Driving off birds using acft radar
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Nominal power output on one of the radars on A320 is 125 Watts... over a 30" antenna flat plate, that is about 239 cm2. That is 8 times less powerfull than a home microwave, and 16 times less powerfull than a vaccum cleaner.
I bet I can scare the birds off with the vacuum cleaner on full power with better efficiency than the radar!
Now, if we strech the theory reaaaaaally good: many migrating birds have magnetite crystals in parts of their beak or brain, which supposedly helps them navigate. Having an electromagnetic wave pointed directly at them could have a disturbing effect, maybe? But even if that ws the case, would it really make the birds fly away? And in which direction? Maybe they'd come flying straigh towards the source!
I bet I can scare the birds off with the vacuum cleaner on full power with better efficiency than the radar!
Now, if we strech the theory reaaaaaally good: many migrating birds have magnetite crystals in parts of their beak or brain, which supposedly helps them navigate. Having an electromagnetic wave pointed directly at them could have a disturbing effect, maybe? But even if that ws the case, would it really make the birds fly away? And in which direction? Maybe they'd come flying straigh towards the source!
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Old friend of mine was a Typhoon fighter pilot during WW2. He said that when German radar controlled anti-aircraft guns were on to him, the first warning was a clicking or similar noise in his headphones (VHF).
He was leading a formation attacking German forces on D-Day. He heard the noise and immediately changed heading. But for some reason one of the formation pilots in his line astern continued straight ahead and was immediately shot down by remarkably accurate AA fire.
However, in the case of birds and radar the theory was the birds were subject to heat from the weather radar - not "noise."
He was leading a formation attacking German forces on D-Day. He heard the noise and immediately changed heading. But for some reason one of the formation pilots in his line astern continued straight ahead and was immediately shot down by remarkably accurate AA fire.
However, in the case of birds and radar the theory was the birds were subject to heat from the weather radar - not "noise."
Weather radar energy isn't particularly hot. I know a bloke who was leaning against the radome of a jet, chatting to an engineer, after a while his arm got a bit of a tingling feeling. On return to the cockpit he discovered the radar was transmitting! So leaning against the actual radome with it transmitting he got a slight tingling sensation after some time. Any birds far enough away to have not already noticed the big noisy chunk of metal coming their way aren't going to feel a thing from the radar.
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but SSR makes them squawk
When RAF controllers wished to tell pilots to switch to a new frequency they would say "Squawk Channel Able
If they told the pilot to switch off his transponder the code word was "Strangle" Thus "Strangle your Parrot"
I remember that until a while ago LIPZ/VCE charts contained the standing order to keep the weather radar on for takeoff and landing in order to scare the birds away. It has quietly been stricken out of the book though; one assumes that this is due to this methods proven ineffectiveness.
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De facto: Right. But with a 12 sec delay. This is for the pilots who forgot the radar..
An airline pilot turns his radar on on TO.
An airline pilot turns his radar on on TO.
I dont switch it on when the sky is clear and i am an airline pilot.
de facto
I suspect latetonight might me alluding to the fact that on some aircraft the Wx radar does indeed fire up, whether you've selected it on or not, at some point v. early in the take-off roll ( on the 777 the radar begins scanning once the thrust levers go into the take-off range)...you don't get weather returns displayed on the ND's if you've left the switch off, but nevertheless the radar is scanning and radiating to provide Predictive Windshear....and on the triple PWS alerts become active 12 seconds after the scanning begins.
That said I don't believe for one moment that the birds dive for cover because of the radar...
I suspect latetonight might me alluding to the fact that on some aircraft the Wx radar does indeed fire up, whether you've selected it on or not, at some point v. early in the take-off roll ( on the 777 the radar begins scanning once the thrust levers go into the take-off range)...you don't get weather returns displayed on the ND's if you've left the switch off, but nevertheless the radar is scanning and radiating to provide Predictive Windshear....and on the triple PWS alerts become active 12 seconds after the scanning begins.
That said I don't believe for one moment that the birds dive for cover because of the radar...
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Latetonite,please be so kind and give me the reference of this 12secs delay.
I dont switch it on when the sky is clear and i am an airline pilot.
I dont switch it on when the sky is clear and i am an airline pilot.
Alerts are available approximately 12 seconds after the weather radar begins scanning for windshear. Predictive windshear alerts can be enabled prior to takeoff by pushing the EFIS control panel WXR switch
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Thanks Cosmo Kramer.
I usually do not have the memory to know things and quote a valid reference at the same time. But in this case I can refer to Brady's "The B737 Technical Guide".
I trust anybody discussing technical matters about the B737 series has this one in his library.
I usually do not have the memory to know things and quote a valid reference at the same time. But in this case I can refer to Brady's "The B737 Technical Guide".
I trust anybody discussing technical matters about the B737 series has this one in his library.
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Sorry by reference i meant the SOURCE.,,where did you get this text from?
You are mentioning the weather radar not the pWS.
From the AMM:
And from the AMM again:
I dont.
You are mentioning the weather radar not the pWS.
From the AMM:
Additional to „normal“ weather radar system, the predictive windshear function provides horizontal windshear warning up to a range of 3 nautical miles.
In the 737 aircraft, this an additional, fully automatic mode of the weather radar system and is not controlled by the pilots.
In the 737 aircraft, this an additional, fully automatic mode of the weather radar system and is not controlled by the pilots.
When the airplane is on the ground and either throttle is moved more than 53 degrees, the PWS comes on automatically.
But in this case I can refer to Brady's "The B737 Technical Guide".
I trust anybody discussing technical matters about the B737 series has this one in his library.
I trust anybody discussing technical matters about the B737 series has this one in his library.
Last edited by de facto; 11th Oct 2013 at 18:48.
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Yes, PWS comes on above TLA 53 degrees, same microswitch as your TO Warning, but needs warm up. There is also alternate scanning involved, between use of the radar disc for weather and PWS, and alternate scanning for the Captain and F/O, leading to a possible delay of PWS detection of 12 seconds.
Given a 36 sec average time to rotation, the first third of your take off, when the PWS caution is active, you have thus possibly no indication.
I was kind a weary you do not have those reference books handy.
Nowadays most people I train, get their knowledge from SOP's and answering multiple choice questions. Times have indeed changed.
That does not mean I changed accordingly. I like to keep it simple, and have my WX radar switched on at Line up.
In our company we do not pay for the unavoidable extra fuel burn this habit creates.
Given a 36 sec average time to rotation, the first third of your take off, when the PWS caution is active, you have thus possibly no indication.
I was kind a weary you do not have those reference books handy.
Nowadays most people I train, get their knowledge from SOP's and answering multiple choice questions. Times have indeed changed.
That does not mean I changed accordingly. I like to keep it simple, and have my WX radar switched on at Line up.
In our company we do not pay for the unavoidable extra fuel burn this habit creates.
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De facto,
The source is your FCOM Chapter 15 Warning Systems.
And to add to what latetonite already said:
Hence, without turning the WX radar on, you have no predictive windshear alerts for the first 12 seconds, and no predictive windshear alerts after 100 knots.
Basically you are taking off without predictive windshear at all with the radar turned off.
The source is your FCOM Chapter 15 Warning Systems.
The weather radar automatically begins scanning for windshear when:
• thrust levers set for takeoff
(....)
Alerts are available approximately 12 seconds after the weather radar begins scanning for windshear. Predictive windshear alerts can be enabled prior to takeoff by pushing the EFIS control panel WXR switch.
• thrust levers set for takeoff
(....)
Alerts are available approximately 12 seconds after the weather radar begins scanning for windshear. Predictive windshear alerts can be enabled prior to takeoff by pushing the EFIS control panel WXR switch.
Predictive Windshear Inhibits
During takeoff and landing, new predictive windshear caution alerts are inhibited between 80 knots and 400 feet RA, and new warning alerts between 100 knots and 50 feet RA.
During takeoff and landing, new predictive windshear caution alerts are inhibited between 80 knots and 400 feet RA, and new warning alerts between 100 knots and 50 feet RA.
Basically you are taking off without predictive windshear at all with the radar turned off.
I can tellya that the high-power military radars in our fighters( not the weather radar that the heavies have) would fry a bird or human if turned on when the "target" was a few feet away. We also had interference problems with other systems at takeoff, so the 'dar didn't come on until we were rolling or actually WOW.
BTW, there's a new anit-personnel microwave system out there that will cause your skin to itch and maybe boil out at a thousand meters or so. One of the "non-lethal" systems we Yanks seem to be concerned with, heh heh.
Newer systems like the agile scanned phased array dars on the F-22 and F-35 don't have this problem. Yeah, the B-2 and later fighters.
BTW, there's a new anit-personnel microwave system out there that will cause your skin to itch and maybe boil out at a thousand meters or so. One of the "non-lethal" systems we Yanks seem to be concerned with, heh heh.
Newer systems like the agile scanned phased array dars on the F-22 and F-35 don't have this problem. Yeah, the B-2 and later fighters.
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The FAA has an Advisory Circular regarding distance to stay away from a radar disk. It is the greater distance of 1.) where the radar beam forms away from the antenna and 2.) Where the radiation level reaches 10 mW per square cm.
Honeywell publishes a safe distance of 14 ft away from the center of the disc for their state of the art RDR-4000 series radar, to comply with this circular AC20-68B.
Even in test mode a distance of 3.5 ft is required.
Honeywell publishes a safe distance of 14 ft away from the center of the disc for their state of the art RDR-4000 series radar, to comply with this circular AC20-68B.
Even in test mode a distance of 3.5 ft is required.
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Latonlite,
With no WR selected on there is no time delay....On take off once either throttle goes above 53 degrees the PWS detection is ON. I think you may be confused with the 12 second thing. If WR is not selected on before takeoff then all sweeps of the dish are detecting WS. If WR is selected on before takeoff see below:
Takeoff WR selected on with throttles >53 degrees:
Sweep 1 left to right: Capt WR for the first 3 second period.
Sweep 2 right to left: Both PWS for the next 3 second period.
Sweep 3 left to right: F/O WR for the next 3 second period.
Sweep 4 right to left: Both PWS for the next 3 second period.
And then so on. The most time delay you could have is 3 seconds.
As for the birds..................
With no WR selected on there is no time delay....On take off once either throttle goes above 53 degrees the PWS detection is ON. I think you may be confused with the 12 second thing. If WR is not selected on before takeoff then all sweeps of the dish are detecting WS. If WR is selected on before takeoff see below:
Takeoff WR selected on with throttles >53 degrees:
Sweep 1 left to right: Capt WR for the first 3 second period.
Sweep 2 right to left: Both PWS for the next 3 second period.
Sweep 3 left to right: F/O WR for the next 3 second period.
Sweep 4 right to left: Both PWS for the next 3 second period.
And then so on. The most time delay you could have is 3 seconds.
As for the birds..................
Last edited by Gas Bags; 12th Oct 2013 at 10:39.
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Gas Bags,
Please read the quote from Cosmo Cramer from the FCOM.
Then, Chris Brady mentions 12 sec delay, and blames it to warm up time in his publication.
At the end, if I switch the Wx radar on on line up, I am sure it is available when I push TOGA.
Please read the quote from Cosmo Cramer from the FCOM.
Then, Chris Brady mentions 12 sec delay, and blames it to warm up time in his publication.
At the end, if I switch the Wx radar on on line up, I am sure it is available when I push TOGA.
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Thereby confirming my fears, expressed elsewhere in these fora, about the total and utter tosh being dispensed by those with the title of "trainer"!
Having spent many happy hours on RAF airfields, observing the feathered species cavorting, feeding and possibly breeding within very short distances of those airfields' surveillance and PAR (nodder & wagger) scanners, I would say that the myth seems to live on and we can't get rid of it.
Better to spend your pre-departure taxi phase performing what the engineers describe as a "confidence check", being wary of the quoted 15m radhaz area for humans and the 300 ft hazard area for the aircraft's radar self-damage potential when bounced off other aircraft, bowsers and other vehicles, terminal and other building structures which will reflect damaging signal strength back into the very sensitive receiver circuitry, which is the secret of the performance of modern Wx radars.
Strangely no company even mentions such a check in their SOPs, though the NG MM states that the ordinary weather test, though it fills the screen with pretty colours and blasts off 1 squirt of emf, is not a proper test of the radar's ability to work properly.
Post radar problem rectification, the engineers have to move the 'frame to a suitable position where it can be "fired up" properly to confirm succsessful fixing.
Better to find out before V1 and later, that the "weapon" is not functioning, than to discover the hard way, as some recent hail damage incidents have illustrated?
Maybe a polite request to the relevant "trainer" as to where it is written will provide us all with the Holy Grail of Bird Repellant Radar, meantime remember the turtle story!!
"I dont switch it on when the sky is clear and i am an airline pilot" ????? Highly inadvisable, the sky may be clear on departure, but what about enroute and destination?.
As for that posting referring to a "professional" pilot who believed the weather radar ATTRACTED lightning strikes, now I know there are fairies at the bottom of my garden!
Having spent many happy hours on RAF airfields, observing the feathered species cavorting, feeding and possibly breeding within very short distances of those airfields' surveillance and PAR (nodder & wagger) scanners, I would say that the myth seems to live on and we can't get rid of it.
Better to spend your pre-departure taxi phase performing what the engineers describe as a "confidence check", being wary of the quoted 15m radhaz area for humans and the 300 ft hazard area for the aircraft's radar self-damage potential when bounced off other aircraft, bowsers and other vehicles, terminal and other building structures which will reflect damaging signal strength back into the very sensitive receiver circuitry, which is the secret of the performance of modern Wx radars.
Strangely no company even mentions such a check in their SOPs, though the NG MM states that the ordinary weather test, though it fills the screen with pretty colours and blasts off 1 squirt of emf, is not a proper test of the radar's ability to work properly.
Post radar problem rectification, the engineers have to move the 'frame to a suitable position where it can be "fired up" properly to confirm succsessful fixing.
Better to find out before V1 and later, that the "weapon" is not functioning, than to discover the hard way, as some recent hail damage incidents have illustrated?
Maybe a polite request to the relevant "trainer" as to where it is written will provide us all with the Holy Grail of Bird Repellant Radar, meantime remember the turtle story!!
"I dont switch it on when the sky is clear and i am an airline pilot" ????? Highly inadvisable, the sky may be clear on departure, but what about enroute and destination?.
As for that posting referring to a "professional" pilot who believed the weather radar ATTRACTED lightning strikes, now I know there are fairies at the bottom of my garden!