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looserfer
11th Mar 2009, 13:42
Hello there

Any of you know if turning on your weather radar will have an effect on birds, scaring them of..???:ugh:

Regards Loo

Captain Smithy
11th Mar 2009, 14:06
I highly doubt it, although I have heard a number of tales from pilots who do say that it helps. Depending on the transmit power of the antenna it may cook the birds though...

Microwaved pigeons anyone? :uhoh:

Smithy

BelArgUSA
11th Mar 2009, 14:14
It is correct - It is said that birds "feel" weather radar signals.
Apparently, it makes bird uncomfortable, scares them, and makes them "takeoff".
So, there are those airlines with a policy "operate your radar" to chase birds.
Then other airlines who say "no radar", as they will fly... into your engines.
xxx
At PanAm, we once had an ornithologist lecturing a few instructors.
He said that birds takeoff agaist the wind, exactly like airplanes do.
You see - birds study second segment performance better than some of you guys.
Runway 09, wind from the North, birds on South side, they will takeoff in your path.
xxx
Exact science...? - Or just "for the birds"...?
Once took off with a 747, got a (few) big ones in n 4. Lucky was only one engine.
They had discounts on chicken dinners at the airport restaurant that evening.
xxx
:*
Happy contrails

Captain Smithy
11th Mar 2009, 14:21
Yes, the birds will feel the heatup of tissue caused by the radio waves; although with today's low-powered Wx Radars the birds would have to be pretty close to feel it... probably so close that you'll have hit them anyway. Different story however with older, high-powered antennae or military hardware.

Another nice story there, BelArg, thanks for that. I enjoy your anecdotes that crop up every now and again!

Smithy

ChristiaanJ
11th Mar 2009, 15:09
Yes, the birds will feel the heatup of tissue caused by the radio waves; although with today's low-powered Wx Radars the birds would have to be pretty close to feel it... probably so close that you'll have hit them anyway. Different story however with older, high-powered antennae ...I always thought it was more of a legend, but you're probably right, birds are probably far more sensitive to small tissue temperature changes than we are, and even we can walk into a kitchen and feel that an electric hot plate has been left on.

Even so it's not much use to the birds... since a radar scans, they'd feel a blip every second or so, not enough to D/F and take avoiding action, but maybe enough to upset them. Now whether you want that, remains a wide-open question.

There's not much difference between today's Wx radars and older ones, in the sense that the average power (which is what matters here) is not very different.

.... or military hardware.You're right there. But the question is the same, do you want to upset the birds?

CJ

forget
11th Mar 2009, 15:26
Any of you know if turning on your weather radar will have an effect on birds,

Probably not, but the Radome does.

ChristiaanJ
11th Mar 2009, 15:37
forget,
Shouldn't that be: "birds have an effect on radomes (usually nasty)" ?

Graybeard
11th Mar 2009, 16:16
The old magnetron Wx radar transmitter's output was on the order of 60 KW, pulsed, for an average power of about 600 watts, like the microwave in your kitchen, just at higher frequency.

Solid state radar transmitters, introduced in about 1980, have 75-150 watts pulsed power, or less than 1 watt average power, even in doppler turbulence detection mode.

I rank Wx radar effect on birds in the same category as Wx radar attracting lightning.

You're most likely to get a wrong evasive reaction from birds if you're approaching them from below, as their quickest escape is to pull in the wings and dive.

GB

Storminnorm
11th Mar 2009, 16:34
Dunno about radar warming birds up, but used to frequently
watch birds, especially at LGW for some strange reason, take
off and fly through the engine exhaust gasses of A/c taxying in
or out when it was in the Minus regions.

Canuckbirdstrike
11th Mar 2009, 17:10
Once again the urban legend resurfaces.......

Birds are unable to detect and do not react to aircraft weather radar. I can assure you there is no scientific evidence to support the theory. I did a great deal of research with the avian biology experts on the issue for the Transport Canada book, Sharing the Skies. It is available online at the Transport Canada website if you wish to learn more facts about bird strikes and the urban legends.

Airborne weather radar is very low power and the signal strength decreases as the square of the distance to the birds. The legend appears to have been based on certain early military weapons radar systems, but it was only anectdotal and never tested with any sicentific methodology.

There is no value in turning it on, other than to make you feel good.

ChristiaanJ
11th Mar 2009, 17:49
Graybeard,
Thanks, I didn't realise average power of the more modern solid state radars was that low.

Canuckbirdstrike,
You clearly have studied the subject, I haven't, so I take your word for it.

I just thought of another point "for the prosecution"....
Most airports have one or more operating radars, some even inside the airport perimeter, most with lots more power than a weather radar.
Hasn't kept birds off airports, now, has it?

So even in the hypothetical case that birds can sense a nearby radar, adding your weather radar to the "noise" (to them) is unlikely to impress them.

Sorry, Loo, but the consensus seems to be that turnng the wx radar on to scare the birds is about as much use as hanging a St. Christopher medal on the standby compass.

CJ

mvsb1863
11th Mar 2009, 18:57
Using Weather Radar turned on in order to avoid a bird strike ??? No way, I repeat, NO WAY !!! The weather radar beam strength is so low and so thin, the same width of a pen, that I can say that it's IMPOSSIBLE.
During takeoff in a clear day you just need the Predictive Windshear feature working fine and to turn it on you need the Thrust Levers beyond 53 degrees of TLA and that's all, I mean in the B-737NG.

Cheers

Boroda
11th Mar 2009, 19:24
I cannot give you the reason, but just info. In Venice Tessera airport it is a requirement to use aircraft WX radar for bird scare.

ChristiaanJ
11th Mar 2009, 21:04
I cannot give you the reason, but just info. In Venice Tessera airport it is a requirement to use aircraft WX radar for bird scare.Now that you mention it, I've seen that too!
But then, airport officials are unlikely to have any technical or scientific education, and are as likely to believe urban legend as the general public....
So yes, plausible.

CJ

Flare-Idle
11th Mar 2009, 21:11
Canuckbirdstrike

Thanks for the reference, highly appreciated. Posts like yours make pprune worth a read once in a while. Unfortunately ,in general, too much of rubbish to dig through in order to find "golden nuggets" like yours...

Regards from over the pond...

FI

BelArgUSA
11th Mar 2009, 21:31
For whatever it is worth (to the birds or not) -
xxx
Our (PanAm) GOM said to operate WX Radar to chase birds, and to turn off the radar when approaching terminal and facing people such as the agent marshalling the aircraft to the parking spot.
xxx
Remember one time, as F/O arriving in Calcutta, I forgot to turn-off the radar after landing. Oops... we bombarded the marshall with a lot of nasty rays from our antenna. Captain said "not to worry, we made the bloke unable to make babies, not a concern with the local population boom".
xxx
Apparently, radar renders males unable to procreate...???
Full blast in China and India with your radars...!
xxx
:hmm:
Happy contrails

Canuckbirdstrike
11th Mar 2009, 23:41
The Venice notes are a feeble attempt at liability mitigation. Specifically, the goal is to cover off the concept of "duty of care" and "duty to warn". In the event of an accident or incident you can bet the first question the crew will be asked is "did you have the weather radar on".

The good news is that with only some minor effort this will be shown in court as utterly ridiculous.

This warning/requirement is much like airports that constantly broadcast "Pilots take caution due to bird activity" in ATIS messages. Eventually this becomes "white noise" and pilots ignore it. This type of general or blanket warning will inevitably be tested in court and is most likely to fail the test of "reasonable standard of care" and "due diligence".

Unfortunately, in the field of airport wildlife management and bird strike mitigation there is a belief that this is "nature and it can't be changed" and even more concerning to much pseudo-science, urban legends and people selling products that should only be sold at 0300 on infomercials.

lomapaseo
12th Mar 2009, 00:03
But then, airport officials are unlikely to have any technical or scientific education, and are as likely to believe urban legend as the general public....

especially true if they read Pprune for their info.

Captain Smithy
12th Mar 2009, 07:36
BelArg

Yes, I believe that non-ionising radiation causes the most damage to parts of the body where there are few blood vessels, since this means that the tissue is not good at dissapating the heat caused by RF (can medical types confirm/correct here?). The most vulnerable parts are the eyes and testes.

Prolonged RF exposure can lead to cataracts and can make an effective birth-control method...

Like I said originally, I highly doubt that radar scares the birds away. Thanks Canuckbirdstrike and Greybeard for your informative posts.

Smithy

cwatters
12th Mar 2009, 08:09
This paper appears to confirm birds are not effected by radar.

http://jeb.biologists.org/cgi/reprint/202/9/1015.pdf

BEHAVIOUR OF MIGRATING BIRDS EXPOSED TO X-BAND RADAR AND A BRIGHT
LIGHT BEAM

The Journal of Experimental Biology 202, 10151022 (1999)
BRUNO BRUDERER*, DIETER PETER AND THOMAS STEURI
Swiss Ornithological Institute, CH-6204 Sempach, Switzerland

"Switching the radar transmission on and off, while continuing to track selected bird targets using a passive infrared camera during the switch-off phases of the radar, showed no difference in the birds behaviour with and without incident radar waves."

Luap
13th Mar 2009, 02:48
It is possible to 'hear' microwaves, so even if weather radar doesn't put birds away, a device that repels birds might be possible.

http://en.wikipedia.org/wiki/Microwave_auditory_effect

Microwave auditory effect
From Wikipedia, the free encyclopedia

The microwave auditory effect, also known as the microwave hearing effect or the Frey effect, consists of audible clicks induced by pulsed/modulated microwave frequencies. The clicks are generated directly inside the human head without the need of any receiving electronic device. The effect was first reported by persons working in the vicinity of radar transponders during World War II. These induced sounds are not audible to other people nearby. The microwave auditory effect was later discovered to be inducible with shorter-wavelength portions of the electromagnetic spectrum. During the Cold War era, the American neuroscientist Allan H. Frey studied this phenomenon and was the first to publish (Journal of Applied Physiology, Vol. 17, pages 689-692, 1962) information on the nature of the microwave auditory effect; this effect is therefore also known as the Frey effect.
Dr. Don R. Justesen also published Microwave and Behavior at The American Psychologist (Volume 30, March 1975, Number 3)
Research by NASA in the 1970s showed that this effect occurs as a result of thermal expansion of parts of the human ear around the cochlea, even at low power density. Later, signal modulation was found to produce sounds or words that appeared to originate intracranially. It was studied for its possible use in communications but has not been developed due to the possible hazardous biological effects of microwave radiation. Similar research conducted in the USSR studied its use in non-lethal weaponry.
........................................

Graybeard
13th Mar 2009, 15:07
That auditory info is interesting, because there was an A.D. on the early 737-300, where a 180 Hz pulse repetition frequency from the X-band Wx radar was leaking in the power/signal wiring over to the nose localizer antenna and causing a false signal.

GB

A37575
14th Mar 2009, 08:59
I talked to a former RAF pilot who flew Hawker Typhoons over Europe. When German radar controlled anti-aircraft guns were tracking them, pilots would hear a series of clicks in their headsets and within seconds the 88mm shells were coming their way.

Hot 'n' High
14th Mar 2009, 09:36
You try walking around on the flight deck on a ship with a "mag loop" talking headset on! If you can count fast enough, you not only clearly get the scan rate of the ships radar, but its PRF as well! :eek:

Worked in an AEW radar workshop for a while. Big bits of kit them. Hook it up to a dummy load, insert pies in waveguide, Tx for 3 - 4 sec, red hot pies ready for lunch! :ok:

Only snag, get distracted at the critical moment - Tx for 5+ sec and the cry of "Who's burnt the ******* pies?" went up!!!! Oh, and whatever you do, do take 'em out the tin foil before you try this one at home folks!!!!

For info, this technique worked on any pie - not just chicken! Never did try a full Sunday roast tho! ;)

H 'n' H

TinyTim2
17th Mar 2009, 16:28
The typical safety zone for a modern weather radar is approx 9ft , in the modern litigation society would any manufacturer quote any safety zone that was not absolutely safe ???...I doubt it ...If birds did get anywhere near that they and the aircraft are in big trouble!!!!!

GlueBall
18th Mar 2009, 06:46
A37575 . . . "When German radar controlled anti-aircraft guns were tracking them, pilots would hear a series of clicks in their headsets and within seconds the 88mm shells were coming their way."

Too much radiation, or perhaps just ambitious imagination may be playing tricks on your mind; but no German [Krupp] anti aircraft 88mm guns were "radar controlled" during WWII. :ooh:

bflyer
18th Mar 2009, 09:13
Not the 88mm..that's right but i think they had AA 105 mm that were radar controlled....

ChristiaanJ
18th Mar 2009, 17:18
I quite believe those anecdotes... a lot of electronics will "detect" a radar at appreciable distances.

All that's needed is a lack of shielding and something non-linear, like a diode, a transistor, a mixer tube in a radio receiver....

When I had a car without a cassette player, I took my home cassette player along, lying on the seat. It would "beep", matching scan rate and prf, whenever I drove past the local airbase, with the radar at least half a mile away.

And I remember playing with a tiny dish (10" or so) from a surplus Hunter gun-ranging radar. Just a diode in the waveguide, and a few stages of audio, and it would pick up aircraft weather radars 20 or so mile away.

CJ


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