22: 15: 12: 11: 5: 2697: 2695: 2687: 2686: 2681: 2676: 2671: 2666: 2661: 2656: 2651: 2646: 2636: 2635: 2629: 2628: 2626: 2625: 2615: 2604: 2601: 2600: 2585:Satellite link 2583: | 2557:ILS glide path 2487: | 2401:Mobile station 2375: 2373: 2365: 2364: 2357:Radio stations 2349: 2347: 2346: 2339: 2332: 2324: 2318: 2317: 2296: 2291: 2278: 2273: 2268: 2263: 2257: 2249: 2248:External links 2246: 2245: 2244: 2238: 2232: 2227: 2224: 2222: 2221: 2176: 2161: 2136: 2117: 2093: 2084: 2061: 2030: 2018: 1981: 1968: 1932: 1926:ICAO Annex 10 1919: 1902: 1876: 1841: 1821: 1802: 1771: 1735: 1724: 1721:on 2009-03-03. 1706: 1690: 1672: 1654: 1630: 1598: 1570: 1556: 1549: 1530: 1528: 1525: 1523: 1522: 1516: 1510: 1504: 1498: 1493: 1487: 1481: 1475: 1470: 1464: 1458: 1452: 1447: 1441: 1435: 1430: 1424: 1419: 1413: 1408: 1402: 1397: 1394: 1389: 1383: 1381: 1380: 1359: 1356: 1320: 1317: 1316: 1315: 1304: 1294: 1288: 1271: 1268: 1267: 1266: 1257: 1256: 1251: 1246: 1241: 1236: 1231: 1226: 1221: 1216: 1211: 1201: 1198: 1188: 1185: 1141: 1138: 1094: 1091: 1080:takeoff minima 1007: 1004: 989: 988: 979: 970: 961: 952: 938: 937: 934: 933: 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2539: | 2538: 2537:Primary radar 2535: | 2534: 2531: | 2530: 2527: | 2526: 2523: | 2522: 2519: | 2518: 2515: | 2514: 2511: | 2510: 2507: | 2506: 2503: | 2502: 2499: | 2498: 2495: | 2494: 2491: | 2490: 2486: 2483: | 2482: 2479: | 2478: 2475: | 2474: 2471: | 2470: 2467: | 2466: 2463: | 2462: 2459: | 2458: 2455: | 2454: 2451: | 2450: 2447: | 2446: 2443: | 2442: 2439: | 2438: 2435: | 2434: 2433:Coast station 2431: | 2430: 2427: | 2426: 2423: | 2422: 2419: | 2418: 2415: | 2414: 2411: | 2410: 2407: | 2406: 2403: | 2402: 2399: | 2398: 2395: | 2394: 2393:Fixed station 2391: | 2390: 2387: | 2386: 2385:Space station 2383: | 2382: 2381:Earth station 2379: | 2378: 2374: 2366: 2362: 2358: 2353: 2345: 2340: 2338: 2333: 2331: 2326: 2325: 2322: 2306: 2302: 2297: 2295: 2292: 2289: 2285: 2282: 2279: 2277: 2274: 2272: 2269: 2267: 2264: 2261: 2258: 2255: 2252: 2251: 2247: 2242: 2239: 2236: 2233: 2230: 2229: 2225: 2217: 2211: 2197:on 2014-02-22 2193: 2186: 2180: 2177: 2172: 2165: 2162: 2151:on 2011-03-06 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702: 690: 687:(abbreviated 686: 677: 673: 668: 660: 658: 656: 652: 648: 643: 639: 634: 626: 624: 622: 617: 613: 607: 606:Marker beacon 599: 597: 595: 591: 583: 581: 574: 572: 569: 565: 557: 552: 549: 546: 542: 538: 534: 533: 529: 527: 525: 520: 516: 509: 507: 499: 493: 489: 484: 479: 471: 469: 466: 464: 461: 454: 450: 445: 440: 432: 430: 428: 423: 421: 417: 413: 405: 403: 401: 391: 387: 384: 379: 371: 367: 364: 360: 356: 350: 348: 344: 339: 337: 331: 328: 324: 319: 315: 313: 309: 305: 301: 297: 292: 290: 286: 278: 276: 272: 270: 264: 261: 257: 251: 243: 241: 239: 235: 231: 227: 223: 219: 210: 203: 201: 199: 194: 190: 186: 181: 179: 175: 171: 167: 163: 159: 155: 151: 146: 144: 140: 139:middle marker 136: 135: 130: 126: 122: 118: 114: 110: 109:radio signals 102: 98: 93: 89: 86: 82: 68: 64: 60: 56: 52: 48: 39: 33: 19: 2573:Space system 2548: 2453:Port station 2441:Ship station 2417:Base station 2409:Land station 2311:14 September 2309:. 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