An electronic flight instrument system ( EFIS ) is a flight deck instrument display system that displays flight data electronically rather than electromechanically. An EFIS typically consists of a main flight view (PFD), a multi-function display (MFD), and a machine showing and viewing the crew warning system (EICAS). Early EFIS models using cathode ray tubes (CRTs) were shown, but liquid crystal display (LCD) is now more common. The indicators of directors of complex electromechanical attitudes (ADI) and horizontal situation indicators (HSI) are the first candidates to replace EFIS. But now, some flight deck instruments can not be replaced by electronic screens.
Video Electronic flight instrument system
Overview
EFIS installation varies greatly. A light aircraft may be equipped with a display unit that displays flight data and navigation. A large commercial airliner is likely to have six or more display units. Typical EFIS views and controls can be viewed on the B737's technical information website. Equivalent electromechanical instruments are also shown here.
EFIS installation follows the sequence:
- Displays
- Controls
- Data processor
Basic EFIS may have all these facilities in one unit.
Maps Electronic flight instrument system
Display unit
Main flight view (PFD)
On the flight deck, the display unit is the most obvious part of the EFIS system, and is a feature that leads to the term cockpit glass . The display unit that replaces ADI is called the main flight display (PFD). If a separate screen replaces HSI, it is called a navigation view. PFD displays all important information for the flight, including calibrated airspeed, altitude, heading, attitude, vertical speed and yaw. PFD is designed to raise awareness of pilot situations by integrating this information into one screen instead of six different analog instruments, reducing the amount of time required to monitor the instrument. PFD also increases situational awareness by alerting aircrew to unusual or potentially hazardous conditions - for example, low airspeeds, high rates of offspring - by changing the color or shape of the screen or by providing audio alerts.
Name of Electronic Direction Indicator and Electronic Horizontal Situation Indicator is used by several manufacturers. However, ADI simulation is only the core of PFD. Additional information is superimposed and arranged around this graph.
Multi-function view can make a separate navigation view unnecessary. Another option is to use one large screen to display PFD and navigation view.
PFD and navigation view (and multi-function display, if installed) are often physically identical. The information displayed is determined by the system interface in which the display unit is installed. Thus, the holding of parts is simplified: a display unit can be mounted in any position.
LCD units produce less heat than CRTs; advantage in a solid instrument panel. They are also lighter, and occupy a lower volume.
Multi-function display (MFD)
The MFD (multi-function display) displays navigation and weather information from multiple systems. MFDs are most often designed as "chart-centric", in which aircrew can coat various information on a map or chart. Examples of MFD overlay information include current aircraft route plans, weather information from on-board radar or lightning detection sensors or ground-based sensors, eg, NEXRAD, limited airspace and air traffic. MFD can also be used to view other types of non-overlay data (for example, the current route plan) and calculate overlay type data, for example, the airborne radius, given its current location over terrain, wind, and plane speed and altitude.
MFD can also display information about aircraft systems, such as fuel and electricity systems (see EICAS, below). Like PFD, MFD can change the color or shape of data to remind the crew of the aircraft into dangerous situations.
Machine indication and crew warning system ( EICAS)/electronic centralized aircraft monitoring (ECAM)
EICAS (Engine Indications and Crew Alerting System) displays information about aircraft systems, including fuel, power and propulsion systems (machines). EICAS displays are often designed to mimic traditional round gauges while also providing digital readout of parameters.
EICAS enhances situational awareness by allowing aircrews to view complex information in graphical formats and also by alerting crews to unusual or dangerous situations. For example, if the engine begins to lose the oil pressure, the EICAS may sound a warning, divert the display to the page with oil system information and decipher the low oil pressure data with the red box. Unlike traditional lap times, many warning and alarm levels can be set. Appropriate care should be taken when designing EICAS to ensure that aircrew is always provided with the most important information and is not filled with warnings or alarms.
ECAM is a similar system used by Airbus, which in addition to providing EICAS functions also recommends remedial action.
Control panel
EFIS provides pilots with controls that select a range of views and modes (for example, map or compass go up) and enter data (such as the selected title).
When other equipment uses pilot input, the data bus broadcasts the pilot's choice so that the pilot only needs to enter a single election. For example, the pilot chooses the desired level-off height on the control unit. EFIS repeats this selected height on the PFD, and by comparing it with the actual height (from the aerial data computer) results in a display of altitude errors. This same height selection is used by automated flight control systems to equalize, and by altitude alert systems to provide precise alerts.
Data processor
The visual display of EFIS is produced by the symbol generator. It accepts input data from the pilot, the signal from the sensor, and the selection of EFIS formats created by the pilot. Symbol generators can use other names, such as display-processing computers, electronic display units, etc.
The symbol generator is nothing more than generating symbols. It has (at least) monitoring facilities, graphics generators and display drivers. The input of the sensor and control arrives via the data bus, and checked its validity. The required computations are done, and the graphics generator and display driver generate input to the display unit.
Ability
Like personal computers, aviation system systems require self-on-self-test facilities and ongoing self-monitoring. However, the flight instrument system requires additional monitoring capabilities:
- Input validation - verify that each sensor provides valid data
- Data comparison - crossed input of duplicate sensor
- Monitor display - detects failures in the instrument system
Exercise
The traditional display (electromechanical) is equipped with a synchronization mechanism that transmits pitch, roll, and heading shown on the captain and the first officer instrument to the instrument comparator. The comparator warns of the excessive difference between the Captain and the Main Officer. Even the fault as far as downstream as a standstill, say, the ADI scrolling mechanism triggers a comparator warning. Instrument comparison tools provide monitoring of comparators and display monitoring.
Comparator monitoring
With EFIS, the comparison function is simple: Is the angle bank data from sensor 1 equal to the data winding of sensor 2? If not, display a warning caption (such as CHECK ROLL ) on both PFDs. The comparison monitor provides warnings for airspeed, pitch, roll, and altitude indications. The more advanced EFIS systems have more comparator monitors.
Display monitoring
In this technique, each symbol generator contains two display monitoring channels. One channel, internal, sample the output from the symbol generator itself to the display unit and calculate, for example, what roll attitude should produce that indication. The calculated roll attitude is then compared with the input attitude of the rolls to the symbol generator of the INS or AHRS. Any differences may have been introduced by the wrong process, and trigger a warning on the relevant screen.
The external monitoring channel performs the same check on the symbol generator on the other side of the flight deck: Captain symbol generator checks Officer First, First Officer checks Captain. Any symbol generator that detects an error, installs a warning in its own appearance.
The external monitoring channel also checks the sensor input (to the symbol generator) to make sense. False input, such as radio heights greater than the maximum radio altimeter, generates a warning.
Human factors
Clutter
At various stages of flight, a pilot needs different combinations of data. Ideally, avionics only shows the data used - but the electromechanical instrument must be visible all the time. To improve the clarity of the display, ADI and HSI use complex mechanisms to eliminate excessive indications temporarily - for example, removing glaze slope scales when pilots do not need them.
Under normal circumstances, EFIS may not display some indication, e.g., Vibration engine. Only when some parameters exceed its limit does the system display the readings. In the same way, EFIS is programmed to show glideslope and pointer scales only during the ILS approach.
In case of input failure, the electromechanical instrument adds another indicator - typically, a bar goes down across the wrong data. EFIS, on the other hand, removes invalid data from the screen and replaces the appropriate warnings.
The de-clutter mode is activated automatically when circumstances require the attention of the pilot for a particular item. For example, if an aircraft rises or falls outside the specified limit - typically 30 to 60 degrees - the attitude indicator will stop other items from view until the pilot carries the pitch to an acceptable level. This helps the pilot focus on the most important tasks.
Color
Traditional instruments have long used color, but lack the ability to change color to indicate some changes in conditions. EFIS electronic display technology has no such limitations and uses color extensively. For example, when an aircraft approaches a slope, the blue description can show an armed slope, and the capture may change the color to green. The EFIS system is a typical color-coded needle navigation to reflect the type of navigation. The green needle shows ground-based navigation, such as VOR, Localizers and ILS systems. Magenta needle shows GPS navigation.
Benefits
EFIS provides versatility by avoiding the physical limitations of traditional instruments. A pilot can change the same display that indicates course deviation indicators to show the planned track provided by the navigation system or flight management. Pilots can choose to place in weather radar images on the route shown.
The flexibility afforded by software modifications minimizes the cost of responding to new aircraft regulations and equipment. Software updates may update the EFIS system to expand its capabilities. Updates introduced in the 1990s include a ground proximity warning system, and traffic collision avoidance systems.
The level of redundancy is available even with the installation of two simple EFIS screens. If PFD fails, transfer switching repositioning to vital information to the screen is usually occupied by the navigation display.
Progress in EFIS
In the late 1980s, EFIS became the standard equipment in most Boeing and Airbus aircraft, and many business aircraft adopted EFIS in the 1990s.
Recent advances in computing power and cost reduction of liquid crystal displays and navigation sensors (such as GPS and attitude and directional reference systems) have brought EFIS into common aviation aircraft. Important examples are Garmin G1000 and Chelton EFIS-SV Flight Systems.
Some EFIS manufacturers are focusing on the experimental aircraft market, producing EFIS and EICAS systems for only US $ 1,000-2,000. Low cost is possible because of the sharp decline in sensor and display prices, and equipment for experimental aircraft does not require expensive Federal Aviation Administration certification. This latter point limits its use to experimental aircraft and certain other aircraft categories, depending on local regulations. Uncertified EFIS systems are also found in Sport Pilot category aircraft, including factory-made aircraft, microlight, and ultralight. This system can be installed on a certified aircraft in some cases as a secondary or backup system depending on local flight rules.
See also
- Acronyms and abbreviations in avionics
Note
Further reading
- Views of AC25-11A Electronic Flight Deck Circular, in the U.S. Federal Aviation Administration
Source of the article : Wikipedia
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