The EGPWS

[akafrank07]

I understand that EGPWS provides a greater level of protection than a standard GPWS, and from what i have read it provides terrain mapping which the GPWS does not, is that correct?

"The EGPWS terrain mapping can be shown on the navigation displays by using the weather system"

What would this weather system be, is that the weather radar? and does it pick up ground elevations from its beams as well as the weather condition to be displayed on the nav displays?

Thanks

[keith williams]

If you do a GOOGLE search for EGPWS you will find lots of material including the answers to your questions.

[akafrank07]

Hi
I didn't think that i would find these answers on google, though i did find out that the GPWS doesn't have a terrain mapping function, however my question still stands:

What would this weather system be, is that the weather radar? and does it pick up ground elevations from its beams as well as the weather condition to be displayed on the nav displays?

I would like to know what this weather system is that's providing the tarrain mapping, i presume its the weather radar and that it is using radar beams to check for weather in addition to providing altitude though i'm still not sure

[trainee99]

Hi. Egpws doesn't use the weather radar beam to provide any sort of mapping function. The map is a terrain database used in conjunction with aircraft location information. I think the statement refers to the display unit only. In an Airbus for example-I would assume a Boeing is the same..- weather radar information is shown on the nd. This can be replaced by the terrain display by pressing the terrain push button. There is also an automatic 'pop-up' function for the terrain display-the terrain display automatically replaces weather radar information on the nd in the event of terrain proximity.

[galaxy flyer]

Synthetic vision uses the PFD to display a terrain picture based on location and terrain from the EGPWS database. Pretty realistic, too.

[keith williams]

I've just done a google search and it found about 8 links on EGPWS. One of these was a link to a video YouTube, which answers your questions.

www.youtube.com/watch?v=TUZbOoQrlXQ
The pprune system is preventing the link from working directly, but if you do the google search you can open it from there.

[argyle]

EGPWS

The weather radar uses the signal from the EGPWS for auto tilt.
The data base in the EGPWS contains infomation of the high ground and some radars have an auto tilt function. Armed with this information the tilt angle will be changed to elliminate ground clutter.
Not all weather radar auto tilts use the EGPWS data base, some have a data base of high ground built into the radar.

[PEI_3721]

akafrank07, EGPWS does not ‘protect’ anyone, it’s up to the pilot to act on the alerts and warnings provided.

The map mode is a valuable and potentially powerful aid to situation awareness, but equally a potentially powerful distraction if the source of the navigational position is in error (map slip) or the databases are out of date. The most appropriate navigation source is the optional EGPWS’s internal GPS receiver, but even then the map should not be used as the prime means of navigation.

Go to www.egpws.com or EGPWS then look at the multimedia/descriptions, products and services, safety examples, and support/operation sections.

[akafrank07]

Thanks for the replys guys, i understand the concept of EGPWS now also Keith that youtube video explained it well, i missed that

[avionimc]

TAWS

GPWS and EGPWS are the names used by AlliedSignal/Honeywell.

The more generic and commonly used name is TAWS, here is an AEA article for general understanding.

[grounded27]

IRU's provide stabilization for the WXR. EGPWS is simply like "Microsoft" providing terrain mapping based on calculated position in the "FS" game. Usually provided by a company like Honeywell and updated on a monthly basis for accuracy as terrain and objects on the ground change.

[ZFT]

and updated on a monthly basis for accuracy as terrain and objects on the ground change.

The EGPWS database is not updated on the normal 28 day cycle, in fact, unlike FMS etc there is no regulatory requirement to ever update it!!!

[Denti]

And that is why there is the Terrain Inhibit switch, to silence those many nuisance warnings you get if flying around with an old database. There might not be any regulatory demand for updating on a cycle, there is however in stuff like alliance audits and IOSA.

[JammedStab]

Originally Posted by Denti

And that is why there is the Terrain Inhibit switch, to silence those many nuisance warnings you get if flying around with an old database.

Or,you could be using terrain inhibit for valid databases but warnings that are unavoidable for landings at certain airports, usually mountainous. I used to fly into a couple of airports that had close in high terrain, one of which gave occasional Terrain alerts and the other one that gave alerts every time. As this was in the visual segment of an approach, the company procedure was to select Terrain Inhibit. Keep in mind that not all alerts are inhibited when this is done so if you are coming in close over a hill or cliff and get too close, you still get an alert.

The other situation was arriving at a relatively flat airport but with an open pit mine on short final with the aircraft at about 500 feet above airport elevation. The radar altimeter would suddenly increase several hundred feet as we passed over the deep mine and then have a sudden closure rate as we crossed over the far edge of the mine. The sudden decrease in radalt altitude triggered a terrain warning that could not be cancelled.

[galaxy flyer]

Another example, we've had--landing at a private airport not in the database. Our case was at a mining airfield in Australia.

GF