WX Radar

[AERO DYNAMIK]

So I'm taxing out in my A330 at LHR, my company SOP as part of the pre departure checks is to switch on the wx radar during taxi, however taxing just ahead of me is a 747. My question...are the high frequency radio waves reflected back off the jumbo of any danger to me in he flightdeck

Thanks

AD

[alexban]

He,he...how about the poor guys in the jumbo that are getting a nice tan without even knowing...:)
Actually,the wx radars we have today are not so dangerous (do not operate within 15' of people says in the 737 FCOM)..so I guess you'll not be closer than this to a 747,right...?
One question ,though,..why do you have to keep the radar on during taxi ? Why did they put this in your SOP ?
Brgds...Alex

[FE Hoppy]

Does the wxr transmit when you "switch it on " on the ground? If so is it transmitting at full power?

[Old Smokey]

If your Wx radar is actually transmitting.......

(1) There should be no danger to the occupants of the aircraft ahead, they should be well protected by the reflective structure.

(2) There should be no danger to you or the occupants of your own aircraft, you should be well protected by your own reflective structure.

(3) There could be considerable risk to your own radar, which is calibrated to receive less than 0.1% of the energy transmitted, but is now receiving probably 20 to 30% of it, and overloading the receiver. Perhaps your radar has a pre-set received signal threshold beyond which incoming energy is blocked, but it certainly WAS a problem on some aircraft at an earlier time.

Regards,

Old Smokey

[swh]

AERO DYNAMIK,

FCOM vol 3 supp techniques, Wx radar, should answer your question, no large metallic objets within 5 meters in arc +/- 90 deg of the aircraft centreline, no person withing 5 m within 135 deg of the a/c cetererline before selecting WX, WX/T, MAP modes.

:ok:

[HEATHROW DIRECTOR]

Have you guys considered how much power your wx radar transmits? I bet it's minimal.. Now check out what's coming from that big antenna just as you come out of the tunnel at Heathrow. On with the lead underpants boys...

[Flughaven]

Just while we're on the subject of WX radar, can anyone remember the formula for calculating the top's of clouds?
Something like 0.5 the beam width* tilt angle???

[P-T-Gamekeeper]

"Why have my weather radar on for taxi"

Probably so that it is stabilised, to prevent damage.

It will also give you a good view of weather on your intended SID.

The safety range of my radar is inside the radome, so you could stand in front of it in perfect safety (if very brave!).


Also, can't remember the formula, but it is based on the 1:60 rule, so, for example:

Tilt -2
Distance 30nm
Beam width 5 deg

Cloud is 2250' below (I hope thats right!!)

[Hudson]

P-T Gamekeeper. Jeez - I hate these complicated usernames.
Taxying with radar on for stabilisation is an old wives tale.
If there was a problem with the antenna bouncing around while taxying you can be sure that the manufacturer's pilot information manual would say so and state a specific procedure to prevent damge.

[P-T-Gamekeeper]

Sorry - I must be an old wife!! I am a herc driver, and thats the reason we switch on prior to taxi. The other point is valid, whatever the technology. The C130-J has a modern radar, but we still switch on for stabilisation, so maybe I'm not the only old maid out there.

Maybe the manufacturors procedure is - wait for it - taxi with the radar on!

[IRRenewal]

Exposure to RF from modern WX radars is greatly exaggerated. Have a look at this (http://hps.org/publicinformation/ate/q315.html) link.



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