1、 Civil Aviation Flight University of China Ground Proximity Warning System 近地警告系統(tǒng)Ground Proximity Warning System （GPWS） Civil Aviation Flight University of China Despite the significant advances in an aeronautical technology and operational standard of modern airlines, fatal accidents involving airl

2、ine aircraft continue to occur throughout the world. With few exceptions, most fatalities in airline accidents result from controlled flight into terrain (CFIT). Ground proximity warning systems (GPWS) are used as a method of alerting pilots to abnormal closing rates with terrain that they may other

3、wise not detect. Bad weather, poor cockpit coordination, and dealing with abnormal situations can distract crews at a time when proximity to terrain presents the greater hazard.Ground Proximity Warning System （GPWS） Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） A t

4、ypical GPWS is a system that computes closure with terrain and then compares that result with acceptable values that have been pre-programmed.Inputs to the GPWS are typically: Radio altitude; Airspeed/mach; Barometric altitude; Landing gear position; Flap position; and Glideslope deviations. Civil A

5、viation Flight University of China Ground Proximity Warning System （GPWS） Some modern GPWSs are equipped to provide windshear warning as well. For this function the GPWS must also have inputs of angle of attack from the stall warning computer and sensitive acceleration inputs from the inertial refer

6、ence system(IRS). Typical warnings provided by a modern GPWS are in the form of aural alerts, where a synthesized voice makes the appropriate aural statement or a buzzer/horn is activated. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） The various situations that ca

7、n initiate a GPWS alert are normally called “modes”. Most modes provide two levels of alert as terrain is approached and safe margins are infringed. When initial limits are exceeded the first warning that is given is usually termed a soft warning (i.e. caution). If the aircraft then gets closer to t

8、errain and exceeds the level set by the system, a hard warning is given. Hard warnings are usually sufficient to wake the dead. GPWS Alert Modes Civil Aviation Flight University of China Figure 8.1 Ground Proximity Warning System （GPWS） MODE 1 Excessive Descent Rate Mode 1 is normally independent of

9、 aircraft configuration and provides an alert on the basic of excessive rates of descent at low altitude. In most installations this mode does not become active until below 2,500 ft radio altitude. This mode has inner and outer alert boundaries. Civil Aviation Flight University of China Ground Proxi

10、mity Warning System （GPWS） Penetration of the outer boundary activates the “PULL UP” warning lights and “SINKRATE, SINKRATE” alert enunciation. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） Penetration of the inner boundary changes the audio message to “WHOOP，WHOOP

11、，PULL UP” which repeats continuously until the inner warning boundary is exited. MODE 1 Excessive Descent RateDescent RateRadio AltitudeRadio AltitudeMODE 1 Excessive Descent RateDescent RateRadio AltitudeMODE 1 Excessive Descent RateDescent RateRadio AltitudeMODE 1 Excessive Descent RateDescent Rat

12、e方式1 Civil Aviation Flight University of China Ground Proximity Warning System （GPWS）Figure 8.2 MODE 2 Excessive Terrain Closure Rate 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

13、 Radio Altitude and on how rapidly Radio Altitude is decreasing (closure rate). Mode 2 exists in two forms, 2A and 2B. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） MODE 2A Mode 2A is active during climbout, cruise, and initial approach（flaps not in the landing con

14、figuration and the aircraft not on glideslope centerline）. If the aircraft penetrates the Mode 2A caution envelope, the aural message “TERRAIN，TERRAIN” is generated and the “PULL UP” warning lights will illuminate. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） MODE

15、 2A If the aircraft continues to penetrate the envelope, the aural warning message “Whoop, Whoop, PULL UP” is repeated continuously until the warning envelope is exited. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） MODE 2A Upon exiting the warning envelope, if ter

16、rain clearance continues to decrease, the aural message “TERRAIN” will be given until the terrain clearance stops decreasing. In addition, the visual alert will remain on until the aircraft has gained 300 feet of barometric altitude, 45 seconds has elapsed, or landing flaps or the flap override swit

17、ch is activated. Radio AltitudeMODE 2 Excessive Terrain Closure RateClosure RateRadio AltitudeMODE 2 Excessive Terrain Closure RateClosure RateRadio AltitudeMODE 2 Excessive Terrain Closure RateClosure RateRadio AltitudeMODE 2 Excessive Terrain Closure RateClosure Rate Civil Aviation Flight Universi

18、ty of China Ground Proximity Warning System （GPWS） 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 or when making an ILS approach

19、with Glideslope and Localizer deviation less than 2 dots. It is also active during the first 60 seconds after takeoff. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） MODE 2B During an approach, if the aircraft penetrates the Mode 2B envelope with either the gear or

20、flaps not in the landing configuration, the aural message “TERRAIN, TERRAIN” is generated and the “PULL UP” warning lights illuminate. If the aircraft continues to penetrate the envelope, the aural message “Whoop, Whoop, PULL UP” is repeated continuously until the warning envelope is exited. If the

21、aircraft penetrates the Mode 2B envelope with both gear and flaps in the landing configuration, the aural “Whoop, Whoop, PULL UP” messages are suppressed and the aural message “TERRAIN” is repeated until the envelope is exited.Radio AltitudeMODE 2 Excessive Terrain Closure RateClosure RateB 方式2 Civi

22、l Aviation Flight University of China Ground Proximity Warning System （GPWS）Figure 8.3 MODE 3 Altitude Loss after Take-off/Go-around Mode 3 provides alerts for significant altitude loss after takeoff or low altitude go-around (less than 245 feet AGL or 150 feet, depending on aircraft type) with gear

23、 or flaps not in the landing configuration. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS）Figure 8.3 MODE 3 Altitude Loss after Take-off/Go-around This protection is available until the GPWS determines that the aircraft has gained sufficient altitude that it is no l

24、onger in the takeoff phase of flight. Significant altitude loss after takeoff or during a low altitude go-around activates the “PULL UP” warning lights and the aural message DONT SINK, DONT SINK”. Upon establishing a positive rate of climb, the “PULL UP” warning lights extinguish and the aural alert

25、 will cease.Radio AltitudeMODE 3 Altitude Loss after Take-off/Go-aroundLoss of Inertial Altitude Radio AltitudeLoss of Inertial Altitude MODE 3 Altitude Loss after Take-off/Go-around 方式3 Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） MODE 4 Insufficient Terrain Clea

26、rance Mode 4 provides alerts for insufficient terrain clearance with respect to phase of flight, configuration, and speed. Mode 4 exists in two forms, 4A and 4B. 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

27、 approach with the gear in the landing configuration and flaps not in the landing configuration. Mode 4 alerts activate the “PULL UP” warning lights and aural messages. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS）Figure 8.4 Civil Aviation Flight University of Chin

28、a Ground Proximity Warning System （GPWS） MODE 4A Below 1000feet AGL and above 190 knots airspeed, the Mode 4A aural alert is “TOO LOW TERRAIN”. This alert is dependent on aircraft speed such that the alert threshold is ramped between 500 feet at 190 knots to 1000 feet at 250 knots. Below 500 feet AG

29、L and less than 190 knots airspeed, the Mode 4A aural alert is “TOO LOW GEAR”. The “PULL-UP” warning lights extinguish and aural messages cease when the Mode 4A alert envelope is exited. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） MODE 4B Below 1000 feet AGL and

30、above 159 knots airspeed, the Mode 4B aural alert is “TOO LOW TERRAIN”. This alert is dependent on aircraft speed such that the alert threshold is ramped between 245 feet at 159 knots to 1000 feet at 250 knots. Below 245 feet AGL and less than 159 knots airspeed, the Mode 4B aural alert is “TOO LOW

31、FLAPS”. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） MODE 4B If desired, the pilot may disable the “TOO LOW FLAPS” alert by engaging the Flap Override switch (if installed). This precludes or silences the Mode 4B flap alert until reset by the pilot. The “PULL UP”

32、warning lights extinguish and aural messages cease when the Mode 4B alert envelope is exited.Radio AltitudeMODE 4A Insufficient Terrain Clearance with the gear and flaps not in the landing configuration.AirspeedRadio AltitudeMODE 4A Insufficient Terrain Clearance with the gear and flaps not in the l

33、anding configuration.AirspeedRadio AltitudeMODE 4A Insufficient Terrain Clearance with the gear and flaps not in the landing configuration.AirspeedRadio AltitudeMODE 4B Insufficient Terrain Clearance with gear down and flaps not in the landing configurationAirspeedRadio AltitudeAirspeedMODE 4B Insuf

34、ficient Terrain Clearance with gear down and flaps not in the landing configurationRadio AltitudeAirspeedMODE 4B Insufficient Terrain Clearance with gear down and flaps not in the landing configuration 方式4 Civil Aviation Flight University of China Figure 8.5Ground Proximity Warning System （GPWS） MOD

35、E 5 Excessive Deviation Below Glideslope Mode 5 provides two levels of alerting for when the aircraft descends below glideslope, resulting in activation of the “BELOW G/S” caution lights and aural messages . Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） The first l

36、evel alert occurs when below 1000 feet Radio Altitude and the aircraft is 1.3 dots or greater below the beam. This turns on the “BELOW G/S” caution lights and is called a soft” alert because the audio message “GLIDESLOPE” is enunciated at half volume. Civil Aviation Flight University of China Ground

37、 Proximity Warning System （GPWS） The second level alert occurs when below 300 feet Radio Altitude with 2 dots or greater glideslope deviation. This is called a “hard” alert because a louder “GLIDESLOPE, GLIDESLOPE” message is enunciated every 3 seconds continuing until the hard” envelope is exited.

38、The “BELOW G/S” caution lights remain on until a glideslope deviation less than 1.3 dots is achieved. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） Mode 5 alerts can be canceled by pressing the Glideslope Cancel switch (if installed). This is automatically reset wh

39、en the aircraft descends below 30 feet or climbs above 2000 feet AGL (1000 feet AGL for current Boeing production aircraft). Mode 5 alerts are inhibited during backcourse approaches to prevent nuisance alerts due to false fly up lobes from the Glideslope. The GPWC determines a backcourse approach if

40、 either: 1) the aircrafts magnetic track is greater than 90 degrees from the runways approach course, or 2) a glideslope inhibit discrete is set.Radio AltitudeMODE 5 Excessive Deviation Below Glideslope Deviation Below GlideslopeRadio AltitudeMODE 5 Excessive Deviation Below Glideslope Deviation Bel

41、ow GlideslopeRadio AltitudeMODE 5 Excessive Deviation Below Glideslope Deviation Below Glideslope 方式5 Civil Aviation Flight University of China Ground Proximity Warning System （GPWS）Figure 8.6MODE 6 Advisory Callout Mode 6 provides GPWS advisory callouts. These callouts consist of predefined Radio A

42、ltitude based voice callouts or tones and an excessive bank angle warning. There is no visual alerting provided with these callouts. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS）MODE 6 Advisory Callout During preparation for an instrument approach, the pilot can pr

43、ogram the GPWS for the minimum published altitude of the approach. This will be the “Ceiling” on instrument approach charts. When the radar altimeter senses this value, the GPWS gives an aural “MINIMUMS - MINIMUMS” warning. This mode will only operate with the landing gear down and only values below

44、 1,000 ft radar altitude can normally be set. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS）Figure 8.7 The callout “BANK ANGLE, BANK ANGLE” advises of an excessive roll angle. The GPWS provides several excessive bank angle envelopes supporting Air Transport, Busines

45、s, or Military aircraft types. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS）Figure 8.8 One envelope is defined for turbo-prop and jet business aircraft . Bank angles in excess of: 10 between 5 and 30 feet, 10 to 40 between 30 and 150 feet, 40 to 55 between 150 and

46、2450 feet,produce the bank angle advisory(Shaded area). Bank angle advisories are inhibited below 5 feet. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS）Figure 8.9 Three envelopes are defined for Air Transport aircraft. These are identified as Basic Bank Angle, Bank

47、Angle Option1, and Bank Angle Option 2 advisories. The Air Transport Basic Bank Angle limits are similar to the Business Aircraft Bank Angle limits except above 150 feet the bank limit remains at 40. Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） Bank Angle Option 1

48、 provides bank angle advisory thresholds at 35, 40, and 45 independent of altitude. In this case, an advisory at 35 is provided and another is not given unless 40 is exceeded and then again only if 45 is exceeded. Bank Angle Option 2 provides a combination of the Basic Bank Angle and Bank Angle Opti

49、on 1. The Basic Bank Angle limits are provided below 130 feet, and Bank Angle Option 1 is provided above 130 feet. MODE 6 Advisory CalloutMODE 6 Advisory Callout MODE 6 Advisory Callout MODE 6 Advisory Callout 方式6 Civil Aviation Flight University of China Ground Proximity Warning System （GPWS） MODE

50、7 Windshear Alerting Mode 7 is designed to provide alert if the aircraft encounters windshear. Two alerting envelopes provide either a Windshear Caution alert or a Windshear Warning alert. Windshear Caution alerts are given if an increasing headwind(or decreasing tailwind)and/or a severe updraft exceed a defined threshold. These are characteristic of conditions preceding an encounter with a microb