EGPWS
 

I was recently in discussion with a company who claim they are the only approved FAA/CAA for EGPWS. I was told by them that the biggest job in the system installation was the arial, which has to be placed on top of the a/c. When I asked whether it could be fitted on the bottom of the a/c for ease of maintenance, the answer was negative. Anybody can advise? Cheers

REMEMBER FLYING IS THE SAFEST WAY TO FLY

Which aerial do you mean?
Some (but not all) EGPWS use GPS for accurate position information. The GPS aerial would need to be on the roof to be line of site with the satellites.
The radio altimeters used by standard and enhanced GPWS obviously need to be on the belly.

If I'm not mistaken, EGPWS also uses the radar, so there's an aerial in front as well!

Thank you gentlemen for your input. However, the a/c type is B757 which already has INS, Radio Altimeters, ETC, so why does it need GPS? Cheers
REMEMBER FLYING IS THE SAFEST WAY TO FLY

GPS provides more accurate position information so EGPWS computer knows exactly where A/C is, on its inbuilt map.
IRS is subject to drift after after a long flight, and in remote areas, there may not be DMEs or VORs to update IRS position.
Having said that, some A/C only use FMC/IRS position inputs to EGPWS but then there is more chance of false warnings due to inaccuracies.

Try www.egpws.com for loads of info.
Jetmender;I'll contact your other half to arrange a night out after payday. Can't do the mex place in Ampthill though, have an unpaid bill since before xmas!!

Spanners,
You are mistaken !
EGPWS doesn't use WXR. The info is fed from the EGPWS computer to the EHSI (B757) using the WXR data buses.
You either select WXR or EGPWS.

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Jetmender
Most Egpws sys uses FMC pos. it´s just a question how the FMC determins it´s position.