Use of Radio Nav Aids EFIS, GPWS & EGPWS

Use of Radio Nav Aids EFIS, GPWS & EGPWS

Electronic Flight Instrument System ELECTRONIC FLIGHT INSTRUMENT SYSTEM (EFIS): is a flight deck instrument display system in which the display technology used is electronic rather than electromechanical. EFIS normally consists of a primary flight display (PFD), multi-function display (MFD) and engine indicating and crew alerting system (EICAS) display. Although cathode ray tube (CRT) displays were used at first, liquid crystal displays (LCD) are now more common.

INTERFACE : EFIS Typical Interface between EFIS (Glass cockpit) and Signal Inputs EFIS ( it replaces FDS system ) It consists of : a) Control Panel b) EADI (Electronic Attitude Direction Indicator) Display c) EHSI (Electronic Horizontal Situation Indicator) Display. EHSI is also called Navigation Display ( ND ) d) Six Modes of EHSI Other Related Equipment for Aircraft Systems a) EICAS Engine Indicating and Crew Alerting System (Boeing) b) ECAM Engine Centralized Aircraft Monitoring (Airbus)

EFIS Vs ANALOGUE These systems provide many advantages such as being lighter, more reliable, no moving parts to wear out, consuming less power, and replacing numerous mechanical indicators with a single glass display. Because the versatility offered by glass displays is much greater than that offered by analog displays, the use of such systems will only increase with time until analog systems are eclipsed.

What is EADI (PFD)? EADI ( Electronic Attitude Director Indicator) is also called Primary Flight Display or PFD. EADI is a fairly standard Artificial Horizon providing Pitch & Roll information & lends Attitude to the name of the instrument. The Director part comes from the instrument ability to display demand information from the Flight Director System using Flight Director Command Bars.

EADI ( or PFD) EADI /PFDs provide increased situational awareness to the pilot by replacing the traditional six instruments used for instrument flight with an easyto-scan display that provides the horizon, airspeed, altitude, vertical speed, trend, trim, rate of turn among other key relevant indications. Examples of PFDs are illustrated in next Figure

PFD & SIX ANALOGUE INSTRUMENTS

BACK UP INSTRUMENTS

HSI

Interface between EFIS and Signal Inputs

MODES - FULL VOR MODE

FULL ILS MODE

CONTROL PANEL ) ) ADI HSI

EFIS Control Panel

FLY DOWN BANK RIGHT

SYMBOLS

SYMBOLS

SIX MODES OF EHSI The EHSI presents a selectable, dynamic color display of flight progress and a plan view orientation. Four principle display modes that may be selected on the EFIS control panel. 1) VOR 2) ILS 3) MAP 4) PLAN VOR and ILS can be displayed as full or expanded compass displays. This makes it a total of six modes of EHSI

Modes of EHSI Map Mode (Refer as Mode 1)

Modes of EHSI Plan Mode (Refer as MODE 2)

Modes of EHSI Full VOR Mode (Refer as MODE 3)

Modes of EHSI VOR Expanded (Refer Mode 4)

Modes of EHSI Full ILS Mode (Refer as 5)

Modes of EHSI Expanded ILS Mode (Refer as 6)

Display for Aircraft Systems EICAS and ECAM a) EICAS Engine Indicating and Crew Alerting System (Boeing) b) ECAM Engine Centralized Aircraft Monitoring (Airbus) EICAS & ECAM display information for a/c systems. The computer generated electronic displays in respect of these a/c systems are jointly known as either EICAS or ECAM.

Other Related Pictures (F)

GPWS - Introduction Controlled Flight into Terrain (CFIT) is the most common type of fatal accident of aircraft. The development of computers and electronics in the cockpit was utilized to improve safety of flight. The purpose of GPWS was to give both visual and audible warning signals to the pilot whenever ac was likely to enter a potentially dangerous ground proximity situation. The function of GPWS varies from ac to ac as the flight parameters, engine response and warning envelope of each would vary.

Elements of GPWS

GPWS Modes & Alerts GPWS monitors six basic modes of ac operation and puts out warnings if a hazardous situation is arising. The design of the eqpt is such that it automatically selects the correct mode with no action from the crew. The responses are classified as alerts and warnings. Alert: when GPWS produces alert which is regarded as a caution the pilot must respond immediately by correcting the flight path or ac configuration so that alert ceases. Warning: When GPWS generates a warning pilot should immediately respond by leveling wings and initiating a maximum gradient climb and maintaining the climb until the minimum safe altitude is reached.

GPWS: LIMITATIONS It must be remembered that GPWS is not a forwarding looking Equipment. Any warning that the Aircraft is flying towards high ground will not be there as the hill or high feature in front will not generate any warning at all. Early GPWS simply viewed the terrain below the aircraft, providing a 30-second (at best) alert prior to possible impact. Thus it became necessary to add a predictive terrain hazard warning function to the system.

WHAT IS EGPWS? The EGPWS is a Terrain Awareness and Alerting system providing terrain alerting and display functions with additional features. A terrain or obstacle conflict results in the EGPWS providing a visual and audio caution or warning alert. The primary function of a terrain awareness and warning system such as EGPWS is to reduce CFIT.

EGPWS The two major causes of commercial-aviation fatalities - controlled flight into terrain (CFIT) and approach-and-landing accidents (ALAs) accounted for 80 percent of fatalities in commercial transport aircraft accidents in the 1980s. But over the last two decades, flight safety has improved thanks to the introduction of Enhanced Ground Proximity Warning System (EGPWS) technology

As a result of EGPWS, the risk of controlled flight into terrain is now 50 times less in Western Europe and North America than it was in 1991, making this one of the biggest success stories in the history of aviation. Since the introduction of EGPWS in 1996, Honeywell has received reports of more than 30 incidents where the EGPWS gave an alert and provided pilots with timely awareness of terrain in flight situations

HOW EGPWS WORKS Basically, a Class A EGPWS works as: It uses data from the GPS and other navaids, the FMS, and the air data sensors to determine the aircraft position both longitudinally and vertically (lat /long). Then it adds that information to data from the terrain/runway database to form a display showing the terrain elevations around the aircraft. Early GPWS simply viewed the terrain below the aircraft, providing a 30-second (at best) alert prior to possible impact. But look-ahead algorithms provide data to predict possible incursions with terrain at up to two minutes in advance.

HOW EGPWS WORKS The EGPWS provides both horizontal and vertical lookahead. With the horizontal look-ahead, the airplane can "see" at least a quarter mile on each side of the aircraft. So, if the aircraft enters into a bank turn, the EGPWS can "anticipate" the turn and warn against possible CFIT. This is in addition to the advisory callout heard when the bank angle is too steep a feature tailored to either air transport aircraft or business jets.

USE in HELICOPTERS With Class A performance, the EGPWS offers look-ahead alerts, altitude callouts, and terrain display. It also provides a highresolution terrain database for both on- and off-airport/heliport operation, and gives callouts during an autorotation. It even helps prevent tail strikes during a landing by using inputs from the aircraft s attitude heading reference system (AHRS).

USE of EGPWS IN HELICOPTERS Systems with the Class B designation offer many of same features as Class A systems. Both have built-in, internal Global Positioning System (GPS) capabilities. However, the Class B system requires no radio altimeter interface, and its database is somewhat limited; for example, it will provide the aircrew with the elevations of runways and heliports, but not of the terrain around them.

MODE 1 Mode 1 provides alerts for excessive descent rates with respect to altitude AGL and is active for all phases of flight. Pull Up may be preceded by Whoop, Whoop in some configurations based on the audio menu option selected.

MODE 2 Mode 2 provides alerts to help protect the aircraft from impacting the ground when rapidly rising terrain with respect to the aircraft is detected. Mode 2 is based on Radio Altitude and on how rapidly Radio Altitude is decreasing (closure rate). Mode 2 exists in two forms, 2A and 2B.

MODE 2 A If the aircraft penetrates the Mode 2A caution envelope, the aural message TERRAIN, TERRAIN is generated and cockpit EGPWS caution lights will illuminate. If the aircraft continues to penetrate the envelope, the EGPWS warning lights will illuminate and the aural warning message PULL UP is repeated continuously until the warning envelope is exited.

Pull Up may be preceded by Whoop, Whoop in some configurations based on the audio menu option selected.

MODE 2B Mode 2B provides a desensitized alerting envelope to permit normal landing approach maneuvers close to terrain without unwanted alerts. Mode 2B is automatically selected with flaps in the landing configuration (landing flaps or flap over-ride selected) or when making an ILS approach with Glide slope and Localizer deviation less than 2 dots. It is also active during the first 60 seconds after takeoff.

MODE 3 Mode 3 provides alerts for significant altitude loss after takeoff or low altitude go-around (less than 245 feet AGL) with gear or flaps not in the landing configuration. Significant altitude loss after takeoff or during a low altitude go-around activates the EGPWS caution lights and the aural message DON TSINK, DON TSINK Upon establishing a positive rate of climb, the EGPWS caution lights extinguish and the aural alert will cease.

MODE 4 Mode 4 provides alerts for insufficient terrain clearance with respect to phase of flight, configuration, and speed. Mode 4 exists in three forms, 4A, 4B, and 4C. Mode 4A is active during cruise and approach with the gear and flaps not in the landing configuration. Mode 4B is active during cruise and approach with the gear in the landing configuration and flaps not in the landing configuration. Mode 4C is active during the takeoff phase of flight with either the gear or flaps not in the landing configuration.

MODE 4A Below 1000 feet AGL and above 190 knots airspeed, the Mode 4A aural alert is TOO LOW TERRAIN Below 500 feet AGL and less than 190 knots airspeed, the Mode 4A aural alert is TOO LOW GEAR

MODE 4B Below 1000 feet AGL and above 159 knots airspeed, the Mode 4B aural alert is TOO LOW TERRAIN Below 245 feet AGL and less than 159 knots airspeed, the Mode 4B aural alert is TOO LOW FLAPS

MODE 4 C

MODE 5 Mode 5 provides two levels of alerting for when the aircraft descends below glide slope, resulting in activation of EGPWS caution lights and aural messages. The first level alert GLIDESLOPE occurs when the aircraft is 1.3 dots BELOW the beam and 1000ft radio altitude. The second level alert GLIDESLOPE, GLIDESLOPE occurs when below 300 feet Radio Altitude with 2 dots or greater glide slope deviation.

MODE 6 Mode 6 provides EGPWS advisory callouts which consist of predefined Radio Altitude based voice callouts or tones and an excessive bank angle warning. There is no visual alerting provided with these callouts. In some cases a callout is stated twice (e.g., MINIMUMS,MINIMUMS ) but in all cases a given callout is only enunciated once per approach.

MODE 7 Mode 7 is designed to provide alerts if the aircraft encounters wind shear. Two alerting envelopes provide either a Wind shear Caution alert or a Wind shear Warning alert each with distinctive aural and visual indications to the flight crew. A Wind shear Caution if enabled results in illumination of amber Wind shear Caution lights and the aural message CAUTION, WINDSHEAR