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-   -   Weather Radar in Cavok Condition? (https://www.pprune.org/tech-log/597845-weather-radar-cavok-condition.html)

pineteam 3rd Aug 2017 11:38

Weather Radar in Cavok Condition?
 
Hello guys,

I Would like to have your opinion about it. I'm honestly shocked that some arlines request the cockpit crew to keep the weather radar ON for every flight regardless of the weather condition?! Why would you keep a device suffering from wear and tear when you have clear skies and thus obviously not required?
I'm flying on the A320 and Airbus clearly mentions to use it "as required". Luckily the airline I work for follows Airbus SOP in that aspect. I'm not an engineer, but I believe having a microwave running under your balls all the times can't be great for the crew and definetely not for the radar mechanism itself.
Thank you.

gearlever 3rd Aug 2017 11:47


Originally Posted by pineteam (Post 9850814)
I'm honestly shocked that some arlines request the cockpit crew to keep the weather radar ON for every flight regardless of the weather condition?!

Really? Haven't heard about that. Some are argueing wx-radar is reducing risk of bird strike.

schooner 3rd Aug 2017 12:04

Leaving it turned on means you don't forget to turn it on when you may actually need it. Belt and braces.

Jonnyknoxville 3rd Aug 2017 12:22

what schooner said for me as well

Chesty Morgan 3rd Aug 2017 12:25

Ergo, leaving it on means you might forget to turn it off when you should.

Quite how you'd forget to turn it on if you need it is beyond me.

schooner 3rd Aug 2017 12:30

Checklist will catch that after landing/shutdown. People have flown through weather before because they haven't had the radar on.

Stan Woolley 3rd Aug 2017 12:30


what schooner said for me as well
Me too. :ok:

But don't forget to turn the tilt to some useful setting!

STBYRUD 3rd Aug 2017 12:35

The radars I am familiar with are transmitting continuously anyway when airborne to provide PWS capability, what you select on your ND and WXR panel will only affect what kind of scan it will perform (in between PWS scans)

wiedehopf 3rd Aug 2017 12:35

the radar beam is pointed forwards ... that is where the energy goes.
and there is plenty aluminium between you and that radar emitter. the microwaves bounce right off aluminium.

sometime i think people have no idea there is a difference between gamma rays and microwaves. oh well.

STBYRUD 3rd Aug 2017 12:40

The people who turn it off to protect themselves from radiation also shouldnt be performing walkarounds next to powered up aircraft (radio altimeters, surprisingly high powered!:})

testpanel 3rd Aug 2017 12:59

Talking about

wear and tear
Also

I'm honestly shocked that
some pilots try to make a nice landing (landing loooong) and once on the ground trying to make that intersection by hitting the brakes so hard, my ribs still hurt from the seatbelt....:ugh:

pineteam 3rd Aug 2017 13:48


Originally Posted by schooner (Post 9850835)
Leaving it turned on means you don't forget to turn it on when you may actually need it. Belt and braces.

Yes it's safer. It's also safer to fly with wings and engines anti ice ON in case we forget in icing conditions...lol. I wanted to say why not keeping also the gears down but since Air India... Haha. I mean it's just common sense. When we check the weather at dispatch and the satellite image shows clear sky, using the radar is just as useless as flying with the dome light on bright during day times like some guys love to do.





Originally Posted by STBYRUD (Post 9850866)
The people who turn it off to protect themselves from radiation also shouldnt be performing walkarounds next to powered up aircraft (radio altimeters, surprisingly high powered!:})

Honestly, I'm not flying with radar off to protect myself but mainly to save on maintenance cost. I can still remember my former boss from a small charter company to repeatedly tell me to minimize the use of radar to preserve it.
I do not walk under the 4 RA antennas btw.:p



Originally Posted by wiedehopf (Post 9850862)
the radar beam is pointed forwards ... that is where the energy goes.
and there is plenty aluminium between you and that radar emitter. the microwaves bounce right off aluminium.

sometime i think people have no idea there is a difference between gamma rays and microwaves. oh well.

Well most people like me here are just pilots so yeah I have no clue. I will have a look. Haha



Originally Posted by testpanel (Post 9850880)
Talking about

Also some pilots try to make a nice landing (landing loooong) and once on the ground trying to make that intersection by hitting the brakes so hard, my ribs still hurt from the seatbelt....:ugh:

Could not agree more... I hate it also. :}

Centaurus 3rd Aug 2017 13:55

37 years ago I wrote to Bendix in USA requesting their advice about turning the radar switch to off rather than standby during cruise flight when weather ahead was clear as far as you could see. Our radar on the 737-200 was monochrome type. The chief pilot insisted it was better for the radar to always be left on. He said that electronics don't like being switched off and on. Bendix replied that switching the radar off was perfectly OK and increased the life of the unit.

Lots of pilots are full of personal opinions not always based on facts. Management pilots are not immune to this. I have learned that an aeronautical manufacturer's advice is generally more reliable on technical matters

FlyingStone 3rd Aug 2017 13:56

1. Wear and tear. As long as you don't need to pay the mx bills personally, I wouldn't care. It's like brakes/reverse policies. You do what they want - as long as it's safe. I don't see any safety issues with WXR on from takeoff to landing...

2. With all the radiation that you are exposed to with high altitude flying, weather radar would be the least of my concern. Think RA sensors, other aircraft radars, military radars, sitting on top of 100+ computers in avionics bay, etc.

3. Plenty of people have flown into CBs with weather radar OFF or picture not clearly visible. It's well recognized risk from Airbus. On the topic, why is it possible to almost completely dim WXR returns on ND, and barely able to dim TERR display?

Check Airman 3rd Aug 2017 14:09

Nice clear day, or night time with a full moon- I probably have it off. As someone alluded to earlier, do you turn on the dome light at midday?

Check Airman 3rd Aug 2017 14:14


Originally Posted by FlyingStone (Post 9850940)
On the topic, why is it possible to almost completely dim WXR returns on ND, and barely able to dim TERR display?

I imagine you may survive an unexpected weather encounter, but you won't survive an unexpected terrain encounter ;)

In the planes I've flown with LCDs, I've never had a problem with dimming the terrain as much as I please. Do you use CRTs?

I've often wondered about why the weather display can be turned so low myself. Doesn't seem to make sense. On airplanes with the new radar, you actually get a message on the ND when weather is detected, prompting you to increase the brightness if required.

Meikleour 3rd Aug 2017 14:21

When I was working in south east asia the company went through a phase whereby the wx radar was to be switched off unless it was needed - to save cost. With the high relative humidity on the ground condensation would collect on the gimbals which would then freeze at altitude - thus rendering the unit u/s! The law of unintended consequences at play again!

Centaurus 3rd Aug 2017 14:27


As someone alluded to earlier, do you turn on the dome light at midday?
As useless as some operators telling passengers the cabin lights will be dimmed for take off and landing even though it is broad daylight. :ugh:

wiedehopf 3rd Aug 2017 14:35

while all electromagnetic radiation, including radiowave, microwave, infrared, visible light, UV, x-rays, gamma-rays, has common properties, the massively differing energies make it behave very differently.

and that means the energy per photon or minimal unit of radiation.
microwaves and x-rays for example have at least a factor of 1 million between them.

one main effect is that below UV and x-rays said radiation will mostly just heat up body tissue and while that can be bad mostly the heatup is low and you just don't care.

x-rays and above can knock stuff around at a molecular level leading to cancer at very low total power outputs. so they f you up long before they cook you.

and then x-rays and above also don't get stopped by metals as stuff below does.

aluminium foil will happily stop anything below x-rays.


so while mobile phones and microwaves might have negative influences on living tissue apart from heating it up a little bit we have not seen a lot of evidence of that.

x-rays and atomic bombs: ionizing radiation
pretty much everything else: non ionizing radiation
of that everything else ultraviolet is the highest energy still being able to destroy your skin without ionizing it ;P

weather radar even walking through the beam should not be a problem. it needs time to cook you :)
and that's what it would literally do if you stood there long enough. but don't count on feeling it either because we are used to heat coming from the outside so we feel heat only on the skin.
but microwaves cook you evenly more or less.

LimaFoxTango 4th Aug 2017 00:49


schooner - Checklist will catch that after landing/shutdown. People have flown through weather before because they haven't had the radar on.
Checklist will catch that after landing/shutdown. People have flown through weather before because they weren't looking where they were going.

There, I fixed it for ya. I don't see why in broad daylight clear skies you'd have the radar on. If you hit something then, you clearly weren't looking in front . Moonless night is another story.


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