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HAWK21M
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Joined: Fri Jan 05, 2001 10:05 pm

Egpws Indicator Working

Sat Dec 18, 2004 9:25 pm

Can Anyone from Avionics explain the Working of the Indicator on a Typical EGPWS system.The displays,Indications with pics if possible.
Thanks.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
RightWayUp
Posts: 80
Joined: Wed Oct 10, 2001 5:40 am

RE: Egpws Indicator Working

Sat Dec 18, 2004 10:00 pm

Hawk,
I am not sure if it is the tech side or the operational side you require, but if it helps I'll try to explain the operational side. The basic EGPWS display can vary from system to system on what colours will signify terrain clearance. Reading an old airbus FCOM writeup the relationship between colours and terrain clearance are as follows: Terrain Ref to aircraft altitude
Light Density Green - 2000 ft below upto 1000 ft below aircraft.
Medium Green - 1000 ft below upto 500 ft (gear up) or 250 ft (gr dn) below ac
Medium Yellow - 250 ft (gr dn) or 500 ft (gr up) below upto 1000 ft above a/c
High Density Yellow - 1000ft above to 2000ft above aircraft
High Density Red - 2000 ft above aircraft and upwards.

Solid Yellow - Signifies terrain caution - collision calculated in certain time
Solid Red - signifies terrain warning - basically imminent collison.

The system I use now also has blue to signify the sea. It also has two numbers, one to signify the highest terrain elevation diplayed, and the other to signify the lowest terrain elevation displayed.

I will try to take a picture of the display next week if that helps
 
airplay
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RE: Egpws Indicator Working

Sat Dec 18, 2004 11:03 pm

We must remember that EGPWS is a term used exclusively by Honeywell for their TAWS system. The proper term is TAWS.

For the most part all the systems offer the same information, with some deviation. They must comply with TSO C151b.

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/cc60d6b4c807869586256dc700717e5f/$FILE/C151b.pdf

The primary interface to the flight crew is through annunciators and aural alerts. There are two levels of alerts. "Cautions" are represented by amber annunciations such as "GPWS" or "G/S" and corresponding aural alerts. "Warnings" are represented by a red "PULL UP" annunciator and an aural "PULL UP" (or modified) alert.

A terrain display is also required and as mentioned, some systems now provide blue signifying water at sea level and there is also grey or magenta signifying areas that are not represented in the terrain database.

The Honeywell system offers some unique alerts for man made obstacles as well as an optional "PEAKS" mode that displays the highest and lowest altitude of terrain displayed. Most of the software versions of the Honeywell system also include a feature called "geometric altitude" that incorporates GPS vertical position into the terrainn altitude equation. This prevents erroneous terrain display indications based on incorrect altimeter settings.

The other major TAWS system available is the Universal TAWS. Again, for the most part it operates much like the Honeywell system, but it offers improved graphics, a profile and 3D view terrain display as well as flight plan overlay when coupled with a Universal FMS.

Here are some images of the Universal system. I need to dig deeper in my archives for Honeywell pics, but you can get plenty at www.egpws.com.

http://members.shaw.ca/airplay1/IMG_1462.JPG
http://members.shaw.ca/airplay1/IMG_1463.JPG
http://members.shaw.ca/airplay1/IMG_1475.JPG

 
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HAWK21M
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RE: Egpws Indicator Working

Sun Dec 19, 2004 3:29 pm

Thanks.Thats exactly what I needed.
To Add.
On Ground if the Aircraft is parked facing say 330 deg.With a 20 ft high building in front.
What will my display read.
33 on the compass display [EGPWS]
what colour would be building display.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
airplay
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Joined: Sat Oct 25, 2003 1:58 am

RE: Egpws Indicator Working

Mon Dec 20, 2004 1:00 am

Buildings and other man made obstacles will not be displayed on the terrain display. The "OBSTACLE" callout available with the Honeywell system offers only the visual GPWS annunciator and the "OBSTACLE" aural callout.

The resolution of the terrain display varies between 1 mile and 1/4 mile in most of the database coverage area.
 
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HAWK21M
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RE: Egpws Indicator Working

Mon Dec 20, 2004 3:42 pm



Managed to get a Pic on the same.
This was on the Aircraft at Mumbai [Bombay] INDIA.Hence at Range selction of 320,one can see the Gujarat Peninsula clearly.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
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HAWK21M
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Joined: Fri Jan 05, 2001 10:05 pm

RE: Egpws Indicator Working

Tue Dec 21, 2004 4:46 pm

What does the Mode button operate.[Lower at 6 O'Clock posn]
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
scxmechanic
Posts: 479
Joined: Sat Dec 25, 1999 10:20 am

RE: Egpws Indicator Working

Sat Dec 25, 2004 4:22 pm

http://www.egpws.com

Great website with t/s tables and all kinds of other good info...
 
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HAWK21M
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Posts: 30125
Joined: Fri Jan 05, 2001 10:05 pm

RE: Egpws Indicator Working

Mon Dec 27, 2004 1:49 am

How about Rephrasing.
What does the Mode button on the Indicator mean in a typical B737.
regds
MEL
I may not win often, but I damn well never lose!!! ;)

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