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Weather Radar interpretation

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Weather Radar interpretation

Old 16th Mar 2011, 11:04
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Weather Radar interpretation

How do you determine if a heavy/red radar return is :
- heavy stratus rain (meaning it safe to fly through)
or
- thunderstorm / CB cloud (not wise to fly through)

Sometimes the return will be solid red but you know it is only heavy rain so you continue to fly through it.

Other times it might be a CB

How did you tell the difference.
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Old 16th Mar 2011, 11:53
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Try reducing the manual Gain control (if fitted) to minimum setting (as against Auto/Cal/ or max). If the picture is still strongly red then avoid like a plague. This technique was usually successful when operating into Pacific islands where very heavy rain associated with towering Cu would cover the radar screen with red returns. By experiementing with the Gain control you could eliminate most of the heavy returns and the last one left was the one to avoid as it may be a CB rather than a towering Cu.

Same principle for high altitude cruise with certain types of radar. In this case set the Gain out of the automatic position into the MAX gain and the tops of CB normally invisible in AUTO gain, would show up as a very small echo. But enough to arouse suspicion that something big is in front. Tops of big CB up to 50,000 ft are usually dry and thus no reflection but with MAX gain often something shows up as a tiny return.

Get a copy of the radar manufacturer's Pilot Information Manual. Always good information in it.
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Old 16th Mar 2011, 11:58
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How do you determine if a heavy/red radar return is :
Years of flight experience helps, the RED color alone is no guarantee that dangerous weather exists, there are so many other factors, like shape and geographic area.

Cheers, D.L.
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Old 16th Mar 2011, 22:09
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Right.


By experiementing with the Gain control you could eliminate most of the heavy returns and the last one left was the one to avoid as it may be a CB rather than a towering Cu.
By experimenting i.e reducing the gain, you may find yourself in the middle of the 5hit very easy.

If you were "experimenting" i.e. moving your radar beam up and down, as necessary, using Tilt, you would be in a much better situation.
 
Old 16th Mar 2011, 23:17
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john citizen

invest in an archie trammel radar course or video...great stuff. play around with tilt and gain ALOT!

some radars have a magenta tone in the red and that can be really bad.

I've learned that it is the boundry between colors that can really smack you upside the head.
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Old 16th Mar 2011, 23:49
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John Citizen

Unfortunately, much of what you read here on PPrune is utter nonsense. I strongly suggest you have a look at the Airbus documents....two in particular....one is Getting to Grips with Aircraft Surveilance, the other is Optimum Use of the Weather RADAR.

This is a start......

Next, discuss this issue with someone in your training department.

Asking the opinion of an experienced captain may be f benefit, as well.


Fly safe,

PantLoad
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Old 17th Mar 2011, 00:32
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john citizen

my airline issued us the archie trammel course and everyone loved it.

certainly read what your airline gives you. but you have just heard it from an experienced airline captain...

come on pantload
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Old 17th Mar 2011, 02:29
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John Citizen

Check your pms'.
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Old 17th Mar 2011, 11:31
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How do you determine if a heavy/red radar return is :
- heavy stratus rain (meaning it safe to fly through)
or
- thunderstorm / CB cloud (not wise to fly through)
It's a combination of the latitude you are flying at, and the radar height of the cloud you are studying. The radar is calibrated for temperate zone weather - so gives a falsely strong reading in tropical zones, and a falsely weak reading in desert zones. Calibrated gain adjustments can correct for this if you know what you are doing! Determining the radar height of the cloud is part of the picture as well.

There are plenty of threads here on it (including Archie Trammel's info):

http://www.pprune.org/tech-log/48016...tml#post440714

http://www.pprune.org/tech-log/37673...her-radar.html

http://www.pprune.org/tech-log/23512...adar-tilt.html

http://www.pprune.org/tech-log/40341...-question.html

etc etc
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Old 18th Mar 2011, 13:07
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Asking the opinion of an experienced captain may be f benefit, as well.
I think you will find quite a few Pprune contributors are (or used to be) experienced pilots. You don't have to be a captain to be an experienced pilot.
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Old 18th Mar 2011, 13:15
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For my benefit, what is "heavy stratus rain", JC?
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Old 22nd Mar 2011, 14:03
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what is "heavy stratus rain", JC
It should not be too hard for an intelligent person to work out what it is if you know the meaning of each of the individual words :
1. Heavy
2. Stratus
3. Rain

You can find many references to "Stratus Rain" in this Honeywell document if you still can't work it out

Airborne Weather Radar Interpretation
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Old 22nd Mar 2011, 15:00
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JC - as A37575 stated, decrease sensitivity at low altitude, increase sensitivity(gain) at high altitude. Newer aircraft can reduce gain below the old 'auto/calibrated/normal' setting.

Tilt is inverse to altitude. Low alt = tilt up, high alt = tilt down.

Rapid increase in intensity is not good.

Practice(gain/tilt) with storms you can see as you manuever past them. Use that knowledge(experience) at night or when you're in clouds (IMC) and can't see the storms.

Not a fan of the official guidance in the AFM's re: radar use. Air France President spoke about another flight (AF?) hitting turbulence at altitude along the same route as AF447. Said the Captain switched to a more sensitive setting (that is not AFM guidance..) and changed his route of flight based on the new radar depiction.

After all this there is no guarantee about weather you're penetrating. Sometimes it's better, and sometime it's worse, than you'd expect.
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Old 22nd Mar 2011, 17:03
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JC - I'm sure that is a fantastic book you have linked, but here is the definition of 'Stratus' cloud/rain for you. You do not get 'heavy rain' from Stratus cloud as you can see, hence my query

"Stratus clouds are more known for drizzle than for precipitation, however. When heavier rain falls from them, their title is changed to nimbostratus clouds

Nimbostratus clouds form at or below 6,000 feet. They are dark, low level clouds that bring light to moderately heavy prolonged precipitation, such as snow or rain.

Altostratus clouds are incapable of producing heavy precipitation, but they are often the cause of a light drizzle. Following altostratus clouds are nimbostratus clouds, which are the source of heavier precipitation."

I believe '"Nimbus" is 'Rain cloud' in Latin. Hope this helps!
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Old 23rd Mar 2011, 00:37
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jeezus JC...

If you have questions about "heavy/red radar return", do you expect everyone to know which system you are using?

Aside from that.....

You would ask the question on a forum ( and F with the people that respond) rather than your chain of command?
It should not be too hard for an intelligent person to work out what it is if you know the meaning of each of the individual words :
Yet ..YOU..as an intelligent person, can find no avenue for an operational response other than the anonymous internet...

Liability...your respective operations SOP, or an anonymous internet forum?
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Old 23rd Mar 2011, 01:32
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Remember just this one thing:

If you get banjoed by lightning, word your ASR defensively.

I wish I had.

Turning the gain down is useful as wx radar nowadays paints too much stuff red.

Think about turning away if its on your FAT. That 10 mins that you lose manoevering will be easy compared to one hour of form filling!
 
Old 23rd Mar 2011, 03:34
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Originally Posted by OBN
You would ask the question on a forum ( and F with the people that respond) rather than your chain of command?
Bit harsh there. Apart from JC's indiscretion with BOAC, I see no problem with people asking advice here. Who knows, maybe he has already asked his "chain of command" and got nowhere? Quite possible these days.

Why not tap into the global knowledge available on Tech Log? If nothing else, some good links have popped up.
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Old 23rd Mar 2011, 05:03
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global knowledge...good idea

and no one has said always make sure to be painting something, even if distant ground clutter.

While out flying near Baltimore, Maryland, USA, I heard some American Airlines pilot complaining that her wx radar wasn't working and asked ATC to point her at some weather to make sure it was working right.

yikes.
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Old 23rd Mar 2011, 05:37
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A bit of light relief here.


British Eagle (second biggest local carrier after BEA/BA) had a fleet of Viscounts. When a 12" dish was developed, they opted for those. The trouble was they had been the only ones to own the old jig for building a pressurized bulkhead for a raydome. They'd sold it for something like 14k quid. When they got Marshalls ???? to do the work, they cost about that each to do the job. They kind of worked.


When we got the first (all green) digitals, we thought we were in the modern world. Little blocks of square pixels used to flash if the return was too great.

Into the flightdeck comes the head opps bloke. Look at that! I'd say. That little flashing rectangle is Buckingham palace. This one, Westminster. When they flash, it means the Queen's in residence.
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Old 23rd Mar 2011, 08:43
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Hopefully maintaining LR's efforts.......

Time to tell again the story of the grumpy Captain who's F/O (un-noticed) wound the scanner angle right down and immediate avoiding action was taken on the island of Jersey
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