Misplaced Pages

#42957

85-526: In modern glass cockpit aircraft, the TCAS display may be integrated in the Navigation Display (ND) or Electronic Horizontal Situation Indicator (EHSI). In older glass cockpit aircraft and those with mechanical instrumentation, an integrated TCAS display including an instantaneous vertical speed indicator (IVSI) may replace the mechanical IVSI, which only indicates the rate at which the aircraft

170-403: A ferrite rod ), and efficiency (again, affected by size, but also resistivity of the materials used and impedance matching). These factors are easy to improve without adjusting other features of the antennas or coincidentally improved by the same factors that increase directivity, and so are typically not emphasized. High gain antennas are typically the largest component of deep space probes, and

255-482: A low-gain antenna ( LGA ) is an omnidirectional antenna , with a broad radiowave beam width, that allows the signal to propagate reasonably well even in mountainous regions and is thus more reliable regardless of terrain. Low-gain antennas are often used in spacecraft as a backup to the high-gain antenna , which transmits a much narrower beam and is therefore susceptible to loss of signal. All practical antennas are at least somewhat directional, although usually only

340-399: A trackball , thumb pad or joystick as a pilot-input device in a computer-style environment. Many of the modifications offered by the aircraft manufacturers improve situational awareness and customize the human-machine interface to increase safety. Modern glass cockpits might include synthetic vision systems (SVS) or enhanced flight vision systems (EFVS). Synthetic vision systems display

425-538: A backup battery. In 2010, the NTSB published a study done on 8,000 general aviation light aircraft. The study found that, although aircraft equipped with glass cockpits had a lower overall accident rate, they also had a larger chance of being involved in a fatal accident. The NTSB Chairman said in response to the study: Training is clearly one of the key components to reducing the accident rate of light planes equipped with glass cockpits, and this study clearly demonstrates

510-481: A certain direction is desired, or in receiving antennas receive radio waves from one specific direction only. This can increase the power transmitted to receivers in that direction, or reduce interference from unwanted sources. This contrasts with omnidirectional antennas such as dipole antennas which radiate radio waves over a wide angle, or receive from a wide angle. The extent to which an antenna's angular distribution of radiated power, its radiation pattern ,

595-464: A combination of a line feed with an enormous spherical reflector (as opposed to a more usual parabolic reflector), to achieve extremely high gains at specific frequencies. Antenna gain is often quoted with respect to a hypothetical antenna that radiates equally in all directions, an isotropic radiator . This gain, when measured in decibels , is called dBi. Conservation of energy dictates that high gain antennas must have narrow beams. For example, if

680-449: A correctly operating mode C or mode S transponder. A unique 24-bit identifier is assigned to each aircraft that has a mode S transponder. The next step beyond identifying potential collisions is automatically negotiating a mutual avoidance manoeuver (currently, manoeuvers are restricted to changes in altitude and modification of climb/sink rates) between the two (or more) conflicting aircraft. These avoidance manoeuvers are communicated to

765-470: A factor of 4. Although ACAS III is mentioned as a future system in ICAO Annex 10, ACAS III is unlikely to materialize due to difficulties the current surveillance systems have with horizontal tracking. Currently, research is being conducted to develop a future collision avoidance system (under the working name of ACAS X). Originally designated TCAS II Enhanced, TCAS III was envisioned as an expansion of

850-414: A factor. TCAS IV development continued for some years, but the appearance of new trends in data link such as Automatic Dependent Surveillance – Broadcast ( ADS-B ) have pointed out a need to re-evaluate whether a data link system dedicated to collision avoidance such as TCAS IV should be incorporated into a more generic system of air-to-air data link for additional applications. As a result of these issues,

935-429: A far greater signal than can be obtained on a standard cell phone . Satellite television receivers usually use parabolic antennas . For long and medium wavelength frequencies , tower arrays are used in most cases as directional antennas. When transmitting, a high-gain antenna allows more of the transmitted power to be sent in the direction of the receiver, increasing the received signal strength. When receiving,

SECTION 10

#1732790588043

1020-419: A full-time system in both visual and instrument meteorological conditions (IMC) on three different aircraft types. The operational evaluation programs continued through 1988 to validate the operational suitability of the systems The implementation of TCAS added a safety barrier to help prevent mid-air collisions . However, further study, refinements, training and regulatory measures were still required because

1105-423: A green arc indication directing the pilot to level off the aircraft. This could place the aircraft dangerously into the path of the intruder above, who is descending to land. A change proposal has been issued to correct this problem. TCAS technology has proved to be too expensive for small business and general aviation aircraft. Manufacturers and authorities recognized the need for an alternative to TCAS; this led to

1190-427: A head-on situation, one aircraft might be directed, "turn right, climb" while the other would be directed "turn right, descend." This would act to further increase the total separation between aircraft, in both horizontal and vertical aspects. Horizontal directives would be useful in a conflict between two aircraft close to the ground where there may be little if any vertical maneuvering space. TCAS III attempted to use

1275-472: A high gain antenna captures more of the signal, again increasing signal strength. Due to reciprocity , these two effects are equal—an antenna that makes a transmitted signal 100 times stronger (compared to an isotropic radiator ) will also capture 100 times as much energy as the isotropic antenna when used as a receiving antenna. As a consequence of their directivity, directional antennas also send less (and receive less) signal from directions other than

1360-415: A high gain antenna makes a 1  Watt transmitter look like a 100 Watt transmitter, then the beam can cover at most ⁠ 1 / 100 ⁠ of the sky (otherwise the total amount of energy radiated in all directions would sum to more than the transmitter power, which is not possible). In turn this implies that high-gain antennas must be physically large, since according to the diffraction limit ,

1445-650: A realistic 3D depiction of the outside world (similar to a flight simulator ), based on a database of terrain and geophysical features in conjunction with the attitude and position information gathered from the aircraft navigational systems. Enhanced flight vision systems add real-time information from external sensors, such as an infrared camera. All new airliners such as the Airbus A380 , Boeing 787 and private jets such as Bombardier Global Express and Learjet use glass cockpits. Many modern general aviation aircraft are available with glass cockpits. Systems such as

1530-407: A revised TCAS II Minimum Operational Performance Standards (MOPS) document has been jointly developed by RTCA (Special Committee SC-147) and EUROCAE. As a result, by 2008 the standards for Version 7.1 of TCAS II have been issued and published as RTCA DO-185B (June 2008) and EUROCAE ED-143 (September 2008). TCAS II Version 7.1 will be able to issue RA reversals in coordinated encounters, in case one of

1615-636: A serious glass-cockpit blackout, losing half of the Electronic Centralised Aircraft Monitor ( ECAM ) displays as well as all radios, transponders, Traffic Collision Avoidance System ( TCAS ), and attitude indicators. The pilots were able to land at Newark Airport without radio contact in good weather and daylight conditions. Airbus has offered an optional fix, which the US National Transportation Safety Board (NTSB) has suggested to

1700-545: A single frequency or a group of frequencies. For example, in the case of wideband TV antennas the fall off in gain is particularly large at the bottom of the TV transmitting band. In the UK this bottom third of the TV band is known as group A. Other factors may also affect gain such as aperture (the area the antenna collects signal from, almost entirely related to the size of the antenna but for small antennas can be increased by adding

1785-478: A three dimensional map of aircraft in the airspace, incorporating their range (garnered from the interrogation and response round trip time), altitude (as reported by the interrogated aircraft), and bearing (by the directional antenna from the response). Then, by extrapolating current range and altitude difference to anticipated future values, it determines if a potential collision threat exists. TCAS and its variants are only able to interact with aircraft that have

SECTION 20

#1732790588043

1870-440: A true departure. They look and behave very similarly to other computers, with windows and data that can be manipulated with point-and-click devices. They also add terrain, approach charts, weather, vertical displays, and 3D navigation images. The improved concepts enable aircraft makers to customize cockpits to a greater degree than previously. All of the manufacturers involved have chosen to do so in one way or another—such as using

1955-574: Is an aircraft cockpit that features an array of electronic (digital) flight instrument displays , typically large LCD screens, rather than traditional analog dials and gauges. While a traditional cockpit relies on numerous mechanical gauges (nicknamed "steam gauges") to display information, a glass cockpit uses several multi-function displays and a primary flight display driven by flight management systems , that can be adjusted to show flight information as needed. This simplifies aircraft operation and navigation and allows pilots to focus only on

2040-439: Is concentrated in one direction is measured by a parameter called antenna gain . A high-gain antenna ( HGA ) is a directional antenna with a focused, narrow beam width , permitting more precise targeting of the radio signals. Most commonly referred to during space missions , these antennas are also in use all over Earth , most successfully in flat, open areas where there are no mountains to disrupt radiowaves. In contrast,

2125-650: Is descending or climbing. Research into collision avoidance systems has been ongoing since at least the 1950s, and the airline industry has been working with the Air Transport Association of America (ATA) since 1955 toward a collision avoidance system. ICAO and aviation authorities such as the Federal Aviation Administration (FAA) were spurred into action by the 1956 Grand Canyon mid-air collision . Although ATCRBS airborne transponders were available, it wasn't until

2210-581: Is reflected in the total acceptance of electronic flight displays. The safety and efficiency of flights have been increased with improved pilot understanding of the aircraft's situation relative to its environment (or " situational awareness "). By the end of the 1990s, liquid-crystal display (LCD) panels were increasingly favored among aircraft manufacturers because of their efficiency, reliability and legibility. Earlier LCD panels suffered from poor legibility at some viewing angles and poor response times, making them unsuitable for aviation. Modern aircraft such as

2295-442: Is the possibility that a recommended avoidance maneuver might direct the flight crew to descend toward terrain below a safe altitude. Recent requirements for incorporation of ground proximity mitigate this risk. Ground proximity warning alerts have priority in the cockpit over TCAS alerts. Some pilots have been unsure how to act when their aircraft was requested to climb whilst flying at their maximum altitude. The accepted procedure

2380-452: Is to follow the climb RA as best as possible, temporarily trading speed for height . The climb RA should quickly finish. In the event of a stall warning, the stall warning would take priority. Both cases have been addressed by Version 7.0 of TCAS II and are currently handled by a corrective RA together with a visual indication of a green arc in the IVSI display to indicate the safe range for

2465-563: The Boeing 737 Next Generation , 777 , 717 , 747-400ER , 747-8F 767-400ER , 747-8 , and 787 , Airbus A320 family (later versions), A330 (later versions), A340-500/600 , A340-300 (later versions), A380 and A350 are fitted with glass cockpits consisting of LCD units. The glass cockpit has become standard equipment in airliners , business jets , and military aircraft . It was fitted into NASA's Space Shuttle orbiters Atlantis , Columbia , Discovery , and Endeavour , and

2550-604: The Diamond DA42 . The Lockheed Martin F-35 Lightning II features a "panoramic cockpit display" touchscreen that replaces most of the switches and toggles found in an aircraft cockpit. The civilian Cirrus Vision SF50 has the same, which they call a "Perspective Touch" glass cockpit. Unlike the previous era of glass cockpits—where designers merely copied the look and feel of conventional electromechanical instruments onto cathode-ray tubes—the new displays represent

2635-576: The Garmin G1000 are now available on many new GA aircraft, including the classic Cessna 172 . Many small aircraft can also be modified post-production to replace analogue instruments. Glass cockpits are also popular as a retrofit for older private jets and turboprops such as Dassault Falcons , Raytheon Hawkers , Bombardier Challengers , Cessna Citations , Gulfstreams , King Airs , Learjets , Astras , and many others. Aviation service companies work closely with equipment manufacturers to address

Traffic collision avoidance system - Misplaced Pages Continue

2720-724: The McDonnell Douglas MD-80 , Boeing 737 Classic , ATR 42 , ATR 72 and in the Airbus A300-600 and A310 , used electronic flight instrument systems (EFIS) to display attitude and navigational information only, with traditional mechanical gauges retained for airspeed, altitude, vertical speed, and engine performance. The Boeing 757 and 767-200/-300 introduced an electronic engine-indicating and crew-alerting system (EICAS) for monitoring engine performance while retaining mechanical gauges for airspeed, altitude and vertical speed. Later glass cockpits, found in

2805-475: The attitude indicator and horizontal situation indicator (HSI). However, the 2707 was cancelled in 1971 after insurmountable technical difficulties and ultimately the end of project funding by the US government. The average transport aircraft in the mid-1970s had more than one hundred cockpit instruments and controls, and the primary flight instruments were already crowded with indicators, crossbars, and symbols, and

2890-566: The integrated standby instrument system . Glass cockpits originated in military aircraft in the late 1960s and early 1970s; an early example is the Mark II avionics of the F-111D (first ordered in 1967, delivered from 1970 to 1973), which featured a multi-function display . Prior to the 1970s, air transport operations were not considered sufficiently demanding to require advanced equipment like electronic flight displays. Also, computer technology

2975-412: The 1090 MHz radio frequency. ADS-B messages are also carried on a Universal Access Transceiver (UAT) in the 978 MHz band. TCAS equipment which is capable of processing ADS–B messages may use this information to enhance the performance of TCAS, using techniques known as "hybrid surveillance". As currently implemented, hybrid surveillance uses reception of ADS–B messages from an aircraft to reduce

3060-488: The ACAS II standards set by ICAO was Version 7.0 of TCAS II, produced by three avionics manufacturers: Rockwell Collins , Honeywell , and ACSS (Aviation Communication & Surveillance Systems; an L3Harris and Thales Avionics joint venture company). After the 2002 Überlingen mid-air collision (July 1, 2002), studies have been made to improve TCAS II capabilities. Following extensive Eurocontrol input and pressure,

3145-673: The Boeing 737NG , 747-400 , 767-400 , 777 , Airbus A320 , later Airbuses, Ilyushin Il-96 and Tupolev Tu-204 have completely replaced the mechanical gauges and warning lights in previous generations of aircraft. While glass cockpit-equipped aircraft throughout the late 20th century still retained analog altimeters , attitude , and airspeed indicators as standby instruments in case the EFIS displays failed, more modern aircraft have increasingly been using digital standby instruments as well, such as

3230-582: The East coast of the US. Hybrid surveillance does not make use of ADS–B's aircraft flight information in the TCAS conflict detection algorithms; ADS–B is used only to identify aircraft that can safely be interrogated at a lower rate. In the future, prediction capabilities may be improved by using the state vector information present in ADS–B messages. Also, since ADS–B messages can be received at greater range than TCAS normally operates, aircraft can be acquired earlier by

3315-499: The RA is reported by the pilot. Once the RA is reported by the pilot, ATC is required not to attempt to modify the flight path of the aircraft involved in the encounter. Hence, the pilot is expected to "follow the RA" but in practice this does not always happen. Some countries have implemented "RA downlink" which provides air traffic controllers with information about RAs posted in the cockpit. Currently, there are no ICAO provisions concerning

3400-676: The Russian Soyuz TMA model spacecraft that were launched for the first time in 2002. By the end of the century glass cockpits began appearing in general aviation aircraft as well. In 2003, Cirrus Design 's SR20 and SR22 became the first light aircraft equipped with glass cockpits, which they made standard on all Cirrus aircraft. By 2005 , even basic trainers like the Piper Cherokee and Cessna 172 were shipping with glass cockpits as options (which nearly all customers chose), as well as many modern utility aircraft such as

3485-503: The TCAS II concept to include horizontal resolution advisory capability. TCAS III was the "next generation" of collision avoidance technology which underwent development by aviation companies such as Honeywell . TCAS III incorporated technical upgrades to the TCAS II system, and had the capability to offer traffic advisories and resolve traffic conflicts using horizontal as well as vertical manoeuvring directives to pilots. For instance, in

Traffic collision avoidance system - Misplaced Pages Continue

3570-488: The TCAS IV concept was abandoned as ADS-B development started. Although the system occasionally suffers from false alarms, pilots are now under strict instructions to regard all TCAS messages as genuine alerts demanding an immediate, high-priority response. Only Windshear Detection and GPWS alerts and warnings have higher priority than the TCAS. The FAA , EASA and most other countries' authorities' rules state that in

3655-484: The TCAS directional antenna to assign a bearing to other aircraft, and thus be able to generate a horizontal maneuver (e.g. turn left or right). However, it was judged by the industry to be unfeasible due to limitations in the accuracy of the TCAS directional antennas. The directional antennas were judged not to be accurate enough to generate an accurate horizontal-plane position, and thus an accurate horizontal resolution. By 1995, years of testing and analysis determined that

3740-418: The TCAS operation based on TCAS II, since this is the version that has been adopted as an international standard (ACAS II) by ICAO and aviation authorities worldwide. TCAS II can be currently operated in the following modes: TCAS works in a coordinated manner, so when an RA is issued to conflicting aircraft, a required action (i.e., Climb. Climb. ) has to be immediately performed by one of the aircraft, while

3825-526: The TCAS tracking algorithms. The identity information present in ADS–B messages can be used to label other aircraft on the cockpit display (where present), painting a picture similar to what an air traffic controller would see and improving situational awareness. TCAS I is a cheaper but less capable system than the modern TCAS II system introduced for general aviation use after the FAA mandate for TCAS II in air transport aircraft. TCAS I systems are able to monitor

3910-539: The US Federal Aviation Administration (FAA) as mandatory, but the FAA has yet to make it a requirement. A preliminary NTSB factsheet is available. Due to the possibility of a blackout, glass cockpit aircraft also have an integrated standby instrument system that includes (at a minimum) an artificial horizon , altimeter and airspeed indicator . It is electronically separate from the main instruments and can run for several hours on

3995-506: The aircraft doesn't follow the original RA instructions (Change proposal CP112E). Other changes in this version are the replacement of the ambiguous "Adjust Vertical Speed, Adjust" RA with the "Level off, Level off" RA, to prevent improper response by the pilots (Change proposal CP115).; and the improved handling of corrective/preventive annunciation and removal of green arc display when a positive RA weakens solely due to an extreme low or high altitude condition (1000 feet AGL or below, or near

4080-488: The aircraft top ceiling) to prevent incorrect and possibly dangerous guidance to the pilot (Change proposal CP116). Studies conducted for Eurocontrol , using recently recorded operational data, indicate that currently the probability of a mid-air collision for each flight hour in European airspace is 2.7 x 10 which equates to one in every 3 years. When TCAS II Version 7.1 is implemented, that probability will be reduced by

4165-478: The assistance of Air Traffic Control. When a threat has passed, the system announces "Clear of conflict" . TCAS II is the first system that was introduced in 1989 and is the current generation of instrument warning TCAS, used in the majority of commercial aviation aircraft (see table below). A US Airways 737 was the first aircraft certified with the AlliedBendix (now Honeywell) TCAS II system. It offers all

4250-404: The benefits of TCAS I, but will also offer the pilot direct, vocalized instructions to avoid danger, known as a "Resolution Advisory" (RA). The suggestive action may be "corrective", suggesting the pilot change vertical speed by announcing, "Descend, descend" , "Climb, climb" or "Level off, level off" (meaning reduce vertical speed). By contrast a "preventive" RA may be issued which simply warns

4335-520: The case of a conflict between TCAS RA and air traffic control (ATC) instructions, the TCAS RA always takes precedence. This is mainly because of the TCAS-RA inherently possessing a more current and comprehensive picture of the situation than air traffic controllers, whose radar / transponder updates usually happen at a much slower rate than the TCAS interrogations. If one aircraft follows a TCAS RA and

SECTION 50

#1732790588043

4420-443: The climb or descent rate. However, it has been found that in some cases these indications could lead to a dangerous situation for the involved aircraft. For example, if a TCAS event occurs when two aircraft are descending one over the other for landing, the aircraft at the lower altitude will first receive a "Descend, descend" RA, and when reaching an extreme low altitude, this will change to a "Level off, level off" RA, together with

4505-406: The concept was unworkable using available surveillance technology (due to the inadequacy of horizontal position information), and that horizontal RAs were unlikely to be invoked in most encounter geometries. Hence, all work on TCAS III was suspended and there are no plans for its implementation. The concept has later evolved and been replaced by TCAS IV. TCAS IV uses additional information encoded by

4590-410: The controller is no longer responsible for separation of the aircraft involved in the RA until the conflict is terminated. On the other hand, ATC can potentially interfere with a pilot's response to RAs. If a conflicting ATC instruction coincides with an RA, a pilot may assume that ATC is fully aware of the situation and is providing the better resolution. But in reality, ATC is not aware of the RA until

4675-483: The development of the Traffic Advisory System. TAS is actually a simplified version of TCAS I. The system structure, components, operation, traffic display and TA logic are identical, but the minimum operational performance standards (MOPS) of TAS allow some simplification compared to TCAS I: The following documents contain all of the differences between TCAS I and TAS: In spite of all this, most of

4760-455: The direction in the plane parallel to the earth is considered, and practical antennas can easily be omnidirectional in one plane. The most common directional antenna types are These antenna types, or combinations of several single-frequency versions of one type or (rarely) a combination of two different types, are frequently sold commercially as residential TV antennas . Cellular repeaters often make use of external directional antennas to give

4845-468: The electro-mechanical flight instruments in the space shuttles with glass cockpit components. The articles mentioned how glass cockpit components had the added benefit of being a few hundred pounds lighter than the original flight instruments and support systems used in the Space Shuttles. The Space Shuttle Atlantis was the first orbiter to be retrofitted with a glass cockpit in 2000 with

4930-476: The field of beacon-based collision avoidance systems and air-to-air discrete address communication techniques that used Mode S airborne transponder message formats. A short time later, prototypes of TCAS II were installed on two Piedmont Airlines Boeing 727 aircraft, and were flown on regularly scheduled flights. Although the displays were located outside the view of the flight crew and seen only by trained observers, these tests did provide valuable information on

5015-438: The flight crew by a cockpit display and by synthesized voice instructions. A protected volume of airspace surrounds each TCAS equipped aircraft. The size of the protected volume depends on the altitude, speed, and heading of the aircraft involved in the encounter. The illustration below gives an example of a typical TCAS protection volume. A TCAS installation consists of the following components: The following section describes

5100-499: The frequency and circumstances of alerts and their potential for interaction with the ATC system. On a follow-on phase II program, a later version of TCAS II was installed on a single Piedmont Airlines Boeing 727, and the system was certified in April 1986, then subsequently approved for operational evaluation in early 1987. Since the equipment was not developed to full standards, the system

5185-457: The growing number of cockpit elements were competing for cockpit space and pilot attention. As a result, NASA conducted research on displays that could process the raw aircraft system and flight data into an integrated, easily understood picture of the flight situation, culminating in a series of flights demonstrating a full glass cockpit system. The success of the NASA-led glass cockpit work

SECTION 60

#1732790588043

5270-490: The highest gain radio antennas are physically enormous structures, such as the Arecibo Observatory . The Deep Space Network uses 35 m dishes at about 1 cm wavelengths. This combination gives the antenna gain of about 100,000,000 (or 80 dB, as normally measured), making the transmitter appear about 100 million times stronger, and a receiver about 100 million times more sensitive, provided

5355-551: The launch of STS-101 . Columbia was the second orbiter with a glass cockpit on STS-109 in 2002, followed by Discovery in 2005 with STS-114 , and Endeavour in 2007 with STS-118 . NASA's Orion spacecraft will use glass cockpits derived from Boeing 787 Dreamliner . As aircraft operation depends on glass cockpit systems, flight crews must be trained to deal with failures. The Airbus A320 family has seen fifty incidents where several flight displays were lost. On 25 January 2008, United Airlines Flight 731 experienced

5440-576: The life and death importance of appropriate training on these complex systems... While the technological innovations and flight management tools that glass cockpit-equipped airplanes bring to the general aviation community should reduce the number of fatal accidents, we have not—unfortunately—seen that happen. Directional antenna A directional antenna or beam antenna is an antenna which radiates or receives greater radio wave power in specific directions. Directional antennas can radiate radio waves in beams, when greater concentration of radiation in

5525-589: The limitations and misuse of the system still resulted in other incidents and fatal accidents which include the: TCAS involves communication between all aircraft equipped with an appropriate transponder (provided the transponder is enabled and set up properly). Each TCAS-equipped aircraft interrogates all other aircraft in a determined range about their position (via the 1030  MHz radio frequency ), and all other aircraft reply to other interrogations (via 1090 MHz). This interrogation-and-response cycle may occur several times per second. The TCAS system builds

5610-652: The main beam. This property may avoid interference from other out-of-beam transmitters, and always reduces antenna noise. (Noise comes from every direction, but a desired signal will only come from one approximate direction, so the narrower the antenna's beam, the better the crucial signal-to-noise ratio .) There are many ways to make a high-gain antenna; the most common are parabolic antennas , helical antennas , Yagi-Uda antennas , and phased arrays of smaller antennas of any kind. Horn antennas can also be constructed with high gain, but are less commonly seen. Still other configurations are possible—the Arecibo Observatory used

5695-573: The manufacturers do not take the above-mentioned opportunities to make simplified devices. As a result of market forces, many TAS systems operate just like TCAS I (with interference limiting, using TCAS I symbology, etc.), with some having even have better surveillance performance (in range and tracked aircraft) and specifications than TCAS I. Automatic dependent surveillance – broadcast (ADS–B) messages are transmitted from aircraft equipped with suitable transponders, containing information such as identity, location, and velocity. The signals are broadcast on

5780-468: The mid-1970s that research focused on using their signals as the cooperative element for a collision avoidance system. This technical approach enabled an independent collision avoidance capability on the flight deck, separate from the ground system. In 1981, the FAA decided to implement the Traffic Alert and Collision Avoidance System (TCAS), which was developed based on industry and agency efforts in

5865-636: The most pertinent information. They are also popular with airline companies as they usually eliminate the need for a flight engineer , saving costs. In recent years the technology has also become widely available in small aircraft. As aircraft displays have modernized, the sensors that feed them have modernized as well. Traditional gyroscopic flight instruments have been replaced by electronic attitude and heading reference systems (AHRS) and air data computers (ADCs), improving reliability and reducing cost and maintenance. GPS receivers are usually integrated into glass cockpits. Early glass cockpits, found in

5950-433: The narrower the beam desired, the larger the antenna must be (measured in wavelengths). Antenna gain can also be measured in dBd, which is gain in decibels compared to the maximum intensity direction of a half wave dipole. In the case of Yagi-type aerials this more or less equates to the gain one would expect from the aerial under test minus all its directors and reflector. It is important not to confuse dB i and dB d ;

6035-631: The needs of the owners of these aircraft. Today, smartphones and tablets use mini-applications, or "apps", to remotely control complex devices, by WiFi radio interface. They demonstrate how the "glass cockpit" idea is being applied to consumer devices. Applications include toy-grade UAVs which use the display and touch screen of a tablet or smartphone to employ every aspect of the "glass cockpit" for instrument display, and fly-by-wire for aircraft control. The glass cockpit idea made news in 1980s trade magazines, like Aviation Week & Space Technology , when NASA announced that it would be replacing most of

6120-467: The other follows conflicting ATC instructions, a collision can occur, such as the July 1, 2002 Überlingen disaster . In this mid-air collision, both airplanes were fitted with TCAS II Version 7.0 systems which functioned properly, but one obeyed the TCAS advisory while the other ignored the TCAS and obeyed the controller; both aircraft descended into a fatal collision. Glass cockpit A glass cockpit

6205-524: The other one receives a similar RA in the opposite direction (i.e., Descend. Descend. ). TCAS II issues the following types of aural annunciations: When a TA is issued, pilots are instructed to initiate a visual search for the traffic causing the TA. If the traffic is visually acquired, pilots are instructed to maintain visual separation from the traffic. Training programs also indicate that no horizontal maneuvers are to be made based solely on information shown on

6290-430: The pilots not to deviate from their present vertical speed, announcing, "Monitor vertical speed" or "Maintain vertical speed, Maintain" . TCAS II systems coordinate their resolution advisories before issuing commands to the pilots, so that if one aircraft is instructed to descend, the other will typically be told to climb – maximising the separation between the two aircraft. As of 2006, the only implementation that meets

6375-496: The rate at which the TCAS equipment interrogates that aircraft. This reduction in interrogations reduces the use of the 1030/1090 MHz radio channel, and will over time extend the operationally useful life of TCAS technology. The ADS–B messages will also allow low cost (for aircraft) technology to provide real time traffic in the cockpit for small aircraft. Currently UAT based traffic uplinks are provided in Alaska and in regions of

6460-700: The system improves safety in the airspace by a factor of between 3 and 5. However, it is well understood that part of the remaining risk is that TCAS may induce midair collisions: "In particular, it is dependent on the accuracy of the threat aircraft's reported altitude and on the expectation that the threat aircraft will not make an abrupt maneuver that defeats the TCAS Resolution Advisory (RA). The safety study also shows that TCAS II will induce some critical near midair collisions..." (See page 7 of Introduction to TCAS II Version 7 and 7.1 (PDF) in external links below). One potential problem with TCAS II

6545-535: The target aircraft in the Mode S transponder reply (i.e. target encodes its own position into the transponder signal) to generate a horizontal resolution to an RA. In addition, some reliable source of position (such as Inertial Navigation System or GPS ) is needed on the target aircraft in order for it to be encoded. TCAS IV had replaced the TCAS III concept by the mid-1990s. One of the results of TCAS III experience

6630-485: The target is within the beam . This beam can cover at most one hundred millionth (10 ) of the sky, so very accurate pointing is required. Use of high gain and millimeter-wave communication in WPAN gaining increases the probability of concurrent scheduling of non‐interfering transmissions in a localized area, which results in an immense increase in network throughput. However, the optimum scheduling of concurrent transmission

6715-508: The traffic display. Slight adjustments in vertical speed while climbing or descending, or slight adjustments in airspeed while still complying with the ATC clearance are acceptable. When an RA is issued, pilots are expected to respond immediately to the RA unless doing so would jeopardize the safe operation of the flight. This means that aircraft will at times have to manoeuver contrary to ATC instructions or disregard ATC instructions. In these cases,

6800-427: The traffic situation around a plane (to a range of about 40 miles) and offer information on the approximate bearing and altitude of other aircraft. It can also generate collision warnings in the form of a "Traffic Advisory" (TA). The TA warns the pilot that another aircraft is in near vicinity, announcing "Traffic, traffic" , but does not offer any suggested remedy; it is up to the pilot to decide what to do, usually with

6885-401: The two differ by 2.15 dB, with the dBi figure being higher, since a dipole has 2.15 dB of gain with respect to an isotropic antenna. Gain is also dependent on the number of elements and the tuning of those elements. Antennas can be tuned to be resonant over a wider spread of frequencies but, all other things being equal, this will mean the gain of the aerial is lower than one tuned for

6970-505: The use of RA downlink by air traffic controllers. The following points receive emphasis during pilot training: An RA occurs on average every 1,000 flight hours on short/ medium-haul aircraft and every 3,000 hours for long-haul aircraft. In its December 2017 ACAS guide, Eurocontrol found in about 25% of the cases, the pilots follow the RA inaccurately. Airbus offers the option of an autopilot / flight director TCAS for automatic avoidance maneuvers. Safety studies on TCAS estimate that

7055-437: Was not at a level where sufficiently light and powerful electronics were available. The increasing complexity of transport aircraft, the advent of digital systems and the growing air traffic congestion around airports began to change that. The Boeing 2707 was one of the earliest commercial aircraft designed with a glass cockpit. Most cockpit instruments were still analog, but cathode-ray tube (CRT) displays were to be used for

7140-611: Was only operated in visual meteorological conditions (VMC). Although the flight crew operated the system, the evaluation was primarily for the purpose of data collection and its correlation with flight crew and observer observation and response. Later versions of TCAS II manufactured by Bendix /King Air Transport Avionics Division were installed and approved on United Airlines airplanes in early 1988. Similar units manufactured by Honeywell were installed and approved on Northwest Airlines airplanes in late 1988. This limited installation program operated TCAS II units approved for operation as

7225-399: Was that the directional antenna used by the TCAS processor to assign a bearing to a received transponder reply was not accurate enough to generate an accurate horizontal position, and thus a safe horizontal resolution. TCAS IV used additional position information encoded on an air-to-air data link to generate the bearing information, so that the accuracy of the directional antenna would not be

#42957